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Chilton’s

MOTORCYCLE
TROUBLESHOOTING
GUIDE

’ OCee Ritch

\LLUSTRATED

CHILTON BOOKS

A Division oi chilcon Company
Publishers
Philadelphia and New York

  

1‘ 1966 by OCCC Rum ”LL-hjmj m PH e'pm L,

  

u and :‘mullamcn m Tcrc'n: Ca
Ambamcsr Eggs, Lm AH Hj'VYS huftlld Mawimumd m vhe
Umvcd 5mm 0! Am.r :J

Lurny or Cungm,; C: 'd N: 56-27619

 

3mm Pymnng. Jamar» ‘95’

I, THE roux-STROKE ENGINE

Siamng procedures

The engme won't start

The engmo is hard to start or runs
erraIically

Englne dles when thronle opened

Mlshres on aeeelorahon

Misfire; under load

Mlsflres at hrgh RPM

Poor low speed perlormance

Poor hrgh spccd perlormance

Poor general aortormanee

overheahng

Mlscellaneous cavbmcmr pvoblems

Other englne pmblems

Vlbvanan and noises

1. THE "40.5110“ [NGINE

Slamng procedure

The englne .5 hard to start or mns
Crrallzally

Engine dlcs when throttle opcncd

Mlslives on ztceleralion

Mlsllves undev load

Mtsllres at hlgh speed

Pam low speed pevfcrmancc

Poor hrgh speed perlorrnaneo

Poor geneval perlormanze

Overheating and sclzmg

Vlbvanon

Noises

The ollers

on pump operatlon

. ELECTRICAL SVSYEMS

Magneto
DC generator

Contents

mumul

l0
II
II
II
I2
H

23
24
25
26
27
27
27
25
30
30
31
32
33

37
39

.‘

u.

9‘

Battery ups
Regulator
Alternator
RBCMIEVS
Energy translsr
Pornts and plugs
Coil

CLUTCH AND TRANSMISSION

Cluteh slippage
Gear grindrng
Transmissrons
Jumplng cm of gear
Won't shrn
Jumping out ol gear

Sllpping kick starter

t CARBURETOIIS AND TUNING

General (arbulcmr troubleshooting
Amal

Blng

Dull Ono

Jlkav

Kelhm

KalhmeHonda C/v
Mlkunl
LlnkeneSChebler
Zenilh

Tunlng

Tumng specrheetrons

FRAME AND RUNNING GEAR

Abnormal tire wear
Wheels and suspensmn
Brakes .

Chain Ilps .

40
40
42
41
46
47
48

49

V53

55
55
58
58
59

6]
63
68
69

,69

71
74
80
54
85
86
87

Chapter 1

The Four- Stroke Engine

The commonest complaint or trouble encotln~
term! by the motorcyclist is ”it“ the machine will
not start. The reason can be ettrontoly simple or
it can he more compti rted, but the hIhIC proce»
dun: for determining what the cztttsc of nun-\Iurt-
ing is and [10“! it can l»: corrected should be lol-
lowed in order to save time and to cmL‘r ill] the
posstbrhrics. lly iollowin an outline. the trouble-
shooter can also mentally or visually eliminate
some steps and begin his trottblc watch at any
point in the sequence knowing that he still not
hate to l‘llle-ll'thk

Non-starting is extremely frustrating in \icw of
the tact that it h g nerally accompanied by some
severe physical exertion. Pumping a kick \titrl
lever on it blgedispluccmcnt bike adds to the rider's
indignation and the most common reaction is to
hurriedly guess at thc cause ol ntfllfttnclimti
which usually leads to disgust and . andonmcnl
of the project. The lirst rule is to go \tcp-b step
and methodically eliminate possible causes.

Like any tour-stroke-cycle engine the motor-
cycte't powerplant obeys certain laWs. The first
law l~ that there must be tuel and air in the proper
proportion. The second is that there must he
spark at the proper time, if these two are present.
combustion must take place, The motor may not
run long, smoothly, quietly or with good power,
but it should at leatt run. Therefore the first step
”1 starting it bulky bike is to be absolutely sure you
are lollouing the corn-('1 mining procedure.

Thi\ mzt) seem Iik worthless advice to the
owner who has been ri ng a given cycle tor some
time, but if you are at all unfamiliar with it bike
engine it it easy to apply the wrong technique and
get results unly part or the time.

 

 

 

 

 

STARTING PROCEDURES

Question. ls this fuel tap really “On"? If there
is any doubt about fuel level, turn the tap tn
"Reserve." On many British bikes there are two
taps, one tor regular and one tor reservet With a
double—ended push-tap, the hex end controls the
reserve. it you aren't sure. before making any
starting nttemph, remove the line at the tap and
observe fuel flow.

With a supply or tuol assured to carburetor. tle—
press the float tiokler (on Amal type carburetors)
until gas flppean and closc the air slide or close
the choke. On some older Triumphs. the s,u.
(nulomobilc type) carburetor has a lever at the

bottom uhich ix to be pulled up {or starting and
pushed back doun when the engine warms up. in
any event, richen the miflurc [or starting in the
appl able way.

Q) Kick- the engine over a couple of times with
witch all and throttle open. (This should also be
done in cold weather on cycles equipped with
Electric vstilrtcr.) Hondus with electric starters can
be turned over with the starter a levy times with
the witch in #1 position. Q opcn throttle slightly
inbuilt l'r ol the total travel and set spark control
(if fitted) to about tins-half of lull advance. On
hr singles uith compression release, push the
starter lever down until the piston is felt coming
to compression, then operate the compression re-
lease and follow through gently on the pedal to
get the piston pint compression This is a couple
oi inches oi pedal travel, generally @ Kick the
engine twcr briskly, getting all or your weight
onto the layer and straightening your leg at the
same time. Note: Resist the temptation to open
the throttle wide at the first cough oi the engine,

 

 

THE ENGINE W0\T START

Assuming that repeated applications of the foot
to tht: putlitl resulted in nothing but sweat on your
ltrovt, it is time to look for malfunctions. Check
lh: cho and throttle controls first,

ls llw [my really on? Tvtiddle the key in the
Witch 2 bit. He sure indicator lights art: on or try
the horn in ill’l cllort to determine if the necessary
elcctrical current is present somewhere in the
system.

1/ (here is In: obvious supply of electricity:
to heck the iuet supply. 5 tab to rcscrvct Turn
switch to emergency start position and try again
If there is it smell of mu gas, or visual evidence
of flooding such as fuel on the carburetor. open
the throttle wide and kick the starter ur operate
the Electric starter to turn the engine over several
times and thus Clear out the excess fuel. If the
bike doesn‘t start now, further checks are neces<
sary in the tuel supply. for which see below.

If indicator lights or other necessaries do
not funt'nfln.‘ stnpccl bad connections, blown
lute or bad battery. For example: even though
some Hondas have an ac magneto system a d .
charged battery in the circuit can make the bike
hard to start and poor running. Check the fuses
in any model: also check all electrical Connections

 

 

 

 

 

 

2 The Four-Stroke Engine

for clcanlinms ilnd lighlnc‘w. particularly ill: bin»
lcrv gmumlr Thi: iV highly crillcnl, (This fuse:
vlill Vary in locallon hm Will always be close |o
lhc buttery.)

II (use; look good and Conncclions \mm in
order, check the balm The following advice
will xcrmdrrlilc hullcry min 'n and lr is admiilcdly
nol gnod prlxcliccr hm you can p y yourself
ihrii lhcrc h jlllcc lur nor) liy \Iriklng a quick rim
acre“ lhc hrillcry lcrml ll\ Vlllh a piece of wire
or ihc handle» of r. pair of pliers. Do Ihis very

 

 

 

 

 

jim cnough to gel 3 flash.

If llm 'mlll'ry is rlrong and a good spark
rcsullm cm’mlinc Ihc lerminalx removing. cleaning
and rcplrlu g if in douhl :13 lo Iheil’ abiliiy ID pass
electric V

If Ilw lulllt'ry rmpomls mm): or not «I all
Io il-u: dirccl»\liorl icchniquc. cilhcr have il
charged. miich lo emergency srarring posilion (if
available) or pmh lhc bike. If a dead haucry is
[he sole problem. mosl cycles will push sun fairly
easily. Cold wcaihcr and a big bike may make Ih:

 

 

 

procen J hii dimciih ph3 $iclllly, biii |hc gcncrlillng
33mm on all model: i3 slcwlgnenl io niii mu pawcr
In low RPM. so ihh holnlul feature which is iioi
present in rho niiioinohilc sivriuiii wurh lor 3oii.
CAUTIU , nyaii lml‘K' t/m briiim- rllm'ul-d. [rad
llll‘ ncri‘mi DI] ELECTRICAL SYSJI..\I.\ iii mir
book Ive/arc riirliiiig down [0 ilii- iiliimi wn‘l'u‘
Klan-ml

ll nrigr I.lkill_ lhi» prccmuiun rho cll_'ni: \Xlll
won'i crirch. ir i» rinio ro chcch lor n snarl ni lhc
plug. (\\'c iiili u~c rlic ~ingiiliir ro mve uonh. ll
)mlr mods‘l llih um“: ”um onc c3linuor. nioriinlly
<iib<iiiulc rho uorrl pliig<1

kcnioro iho plug nnrl mininc th iin. ii i1 i:
we! or cloggou uiih Ci’lrlmn dcpmilx. rhh can be
ihc pruhlcm Roplac: iiuiih [he sprig vuii nluii3<
curry in iliu iool in. Second choicc k in clczm ii
Or.

I/ plug iiiipgiirs lii lir- goal], lean: ir con—
iiccicd nnu plncc ir on iho head. niiiking <iirc ii is
grounded; lhcn lick lhc uaricr briskly. A (at. bluo
Vpark :hoiilri ionp hciwocii rho clocirndm n ihc
‘purk i. u on \muk, chuck the gap ngninu :pecifica-
horn. since u n r be xoo vlidc.

Here is n iric hich will orioii goi |hc ninchinc
runnin iiniil 3ou cnn gci u now plug- Close inc
gap 3 up io 010' or so and I‘Cinslull u k
may be breaking down under pre<<urc in lhc :31»
inder nrul ihc smaller gap vlill pcrniir ii In lunciinn
icnipornrih,

ll 3oii iloir'i how u {celcr gugc. an ordinary
paper nioichliook cmcr ix jun umlcr .010" ihick.
MARC ilic olccirorio gap a slip iii for : iiinrchhool
coror niid ii will be close enough io ploy inn. as
we mail io 51) iii 1h: miiuo hurincw.

l/ rim.» is no xpurk .ll zhc clec|rodcz unil 3ou

 

 

 

 

 

 

B: sun "at luel up is in cullecl nasilinn.

The Engine Won’t Start 3

Al \

when hlke wont start nlzllminaly slag is in make sure
lllal liizl is DIESEM iii lauk

IA n

are slim ihc grounding or Ihc plug is good and
rhni rho high lclh‘ion [cad (plug uire) ix lirnil3
Collncclud ni ouch curl. 3oii‘3o gor igniiian irouble<
No“. lhi~ nin3 bi: a had coil or ollicr problems
Much zlrL' beucr covered in the ELECTRICAL
SYSTEMS Ecclion of this book. Jllsl [u sausf)
3oursclr vlhclhcr ilic sysmm is liinciioning or um.
gmp the plug in one hand nnrl push ihc miner
loicr doun politely. (non'i jump on ii ur your
eyes are liuhlo io lighi up like a pinball grime.)
You'll fc ii iiiiglo if [he igniiioii 53mm is dorol-
oping oiiipiii If 3oii gor no indicalion of clcciricnl
cnci g3. 3ou'3c i<olnicil ihc problcm.

I] Hi.) rpm].- ,ilirg i-l- giiiiil and you gel n lulu:
Spark. ihcrc i: n bnro possibilil)‘ [hnl ilic limin" 5
ac lnr all the hike won'k Elan. Bu| chances are
[he Imuble is wmevhere in [he fuel fi)‘<lem. Check
lhn liming us a preculluon, lhen [urn lhc fuel mp
off and remove the [1ch line {mm (he (an); Then,
huldlng n rng or n coninincr under ilie opening,
tum Ihe lap back on and absent fuel flow, If any.
le cun uho ohmic vrhc|hcr u rc:ill_3 have gm
iii ihc xnnk or some oihcr liqllld4 Such as vlalcr.
Also, if lhc bike hm [men in storage for mm:
iinic. ihc gm can have «compared no such :in
CX|Cnl llml ll vicul'l burn. The lllglll} lulafile elm»
menls Ihul lllzlkc {or quick wrung in (A Incl bland
vaporize ronihu, This makes olrl gm, equal bad
gm. ll gentmll has 1! Wrong. piingcni odor n,
opposed to lhu 3:". liuhi mlcll or rmh fuel.

\Vnicr. or courae, bulk up in liiilo droulcis on

 

  

 

 

 

4 The Four-Shake Engine

 

 

llggle me lgnillan swim and lillzll ii a law times in h:
we nl maklnl mutant. slime mallals have ememncy stall
pnsilinn nil swilcllr

the mg while gru mm righl lllrough, \Vzllcr ulw
sinks lo the lmucm in a conlaincr. Ho“ docfi
\lalcr gel illlo fuel? Condcmalion can zlccounl
for mule. Who linoww‘ how lhc large qumllillcx “c
{omellmcc [ind can be accoulllcd for? Nol me.
bul thcrc lhcy um

u yunl [laws for u mumni, 1m. stops, you
have u pluggcd van Remmc lhc filler cup and
rhe flow ~hollld begin again. ii «0, unplug lllc innk
vcnl, uhciher il l\ “1 [he cap or in [he lankv

0n Honda 350 and 303 mndclx, lllc cork gmkcl
has been knonn lo plug the vcnl hole. lr is ~onlc-
|lmc~ necessary to drill .lnolhcl' vclll halt in [he
cup liner,

 

1/ ml 110m [rod-v, or ii ii i» nlw' ugly dinyx
rmly or Illll of (edlmcnl, lherc will be irollblc
Im‘lhcr along lhc line. So, rcmove [he fuel line at
lhc carhllrclor, lake om lhc \lirc guuzc )ll’flincl’
at [he banjo. i[ so cquippcd, and clean it.

AI lhlV poinl, if ihcrc is fuel at ihe carburetar
:qu rhe plug “EV good and um wru on examinar
lion, try h choking. Make mre Ihc choke lV
reully vlol’ ng Then, if ii doesn't hurt, gel lulu
me cnrbllrclor lightly

 

  

 

Fim: close lhc fuel [up at the tank and replace
Ihc line.

On Anml type tnrburelurs, umcrcw lhc bol-
lam mu using anon-lei virench is hold the larger
nul nboi-c nnd prcvcul ll: luming.

Nmn‘.‘ The larger nul l‘ the jcl retaining mu nucl
it n against a red fihcr waxhcr. If lomcncd, lhe
\vmhcr nlml be replaced became il invariably
leak, 50 Llon'l move il.

Observe lhc amounl and characler of Ike fuel
which fiow< out (if any). If then; is no fuel, Ihe
needle Valve is sluck cloxcd, Trip on the car-
buretor flour bowl and il will free up,

I! lhcrc i» fuel, or VHHCl’, or n mlxlure, mm on
Ihc lap and see if gas flow Ihrollgh [he carbure-
ror in a Vleady quunllly in il mould. This is good
In niulr out i c nccdlc valve Scaling anyway,

01- the K 711'» tarburrlor, such a: is used on
lhc larger Honda), flip lhe vlirc retainer down and
rcmuvc [he fioal bowl hollom. Lula models have
a carburetor howl drain screw. A lWiSl of the
\chW \lill reveal Ihc prcsencc and character of
furl.

m thi» poinl you have pmvcn Illa! ihere is
spark in the plug and fuel al the carburetor. So,
llic only rcaion ihe engine \von‘l fire must be
mechanical.

Before we go farlher, and before you put the
plug back in the hole. lake n pencil. pen or other
ilelldcr, long objccr nud pu‘h it in rlre spark plug
opening uulil il rem on rhe piuon. Then push lire

 

Halllly. lust: and mime! all lanaml nude! m cum all
light sill: nn Ill: Hnnfla En.

 

Tho

 

Twelve vnll battery I: mind In 15“ and Inger model
Hundasy Aunts: is Via rlgmhand cuver.

kick start lever down slowly and observe the mow
mom of the pcnctll It should move up and down.
If not. the Clulch is slipping and all or your kick-
ing is for naught.

Willi the plug removed ir is an opportune time
It} [also n cnmpreSslnn check. (If you don'I hin'c
a Comprcninn gage, you are at a point where a
visit to your friendly mororeyole shop is required
nnyuay.) Thl\i\1l Iriclsy operation for one mnn.
unless he he: the proper long-tube gage (or
three ilrxm), but the requirements are as follows:
0) Remove spark plug from second eylrnde ii
is a twin . . . Io prevent nceidenial runaway at full
:hul. Q) Open throttle fully against the slop.
® Depress .xtnrtcr vigorously |hrcc or four time.»
while holding compression gage firmly in plug
here.

I] compression is low, suspect a bent or
burned valve or poor valve sealing If it is nlly or
extremely low, n holed pislon is probnbly \hc
cause of your trouble. "Low" i< a relative Iermi
to be sure, but the average lonr-simke engine
should upernle after a fashion on so psi com-
pression.

For verification remove the rcckcr bux cover.
or gain access in lhe valve elenrnnce adjusting
position m required, and cheek the valve clear-
ance. A very loose valve is probably rent; a
very tight Valve is probably burned.

Before you panic, adjust the valves to proper
clearances and try to gel the engine [0 run. Poor
adjustment can prevent an engine from starting
(See TUNING, P. 86.)

Likewise. if compression is quite low end you
Want to be sure me: things an: ns bad ns they
seem before you pull the cylinder you can use a
small bayonet bulb, <uch as |hnsc filled as instru-
ment or indicator lights, to help outr Take the
bulb, solder a Wire to Ihc tip. nnolher to the brass
base and connect the two wires la a battery. This

   

Engine Is "art! To Star! a

light is smnll enough re slip rhrough |hc spark plug
Iml illumlndlc lhc lnlcrior of [he Cylintlcri
which i.\ no! pnsx'lblc wi|h llny other source
of lighL

If you vinnl lo rolalc the engine to bring lhe
pisren up for a closer look. don‘r use the siarter
Pul the irnnsniiysion in lop gear and reyelye Ihc
rear th‘Cl \lnwll',

All or this on bring you lo nvo conclusium:
(r) somewhere olong the line electrreol or ignition
problems beyond the scope or rhis chapier wcrl:
Lliscm‘crcil. (2) The engine is sick.

  

THE ENGINE IS ILUID T0 STAR'I‘v—r
0R RUNS EIKRA'I‘ICAILY

The basic assumption here is ihor we are not
just do ng with r. iired engine. one which is
crumbling inm ruin or held Iogelher wilh wire
and hope. If Much is the case, it .l/muld be hard
to \ler Rather we nssume that the hike is in
normnlly good operating condition and that (D '1
eilhcr hccomes hard is sum and run: erratically
suddenly. or @ the condition has been getting
progressively worse for some lime.

In -'Ihcr case: [D Check lhc electrical syslcm
—paying purucular aucntion lo the bauery if it
is a pan of the sysiem. All connections, it must
be stressed, have to be clean and light. In the
Hondn system a low-charge ballery makes for a
poor running engine, so suspect it first. it is easy
to leave the ignition or lighn on and [he hunery
is quickly discharged to n low state.

@ Check the spark plug [or type nnd condition.
Perhaps lht: wrong heal range is being used, or
another engine condilian can be diagnosed by

 

 

anfl snark Dlug ilzinsl head in make gm gvuund and
kick slaner lever in clerk in! lauliy ignition or had plug.

 

 

6 Th" Faltr-Slrulm Engine

 

linen htzl up anti check nttaltty nl lttel 15 it llnws atti-
tag at inln ennlatnet.

 

Small vent mile in Manna gas can can tteettttte plugged
lllli cause tliiltcttlt slotting at pun! ttttttttttg. lspzclally
at my. need.

exnnining the plug, See the TUNING section
for tletotls on plug [)‘pc and nnalyx

(,9 Check tlte cttthutetot ltch ntixtute screw.
'lttn orten becomes molndjnsted because the
ounet dumn'l walch vthnl his hands otc doing
vlhllc gtipptng o setewtltivet.

CD Check ignition timing and correct if “Yong.
Thix come of hottl \Ltrling and etttttie tunning ie
gtottuol in tts onxel, tothet thon tudtlen, heeeute
it is due to the nettt oi the cam fiber which ettuses
o motion in pain! gup. So, it \uLIan hard \Llrl-
ing _ the Cum o mote kelv suspect is the eopo
tot. chluce .t it palms iln. hunted and dixcolmcd,
nhtoh it n good \lgn of o falllly contlcmcn

47.; ‘lhu hung: us to htul points; uotn, tlitty,

 

   

 

pitted or o' Dteo them ot teploee tpteretnhly)
vu|h a hen get. it tho brcakcl’ poinl area is oily,
tenteuhote thete it a heat oil <cnl in the drivct
Reploee it.

[On hlmighl magneto models. impccl the pickup
nnd slip ting rot dttt nnd grcilsc ontl cotteet the
condition il‘ necexsuty )

(it) lithe engine kick: back on sttttti g. chances
nto'the nutotntttte ttdtunco nieehonism in the div
ttihutot it- not “urking properly.

' ('heek the oit filtet, Remove and eleon it.
t allcicm ttntl :Vccssivcly ditty, get o nevt one,

(9 A clogged ntumet can come htttd hurling.
it the hike i\ n highsmilcllgc joll ot is on oilet,
~u»pec[ this cause tiuht uuoy. it the ditluset i:
Icmuvuhlc. clean it,

[if lt the tnochine has heen ttoted and ha: been
pm into me without pronet ottcntion to prepara—
tion. the cothutetot idle iet eon he clogged with
tintnish ot gum rmiduc. The nutin iet eon Iikewiie
he pl cd with this autumn“. Acetone is o good
«olvenl. ot tegnlnt eothutetot eleonet such as lhal
mad tn motorcycle ihops cun he tned.

 

 

I!

 

ENG“

 

DIES WHEN THROTTLE
IS OPENED

This condition oppcote to cause some eonectn
to beginning tidets and, while it eon be due to
engine problcms, the m0“ common reckon for
web pertormancc ifi (htu (h: lhmulc i: opened loo
tiidcly too suddenly.

But. nteutning that you nte not being ovetly
quick with the twist grip, Ihi‘ sort of dcnlh or
Xhlmp of the engine con he otttibuted almosl
wholly to Cnrbureliont

(I) Make “Arc |hzll [he chokL‘ lever is acmnlly

open ing to open the choke fully when it is
supposed to.
Is the idling speed \cl high enough to ne-
COIHmOLLflC :l Vudllcn incrcme in \‘cmuri area? If
_\0u have [he engine licking mar in 200 RPM, it
lust Can't tntluee enough pteouto drop :1! the jet
to eueh up enough iuol.

 

    
    

l Juttttt'e'ttmg

the m in.
, gent... tum -
' the-nzs't “a

Mum It»:
A.
77,“,
i'o 5

'1 ' Show up

c It
Tu W wouttlnt. mum

onetatittn til Manda tttel (all and IIHlHrap.

 

ADJUSTER

   
   
   
   
  
   
 

THROTTLE
SPRING

NEEDLE
CLIP ' ,7 %

 

THROT TLEV
SLIDE

JET NEEDLEi

T O 7
STOP SCREW

PILOT JETi
PILOT JET _ , A,
COVER NUT

MAIN JET
HOLDER

MAIN JET—

M is fi r05 an A (trolamlion 7

~AAIR VALVE GUIDE

7» AIR VALVE SPRING

 

, VAIR VALVE
7m BLOCK
1%) *BANJO BO‘T
Wax-mo
~ , in LTER

FLOI‘AT NEEDLE
SEATING

, , ”iELOAT NEEDLE

‘ WiiAIR FILTER
CONNECTION

7 FLOAT SPINDLE
BUSH

%COVER SCREW
,7 W, FLOAT CHAMBER
COVER

iCOVER GASKET
,. FLOAT

\\\~7MIXING CHAMBER
\firNEFDLE JET

Exploded View 0' Amzl Mnnnblnc clmuvltnn

@ How about the idle jet? I: it clogged?

Q) Th: whole curburmion ~y<|cm can he |00
rich, See TUNING Eccuon for Keumg IdlL‘ fipccd:
and mixture;

(3; Thu isn‘l likely Inn u an happen: An air
leak at Ihc Carburetor flung: uhich hzu been
cumpcmaled for by inning nnd Ion Ihc engine
run, Inn reduce: mg vacuum. Squin gm {mm m
oil can nmnnd |hc nnnching poim and now
Whether |hc engine Speeds up. Thu I; a kind of

Iasl-rcmn suspect {or Ihi> conduitm, hm n is nut
uncommon in mm or me Innouing:

HISI‘IRES 0X ACCELERA'I'IDN

A: Frnm luw weed

If [he engine is dropping ,hou undcr rum-rum
non pN on [he line, bur running «runfrrcmrily
mhcmim. |hc odds urc Ihut carbureuon I: (he
\Ilein.

 

8 The Four-Stroke Engine

 

Bnunm ul carhmelnr mm: m hlggev Nundas can he
minim hy limping wire [Elallili a Sldl.

The finl lhing lo cxanlinc 2 ill: idlc lumurc.
The cumin «)lnplum lrl lmhnch luv. ”ml nm-
rurc in ninlinng on nppliuinon oi Ihrolllc Thi~
is “(Cunlpanlcd ly n lump} idle in» mm me
enriching for low spccd ix nol vacrdonz. Check
lhc CKlLflISl [or black smoke, etc.

Don't marlmlk |hc lzlcl “h". lhcrc clln be “fllL‘l’
in (he curhllrelm’ (loin liU\\l “hich N xuckml up m
”1: 5|an l‘cforc |he fuel can ll: replaced Walcr
mm nlm llc prawn: In in: mosh sirnincr nnd
mm on some model».

A clogged nrr clcilncr can mun: nll<firing, bui u
lull generally also xho“ up .r< puor pcrlqrnmncc
rhrouplrnui Ihl: range, loo.

A had spark plug. “hora rlic ccrnniic portion i\’
din) ilml clulxlnn l hvthcr. All illxo he remand-
hlc fol Ill|§ UCCul’rchC. \thl': high \ollagc lfi
hcing led rnnr n \}\[cm n clloosm lhl: Dime“ \ml
in go ilnil n dilly plug is rin Open ln\‘ll:lllon lo .
dlrcCl-ln-ground <hon.

 

   

 

   

n any gum-

If Ihc rimming occurx m a givcn RPM, no
lllnllcr “lLII 3c. yin. zlrc ming nnd nn mnucr
uhnl lhc lhmlll: opening. ulfl'iccl lhc ilulommic
\pzll'lx iuluince nlcchilniml in AC rn Clo 5y:-
lcmx. This can he guing cm of pllme in ccrluln

 

 

 

Checking enmpvlssinn using spacial luhl filled gage.

RPM on llzlucry syntmc lhc ignllion may be
mu oi lime U\er-r|cl’lnc>> can aka lie causing
"clghl cycling.”

C Al a gnu-n Ihrnlllc opening.
rnganllcsa oi luau

lr Ihc dropping occun m a ccrmln puinl in (he
lhmulc \ccmr r: lrdlcss of um Rs being Iurnnd
l'y Ill: Engine. mi; ix poor cilrbllrclcr inning or n
bad needle, pcrhnpe one “hich is mcked or
dnnrnged.

 

D: A! no (‘0
or RPM

Inconiislcnl misfiring ii ordinarily dlle lo mal«
lunclionmg “1 [he clccll‘ical iyflcm. Go over (ll:
lnlc from ucrn in stem spanng nolhing from
)our rigorous scruliny. Plugs. poinls, connections,
hWh lemon lend lo Ihc spark plug capilcilol’,
l’h’lflcl’ '7th whole “orks can be individually or
caller cly rexpnnxlhle. The imponnnl pain! in
in cinrlnok nulhlng. For example. on iome
Billlxh hikcs a had Connection all (he headlighl
xhell m ammfler ciln culls: lhc engin: l0 mlsfire
or quil became ii is n link in inc System!

   

lenl llu-oulc opening

 

)IISFIRES UNDER LOAD

TlIlS hezldlng i‘ mean! [0 dc‘crihe a condilion
~omclhing like lhls You an: riding along serene.
ly and appronch a hill. You open |hc |hrol|le and

 

Using lulu m: In chuck valve clunnc: nll lriumuh.

 

 

a: you mmull rhe \Iopc wnh ihe engine pulling
am in best enorli. il begin: in drop n [C\\ lledh.
Gennng (lawn, or rerurmng lo level rond elenrs up
rhe mufiring

r-im Llldgnmk oi lh'n eondirion ix rhni rhe plug
i< hrenklng donn irom orerhgming The wrong
plug i\ heing med or gnp is nrong

Second Chnlcc “‘Ulllkl IVc. ilgdill. dilly all
Clwncr

Too large n nrnin ier, wilh insufficient prmnre
drop or wnle rhrorrle opening .lnd lclnlnch low
\pccd‘ rcslllls In improper nllxulrc Tnning 15
indicated.

Poor luel enn pl , n big role in Ihlx mn or
periermnnee. Premium incl, a~ recommended h;
Ille manuhculren, shmllll be used in all times.
“Chenp” gin i» poor economy

lmproper inning \muld he nhoni ihe rrirh llcm
in line to he enmidered. Sporx liming llccnmcs
more critical in |hc load lncremcs.

Finally, um] um lo be overluokenl: l: [he gellr
being mud loo high [or rhe eondihom Cn-
murdered?

   

 

;\

.‘llSFIRES AT 1110" RPM

Dropping or high R; i\ ~unlc|lnlcx m)\|lf)lng
become so mom lilcclx oi engine innlng ore in-

nsing snnll lighl hull: in wrw inside nyllndu inruugn plug
hnlll Elllh, sfllflulfl In Wile, is infill! In D! insanan.

R PM 9

 

(it High

 

Examine snap common at all pains in! :nlmslnn and
luuszllzssi

\‘(llwlL Belore going into rhem. ii i< rim wkc Io
cunllluh lhlll \.\ll'c firm! i: no! rczpamiblc Same
riders lwlzl rheir engines rrghr np poo ihe redline
nml llcvul ritrlllh) rhnr lhc \‘;i|\'c~ 1m: ermhing
And, lhc mollcrn engine is so sum!) llrnl il can
lake n cerlmn nmounl wdhmil disinlegrnllng. m
thew people never learnAunIil roo lnle. m over-
rc\ pub \l\!§ um llllrlcd all their Scali (\I inch
:rccclerolion mlc< llinl lhe return (faring: cannm
eonrrol them nnd ihcy slay open mo long, man
{:11th down Llllcl’ lhc mm hm nlmcnl pad Ihc
rump. ’lhc prolonged opening period destroys
critical leve liming and causes a Lllluuon of the
(gel chnrge and lhus lhc misfiring.

II lhi: lm'l [he must, lhcn you hznc d wide
Cliulc: oi pimihle orner Clulscs

(D Since the main jcl, wilhmil being influenced
moon by lhc needle. is re<ponohle {or mormre
eonlrel oi high rpeed, il ghould he looked inzo
firsl oil. Fallow rhe $pccillcalions in filling Ihis
imporinnr eomponeni , . V or adluu according to
mining iniurmdlion Supplmd in alhcl’ pans of this
book,

(g Believe il or nol, lliul old diny our cleaner
crop: up ngnin in thk :rmoiion. Check n.

(.9 Improper ficdl level i: a common come o1
hi h \pucd mhfil’i. Sc! I00 low. [he lluill duel no!
pcrmii mmcicm iucl lo occumulolc in Hi: how]
lo <cr\c Ihc need‘ of Ihc carburetor.

G) Spark plug: dirly. wrong henr mngc, lm»
proper gnp. Inully Any or nll or rhese plug loulu
can he le‘pamiblc, High prewre orenhdonn el
n scemingly good plug can alao be the trouble.
Hem rnnge is prerly erineol in dir cooled engines.
If lhc plug is‘ loo cold it sham mil, i! loo hol il
welds. II lhe gnp is 100 greal ihe cylinder [arcs-
Sllrc prcvcnls rhe nrc lrorn forming acrm< lhe
expamc bcwl'tcn llre eleclrodm.

[33 Had egpneilor. Ezpcclzilly on the AC mag-

 

 

 

10 The Four-Stroke Engine

new system, it poor capacitor can perform 51 s-
fuctorily at low speeds yet foil to prevent point
nrcing at higher Rs, Hove it checked or substitute
a new one it everything else is right.

(.3 Gail. Smite sittmtion ns with capacitor.

t, High tension tends lcelting. Be sure the plug
wire is not leaning on metal which would invite
a direct ground. ttet the engine up ant] run
)our lingers along the plug wire. You’ll feel a
tingle if there ts lettkugc.

(3 An 'r lctth in thc exhaust system, where
the pipe joins the head, will cause high speed
dropping. This is also accompanied by “hanging
in the silencer" as our British cousins say.

6 Air leaks tn the carburetor an: another
possibility. Follow recommendations at @ un—
der ENGINE DIES WHEN THROTl'LE lS
OPENED.

[m mttiet ttttntles tut: mill sttew at Duttum tit cavbtm- @ stgghpybnmed whom valve.
‘“”“”"“*'"1'""- r5 improper valve clearance. These two items
ctm cruise high speed misfire, but they should also
make their presence felt in other ways. so this
BEARING symptom tmisfire) should he considered es nddi—
‘ BOB WEIGHT tional evidence leading to a conviction, rather
, thnn a definitive single issue

® Clogged or restricted exhnttst should rtlways

AM he suspected it bike is older or has hnd poor
CENTRAL mum enence. .
FIXING BOLT ® In cnsc it has been overlooked somehow.

ehech the choke. Be sure it isn't being put into
operation.

fl! .
((7% POOR Low SPEED PERFORMANCE
‘ BEARING This symptom is presumed to he npparent ns

stumbling or lack oi power at low ks which

BOB WEIGHT clears out in the upper range of the engine. This
is not to he mistaien, of count: tor the loading
up which occurs at prolonged die and which
disappears as soon as etcess fuel and carhen are
hlown out, hut rather a consistent lack ot per.
tormnnce in the hottom hutt ot the power curve.

Number one troublc-Cuuscr in this motion is
improper cerburetio . Wrong idle ndjustntent,
wrong needle setting, etc. Tuning is the nnswer.

second, rtnd not too tnr behind in frequency,
is improper spnrlt advance. Between these two»
you'll find the trouble in most cases

 

   

     
  

Automatic advance unit ttutssl iynical nl trust ignition
systems using mil.

 

 

POOR HIGH SPEED PERFORMANCE

Complaints here are a laclt oi power at. what
should he the peak torque of the engine, reduced
top speed and the need to shift down more ire-
. quently, Actually, in most cases, the rider just
- ' 0' docm'l notice it but there is a general lack of
h -- V' ‘ , power throughout the rnnge or the engine. It is
Exintllle hnakef paints lat ctntittitn when ham slaninl 5’an ““1 “ hm“? m0" “O“mt’!“ _“"?°“ more

at erratic running is the symptom |\‘ asked of the engtnc. However, if II is clearly

 

 

only ihe iop end:

(D Again, wrong enrhurerion :idjustmcm ix rhe
prlmc MISPCCI.

Q Diny. clogged or had Ilil’ elenner. Thix
eondirion can he hnrderliue. periniiiing enough
air non io hike can! oi low speed npcmlinn hui
calming :In incl-rich cundi Il’l nl I'll]! nicmumi

@ Igniiion liming imd cleanliness (ll igni|ion
xisrem play n hig pen in rop-end periormnnee.

(9 Spnrk plug and wiring.

Sac MISFIR AT HIGH RPM (abm‘c)
ior more dei ' The engine ezin drop oil in
power ye| lippiu‘cnli)’ he hiiiing on exery power
“ka.

( Hnw is Ihc Imnct Don‘t overlook this
link in the . n K intended [a complelc n
ohm or vihich ihe igniiion is ii pan.

{1) Weak vnlve xpringx. 0n nn oleler eyele nr
uric which is mmcwhnl fired. lhi\ ciunililii»n con
prevail “Uh Ihis oorl of rcsulL Usually accum-
pnnied by mmc mixrrring. however.
l'ck or eomprexxion. Poor meehiin‘ienl
cnndi im with worn ringx valves in need of
grinding iind xo on xhowx iip rim 3% lnek or iop
end perlomriinee.

6‘ is [he rider I00 hei 'y for ma machine?
Mag e rhe lond enpneiiy ix heing exceeded. /\
300 pennder on n 50 cc. Honda can‘l expeci
hlniing perrenniinee.

@ 1: ii n dipping clinch? Could he. See
CLUTCH AND TRA MISSION suction.

GE Tim pressure check. Low lire: cauic in-
crensed rolling resialnncc which l norieeiihle. par-
Iiclllarly on xmiill elixplncemenx eyelex.

® Pririiiilly plugged innk Vcnl.

 

 

 

 

   

 

    
 

 

POOR GENERAL PERFORMANCE

Under lhk heiiiling. noiiirnllv. enn he lumped
nny singli: cuiw; or eonihinnrinn oi eiiuxee eon-
ceixuhly conneered with ma engine . ind ior
ihni miiirer o|her poriionx of ihe hike. Bur ler'x
run ihioiigh [he mus! common enuxer. in order
of rheir frequency.

6‘ Finl nopieion xhoiild inn on ihe igniiion
iimin lr ii i5 on ihe engine is jusl hopelezs in
perfnrmzmce.

@ Spnrk plug. Improper rype. rouled. drriy.
etc

(i; [’nnr carhurclinn. Synlplom< of mar-richr
ness or lucrlciin n mi.\|urc nre enxy xo deieei h_\'
exurninniion ni plug iind c\hau\l pipe. Sec
TUNING (p. 86) ror clues.

@ ls rhe hike running iree? Check ihe renr
nheel in ihe mnehine sir; on ihe x-mnd. noex ii
Ulm ioer enxiw I< lhe hmkc dragging” Arc
wheel bearings hrid l< ihe ehnin ioo iighi': Any
or (best: iremx eiin dow ihe hike m rniieh rhni
rhe icndeney ix ie <|I§pcc| a poor-perrorming

 

 

 

 

   
 

Orprlmuliug 1]

M
may: ~
WASHER.

 

 

Carhunior mnun g gasket: which can cause (mum: via
air Italian.

engine.

( Slipping eluieh. Thi: xhonld he on obvious
eond-iion in even i. nu‘icc rider. hiir n xiirpridng
niiniher or people don'i noiiee it.

{A improper vnhe neljuxuueni. hiirni or heni
\ul x can rediiee huncmmcr. Check \hese iienix

on! :is dircclcd unilci THE ENGINE WON'T

 

   

   

or eoninres ion ix iho cine io xhe
meehxinieiili ‘ rig engine. wiihoui good com.
prexsion you eiin‘i hirxe good perrorninnee.

iv, ls ihe xiimp loudcd uiih oil. by nychilncc‘f
Too much oil eelleeiing in ihe Cmnkcusu will slnvi
iin engine donn comidcruhly.

 

 

0\ ERIIEATING

The nix-cooled eng e ix ileugncil in he eooled
h; ii inoiii'iie urenni or riir. The memo ihni ihe
mnehine iniixi he nioxing io inxiire xhiu ihe
dexigner‘x dime .ire curried inn. Oh. sum, iour
mumr vii]! sil ihere (Ind hunn E|\\'{\\' uiihour com-
plnini for xevernl nlinulcs, hiii ii im‘l n good men
ro prolong idling or operiiiing uhile ihe hike ix
in ii xiirndxrill, So den'i expeer ir io he hiippy, If
|hl~ ix lhl: "mcrhcallng" eonipliiini. u]! rhni'x
needed is n e - ge oi hxlhili

Hnwdw il ihe engine oxerhen under norrnrrl
riding Condllmr‘hilhi’u ix. ii hegine io loxe pouer.
mixfircs er xianx in icizc up. lhen )ou niuxi nx.
:llnic rhni rhere ix n ninlriineiion or ii poor operzib
ing condiiion.

ii; Too lean a IHIAIUI’U is ihe Comnlnncfl roman
{or m‘erhcilling on ilie rond.

r» Nexr commune»! ieiison ix improper igni on
omin, lnxunie -nr irdiiinee is rhe problem.

7 Wrong heur rnnge xpnri pliig eon 1|i~0 pro.
diiee lhi~ eonduion,

 

 

 

   

 

12 The Four-Stroke Engine

 

Graphic iiiusiuribn ul plug characteristics.

 

bitty, shaken air cleaner utter is responsible in nutty
pettortuattee complaints,

 

BSA ail cleanll Inczllnn.

All of Ihese conditions can be dealt wilh in the
|une-up process. it the engine is tuned properly
and it Slill overheals, than look Io one of the
following:

@ Air leak between carburetor and head—
ruaulling in an excessively [can mixture. and mosl
noticeable under load. This may not be enough
to cause misfiring. but that could be a clue.

6) N01 free-running. See @ under POOR
GE ERAL PERFORMANCE.

5; Low oii live]. The air-cooled engine i< also
cock-d by uil. A full nmnufnclurer'< recommenda-
tion supply <hould be carried.

»\ improper oil viscosity. A higher viscosity
oil ts required (or hot weather, Do you have the
proper grade in the sump?

3 is bike's capacity being exceeded? ever.
loading is immediately produclivc of overheating,
K? is the engine dirty? Cooling fins. particu—
, and the rest or the motor casting generally.
must dissipate the heat generated by combustion
and friction. If there i: a film of dirl and oil on

 

   

the surface, dissipation i< retarded. Gunk ii,
Remember: A clean bike rum he||er,
RIISCEHANEOUS CARBURETOR

PROBLE‘IS WHICH CAN CAUSE HARD
STr\RTING 0R POOR PERFORMANCE

3 The main jet cap on many carburetors acts
as a sediment and water trap.

Q 11 |hc \mnll brass spacer is lert on the float
support spindle on Amal Monoblocs the float will
move :tlleling the needle valve to drop into the
bowl dnd came flooding,

a: bent needles can upset air ruel ratio. Fuel
comumplion will rise ii needle is worn.

@ “0"»ring gasket on Amal type carburetors
can rail or be pinched on assembly and permit
air leaking.

(s) Warped flanges will not seal against head
and permit air leak,

is: A sntall amount or water retained in line
filters at banjo can cause prolonged dimculty.

A carburetor which has been mounted
rigidly, instead or with flexible mounts as original-
I). fitted. can cause ruel rrothtng and a mysterious
misfiring.

t3; incorrect tloat level should always be sus-

pected in case or poor high speed pertormance.

 

OTHER E GINE PROBLEMS

Excess oil consumption

All engines use oil. even four strorers. so expect
the consumption or a certain antount or lubricant,
The greater the clearances in the engine, the more
oil will be uwd. Even it the high-miler is clean
externally, it will absorb, The leaky bike rum
through even more, naturally. But there is a

  
 

 

limil and if Conallmplion cxceed\ lhe norm, by all
means 100}: mm |hc problem,

What la normal? U is impmuhlc In my. The
me of oil \‘nric: so much “ilh model. dixplacc—
menl and condilion (hm any given figure would
be inaccurmc. Howmer. Ihc Clue, Io cxcculvc Oll
burning an: plain ii you examine the (park plug
and (he c\hl|u§l pipe. A um. black plug k lndl-
culive of oil burning. A gray smoke from lhc
exhaust {m oppmcd lo a black Emoke which
comm with overrich fuel minim-l ix anolher
sign. An exhauu plpc comcd wiih licavy, moly
(lcposiu Ii anolhcr indicamn

If all |hexc arc nlcscm and accounlcd for Ihere
may be one or >cvera| things Wrong.

(3 Are you ming un- righl grade of oil? If
(he oil 1: I00 |igh| for conditions leithel’ riding or
unginc wmr) a In! of il can blo“ righl Cllll [he
cxhnuxl pipe. 00 up a grade and see it il helpfi.
Drain and refill, of course.

@ How i‘ lhc comprcvion'} Worn ring: permil
the passage 01 crankcm upon, uni: c lu-avy
with oil, imo lhc combmlion chamber when they

 

Olhvr Engiml l’rubloms 13

art lmmml. A compmunn check will «lixclmu
(In: condition

(3 IV the ml hclng munnnl lu mpplyl On
dry-ulmp cnginm um is crillcul Check the mean
and [he rclum line from sump.

a) (hack up» sump lnaallm. If it h plugged.
mac“ nil uill bc hunlc

 

 

j‘ nail \'.||\'c pui-lca. \ uh cxcemvu almanac
bcmccn \Llhc mm ilnd guulc hurt, llrc lmpomir
Mt fur a muuu amnunl pl oil burning. Il' com-
prcwun checkx mil ucll. luu olher a 'mpmmx are
pmnnl, measure \|cm~lnguidc cl rllncc by ap—
plying slilc-lo-nd: prmun- ml valn» ~|cm ulin
spring lcnllwcd. n ~hml|d nu. ruck.

   

Lark ur all prmsurr—zmldon

Tim lsn'| a kymplom. ii i: n problcm. Tllc
~)mp|mn\ “mllll hm n nifcdcd Illcmx‘cl x m
mucllllniclll dilllC|Illlm bcLlqu 'xccpl in the rlm:
lmltmcc at n modcl equipped \ulh an all prcuurc
' aim. Ihcrc i: no )lc clue to a lack of
lubrlcmlnn a! crmcal poinh fL'kl by lhc pump.

l’ruwurc railun- gcncrzllll nican: pump lailum
hccml ' of ilcc mulnlcd dchrh In (he chock \ lvc
in mm plunger |ype pump This 1: casll} cured by
removing |llc relllinillg scrub. ipring and mu m
|hc chuck Vlllu: and clclmlng |hc mm with solvcnl.
Rarely. on xomc modclx, does the drive break.
ln \qu lypcx mun ax lhc mull dliplllccmcnl
Hondzu, will wml-nrcxslllc lulmcnuun [0 [he
rocker bo\, |hc grooves in Hue cam “hich feed all
up |n un- iup of um engine can become cloggm]
\\llh muck if lhu engine \ neglccmd long cllnugll
Remove Ihc rocker oil [red boll (sec illustration)
and .\|:II‘| (he Engine. There Vhould be 1| Heady
flow of lubricnnl.

   

 

   

 

 

Schematic diagram shims cimll ' ol Iuhlicanl when
smut? ink and my snmn system is used. "ii: is Rayal
Enlfllfl. lint Iypical at others.

 

 

14 The Four-Stroke Engine

Lntk n1 oil pressure—gradual onsel

Again, if mm i: nn pressure lndlcalor, lhi< ifi
nul Vumclhing the rider “nuld be aware of. If
[here is an uil prmurc gage in [he aucnl and
pmulm begin: In drop or falls ull more lhan
usual \lhcn hnl. lnnh |o cxcmlvc clearance: in
me pzlrls supplied under prci‘urc: connccling
rods and nlainu.

Luck of return In lank

Thl< problem i, accompunlcd by lhc wmplomfi
of heavy “ham! ‘moking und mhcr signs of mu-
olllng «lncc Ihc luhnnam is accunlulaling .n the
hump mum of making m wa} Bull The problem
is generally righl in lhc rclul‘n pump \\‘iIh sheared
drhc, had chuck Valve, loose pump mouming.
lulled gaakcl. clc.

A Return! possibility is lhnl lhc prmurc pump
hax failed for mnlc came. In [his C352. Ihcrc
would he nu smoking. hm lhc almplmn: of no
oil prc<snrc “cull! he prcscnl.

On BSA mm modck. rcmmc |hc sump plat:
and {me up “10 mix phon hall al lhc hmwm
of ill: pickup h_\' llllln i| \\I|h H small mcmlrivcr
or suilahlc inilnlmenl. A slicking hall is ,
limna"vhnppcning.

 

VIBRATION

Excw \ihmlinn i< uulnlly dlrcclly Imccuhlc lu
lame. hmlcn or wnrn mum mmle and all
mmlnllng [lamb \houll‘ I've ln»pcclull law/lull»,
Th: cmphan» on [he lax! uunl u bucaluc a nluunl
plulc can he fractured “mm a hull hcnu aml \hu:
he canccaled

Incorrect clutch zlsstmbh. pum liming. worn
crllnkxhnfl :er mlm pnwlllillllcx lull [h_ are
fairl) cax)‘ m Ime; ~lncc th 0n~cl uuulll cllhcr
hu gnnlual (in lhc cmc of lhc crunll or lulluuin
zuml: llnkcnng ll lhc lulu u new m mm. a
|homugh Inxptclmn of all lhm pamhlc muse:
‘hlluld he carried on! nncc \lhlaunn u llulully a
plullldt m ~unn» son ur [:llIHIC.

 

 

NOISES

,\'m\t\ mun an engine can hc holh nnnn) g
and nlcnlllnglul. l'acll engine h.“ u‘ nun puma
ular m nl’ munlal uum and lb: ruler \hmlld gcl
uwl kl lhcni rhcn uhcn |hcrc u a \1lri1man. nn
numcr how alighl, he is alcrlcd. Sumo :nmll
nnlwcs hall» huh: ugmficancu ulhcr man ln dcnolc
mdmary um uml changing of cluaranw .
\‘lnlw clcamncc, Clo, hul loud, hem) or sudden
mum gem _\ com a) a clap ol' Ihundcr hcforc

 

 

lhc mum. naming nl llual Wclllhcr,
Pinging
Thh u n h rpllchCJ, upper qllndcr mlllc

 

.ll lmc h.llI cnglne spccd and u caused h) pr:-

 

*7

LAYER lvPE
ROCKER FEED

     

YANK
aznmm ,
k

 

 

 

     

a-L suwlv
WE

 

\93
m IEWRN
mp:

Dulaway illustrating diflerencls ill tally 1nd lalll BSA
500-550 oil sunflly.

 

 

 

BSA 5W sump details.

 

 

Mus: Lunnzchuns n1 BSA ianh,

lgnlxmn lderenrmmi) ei Ihc inel elrnree. li eeenrs
nrnsr nmlccrilll) nn neeelcrniinn or under lend nnil
i. llmughl nn In ene nr wwm] mines Principnl
ennse is lewiesl inel. L' Eng n peer erniie (low
oernne rnrinel gnu me in n high ennipressinn
cngme M an epcn IonlIImn In this jnlplnm.

n is mun: Hun nnnnirne .lerennrinn is linrrninl
Io lienrings .md pisinn Sniieli m high |c\l
(prennnnil gnsnline

ll )ou 1m: wing high-mu enselrne and g 1 Nu:
snnie snrrnil. elrnnees nre. lim. rlinr the gniunn
“min; is me “muncul. it your model is n lwm.
he sure rim bnrli sen ni poinn nre opening nr rlie
prnner iinre \\'orn pnrrs liere enn cause n min-
rrnn hcwccn lire we

Anolhcr possibilny is inenrreei sznrk pine lienl
rangcr “herein lhc up is merlienune and neung
like n glow plug in n mode] nrrernn cnginu.

silll unnlhcr ennse enn he cxccsx enrhnn in ilre
eorrilinsrren Chumhcn ur. ii ihe engine hns been
reeenilv nierlrnnleiL n hit ni mckil ma) hm'c
hccn len nrenrnl lire xpm’k plug mile in rlre inrni
of n broken rlrrernl Much is lrenrine and glmung.
The inner rliree pessihles shenlrl he ennsldered
more if rhe pinging occurs only nirer rhe engine
is good nnil hols

 

Chiller

This is generally rhe dC\CrlplI0n llppllcd re ch
ccssivcly Iouw who’ruckcr :Icumnuw ll is more
noticeable “hen Ihc cnglnc is cold than when u
lens vlmmcd rip and is clearly in the upper pan
of me engine. Tlrere is n eerlnin nmnnnr of snlse
noise in nn air cooled engine bill if Illppcl clenr~
ante is even nll rhe wny lhmngh, no one \illvc
slands oul as bcing noisier xlmn rhe orlrers. A
shun lcnglh (‘1‘ ruhllcr Iuhing can he used to lixlcn
lo each ruckcr mm In mm and isallrle the noisy
one A long screwdriver wilh Immllc held In lhc
enr ilnd rip ngnmsi lhc rocker hux enn scrvc ilie
same purpose.

Noises

 

        
  

rliilnsrll.

Le‘l (nmlasc rm

Manda wel sump luhrlnaliun sysiem usn engine).

 

as: 15:] ruling melhnfl—nnle aniisyplinn lull valve in
sump (D) which snmellmls siirlrs.

 

16 The Four-Stroke Engine

 

Szml-nlzxsure ailing sysllm. as examplified by "and:
50cc, uses splash mil in cvankcase. sniral more nn
camshafl m lull uppzr tylindzr eunipenenls.

Clank or slap

Vision slap in rhe airconled engine rakes on a
more meiallic ringing mund rhnn n does in Ihc
walcr-coolcd engine. So it )ou henr a heir-speed
clani. like hringmg n pislan and a cylinder balm]
smarlly lneeiher. chances are ii is pisicn slap
caused by excessive pihlllnelneuall clearance.

Slighr naise. one chal disappears arrer rhe cne
gine is warmed up. can he calerared. hul one
which hangs en should he ini~eslignled To verify
the cause. hrsl derermme il it is cnmmon m bmh
cylinders if ihe engine is n lwn, by removing a
plug wire [rum each cylinder in lurn. The nuns
firing cilinder should nai mnke a disiinci noise.

Ride lhe machine at low speeds under load and
see if (he sound inIenSin increases as Ihrollle is
opened.

Rap

Descripiive of excess clearance in connecling
rod hearings in mosr engines. lhis noise is mosl
noiieealnie when lhc engine is running under a
lighi load deeeleraung. It sheuld also increase in
loudness wnh speed.

Knock

This is n heavier sound than any described so
lar and comes [mm rhe bouom region ol the:
engine. indicaiing [hat ii is :\ main-bearing or
crankshaii problem in rhase engines wilh plain
hearings. Mml easily dcleclcd when under ac-
celeralion or when saarring.

Screech or whine

Since Hondns and nehers have ball and roller
bearings supponing ihe crankshaft, Lh: heavy
nieiallic lhump of a bad plain bearing is not a
~)mplom. lnslead a screeching, whining sound.
like a faulty siren or Ihe rear end of an old Buick,
occur< sshen hearings go bad (very rare under
normal Circumslances).

Doulale knack
Synipiomalie cl excessive pismn pin clearance.

This is rnesl neliceable wi|h \he engine idling
and is a sharp. quick doublerep.

 

Chapter 2

The Two- Stroke

 

Duuway n1 Suzuki lwin 15m,

The tho-strait: cycle cnginc is so bnticnlly
simple lhal it wcnw thrL‘ should be few attuet
of trouble, Thix i< lruc. Lite comparing nn nir—
cooled powerplnnt it: n unteneoolcd one. the two-
slrokcr hnt much In: pog~ihillly of going had then
the four~<lroke type. Thc reduction in mining
pans (llone IS enough to eltnlinnte many potential
problems. But (his (JOCK not necessarily mean
(ha! a lwo-Hmkc i\ more reliable. The ”[5 to
which it i: utbicct are oflcn jutt In prevalent and,
in the Cm: oi lhc rider, jtm as bafllingr

It i5 nxmmed that the render known the cmncc
of the lwo-slroltc cycle principle. if not. refer»
encc to the accompanying Chan will make the gm
flow lhmugh the engine clear , r . and Ihnl‘: abuul
all ”1ch is Ia tlndcrsland. Th: carburclinn and
igni|i0n of Ihc two-“mks are ‘harcd \Vilh the fam-
‘troker and, mide from lubrication, the configura-
lion of the modern power ttnit (cnginc/gcnrbox
together) is nboul lhc same ththr the twri- nr
[nubitrokc princlplc i‘ employed.

This reference [0 [he four-«rake l‘ made be-
Cause the average rider hm at lens! a nodding
hequnintnnce uith the "conventional" cnginc :0
utdcly used in automobilet. If )ou are mod to
dealing wilh Ihe \‘al\‘c»cquippcd type, you will find
tevernl pronounced dtlrerencet in the two-cycle,
If you have no experience wilh cilhcr Iypc of
engine, you can pick up enough hinh here Iu
make the vnrious funclions oi components clenr.

The biggest ouncr Complainl in either that the
engine l‘. hard to filarl or it won‘t um, Olher
gripe: nr troubles dwindle hwny sharply in per-
Ccntnge below theoc lwn. Anyone who hm fiddled

17

with {tn old lwo-flmkc mllbonrd m0|0r, a model
airpldnc, or a model enr engine know: the fru‘»
trntion or lrying to gel cxztclly the rlghl contliliom
Io make the rhingo 3|an and run. Th: modern
lwonstrtvkc motorcycle engine isn‘t nearly so
finicky, but all modcls hilVL‘ lhclr lint] momwnls
and Ihe l‘eU. prncedurc. for amateur and nld-Iimcr
hllhe. it to begin with Ihe correct \lllrlmg proce-
dure m recommended by Ihc manulnclurcrt

If you don‘t have the owner's handbook, or if
the bike h “range to you, here is n procedure
uhich uill get nny two-flrokcr going—if there is
nulhing Wrong with it.

Run lhrotlgh il heiur: you mulm: thnt tomc-
thing is wrong Will! the powcrplnnt.

STARTING PROCEDURE

With cold engine or in cool Ml‘fllllel‘

6‘ Turn the fuel lap to the “on" podtion.
'Iurn the kc) lo the finl notch or mnrk,

( Elm: the choke. (Jigglc (h: carburcmr
ticllcr if to equipped)

(9 Rich the starter or push the clcclric slnrtcr
button.

N010: Do not open the lhrotlle while operating
the slflrler. and resist the lcmplflllon to crank the
throttle on n\ thou :t\ the engine fircx up,

5; m \oon Ln the engine it running smoothly
(lhroltlc >lill Closed}. gradually begin opening Ihc
Chnkc, and a: man as lhc choke can be reduced.
npen the throttle and tpecd the cnginc up. Grad-
ultlly open the chttlte 11) engine vtnrrm up.

 

 

18 The Two-Stroke Engine

With urn-m engine or in llol wcullmr

Fulluuing | and 2 .ihm'c. luim: (he Chukc Alum:
and open the ihmfllc H: m ‘5 and kick |hc cn-
ginc mar on me Sinner.

Seems simple, ducm'i .0 n n hm “ippose Ihc
cligmc docsn’i iirc up right nun- Sr-pnmc yuu
have been kicking the miner [or u thixlcmhic
number of limes ml the nnI) wilnd )cu gc| is
ymrr nun pnniing. Thcn “hiu‘

Then )ou'\c axcppcd inm ilic milighi zone
Mien; rimming in (he wvrld tank! In: “rang. but
chnnccs .rre rhnr only nne of n m» Hump i:
Mm mung Tu find on! Min: “ihrng” and now
in proceed, i| i\‘ ncccmry m follow a slup-b)‘»s(cp

 

   
  
   
 
 
   

NEW Nix‘ruIE uon
mums; m

m rwo
murm you:

Hix‘ruxi ”(on
ruvious mm
mm

:umsssm

”mm mm

rxmurr
Porn

now NEW mxmr

mung.
Po"

mwnzns

method of eliminating Alum. As “ilh a four»
\lmkc, ihcrc is imih in ihc Sialcmcnl lhnl if you
nnxc n ‘1:an nnri you have hml and )nu hing
\hcm mgelhcr under pressure a! [he righl lime,
ymr‘u have an cxplmmn. So. either you haw no
fuel. )ou hm no spark. on have no compression
0r )ou hmn’i gm ihe right lime.

Bear up and follow rnrnugh on 1h: followmg:

Q I/ Nwrr ix (1 sum" 0/ rflw gas, or visual
:\id:nce of flooding such as furl on the car.
hurcmr. (\an ihc ihrnnlc Wide and kick the
Manor. ur operme (he elec|ric mncr in turn lhc

 
  
  
  
   
 
   
   

NEW ”mun: BEING
COMPRESSED READV
rox mm

pmon RISING

Sun AT nu:
lemma nirvuls

Maw

MSCENDMG

0N Iowa
57wa

mm min
unrrn

mxwu

w crmmrr
um:

comma:

 

 

Example of Rolory Valve

Ex I
Dlsk all: as Valve.

upelwd closed

Ex 2
Crank acls as yalve

//
l nuellcd

anemia" ai nu mury valvz.

angina over (cvcral |lmcs and Ihlls clczlr out [he
execs: fuel.

@ L1 lire hey really an? Tviiddlc rhe key in
[he suilch a bit. He iurc indicalor |ighl< are on or
try me horn in determine if lhc neceasnry clccrri-
cal current is prcwnl somewhere in rhe syslcm.

(a; l/ Ilum- is (m nbl'imls supply 0/ plerin’r-
ily, rc-check rhc fuel supply. 5w: ch to rcscrvc.
Turn swilch to emergency alnrr posilion (i1 pres-
em on your model) and try again. If the h ‘c
docsn'l all!” now, furlhcr checks ar: necessary in
the luel wppl v. for which we below.

G) I] l'mlx'cnlnr lights or other (Icrexsan'rs
do nnl function, suspccl bad canncclions, blovm
fuse, or had hauery, For example, even rhough
some hikes have an AC magnerc syslcm, a dis-
charged bauery in rhe circuil can make the bike
hard [0 Marl and resulr in poor running. Check
lhc [mes in «11' model. The fuxea will Va ' in
locarion hur will aluays be close in ihe haucry,
Also check all electrical conneclions lor clean-
liness and lightness. parricularly hauery ground,
This is highly criiical.

ll [uses look good and conneclions ‘ecm in
orderY check the lmllcry, The following advice
will scandahzc banery maken and ir ir adminerlly
no| good pracrice, but you can r My yourself
lhal there is current (or rim) by .lrilmg a quicl
arc acres rhe ballcry rernunals villh a piece of
wire or the handles of a pair of pliers. Do [his
very briefly, juu enough in gcr a flash.

Q) If (he bunny ir rirnng and a good spark
reeulrs, examine lhe rerminah. removing, cleaning.
and replacing lhcm ii in douhl m to Ihcir abiliry
[0 pass clcc|ricily4

(5 if we bnllrry rPxpomh ire-ah 'rlr uni (u
all Io [he direct-shun lechnique, ilher hm‘e ll
charged, swllch to emergency slarling posilion
[if available), or push Ihc bike. 11 a dead ballery
is lhc role problem, man cycles will push 5|an
rairly easily. Cold wealher and a big hike may
make rhe proccae a hii dillicuh physically, bur

 

 

 

 

   

 

 

Slurling Procoduro 19

YA s ENGlNE moi/m VALVE DlAGRAM

 

 

EXHAUST EXHAUST-SWEEP

 

new,

 

20 The Two-Stroke Engine

 

Typiul small disylzclmull Iwnvsuukl, Suluki 5MB M15“.

the generating system on all models is designed
to put out power at low RPM so this helpiul
(tantra which is nol present in the automobile
system works (or you. CA U1 ION: I[ you Inn-e
lllt‘ lvtlltt'l)’ rimmed. rout! 11m rt‘uimi oil L-LECv
TRICAL SYSTEJIS In ”US [took IVE/Ola lllJltiIlg
down In (Ill: ncmcrl :crvl‘cr nation,

it alter taking this preenution the engine still
won't catch. it is time lo check [or spltrk at the
plug. (We will use the singular to so words. If
_\our model hns more Ihun one cylinder. mcnlall)
substitute the word plugs.)

@ Rcmm't: the spnrk plug and examine the tip.
it son he "bridged" wilh n tiny sliver or metallic
deposits hciuccn the electrodes: it can be loulcd
wilh hcmy, uct carbon deposits. the grip can he
too w e or completely closed up. Or, the plug
can he imcrnillly shorted. Clean Ihu tip, at hcllnr,
replnee the plttg with the one you thoughtlttlly
packed into the tool kit

g; ll the plug .tppenrs to he good and you
think |hc Condillon oi the electrodes shouldn't
keep it irom operating, replace the high tension
lead, place it firmly agmml the tins ot the engine
hczid, and kick over lhe ‘tnrlerl You shmtld pct
n int, hlue spntk ii the spark is w k check the
electrode gap. In tht: two-strok: it should be
.020" to 1‘30”. Anything Above .030" is too much.
Less then .020 isn‘t particularly eriuenl. As a
matter at (act, you can sometimes make it plug
work by closing the gap right up. Sci it down to

 

 

.015" or so and re-instnii it, The plug my be
hrenking down under compression and the closer
gap will often permit it to operate until you can
replace it with n new one.

If you don'l have a feeler gage, take a paper
malehhook and a business card. Togclher they
total about .015" in thickness. Adju<l the plug
gnp so thnt this sandwich will just slide between
the electrodes and the gap will he approximately
corrcct.

@ 1i there is no spark at the electrodes and
you are sure the grounding at the plug is good
and thnt the high tension lend (plug wire) is
firmly connected at each and, you‘ve got ignition
troubles. This may be a had coil, bad poinIS, or
other electrical problems which are better covertd
in another section of this hook. Just to satisfy
yourself as to whether the system is lunetioning
or not. grasp the plug in one hand nod push the
sillrlor lever down politely. (Don't jump on it or
your eyes am linhle to light up like a pinball
gnme.) You'll feel a tingle it the ignttton system
is developing output, ll you get no indication or
electrical energy, you've isolated the problem.

@ It the Spark plug is good nnd you get n hlue
- nrk, there is n here possibility that the timing
i so far off the hike won‘l start. But chances
are it is somewhere in the fuel system. Check tht:
timing first its n precaution.

@ To check timing (roughly), pttt a pencil or
other slender objeCI into Ihe spark plug hole; put

  

 

 

Slurling Prm'mlurv 21

  

 

\‘

Make sure mm is wanting pmplfly H mm] slamng is

 

:ncnumzlefl.
Is the me! [an an? H25 n hzm \m an while bike was
ralkedl H 5n. cvankcas: and :arhwelnr mm he NH I11 I fl
uzl nvn'u

Is the key M and swim" making Enntacl? Jikg‘e il
ahnut new. assuming m: Wnlsl. Switchas n! this type
"Mk: I cimli! 1n mum: and can snmllimfl h: IHI
{mama by [lNflYll hum mnunling‘ In CI"! an inllmal
au .

ls mm really a supwy n1 «um And law uld u n?

 

22 The Two-Slroke Engine

 

on many mnflels ii is necessaly (a lake tn: nanny mu in
gel at wiring cunnecliuns.

|hc gcnr xclcclnr in lop ggur nnrl mm lhe enging
m‘cr hy rnuuing rho rcur w ccl. moon n whcn
ihe piuon rcuchox |hc rop or in urnko h) unrohing
the p-‘ncll. Then lurn the wheel IlliermlI “hill
the up of the pencil l: dbmll V." holow ru pcuk
poim. Then rcmm'c rho lm. kcr poini cover nnd
cumin: lhc pninu, Tho puinh \lmllld ho juu
hrcnking upcn. 3c \lln: _\U|I hznc lhc \c| or puinh
which rclmcs in (I'll: righl minder. if i| is a win.
If [he pninls open 1“ mm: polm in If“: amok:
grussl' removed from lhis nurounr oi advance,
(hen lime roughh by lhix mclhud or rollou
|hrollgh in indi i under TUNING.

Ii you have planned lhc plug and lhcrc i< n
good \pdrk, and [he ig on :lppcun in he in
lime. helm: rcpluclng |hc \pnrk plug, kick Ihc
unru-r lcwcr u Couple of Ilnlc~. nr opcrnlo lhc
clcclrlc nurrcr hriclll Thou rcp \CC lhc plug nnd
u} in unn (he cngim nc fire< and lung
only momenmn kuh .l hig cloud of smoke [mm
llic cKhausl, ”IL chances arc the Sump ix loaded
Milh fuel m all. On mml models yml w find :1
sum” llrdin plug in the ccnlcr of lhc honom of
me \llmp |u permil |hc dmm' cc of uich unwnnled
liquid. Il my be necew no kick the engine
Over n lepl: of urns: Mlh lhc plug on! In
achicu‘ [he dc<lrcd rcsull. Thcn rc-cxuminc [he
\pdlk plug.

of, Check Ihc rucl Supply, Pull ihc hrcl line
nil nl Il-lc lap Then, holding u rug or n conuincr
under rho upcnlng. mm rho rnp husk on and
uluorvc fuel now, if any. You can uho ohscrvc
y hm gm 1“ lhc mnk or \unlc
' . wch 1l~ w cr. Alm. f Illc hike ha:
lncn in \mmgc ior <nnrc limc, lhl. in sun hnvc
dccumpmcd lo such nu cucm lhul il won‘l hum.
The highlg Vuldlllc elcmcnu lhui nrukc {or quick

 

 

 

 

      

 

   

 

    

 

walling in a rucl blend vaporize readily. Thi»
mukc< old gas cquul lo bud gus. 11 generally ham
3 mung. pungcnl odor ax opposed |o lhc keen,
light smell of frcfih fuel.

ln Ihmc mudeh which me a fucl~ i1 mixlurc,
you mighi gcl n lol or all und lllllc gilt Mixed
fllcl/oil chm no| ficpamlc hut, in siorogc, Ihc
guxoline sz vaporize, 'ng oil or a loo~rich
[“ther in me hollum of [he lunk.

Walcr h emily rccugnizcd because it bulk up
In dmplcl< on lhg rng while gm walk right in.
ll aka sink} m the bollom in 1| conlaincr.

(a If the fuel flow tor a momcm and [hen
510155, remove lhe gn< lunk cup and we if il slam
again. If it does, [his is the :ympmm or n
clnggad \‘cnl. Dcpcnding on lhc mudcl, |hc vcnl
i« in me cup or in [he mnk. Find il nnd unplug ilk

G] If {llcl fluwx freely, or if iI is ohvioufily
diny. rmly. or run or \cdimunl, (here will he
trouble (urlhcr along the line. So, remove 01:
fuel llnc ni Ih: culhul’clor. lukc out Ihc wire gauze
unrincr al mg :lmju. ir <0 equipped, and clean il.

Al thi.» poim. if ”1ch i\ fuel ill ”16 carburetor
dnd lhc plug was gond nnu no! wc| on examinm
lion. rry heuvy choking. Mnkc mrc the choke i:
ronlh working Then, if H doe‘n] <iurl, gel in|o
lhu hllrcmr lighrh.

r If fuel is prcwm at (he main jcl und you
hue u ~plrk ui lhc plug .u anpmximntcly rhc
rlgl‘ll lime. ond IhC cnginc uill reruwx in come
ulive. r: llkely yml‘vc gnr inuirlicignl comprmlon.

Th m m< a broken pislun, holed piflon,
blown gmkcl, leaky sump or mmclhing hig. To
check i| mu. lake .1 comprc<iion Check. The

 

 

   
   

  

 

'luuls in kit include snark nlug wrench In he used will!
hlafl: nl Phillips Sclewflliver.

 

 

Tim Engine Is "(ml To Slur! 23

   

Sculzfluaklng mug Ilka this is nhvinus clue In M stall nr
harhun womem. nemanemm is mm man Meaninz.

 

Check '0! walk at plul. Ernunflinz plug on head and
working starter In".

 

Elnkll paint Malian in kypical AC maueln systlm
makes It :asy in chick canditinn and up.

average 50 cc morxlrnkc rum mcr IOO [hi coup
prcxxmn nnrnmlly. If il h balm» (x0, chances LIl’L‘
u unn'l nm The 30cc 100cc, um! 125 cc
(mulch \Nlull)‘ run from Hi In 12: pu nmnuull)"
[ha 250‘. have about 140—150 p,' If |h|~ lulh
hcluw M) W on the smaller hikm uml MN! on Ihc
larger uncm 1h yr: 1n Moulds, ~u 12‘ m be your
guide. m u nu mm |0 runl comprcwion dam on
[Ha-unvkcs in unuu ur nu- tummy \cnicc nmn-
unm \u mpcricncc nnd mlc m thumb hmc m hc
me gunlc.)

T To check C|7fllpl'€<\i0n. ordinarily |hc en-
an \hauld be unnu m gm lhc nmu nocurmc
rc. linv In the one o! n non-«an, huwcxcr, i1
Mn cruicul, n 1m of cmupwau N [he came
i! will lac quim 10M750 per ccnl 01 normal 0r \0.
Proceed m ntImu: screw the cauunmian gnga
and into |hc 5pm plug hole (or hold u lirml) ‘r
\ ' g |hc nummmiva I}pc),olmz m [lyrmtIc/ully
nnu klck |hc unncr over n couple of mum.

of cuum you can have cmuprmon m m: lap
and nanc 1M Ihc huunm in u No-umkc and H
“on'l apcrmc. Sn. if u appears m be normal in
mmhuuion prcxsurc, ~|I~pcc| lanking mmp mus
or gaxkcn, cum \ump lenxngc, a \hcnmd muuy
min; pm. or Ihm lhc filvcr hm sheared on" ‘hc
nmul ccnlcr.

l/ du- ongino firz-s occasionally Iml mm":
run lhx: i< a new Kc! of conditions.

If u m a romry \‘alvc model, In: chance» an:
the rolnry \uhc disc As dcfccmc The \‘ulu: is
fiber and ulhjecl lo diuonion [ram moixulre I“
“all .15 shamed drh'm If |hc \alhc i\ had (SEC
illu~|m|inns of mu-Slmkc principle) me mixlure
i~ ci|hcr not drm imo |hc crankcfic or com-
preasion is dmmycd.

 

 

 

 

 

THE ENGINE IS HARD TO START—0R
RUNS ERRATICALLY

The hmic assumplion here k Ihm we are um
um Llcnlmg Wm 11 um} engine, one \\hich i:
crumbhng mlo ruin or held mgcihcr uuh “in:
and hope, If ~uch h lhc Cmc. il would he hard
lo :lnrl. Ralhcr vkc usiumc \hm the bike 15 In
normally good opermiug conduion and that H)
i! ci|hcr l‘ccomm hard Io mm uml rum crmucally
\uddcnl). or (2) Ihc conuuiun has been geuing
pmgrexsnely unne for «mm mm,

In ei|hcr case. 3 check xhc ulcuricnl syslcmi
pa) ng purlicular uuenuon lo the huucry n u n-
u pun of |hc ig [hm \yamu All cnnnccflons. :1
[mm )‘c \Ircsscd. have [a he clean and fight.

@ Chuck Ihc mark plug for up: und condition,
Pcmngn |hc wrong heal range is hclng mm, or
nmnhu engine conduion can he dingnmd by
mmimng [he plug.

 

 

J Chuck lhc carburetor idl: mixmrc <cmvu.
1chme 111:

“In 011m lwcumc» mulmljmlcd

 

 

24 The Two-Stroke Engine

oner duesn'l “Luch what his hand: arc doing
\xhile gripping :i screndrivcr,

@ Check lennion rimlng and com-er lr ii ii is
wrong Thi< cause or hard shining and crmlic
running is gradual in HS enser, rarher lhan sudden,
because ii IS due to ihc “our of ihe cam fiber
which causes a sarlauen in polar gap So, if
<uddcn hard srarring is lhe case. a more likely
suspccl is rhe capnelrer. Replace lr li pcinu are
hurnerl and dizcolorcd, nhlch l< a gend sign of a
fauliy condenser.

3 This bring: us to bad points: peril, dirty,
pnieri, er oily. Dress them or (preferably) replace
them nah a new ser. 1: rhe hreaker point area is
oily, somewhere lhcrc is a bad oil seal in [he
dri\c. Replace it

(On straight magneie models, inapccl rhe pick-
up and slip ring for din imd grease and eorrecl
me condlllon if necessary )

Q If |hc engine klcks back (in starring, chances
are [he Mllommic advance mechanism in [he
disiribumr is nol uorkmg properl).

[1: Chcck Ihc air filter. Rcmmc and clean it
If n is ancicnl and exccmvcly dirn, gel a n:\\‘
ones

’3 A clogged mumer can cause harrl mining,
If rhe hike is a high-mileage 10h. ~\l\pcc| ihis came
righi aviay 1i ihe dllqucr is remainhle. clean ii.

G If the machine has bccn «iorcd and hm been
pul inm use nirhour proper uucnlmn io prepara-
lionr the Ciirimrcior idle It)! can he clogged Mlh
\‘umish or m1 ruiduc The mum jcl can likewifie
be plu eerl u-nh rhls suivunnee. Acclonc u- a good
selvem. or regular earburcmr cleaner ulch as rhai
used in inexorcscie shops can he used.

ENGINE DIES WIIEV THROTTLE
IS OPENED

Aesuming rhar sail are nor heing overly quiek
\\iih ihe iuisi gripe \hi\ mm of denih er slump
of ihc on us can be auribuicd almou viholl) (D
cnrlmrcumi.

(i; \lakc Sure that [he choke lever is :iciimll)
operating in open the choke fully “hen || is sup-
posed lo.

Q Is lhe idling speed sci high enough Io ae-
commodzue a sudden increase in \cnuiri area? If
you h ~ ihe engine ncking ever al 200 RPM. ii
jun can] induce enough presiure drop ai rhe ier
|o suck up enough Inc].

(3) H0“ aheui the idle jc|7 is n cluggedl

Q The phcle carbureiicn system can he too
rich.

6 This lsn’i likely bur il can happen: an air
leak II! the carburetor flange “hich hag been
cempensared for by Jelllng. rhus leinng rhe engine

 

 

/

 

«k i

This in: M can lnenuvene liner) is almnsl \aially immune
ia veni slappage.

 

run. bul reducing lhc vacuum. Squin gns irnrn
an oil can around lhc nlmching [mini and lime
wherher the engine speeds up. This is n kind oi
laSI-I’CSDII :Ilspccl for lhi> condiliml, lml il is nol
uncommon in cvcnl of [be following:

MISFIRES ON ACCFI FRATION

A: From lmv speed

If lhc engine is dropping shols under neeele «—
lion jun ell lhc line, but running siuislneiorily
mhcrwise, [he odds are il-mi carburclmn is the
Villainl

@ Examine ihe idle mixiure. The elnssie
symplom of loo-rich low-speed mivllrc is mks
firing on nppllcnlion ni ihroule, Thii is uecem—
panicd by n lumpy idle. Be sure ihe enriching
(or low speerl is nru overdone.

(2) [Jam overlook lhe (ncl Ihill lhcrc can be
walcr in Ihc cnrbllrclar flcnl ho“! which i< sucked
up ni the sun beiore ihe fuel can he replaced—
or water in ihe mesh sirniner and Imp on some
models.

® A clogged nir elenner enn enuse misfirlng.
bul ir will generally also show up as poor per-
formancc ihreughoui ihe range, [00.

(a A had spark plug. where Ihc eernmle por-
|ion is dirly and Cllluc: flmh-m'cr, can aim he
rcsponsihlc for this occurrence. “’11ch high voll-
age is being fed inln a <yslcm il chnnws lhc :micil
way lo go and n (lirly plug is an open invitation la
n direer-ro-greunrl shon.

B: AI 3 giren mm in any gear
If ihe misruing occurs .u n g en RPM. no

 

Idling mini"! idiuslmanl nn lyniul IWHIIllk: umumnr.

Misfire-s (In Acceleration 25

   
   
   
  
  

Tau
snnug Leei 5rW

 

, leku Aim

    

Blcakel
Plum Luk ' Nl<l\
Sclcw \_ , \
Amusing l Grimm
r
Vansh «
5mm ix» . / Mni
lalc ,
‘ ownerpnfnr ,, Mu pun

Wk ”“‘ LIICK Swen ‘snnum

laynut oi onnlari imam pninls llypiralpdmmul unils
have diflevenl adjusting methufls

.unuer u-hnr genr yml nre ming and no nrnuer
wluu lllc lhrolllc npen _ smpccl lhc lullonmlic
walk llllmncc nieehnnr in in AC magncla sys-
lcmfil This enn he gning am hi phuse at n eerinin
RPM. 0n lmuery syslems lhe ignllion may he
out or ume. Over-richncxa can also he enuslng
“ionr-siroklng."

 

 

. A- n giu'll Illrnlllc (Illrlling,
r-egnrrlle..- oi llml

If lhe dropping oeeurs n! n eernin poim in rhe
ihruule seemr regnrilless 01' ihe Rs heing lllmcd
by the engine. ihls is poor enrhureior inning or a
hnd needle, perhaps one which is nicked or
damaged.

D: At no canslslenl lllroule oprxliug
nr IKl’M

lllcon<i~lcnl llll~firing is ordinarily due to mnl-
functioning in [he clcclri I . Go mcl' Ihc
hike lrom sienr in sieru spa _ from your
rignrous seruiiny. Plugs. puinis, eunneeiions. high
lcnsion lead lo lhc spark plug. capnellor. bmlcry
ilhc Whale works can be induldllnll) or collec-
li\cl) responsible The imporlunl poinl is lo over-
look nothing.

     

 

Mufllll hllfll can hE cleaned in sullenl, ll very dim with
ham “mail it can he heated with I Inlcll.

 

26 The Two-Stroke Engine

)IISFIRES

 

ER LOAD

This heading n mean! lo describe n condiuon
somelhmg like run: You are riding along serenely
and nnprunclr n lull. Yuu open in: Khroulc nncl ns
yuu mounl lhc \lopc uiih lhc engine pulling our
in bcsl clluru, ir begins in drup n (cw hcah‘.
Gearing drum, or rclurmng lo lml ronrl Clears
up ”I: ruirfirrng,

U7 le Lllllgnorvii of [his cundllion IS rhnr the
plug is brcnlrng rluun from merlrenring. The
urong plug i< being mad or the gap ii wrong.

 

Cleamng duty narhumnl rs z naclsszly my in lmiing
Iuel lack. Us! snlvenl and plastic sprzyav.

@ Second choice would lie, nguin, rlirxy air
cleaner.

Q, Too Luge n min in. wilh insumcicnr pres.
Mire drop nr wide lhraulc opening nnd relatively
low speed. rcsuks in imprupel’ mixlure. Tuning
is inurcnrcrl,

(4) Poor fuel can plny n big role in [his son of
performance Premium fuel, ns recommended by

 

m assemnlm \ype spark plug can u: um in check
ignitlnn syslem munul wilnnul dear ui shock.

 

Tzk: no asstmalafl vae um: aparl arm use innzr um
m cmk cnnflllinn nl snark nulpm. Naming :lmmfle near
engine and nuelalin: slarter sllnulfl nrnflllc: zuun spzik.

 

I’aor High Spoor! I’vrlnrmunce 27

Mail! Swlhth C

 
  
 

Secondary
igmrlull Coll

‘ 3/ Spark Plug
/.
1

pnmnry j

4 r

Condenser 426%
l \-._ letaclEicaker

\ Breaker Cain
Diagram oi iznilinll sysum using :nii.

(he nmnufdclurcr. Vhould he ll<ed at all limci.
“Cheap" gm is poor economy.

@ Improper liming would be oboul rhc l‘iirh
ilem in line In bl.‘ cumidcmd. Spark liming be—
comc> more criricol n: rhe lend increasci.

(19 Finally and no! in be overlooked: I\ the
goat heing used loo high icr the condiiiom en-
countered?

.‘lISFIRES AT HIGH SPEED

(3 Since (be main jcr. wirhoul being influenced
much by llle needle. i< responsible for mixiure
control al high \pccd. il (hould be looked inlo firxl
oll', Fullu“ lhc (pecificaliom in filling [his im-
porlanl componcni . . . or :ldjuu according lo
lllning iniormnrion supplied in olhor pnrr: oi lhis
book,

@ Believe it or nor. [hill old dirty air cleaner
crop: up again in mi» \iluallnn Check ir.

@ Improper lloor level ii n common cause of
high speed mi<fir84 Scl loo low. [he "on! don
nol pcrmil sufficient ind! m accumulalc in lhe
bowl [0 serve lhe need: of Ihc carbllrelor.

@ Spark plug: diriy, wrung heal range, im-
proper gap, faull)‘. Any or all of lhcle plug
fnuln can be rc‘pomible. High pressure hrcnl:
down of n sccmingly good plug cnn also he lhe
rrouole. Heal range i: preny crilicnl in air cooled
engines. If lhe plug ie [00 cold ir <hon< our if
roe hol il weldr. If lhc gnp i: we greor rhe
inder pressure prevemfi me ore from rorming
acrose rhe expanse belwoen lhe elcclmdcs.

@ Bad capneiior. E‘pcciully on lhe AC mag-
nero syslcm, n poor capacilor enn perlorm wris-
faclorily at low speeds ycl {nil lo pruvenl polnl
arcing nl higher Rs. Haw: ii checked er subslilule
a new one ii everylhing eke u righr.

@ Coil. Same drunrien m wirh cnpneiror.

@ High rension leadsleoking. Bcsure lhc plug
wire i< no! leaning on melal which would invite
a direer ground. Rev lhc engine up and run your

 

ringcn nlong rhc plug wire. You'll reel n ringle
if iher ngc.

(a Air or rlic cnrhnrelor nnngc ix nnolhcr
lily. Folio“ clllcV under (7:, m L GINE
wll x TIJROTTLF IS our, ‘ D.

«n Lcnllng hood gndrer.

an Lenkmg cilindcr/ernnlcnse gruker.

n Bod crzlnkxhnh oil \cill

These rhree can come roolenn u mixurre nnd
lhlh he rc~ponxihlc ior mnfirlng. Try thc mmc
lucllcx m dcxcrihcd m ohccl ror n lurk in lhc cor-
hurelor ilnn Oflcn a rlcw llrcV~ing or gmkcl
compound rnke core of lhc problem.

9 lJon'i overlook rhe clogged mulller rc—
minder. This eondiiion breeds nil soru or \lmp-
lomz.

     

      

 
 

I‘OOR LOW 51‘]. SI) PERFORMANCE

 

Thix- ompiom i; prcrnmed lo he opporcm m
unmhling or kick or pouer al low k: which clears
our in the upper rrmge of ihe engine. Thi< ie
nol l0 be inixluken. oi course. for (he loading-up
which occur: or prolonged idle nnd which dlsnp—
pcnh m alum m crccsx iuel nnd enrhon nre blown
our, bill miller n condnenr luck or perrormnnce
in ll-lc hollom half of lhc power curve.

{3 Number on: lrollblc-causcr in lhifi silualion
i~ improper carburelio wrong idle ndiuslmenr,
“rung needle Vclling. clc. Tuning x Ihr: nnxwer.

a; Second. nnd nor loo far behind in frequency,
i~ improper \park advance. chccn lhmc two,
)ull'll prohnhly nnd rhe rrouolc.

 

POOR HIGH SPEED PERFORMANCE

Complaint: here are :l lack of power nl whnl
\lmllld he lhc pcnk lorqllc oi lhc engine. reduced
lop <peed end lhc need lo \hll‘l down more ire-
quenrly. Acrunlly. in mon calefi, lhe rider ju<t
doesn‘l malice il bul lhere i\ n gcncml lock of
power throughout lhc rnnge oi lhc engine. ll in
only lhal ir becomefi moxr noliceable when more
is asked or lhc engine. Howevcr. ii n is clearly
onl} rhe rop end:

0) Again, wronu corburerion adjuflnlenl i: lhe
prime su<pecL

@ Dlrly. clogged or bod nir clcanen This con—
dilion can he borderline. permi ing enough nir
flow in rnkc core at low speed opernrion bul
cumin; an over-rich condition al full demand

(9 lgnirion riming nnd clennlinm oi ignirion
“"lcm ploy a big pnrr in rop~cnll periormnnce.

(9 Spark plug and wiring.

Sac MISFIRES AT HIGH SPEED (nbmc) {or
more derailz. The engine can drop oil in power
yer nppnrcnily be hiding on every Vlrokc.

@ unnery condilion is imponnnr in cerruin

 

 

28

The Two-Stroke Engine

  

/.

lrllel Peri Heal ”W'Cew’i
Prooi Pack.ng @ \ “a
Cnrlzmelor spring Washer© @

Carbuvemr Lock Ball. \ ‘ ’
onmureror Sex anll ‘
Curbulelur Lock nu!

 

 

Alr Cleaner

Washer
Giselle! Sel

elcclrical circuits. Have it checked for outpul and
abilily lo eomplere the cireuh.

@ Poor mechanical condilion: bad rings, 10W
compression, leaking gaskcls and seals, clogged
pons. Borderline componenls reveal rhemselves
rirsr m [up speed.

@ is die rider loo heavy ior lhc machine?
Surprisingly enough, rome owner complainls srcm
irom th‘ simple incl Ihnl rhe horsepower isn‘l
enough for the job and there's nurhing wrong with
111: bike dl all.

{9 Check lhc lire pressures. Low lines cause
incrensed rolling resislance bul a large number of
riders fail to lake lhis inlo considerations

(3 Check for slipping clutch. See CLUTCH
AND TRANSMISSION Reclion.

@ possible cause could bl: plugged fuel tank
veru or resuicled gas lines.

POOR GENERAL PERFORMANCE

Under [his heading, naturally, can he lumped
any single cause or combination oi cnuses eon.

    
    
  
  
 

: .Carburelor
Cover Ln

 
  

    
 

 

 

\

@\

s3

ceivnbly connecled wilh the enginc . and for
that mailer olher porrions of Ihe biker Bul lel's
run lhmugh lhc mosl common causes, in order of
their frequency.

(D First suspicion should fall on lhe ignilion
liming. If it is of: the engine is jusl hopeless in
perlormance.

@ Spark plug, Improper iype, touled, diny,
elc.

@ Poor carburelion. Symploms or over-rich-
ness or [00 lean a mixiure are easy lo detect by
exnminniion oi plug and exhaust pipe. See
TUNING for clues.

@ Is the bike running free? Check the rear
wheel as the machine sit: on the snand. Does it
turn over ensilyi rs rhe brake dragging? Are
wheel bearings bud? Is lhe ehnin roo light? Any
of these ilums can slow the bike so much that the
tendency is lo suspecl a poor-performing engine.

(3 Slipping clulch. This should he an ob us
condilion lo even a novice rider. bul a surpr ng
number of people don'l noiice it,

G) Poor general condition, Under this heading

 

 

 

29

Poor Gnm’rul I’nrfurmrm'

 

 

m cellnghane slng helween clnsee uqinls, lug gently
arm male llywheel ln linrlng marks. VPnlms shnulc lusl
Voltage regulalnr and cnnneellnns are under seal ul Yamaha npen and release paper when mzlkualncmla

Big Bear and ether mndels.

 

   

Lnnallnn nl liming marks an Suluki an, lypical nl flywheel

. rnlnr AC magneln syslems.
ll ls necessary ln rmnle gear change level on same

mndlls to like M lransmissl'url S”! naval.

   

aurnen nismll shnws eemence nl vannlilinz al exhaust
Use a skin al cellnghane lrnrn elgarene package in unit lack nl nll, lnn-lezn luel rnixlure, wrung spark
emergency lnr checking llrnlnge advxllnl can nmduce this cnmlilinn.

 

30 The Two-Stroke Engine

we find the low-compression causes: worn piston
rings, had senls at cmnkcnse tcyltntier-tocnse, end
senls of crankshntt), etc. And on the highrmileage
model this shoultl be obuous nitcr n routine check»
up. 0n n newer c}e|e, damage to gnskets, lnulty
senls or non—sentetl rings can he the problem.

OVERHEATING AND SEIZING

The uir~caoled engine is a marvel of efficiency
but it is only human. in the motorcycle installar
tion, without ony cooling ion, the engine depends
on :t Stream of ilir Cztllsetl by |he vehicle'~ mo|ion
to cnrry nwny the heal generated hy combustion
and lriction. Overloading or titling too slowly
will remit in a build-up uf heat which. in turn.
lead: to pioton (eizurc and diilicultiei uf Ihat
nnturc. Howeter. overheating under normnl con-
ditieno (that is. under similar ctrcum‘lanccs which
previously did not cause overheating) is a litirly
common enmplnint,

Must small |\\' -strnkers. of the trail variety
pnrticttlnrly. experience piston seizure or some
time in their cnreer without any real damnge.
In“ lclting the machine can] dm\n and fret: itself
is generally sttnleient, but if the engine tines not
perlnrm up to standard after such an experience.
broken rings and scored Cylinder walls are probe
ath to hlllmnt

If |he bike is prone In merheat, any one of
several camei could be present,

@ Incorrect fuel 'ml mixture. lmufl‘lcient oil in
the mixture or the wrong grotto of oil can ctmse
overheating. If the tank I‘ accidentally filled with
straight gm nncl the engine opernled it will seize
in a ihnrt Iimco

r; Loch of oil in the automatic oiler tank or
inoperatiw oil metering device. (See Vection at
the end of |hi< chapter on these devices.)

(3 Fuel-air ratio wrong. Too lean n mixture is
a prime cnuse oi otcrhcnting. Sct carburetor adr
jttstmenl to pr0\ itle richer mixture

Q) Retarded ignition. Failure of automznic ttd-
t ance mechanism or incorrect Static liming can be
responsible.

Q Entrance oi nir into cnmbmtien mixture
Here ii the leaky gaiket or oil seal hit again.
Carburetor, head. cylinder/sump er crnnkshnit
end seating is poor. Squirting gnsoline trom tin oil
can at the junclium with the engine running is a
crttcle test. it the engine speeds up, you've found
the ma gnsltet without much ctrorl.

[U \vtong hcnt mnge spark plug, Overheating
is ttsttnlly ju~| one oi the symptoms when the
wrong plug is med, it helps confirm the causc oi
mistirtng and loss ot power
e»: enrhon dcpns s in combustion cham-
ber. Tole . compression check it it is grossly
high in" the cycle docin't tnn pnrticularly well,

 

 

 

and e<peeially if it hes a tendency to "run on"
after the ignition. there i: a carbon build-up which
must be remmed to restore performance.

(9 This is wmewhat tare. hot if you don't
know the history of the ailendlng engine. it is
pmsiblc that somebody installed the wrong head
gaslet and compression is too high. Or. the heatl
could have been milled at the case stuffed to in-
crease compression and pertormance with a con-
sequent heat build-up the engine‘s fins weren't
designed to cope with.

69 Clogged exhaust port. Accompanies excess
carbon in comhuition chamber.

(3 Clogged exhaust pipe, Too much bnclt pres-
sure cnn ctntsc merl’lealing. Clean the system.

@ Slipping clutch. This is, again, rare and
seemingly impossible to nverlonk, hot it tins been
known to be the basis or on owner's complaint.

6; Chassis fmtlts: htake dragging. bad wheel
bearings. low tires, etc. all combine Io place n
drag on the engine.

(9; Overloading. This comes under the same
general category as improper use.

@ Dirty engine The cooling fins can't dissi-
pntc much hent it they are covered with mud,
dirt or grime. Not that they have to be spotless.
hut an excess of detritus can couse overhenting

VIBRATION
r-teess Vibration is usually directly traceable to

loose, broken or worn motor mounts and all
mounting pninn shoulcl be inspected carefully.

 

 

 

 

 

 

 

 

canntcttng tort etishakc caused [11 mm trig cml hearings
causes plslun slap.

 

 

 

Noises 31

2 Pure gasoline

MOTOR OIL

OIL TANK

 

AUTOLUBE
(on. lNJECTOR)

 
 
   
 
 
 
  

a}; '5

 

AUTOLUEE
REGULATOR
CABLE

THROTTLE
CABLE

OIL FEED TO
lNDUCTION
TRACT

ROTARV lNLET VALVE

PRlMARV TRANSMlSSlON GEARS

Vanni]: Autnluhe nil illiutinll syslem ill Schlmatin (Mm.

The emphmis on (he lnsl word is because a mount
plate can he iraciured under a bolt head and
ihui be concealed.

incorrect clutch assembly, poor liming. worn
crankshatl are nlhcr possibililics, but ihey are
fairly emy ro rrace since [he cmel would eiiher
be gradual lin (he cine of the crank) or following
snme tinkering, If ihe bike is new to you. a
ihorough inspeclinn of all rhese possible causes
should be carried oui since yihralion is usually a
prelude to same sort or failure.

NOISES

Twoslruke noises are dlflerent mini anything
elxe and in the case of [he air—cooled engine they
are eyen more Llluincl in charaerer, Any ah.
nmmal nuixc~ .er cauxc [or inl'ehlignlinn nllhough
they my be only the mull of normal wear
cuuVing grealer clearances, elc, Unusual noi\c§
can b: classified in lhrcc “(I)“ inlcrmillcnl. con-
linunm and changing according to condilions.

lnlvrmim-nl n

 

cs (not nlwaya prcwm):
5) 0n Imnl acceleration, a dirk or claim

can be lhe result of a build-up of cnrhon depmih

on the rings which dearroys end clearunce, or it

can be ewes" e ring land clearance. A heavier
:mmd, but slill n lighl mechanical sound and
somelimc‘ n double—rap it generally worn pihlon
pins or bushings. A Knock under these circum-
dance: is ordinarily traceable m cnnnccilng rod
bearings. ringine is caused by low—lest fuel,
Carbon build-up in combustion chamber or we
much spark adxance.

. lAl law RI"! a mule, ur dank' is indicnlive
of pluon slap or cxccsmc clearance between
piston and cylinder W1“. A lig/lrrr naive bu!
strictly melallic can be the pittnn impinging on
poll openings, Check Ihis by clming ihe rhrotile
quickly and noting if the cylinder head \‘ibrnms.

 

Changing uuiacs

Nukes which change according lo conditions
ordinarily came and go became of temperature
changet. These are melallic light knocks.

g} 0" ginning engine or ulfl'll cold indi—
cates chcshch plwlnny’cflindcr clearance if it
vanithcd when the engine is hm.

3 AI high lcmpi-miun- if the same Sound as
when cold bui diminished somewhal, lhi\ is 3! sure
sign of we much clczlrancc. If (he sound occurs
more when hol ilmn when cold, ll can be a be"!
connecring red.

32 The Two-Stroke Engine

  

lo eloteh emu.

3m pit/Q

, ‘, [7} 7,,

a in

fl \ i" 7
t; not. gt:

    

Suzuki PnSIanrEe luhlicalinn sysllnl in schlmilic inn".

Continuous noises

@ A ht‘nry thump under nll conditions gen-
erally (lands for hntl crank hearing. However, it
can be a tlywheel rubbing ngeinst the cine be»
cause or improper shimming, causing the crank to
be 05 ccnler.

Sharp knot}: is descriptive oi piston rings
catching on [he lip of a port.

(9 Child: noise; are alien credited to the
engine. Ehccss clearnnee hetween eluteh steel
plates and the l :h is n iooler. The noise here
decrcnfics or quil‘ entirely thn the Clinch i~
disengnged.

THE OILERS

A‘ far in convenient: iind cflicicnc) are run-
L‘emcd. Ihc inlmduclion of automatic ailing \}\~
tents mu a dmmnlic improvement in (“Ur‘tll’uite
motorcycles. However, these pumps and their
nttendnnt plumhing gi\e the rider one more item
to learn About And Comid . The rule of iiiilurl:
nnd [uuhy nperulinn h.“ b no gl’L‘Ale than

 

 

any other oil pump system in any foul-urok:
motorcycle. but since mun) deelere end onnen
hnd netcr worried nhent \uch n det ice on it [HOV
smxkc before. there hate been some loud corn.
plnintt when things neat nrnng.

Tun tystems are used One is exemplified hy
the Ynmehe “Autoluhc.” oil is itnected into the

 

ittel-eir mix|ure behind the carburdor venturi
nnd lubrication is nccomplished in the same mam
net as in the com entienal gas ’oil pie-mix method.
The difl'crence is thnt the mount of lubricant
is metered nccording to engine speed and load
with n rich mixture oi oil ier high speed and a
lesser amount oi oil for idling, etc. in addition
the system provides int luhriention wllh the
throttle completely closed where the engine is
heing used its a hrnke on long downhill runs,

1 he second system is typified by SuLuki's "Pmi-
Force" method where oil is pressureded to the
crankshaft and \ii.\ drilled pnssages to the eon-
necting rod nnd then sprayed into the iuel-ait
mixture in the cylinder. The amount oi lubri—
cnnt delivered is eontrolled hy throttle position
and engine ne

Aecompnn, ng illustrations nill make the parts
relntionship c

in the Ynmahn 250 and 305 the pump is
driten oil the main gear (primary) and is thus
opernted only when the clutch is engaged. in
the stunlti, the pump liikfi on item n gent on
the \uu'lzr \hufl end is in aciion regerdlees oi
whether the clutch is engeged or noL The only
opernung hazard oi the Yamaha system in the
:50 and 305 is Ih‘dl oi running the engine ior
long periods with the clutch lever held down.
This is n had hnhit oi seine rider: who wait out
tretlic signals with first gear engaged and the
Ciulch |hrovm DUI.

, is.

 

 

 

Oil Pump Operation 33

on delivery railure symptoms are overhcming

and piston seizure. You can make a quick check

riot» by disconnecting the deliver) hose on the Auto-
lube Iypc and running the engine at various throt-
» tle openings. The Suzuki puntp is behind a cover
{/ at the rtght rear of the crankcase and it has ImnSv

    
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 

'/ parcnl tubing. so oil flow can be observed wilh
Ihl: engine running.

7 - “ ”W“ In can: of failure (cxccpl Suzuki] you can mix

3' oil wi|h the fuel in the Conventional IWa-Slrokc

fashion and operate the cycle long enough lo get .

it repaired.

x. it some g m

OIL PUMP OPERATION

sttzttki

The Suzuki pttmp is a rotating plunger type
where the rotation of the drive worm and the
plunger body is turned into reciprocating motion
. . . . . b' a machined rant on the end of the 1un er
Suzuklpumpl:dllvlnnflklckslanlrgurlfll. “imaging a plunge‘l’guide- The 1mg”! Poi [gm
plunger stroke is controlled by a cam which
changes position according to throttle opening.
The com holds the plunger away from the
guide and limits the engagement of the machined
ramp when throttle is closed or allows it to
touch all of the ramp rully when open. The rota—
tion of the plunger covers and uncovers inlet
and discharge ports as follows:

@ Oil discharging finishes and the plunger be-
gins moving downward while rotating. Plunger
operation enters the oil intake stage.

@ The plunger moves down more and a vac»
uum is created in the oil pump cylinder above the
plunger.

(9 The plunger nears bottom dead center and
one of the two plunger intake pans aligns with
the cylinder intake port. oil is sucked into the
cylinder by induction created above the plunger.

@ 0il intake ts finlshed and the plunger begins
to move upward while rotating. 91'! in the cylinder
begins to be compressed.

@ The plunger moves up more and the oil is
furlhcr compressed. The oil pressure causes the
difl'erenlia] plunger to be pushed up nnd move

 

Plulul mminn conllnk dzlivuy liming in Suzuki puma.

   

 

34 The Two-Slroke Engine

away from the plunger. In this procedure, the all
in lhc cylindc compressed by Ihc diflercnllal
plunger and oil . discharged smoothly.

© When the plunger nears thc lop dead center
position Ihe plunger diwharge port aligns wilh one
cylinder discharge port. The compressed oil is
discharged.

when the pump driving worm is driven by the
lticlt starter pinion, the plunger, engaged at a
90“ angle with the vloml, rotates. A circular
ramp is machlnetl into the bottom of the plunger.
This ratnp section engages the plttnger guide
screw and the plunger moves up and down by
utiliztng the plunger rotating action.

The combillalian of Totaling action and up
and down movement opens and closes the intake
port and discharge ports, changes displacement in
the OII pump cylinder itnd changes the pressure
of the otl. The oil ts supplied wparalcly to tight
and hell cranks-halt benrtngs through tuo oil dts»
charge ports. The oil pump control cable, which
i\ :)nchmnlzcd \Vllh Ihe lhrollle cable, i< filled
to the oil pump control lever. The control lever
is pulled in accordance with the throttle opening
and mmx n can) filled lo |hc lcvcn When the
throttle is opened only slighll), the cam limits the
leng‘h of the oil pump plunger stroke. When
the lhmlllc opening is inercuscd, the cam tums
and allous a longer plunger stroke, so that the
amount or otl discharged increases.

Check \nhm are located in lhe bolls which
hold the oil linc‘ and ”Te cranked“: bearings IO
lhc Cher lScc illllslrduonJ 1hc)‘ ‘hnultl be
clean and fillud with 01' when rcmm’cd and
replaced. Fill lhc hole: in the crankcase “ilh
aboul lD ct: of 01' to make ull’c.

Nam: Be sure the gaskets on the banjo balls
are installed correctly The grooved side of the
gasket should be against lhe filling. (Sec llltls~

 

  

 

 

 

   

0 55th) clcisi

   

 

Adjustment ol IIII pump cunltnl vault in sutttlti llypical).

tration.l
Correct tightening larques: check valvcili
inchepounds; banjo bollsizl inch-pounds.

Yamaha

Yamaha‘s pump is driven through reduction
gears by the primary gear on the engine's cranks
shalt, Rotary motion of the plunger is turned
into reciprocal motion by an eccentric and guide
pin and the distributor plate on the end of the
shaft alternately covers and uncovers inlet and
outlet holes. Length oi the plunger stroke is con-
trolled according to throttle opening by a cam
which moves the adjusting pulley in or out to
llmll or increase plunger stroke, Clearance be-
Nccn "Adjust Plate" and the boss of the “Adjusl
Pulley" in the illuslralian tlclcrmlues pump slroke,
The pulley is rotated by a wire to the throttle.

A cheek valve prevents oil from seeping (ml or
the pump case when it ts not operating.

 

 

Oil pump problems (liulh Iyprs)

5) Improper ndjuumenr pl con|ro| cahl: or
broken CAME

@ Airlock or pump (or bubbles)

@ Pump fnilure

Suzuki l’oai- urcv ulljuslmenl procedure

Q) Open llre rhronle fully and make sure [here
is no play in lhe 'alllc. (Check horh Cables on
mills and yynehronize rhrolllu if necessary )

Q) kemme pump carer and observe lhe clear-
ance hcmccn the comral lcvcr and lhc pin, This
should he .5 mm (.0l9" 020') II is boner la be
on me ugm \irlc; if lhe gap 3: larger. lea: oil is
dclimrcd.

® Adiuu as nrccssar)‘ (m ihe point slroun in
rhc llluslmlinn) will: lhmulc wide open.

Yrmmlm Aulolullo ndillsllllcnl procedure

Tun adjuumcnl precedure< nre used lor an
mahn ope pumps, \\'ilh all No cylinder en-
gincb rhe mljmlnlcnl or rhe opcrzuinu cable i: made
al cloacd rhrulllc pnsiliun; ull Mnglcs arc ad-
just-n1 nl hillHllmlllc. 0n Ink‘l‘ models Ihcrc is
a small Circle marked on (hi: lhronlc valw ID
sham hall-open pmilion. On earlier modoh il
n necemry [0 measure lhe throulc lrarel and
gage the halruay pmlilon.

Mmsul’emcnl 0| rhe pump slmkc is made (as
shoun m lhc illllxlmlion) hcwcen Ihc laws on Il'lc
adjusl pulloy and Ihc adlml plare wilh a mini-
mum Clcaranc: of .24 mm in .30 mm (,09" to
.12") as mandnrery.

Twin cylinder engines

@ Synchronize [hmulcs and adjust the ihmulc
cable at lhe grip for (he neceasary free-play Leave
lhmlllc Closed.

(1) March adjusl pulley guide pm and v mark
on pulley by first loosening the lock nut, lhen
screwing lllc adjusling nul on rhc pump conrrol
cablcl

Single cylinder engines

(D Block rhe carbureror than]: half open.

@ March lhe v mark on the pulley wirh lhe
guide pin by adjuuing lhe pump conlrol cable al
the sleeve nul on the Cable.

If lhis adjuilnlcnl rebulls in 105: than .24 mm
or more rhan .30 mm clearance between rhc pul—
ley and rhe plnle, ii is necessary [0 change lhe
shim behind lhe plare. This la cxlrcmcly rare
and represenu an assembly error, rarher lhan
wear.

Ari airlock in [he pump ordinarily occurs only
in rhe caxe of a replacemenl pump being nol
properly primed. Bubbles and poor delivery oc-
cul’ when cur cnlcrs |he line from :A leaky oml.
Squirring oil on subpcclcd joinls or smearing rhem
wllh grcme will show up lczlks which occur in

 

    

Oil Pump Ollorttlion 35
_ in mu '
H on» .u ,
yuan >1th l finn-
L ii i nlllly
(V «l H il rlAYl
o, in. 1
upon my

in (Hamill? AM 0”

Lin
culaway nl Suzuki numur
7 L

l r
_r.k

/

PUMP WlRE

 
   
  
 

    
 
 
   

\

ADJUST PLATE
ADJUST PULLEY
RETURN SPRING

Minimum clearance al n is .u-ran mm Luanlz'l in:
lzuanapump.

me ADJUS'HNG SCREW
\

 

 

ABJUST PULLEV
GUlDE PlN

   

Adiuslmenl nl pump on Vamahl singlzs (lyuical).

npparenlly lighl unionsr

Camplclc pump lailure is comparalively rnre
but in rhe Yamaha pump, |llc udjusl pilllc)‘ guide
pin um been known in [all mu. \u if rile pump
obyiaualy quits. rhis a rim plaoe |0100k.

Refer Io rhe following eondpmed lroul-lcshool—
ing guide ror lurlher ale-mill on Yamaha pump
problenu.

 

 

36 The Tim-Stroke Engine

 

*“W

 

‘F

 

Cable Guide

/
Throttle Cable
fif/ Jock Nut

, \Adjuscing Screw
/ 0.5 - 1.0mm

Emmi zdjuslmlnt DI thinllle cahll tin Yamaha twins.

 

Pump wire
Adjust nur

    
  
   

e7 Lock nut

\ Adjusr Pulley

Millstmenl III [Jump Shake nn Yamaha twins (typical).

Yamaha pump lnmliloslmoling
Trouble

@ Poor oil delivery
Came

a. Rubblee in oil in the pump cnse
Rzlnrdy

a. Bleed the pump

b, Check the lollowing points for oil leaking:

(l) Breather gaskel

(2) Suction pipe connector and pump ease

(3) Dislribulor oil seal

(4) Distributor plug

(5) Pump case

(6) Banjo and pump case

(7) Pump and crankcam cover

(8) Pump case cover and pump caee

(9) Terminal oi plunger; plunger cover, plungr

er cam oil tea! and plunger oil seal

'l'ronblx

@ Pump fails to work. (Engine works.)
Cause

a. Delective viorm wheel pin

b. Clogged pin hole

Worn pin halt:
Deiermed return spring

chlcdy
a, Clean pin hole
b. Replace spring
Trouble
@ Plunger does not work.
starter plate rotatcs.)
Came
a. Worn or clogged guide groove ter plunger
cam guide pin
a. Adjust-pulley guide pin missing
Remedy
a, Replace pump case cover
ht Replace pump correctly
Trouble
® Distributor hard to rotate
Callie
a. Incorrect achustmenr oi worm wheel plate
h. lncerrect lining of plunger cum eil seal
Remedy
:1 Proper clearance is 0.05 m 0.] mm
1:. Replace or refit
Trouble
(3 Distributor partly hard to rotate
Cause
a. Worn or dogged guide groove for plunger
cam guide pin
Remedy
a. Replace pump case carer
Trouble
@ Adjusl-pulley fails It) move in conlacl with
com \urlncc
ledc
a. incorrect lining of adjustment cnmpnnents
h. Too right filling bclween adjust pulley and
pump case cover
Reltlcdy
a. Refil
h, Replace
Trouble
® Incorrect pump setting
Cause
a. Defective cam ut adjust pulley
b. Defective plunger cam
c, Wrnng fitting or control cable to adjusl
pulley
d Tnn hig clearance beluga“ adjust pulley
and pump cine cmer
e. Ten much play in cable
Remedy
a. Replace
b. Replace
c Refit
d. Replace
e. Readjusi

(Dislribulnr or

 

 

Chapter 3

Electrical Systems

  

One or hm may he lantthnr
rillcr bcctlllsl: ul ilulttnlullllt‘ c
pt‘ricncc. trill. \ lune rtlmillctltlam \\hlcll :er lc _-
well knoun,

rhc finl :lntl eltlcst is the magneto iur lgnlllt‘n
and dry cells iur lights. this a prcllv rttre hut
some models [runt n b) Imc ern still use lL

ntmt httcs ttith nntgnetu ignition hate :1 DC
gcncmmr m an ttltcrnntur tor lighting ’lhi~ is
typical oi many llS»\. Trutmph anti uthcr Britixh
blkc‘ “llh Lllcm electrically

The second uldctt syttetn, mud hy .’\ grcut
numhcr oi ntutoretcles, ts cxactly likc lhill oi
the atttuntuhtle ntth gcncmltvrrhilllcrl ‘uil systems
using (lll’L | Current. Ylll'll:ll"lll. S|I7lxkl ilntl Kil-
\\:l<..lkl l2 250:: models are probably [he must
ram. tnr examples.

the altcrnntur he been atlnptetl hy molar-
c)clc manufacturers because All i|~ rcliilblllty and
\crsnlilit). In the \C system, there are sexcrnl
Vilrlaliom on :1 h ' idea. One ls lit use 1hr
alternator as a magneto ror ignition and put a rcc~
tifier in the circuit to contert in output Io DC
for llghling. A \ccaml i\ to \tllllzc Ihc illlcmillor
[or both ignition and lighting. cmploting AC {or
anything A lhtrd is to use Ihe Lllternitlor to
supply gnlllun and headlight: hut lime a battery
to feed neutral lnllicuttlr light, horn 11nd slop
light rcganllcfi‘ All “homer lhl: nnltor is running
A \urlutiun M | lo 1th DC {or lgnllion in
addition to slop llg tntltcator and horn.

Generally spenltin_ the smallest displacement
modcls in the Iwn-slmkc bikes have the slmplcsl
system: altcrnatur or AC magneto supplying
output directly to the ignition, with other coils
of thc ultcrnalnl’ dcvulcd lo (a) hendlighls and
tail lights and th) charging the battery. chcml
BSA models also use this system.

 

 

 

 

 

    

 

Magneto

The “c0ntcnlinnal” magneto is gear driven
and puts out a whopping guud spark. incrcllxing
lnlemily th RPM, and is relatitcly tree from
malfunctions, which has caused it to he used
on highrpcrfnrmanct: machines rnthcr widcly.

Two types arc in utc. fixed advance and auto-
matic ndeCm 'lhc iorntcr will be found mostly
on racing b‘ es, and hoth types are largely LucasV
built as far as cycles in Ihis country are Con-
ccrrtetl. A “Magdyno” made by 1 cm, which
incorporates a generator in an attaching case is
found on many older British singles. the “per-
alion or the magnclu is the same as it it was

 

37

 

Disintegmled kiiinuttnn nzmnn contact on magnctn can
Ellis! internatshnn.

 

iixzflaslvancz ntgnttn use: utters-n shall and nut which
rtttttitcr special puller.

 

chtrking irnttiutt tinting ui maznetn with static tinting
llzhl/hlilzeL

38 Electrical Systems

illlmc and Ihc genernlcr likewise.

The mosr common problem cucounlered nilh
lh‘e rungnero rs poor pcrIormanCc cnused by duly,
oily highuension pick up and slip ring. Cronk-
c e lapors seep inlo lhe ease and deposil oil,
which colleels orher grime. Replnce lhe oil seal.

Renimo lho pick upr nnd pipe eleon, Make
sure \hal lhc bru\h praise“ our CI Ih: Case in
lcosr w and work freely, Clean lhe slip ring
h)‘ holding a clean clolh again“ ii and nlrning
lhe engine over,
breaker poinls on mags are possibly nol
as or n1 3‘ orhor rgnirion sysrenis, bur nrusl be
kepl irosh. making good conlacl, properly gopped
and czircflill} aligned or all limes.

Broken “ire: or in|crnixl shorls are rare on
magncms. bul rhe lends from rhe pick ups con
no, or shorr our. rhe syrupronrs ore Complclc
luck of dcliv chorc going inlo rhe end or rhe
case. check Io be sure lhnl (he kilbbllrron win:
is nor grounding.

An inirequcnr occurrence, hul one uhioh hm
been known In follow an unskilled overhaul, is Illc
dcslruclion of lhc carbon Conldcl for lhc I]
bullon. improperly imlzillcd, il con be do» le-
grnled 11nd shorr oul lhe mngnero.

E\cn in mnking n quick check on a nonde-
iiiering moguelo. ir is n good idea lo plll lhe
bike on Ihc bland and mum Ihc rear “heel “ilh
gearbox in lop gear. wrlh rhc brcohor poinl
ooi-er plnle olr, _\0\l eon delernrine righr ouoy li
lhe urmnrure gear is slipping on rho Shnfl. for
example.

The fixed-dduincc nrognelos ullllie rl lopered
shorr and mo geor nursl be ulpped on nnd pulled
off \Kilh u puller. If Once Secllrcd, they seldom
uorh oli, bur n can happen. The aulomanc od-
\ance rype has n <e1f pulling nul lo draw llie gear
onro lhe lapel and il also \lilhdravl< So loose
gear on >hzif| can be n problem. Ordin'
rhis doesn l jml hnppen nnd enule non llc|i\crv oi
spork bol resolrs rn oul oi unie lirrngr firsl

Tu Ics| lh: armalurc coil and condenser. rCr
mmc ii {mm Ihc housing and connccl a wire
from Ame Icrmina] of n lwudall dry cell [0 the
cooler wrcw oi rhc orcoler plnlc. Connccl one
side of an nmmclcr lo the ()1th barlcry Icmunal
and [he olher Side (0 [he drmnlurc. Conlinuil)‘
should be prmcn and a rending or 4 amps indi-
cates normal rcsmance.

L's’ g rhe some horrery or n powur source in
lb: 5 m w” make and break lhe conlzlcl nl
lhc crnlcr screw scwml limes wilh :m nssislnnl
holding one end of n shorr lenglh or plug wire
grounded again“ rhe nrniruure body nnd rho
orher oboul w -.i from rile slip ring conrncl.
ll rhe nigh lension _ de is good il will build up
rhe vollage enough lo rnoke n good spnrl at
rhe gap.

Worn conr rings con cruise such n divergence
\I'I unung on low rhnl lhe niognelo is blamed,

 

 

 

 

 

 

 

 

  

 

(merrier lair-iron
a! Smrlmg s chewing 3mm

 

. __‘. snnvqsmne aircrew

   

4
n.” so.»

 

Surely

sure mm

Wiring diagram lor siarler-grnerrlor.

 

priorily ol ariiisn oilrs sinrr 1951 has been posiliyr
ground; prior morlrl years and all iaponrse cycles have
negzliv: zrnund.

 

 

rr adiosl loosen
rlarrrp ion in and run zenevam in ii: rnorrnr nonrrilon
oi orll shoolri or rpnrorirnairly Vo"

Valocml generaior is driven by hall.

 

Electrical Systems

 

 

 

   

   

 

hem Trouble Causes Resalrs Acrlon
{Meme doong «ioooarry donuom ~No wov ro rcpall
Hm Mmml o c dzslo o 3 (ovfdemh‘y R olo o iolory
Dre 5 m Bow lmrswu Lhmglng -so weer muses rFlrd lvuublo and
g f: "‘ (View! snnrr :llrml 0: Carlos! or cclly
° °" -5olrrrrnn speorlrr [narrow or Lell slog,
own” grow we rrrglr A7 7 , , ,
Pig's: - :oor lfr\l'"nl_)r"g «anon», warutnlm -Nu W m moon
droning ono -Shor' mun wooloco bcmuv
:mfllalglrg won
WWW“ lor u Lune-ll
-hcllery list-lo m
m» llzmpelalllrei
‘Bal‘ery lolr ln Whle dais seen on -ll Sulphallan rs
drulrorgeo plales filgM ballery (an
r, "dlllnn ~5pocrlro grcw‘y be :hurged Mm
-Bcliery osoo drop: and :npntrly ye’v wall :lrnam
Mimi eronnn decruaws ~or lo~o Me
n v
“PM °“ rnoroe ‘Vohuge rises ono sulolrolror rs
xoosoo uln'es olruLles soon when greor 'eploce
NEQU'W soluncn loo r‘rrrl (Hnlqmg oar ml” ‘oonory
Plates ‘anlgF pa'llcles llcl 'oke Umqe
n \u‘mlun
-Repeolr:d Mar ru'e -Bcllery can be rReplace bul'e'y
ol drsrnorgrg (horged our roooon,
Shrinkage Renewed decrecmefi rapldly
averrnhn'glng -Volloge m lrmsn
ul orsanorgrng nrgrr
uni ‘elllpemlwes 'bepc'mcl; becc'rc rkeplncf bellow
Sepcrular corbonlrlng 'H‘g” “‘m‘c” ”We

weal-c gvcvl'y
~VVulped plales

 

Battery llmhlems, causes anrl remedies.

Check liming clmcly and is more R mar: lhan
Ho" \arimion in pislon nlmcnlcnl lo nilccl point
opening, rcplncc Ihc ring.

Exits“ bearing war and conscqucm nrmulurc
\ibmllm—l can be mlslakcn for ollror engine mo-
chanical noisos. The condirlon Vhould ho onond-
ed to inasmuch as damage m rho slrofl resully
If (her: is more Hum .005" \urlical play at the
end of lhe shaft, rcplac: lhc bearings,

DC generalor ayslem

The DC generalor-bawd electrical :ysmm is
nnnlogom l0 that of {he nlllamobilc in some
machinu. sligluly dlflcrcnl in olhcrs. lupanosc
bikes of lhc medium displacomonl Varlcly, web
as Yamaha, Suzuki and Kawasaki lZS—ZSOCC
modck, hzll‘: a complete no system wllh u
slanel-dmumo. \Olmgc regulator. coil, condenser.
om, Ncwu Brllkh cycles goncrolly llavo dynnmm
or filnrlcrrdynnmm and mognom ign' on nllcn
DC is usorl. Japanese sysrern. ore llcgullvc ground,
Erilish mudcls built sine: I95l huvc been posi-
live ground. Prior lo rlnl Ihc) were also neg.-
livc ground. Hurley-Davidsons have negative

ground also.

Tllls prolly well llil‘idcs up llu» lmuhlushnoling
lnlo I\\‘0 calcgarics: (a) full syslom, onrl lb)
ligluing only.

lul's Lliapoy: of Ihc $ Icms wll h use a DC
gcncmlor (or dynamo . you spunk Erilixh) only
ior lighling or pcrhllp\ a slzlrlcrrlhnllmo l‘or
uarring and liglus.

Troubles hem generally rcl'nlvc around no
lrghrs, no norn, no Sklrl camel] by a flul bullury
or bad canncclinnso

In any elm, sllspccl lhc bullcry first since il
is (espon‘iblc 90% or lhc time.

'lh: llrsl place In oncok is :1! lbs hungry lorrni.
nak. li lhcy aro slighlly 100w, corrosion occun
bcmccn Ihl: Icrminal and the cables and m much
rcsiuuncc i. put inlo |hc circuil rlral curronl cal-n
flows ll lake» 3 clrml, firm cunlucx, so make sure
all connccliom fil (his dcscriplion.

You can make a quick run or lhl: balmy by
snarling llirncll)‘ across lhc lcrn‘linuh. for an in-
Slfml, with a wire or the hllnlllm of :l pair of
pliers or lho hllllll: or u \Crcwllrixcr. ll )oll gel
a barely pcrccpllble snark or none, lhc huncry i~,

 

   

 

 

 

40

Electrical Systems

 

 

speetlte Gmwly Conve'smn Chem
10°C O“C 10'C 20’C 30'C AO’C
Temperature “A.“ (32.” .534) (58’?) (ah’Fl (IOA‘F)
1 321 1314 1307 1300 1293 128i)
131: 1 304 1 2:17 1220 1 283 127i:
1 331 1 224 1287 l 280 ' 273 1265
'29' 1 25: 1 277 1270 1263 1256
1213' 1 274 12h7 1250 1253 1246
Specific 127‘. 1 2a: 1 257 1250 1243 1235
grnvlty 1213' 1 254 1247 1 2.10 1 233 1 226
125‘ ' 2:4 1 237 1230 1223 1215
12:1 1234 '227 1220 1 213 1206
1231 122.4 1217 1210 1203 11%
1221 121.4 1207 1200 110,3 1ch
1211 1204 1197 1100 1183 1175
'20‘. 1'91: 1107 ‘ 1180 1173 1 Hob

 

sneeine :ravitytetnnmtm nhnrt.

indeed. discharged.

Obvioust 1011 can recharge it. if it is re
chargeahle. but you will ham [0 know why i! is
fldl.

Battery

The small stnrngu batteries in motorcycles are
of low ampere huur capacity and like all hat-
teries. they are seltdischarging in storage. Most
manufacturers 3min: that dared balleries be
charged once a month. Since many bikes are
not used fur smeml mt‘nlhfi at a lime during the
vtintcr. lhi‘ factor ucwunls for lots of com-
plaint». Others are caused by carelusnesh in lcm‘.
ing lightV on where thix can he done with the
key removed. direct shorts in wiring or faulty
\ultnge regulator.

Do not. rcpcal lint, have a motorcycle baltcry
re-eharged an a quick charger at yeur neigh-
horhond (cnicc ~L’ui0n. The charging rate is tee
high and the halter} will he ruined.

'lnehleeherge only. and [hen at a low rate
tuch m LS to 2 ampere’hourfi. You can gn as
high at 4 a h for short periuds. The haller)‘ will
get pretty narrn. hut its long as il stays below
110” il will nol be damaged.

Fill Ihc bllHCl') In the \pctificd level with
nater hetnre recharging,

Alter charging, check rhe (pacific grmil)‘ ill
the electrolyte. A lZwoll battery \hmlld register
uhme [.250 at ambient Iempcralurc of 68”. A
6401! unil shnuld ht: above 1230. Specific gruVl-
u will he lnuer at higher temperature, higher at
Iovlcr lempe nure, in allowance ean he made it
temperature ifi drastically dliicrcm from 63‘. (See
accompanying chart.)

   

Voltage regulator

If lht: battery is consistently low and weak,
the trouble may he in the voltage regulatorr This
is a simple electromechanical Lic\iC: between the
generator and rhe battery designed to hold gener-
ator output to a specified voltage.

The regulator is an clcclro-magnel with a set
of ConlaCl pninls spring-loaded against its pull.
when generator output reaches ahuut l5 volts
("I the iZVVOIl system) or 7.5 to 8 volts (in the
hault rtsrnml the pull of the magnet is suin-
ciently Virong to separate the points and interrupt
the circuit. There is an ndjuning screw which
regulates the gap between [he pain“ and, thus.
the cut»oul toltage. In aetinn, the points are in
a constant state of Vibration and a regular llow
of CulTenl is permitted.

To check |hl: regulator disconnect the battery
lead. Then ennnect the negative lead ot 3 Vol!-
meter tn the D terminal of the generator and the
positive lead to ground. Start the engine and run
it up (u the poinl where the voltmeter stops
flickering w l' and selllcs down to a slcady
reading Thh is [he cut-out Voltage and should
he apprnximately the values given above.

It the \nllug: is low, shut off the engine and
turn the right-hand adjusting screw slightly to
bring Iht: points closer together. It voltage is
high, adjust the gap wider. it doesn‘t lake much
of a rum on the screw l0 afiect Ihe gap, so take
il easy. Stan the engine, re-check and adjust as
necemry.

The output voltages gi\cn above are [or am-
bient temperature at 60' to 80’. If it is hotter
than 80', lower the reading a bit. say b 5 Volts.
0r, cumerscl)‘, it below 60' substnntially. raise
it a like amount.

 

     

ln ndrlirion lo imprupcr nrliuslnieni, lhe rcgu<
llllnr sullcrs from oihcr ills:
Rogululor problems

He e an: some rcgulnlor ireuhles which can
cause ii to uorl; improper!) or nol all all.

l. Dlrlyconiacl poinrs

2. Burned conlncl poinls

3. Broken er shuricil niring in coil

4. Loose or lmd cormcciions

5‘ Poor ground

Vibration of Ihc cycle cruises most problems
and if lhc reguirnor is nol operaling nr all, search
[or had cnmlccliuns firsl,

Dirl) peinls enn besl he shined up by inserting
n piece of paper or n husiness cnrd hemeen lheni
nnll hurnishing h) rmullng lhe wiper or curd.
llnrned phinls enn he dressed wiih \cr) fine
emery clolh, Hired in llre snmc wa).

A check can be mail: for .1 bad coil by running
[he engine and holding the nrmulurc doun so
lhal poinls npcn. 1i lhe) won'i my down Ihe
wric< \\inding ii bud. I! lhc cnil pull: the
conlncls lipurl bul \lolliigc llocsn'l drop [in imli-
calcd by rho Vollmelcl'). lhe shunl windings are
broken.

Culoul

The ulhcr pan of rhe regulelor is 11 cutout.
a relay, \\' ch permits the non of elcclricil) in
only one direclion. The mngnclic force cxcncd
by in coil is mad lo overcome lhc rcsisluncc of
n spring nnil cinse n circnir m lhnr currenl can
flow lrom Ihc gencrnlor to [he ballcry. Olhervlisc
Ihc circuit is broken, prmcnling current drum
ironr Ihc bnuery,

This cllloul is relnlivnly Irouble free, except for
occasional sticking puinls. lr lnkcfi uhoul 12.5
vcln from Ihc genenuor lo mnke rho cumin
operale in [he lZ-voll s)slem nnd nboul 6.5 in
Ihe 6-voll syslem.

 

)‘Cme Gap

own

Upl /
Vol|agc

   
   
  
 

Donn v

Regoialinq
Ynke Gap
— a 9 rl o

\ ngh~ Speed conlacl
Poinl

an Speed ,.,
Cunlacl Palm

anhu ”Elihu" {typicalli

Poinlcop
am 5

4-1

E lccl ricul S ystvms

/£ Core Gap

/ a.r~n 1

       
   
  
  

 

Up ‘
Voliagei
Downi
Regulating
Plale ' <7Ya°§§lgflap

 

 

 

 

 

>J

PEnl Gap

aka:

 

 

cumin relay (typical).

Complclc DC system

This ysiern uses generaiorrbnllcry currcnr Io
snpph igninnn neetk as well as Ihose or lighling.
In nearly all cases, lhe generator is n sinner-
Llynllmu. This curl) Triumph Thunderblrd is an
exception,

The regulumr. cumin and ballcry problems
are lhc same a: previously described, hill the
ncw elcmcnl of call . d condenser enrcrs lhc
circuilry. Aim lhcre H more opporlllniiy for the
ballcry I0 discharge hccnuec of Ihe added con-
ncclions.

 

 

Gene-ruler problems

If lhe hnucry is 11m, lhc fir“ place in check
is lhc \olmgc rcgulnlor. Disconnccl lhe bnllery
lrom lhc rcglllalm B lcrmlnnl (or A lf bike has
im :inlmelcr) and canncci lhc pusilivc land of Li
vollmeier lo ihe lermlnnl. Ground Ihc olhnr lead.
eilher on line regulalor E ierniinel or n suimblc
5pm on me bike.

Slnrl lhl: engine and run it up {or a check on
regulnlnr oulpui as described before. If there is
no juice, check lhn generalor oulpul by keeping
Ihe engine running a: aboul 3,000 rpm and re-
movmg lhe wire from ihc genornlor F lcrminal
and grounding ii lor nn inslnnl. If Vollilg: rises
to oicr 25 \' (for 12 V) or 13 V ((0! 6 V) Ihcn
lhe genernmr is good and mo rcgulalor is nl
laulr. lf mirage does nol jump up, lhc generalor
ls bad,

Some Hurle)s hme a vollage regulnror, some
do not. 'lhose which haw no rcgulalor employ
a lhrcebrush guncralor or lhe lype round on
Model A Fords. This is a reliable sclllp and
we field coils are used, one lor igniiion, [he

 

 

42 Electrical Systems

other added when li'hls are turned on. The
movcahlc (narrow) third brush Contrels outpul.
Moving the bnhh in the direction of rnlalion in-
creases output, moving it in the opposite direction
reduccsit.

Here are possible causes at generator trouble.
. Pour connections trr shorted terminals

Oil or \ ‘zllcl’ in case
. Carbon tlust rront brushes is shorting out
nindings
Poor brush contact with armature
Worn-out brushes

6. Commutator or armature is dirty, pitted, or

rough Cittmng hats-hes ta milkc poor contact,

7. The gaps between the armature commuta-

tor segments are titled with carbon.

3, Field or Mnlnutrc coils hm'c broken wires.

For a quick test at the generator. tr) to motor
it h} cltltiltg the points or the cutout relny Thi
causes current to than from the ballet) and it
:huultl ipin.

Disassentbly and examination of the generator
should mitkt: tin) of the (“VHS candilivns oht'intts
except broken wiring. T0 check the licltl Coil
for continllit a Scl of [wt leads is nccenary.
Remove Ihc w is from F itnd A terminals and
attach the tester. It there is no continuity, there
is .1 broken wire in the field. If lhi< lens a ,
chuck the airing of thc trike iur poor imulallnn
sthich can be shoning.

The armature is tested for continuil)‘ by prob-
ing the shalt and the camnmtatar. if there is
CUnIll‘llll . there ix 3 «hurt in tht: Windmgfi.

Draw the :lmtnlurc contmlllitlor with fine emery
cloth and undercut the mica insulzllofi with a
pocket knife or a ground hacksaw blade so that
the ~egntents are clearly separated.

The presence of ‘llldel’ till the iitlc nl IllC
homing indicates [hill the generator it ilrroning
solder aml is shorted internally in the arnlnlurc.
Replace lh: armature if in doubl.

ln replacing the generator, it it is necessnrv
to replace a negatitc ground with a nositne
ground, or Vice versa. Motoring the unit for n
few reminds with the current from the battery
nill polarize it to the new polarity.

mu..-

v.3,

 

 

 

 

 

SIarll-r-gcneralnr

This combination is not nlcrcl) an arrange-
ment trherc the generator is motorized. A gener-
ator has very little torque with the normal vtind-
ings. m a \rztner-dynumu has two sets or field
windings and hrttshes. ‘lhe starter windings and
hru~hcs are much heavier than the gcncmml‘ cant-
puncnh, hut are subject to the same problems.

Ptror internal connections can also plague Ihc
starieregencrurur and these units are more suscep-
liblt- to carbon dust. Check lhc same item: in the
starter portion as in the generator portion vis-
ually (ind for C(lnlinui ,' with the to“ lendfi.

 

Ti

starting mnlnl. (I) artist, (2) brush swirl]. (3) min coil,
to) pull core, t5l tcnaiaal, tel internal gear, (1) tall hearing,
[I] sntnnkll shall, (9) Splnckli. (In) 1w hnuslllg. Ill) planes
my gear, (11] can!" nearing hnldll. t13l yarx, (I4) atmatan,
ttst cover band, tisl commutator, ttn cannatatnr eat tum.
tlal liulillg hush.

Separate starter

A separate starter is found on many modern
cycles. It is analogous to the generator in its
|r0uhlc~ and should be handled [hr same way.
Starter drive chain wear and spracltet wear can
ht: a problem on highemileage bikes because the
ordinary ovarhaul does not include a chain un-
lcsr |hc Condition is fairly Critical. This may
he the source of noise when starting. but most
riders do not strip donn to repair it until the
chain or sprocket finally fails.

Alternator

The nllcrnillur is the modern outgrowth of the
tlywheel magneto and is the least troublesome,
mast emciem method of generating power in
|hc small displacement machine. It is reliable
in that there are no hru<hei or slip rings and
no segmented commutator, also the rotor is a

 

 

 

     
  

 

  

Alternator schematic tfizllam and flirts
idlntificatinll. Dllcltiu

 

4.3

E leclricul Systems

 
    
  
 

 

Stator. (t) lst clinging nail, in taimiml black, a) law vnltaz: three-pale earle. l4) insulating snealln, (5) cilil fixing
screw, (5) Satin] washer, in 2nd enarging erril, (8) stator plate, (9) cnil fixing screw, um tin-plated copper wire. iintnr. (It)

Elsinl,(|2l[milnilus,(l3lmlznlt,(Mlhuh,(1511ivzt.

permanent magnet and has no inlemni wiring.

Alternators are mounted on the Crank<hait in
some models, driven by the crank in others.
The operation depends on the principle trial if
a magnetic field is interrupted u currcnl is gener
ated. In the nllomntor, the rotor spins instde n
housing \thich has six coils mounted inside it.
Current {lows in one direction as the field is
intermpted going in and in the opposite direc-
rion going assay,

This is changed into direct current for use
with storage batteries by a selenium or silicon
rectifier or a Zener Diode, doticet which permit
the flovl of current in only one tlircction,

in some models. such as Honda 5055 and
65:6, BSA, Suzuki 50, elm, (tn “energy transfer"
system is used where tho AC is fed directly to
co , puims nnd plug for ignition and to head-
light and taillight. DC is used for charging the
battery nlrich supplies juice for indicator lights,
horn and stoplight.

In this serup the points are wired in purnllel
with the coil rather than in series and the points

are fixed, timed to open al peak output of the
current buildup, and so the current flovts only
one way through the coil.

This d ton of current is accomplished b '
multirpnsition ignition and lighting 3“ itch which
Cuts the coils oi the alternator in and out of the
circuit, Generally mo of the coils are \tircd into
the batten-charging circuit, two to the ignition
and mo tor lights.

Many AC systems are 6-s-olt, others nre 12-
mll. di\ided along displncenrenr lines with the
trigger models having the 12401! system. BSA
and others with Lttcns 12-\olt AC use a Zener
Diode, rather than the rectifier.

To check the alternator output it is necessary
to hme an AC \ollmeler and be able m up 'tte
the engine \Yllh supplementary battery ignition.
In general a fi-voll nlrcrnalor should put out about
4 Volts from the "ignition" coils (first switch
pusitionl plus 2.5 additional {DI the second and

  

 

 

2 Volt: from the third. This is at about
3,000 RPM.

44 Electrical Systems

 

Explnfllfl View ul flywheel malnlln (Suzuki).

Connections ior tzsl lea-h can Lit: mad: {is
iollows;

Disconnect the three alternnlor leads from Ihe
snap connectors and connect a 0~I5 AC voltmeter
viith it 1 ohm loch] rcsisror in parallel with thl.‘
lhrct: lender each in turn. Low reading: on any
group of coils indicate that wiring insulation may
he Chnlcd or broken or that some (if the turns of
wirc in the CDllS are shun Circuitcd. ND reading
for any group of coils indicates that they are
grounded or an open ctrcutt exists. Low read-
ing [or all coils can indicate that the rulor hm
become partly demagnetized.

Lucas RM 13 alternator

The Lucas AC ignition system is connected to
ensure a iully charged battery under all normal
running conditions. in the case of machines
fitlcd I-ly thl.‘ smaller Model RMIS alternator, the
charge rate may not alw be found quite suf-
ficient to meet the requirements 0! low peed
tovm work. the runningrin pcriad, short winter
runs imnlving long periods or parking with the
lights on. Lint] similar cnnditinnx In lhis cvcnl,
the charge rate can be increased by interchanging
two of the three alternator cables where these are
joined by mcnns er snap-connccrors to the main
harness. To do this, switch oil the lighting and
igition switches and disconnect the dark green
and medium green cables by pulling these cables
from their snap—connectors 11.: dark green ai—
tcrnnlur cable mint now be conncclcd t0 the
medium green harness cable, nnd the mediunt
green nlternalor cable to the dark green harners
cable.

[1, due to a change in running cond' ons, the
battery i< found to he oyerchnrged, as indicated
by excessiye gassing or the electro 19. and a
frequent need for topping-up, tht: original connec-
Iions must be restored.

 

 

Reclificr and diode Iroubles

Heat is the enemy ol these units. Keep Ihc
aluminum heat sink OI the diode clean. Be sure
the mounling boll of the rectifier is tight. Don't
take the haltery out of the system and operate
the bike for long periods with Hendas, particular»
ly, because at the danger of overheating the
rectifier.

    

Secondary coil
Hgmhon (Oill

Pttmcrv 207 Pole
iflywheei magneiol

Srllellzlic nl enemy ttanslet ignition syslltll (Sulllkil.

Selenium or silicon rcclifier

Rectifiers are generally filled with [we AC in-
put connections and one DC outlet 0n Lucas
rectifier: the center terminal is the outpul side
and other types are easily identified because of
the diepnsition or the wiring,

To check the rectifier for continuity, simply
Connect one lead of n voltmeter in place of the
battery lead and go to ground with the other.
Then start the engine and read the voltmeter.
II should pass 7 In 7.5 volrsl

To check it for leakage (permitting DC eurrent
to flow I-lnck from the batler connect the
mounting bolt to the appropriate terminal of
a battery (positive or negative depending on the
ground nrrungemenllt Then using a .05 amp
leit hulh. 0r aimilar bulb. Complcle a circuil
from the other battery terminal to the AC tenni-
nals of the rectifier in mm. If the bulb lights.
then: is BKCe§3i\’C back-flow and the rectifier is
not valid.

 

Zt-nt-r Diode

Afiuniing the battery is in a low state of charge
its terminal Voltage (the same voltage as across
the diode) “Ill also be low. Thcrciurc, the maxi-
mum charging current will {law into the battery
from the alternator: at firsl none of the cur-
rent is hy-passed by the diode because of its
being non-conducting due to the low battery
terminal volts, However, as the battery is quickly
restored to a lull slate of charge, the system volt-

 

 

 

Termncls

 

Spacer

\

   

 

Insulators

Sentinnal View ni rlclifilri

acne»; should he

vzio-v lr NA

’3‘

&

 

 

 

 

 

 

 

 

 

buirew ev =/\>(

 

 

a
m

 

 

 

 

/ /

u

Checking rectifier in! "His! WWII“ ilnw (leakage) with
millilmmllr—rezdinz shnuld be less than 10 ml.

  
   
    

Selearw recr‘rer

 

aoitcry

 

A

Simple rectifier test is to con-rm in circuit with hallsry and
lilhl hulh.

 

whrie wan red :rarev

Electrical Systems 45

age rise> until at 14 \‘ulis the chcr Diode bee
crimes parrially conducling, rhcrehy prmiding an
rrlrernaiive pain for a small parr of rhe charg-
ing eurreni. Small increases in hairery \ollngc
rcsull in large increases in Zencr Bonnlucril'ily
unril, al approxinrarcly ls volir, aboui s anipercr
oi the alrernaier eurpur is byepa ing rhc harrery
'lhc hariery u ill continue re receive only a por<
linn of rhe alrernarer ourpur as long as the sys—
icnr volmge is relnlively high.

Deprcs‘ion of the syslem voltage, due to the
use of headlamp or other lighring equipnrcni.
causcx Ihc Zener Diode currenl to decrease and
me balance lo be dchricd and consumed by [he
cumponcm in use.

If the elecrrical loading is suflicienl Io cause
lhc system vellagc re rail to 14 yells, ihe Zener
Diode will rmerl to a high rcfii‘tance sure of
nun-cenducrivrry and rhe full gcncralcd oulpul
will go lo mecl lh: demands or Ihe balmy.

 

Tearing rhe Zener Diode

The [oil procedure given below can be userl
when ll is required in check rhe perlerrnance of
the chcr Diode type ZD715 (supplrerl for 127
Voil originally equipped and 17 oil convened
molorcyclcs) uhilc it is in pas on on \he ma<
chine.

Good qualily moving coil meters should he
used when timing The voltmeter rhould hme a
scale 0—13, and Ihe ammerer 0—5 amps/min The
test procedure is as follows:

1. Disconnect Ihc Cable 1mm Ihc cher Diode
and cunnccl ammclcr (in series) between lhe
diode Lucar lerminal and cable prcho ‘ly‘ dii-
connecred. The arnrnerer red or positive (+)
lead must ConnECI lo the diode Lunar terminal.

1 Connect \‘ollmetcl' across chcr Diode and
heel sink. The red or posilivc lead rnusr cone
necl lo lh: heat sink which is canhcd ro rho
lraare oi inc machine by ils fi\ing bells and e
scpume canh lead. The black lead connccls
lo the Zener Lucnr terminal.

3. Sum ihe engine, cmurc rhar all lighn are off.
and gradually increase engine speed while an
the same rirne ehserring both nrerers:

:r. The series connected nmnlcler musl indi-
eare zcro ampay up to 13.0 volis, which
will be indicated on the :hum conneclcd
vellmcier as engine speed is slowly in—
creased.

h. Increase engine speed srill lurlher, unril
chcr currenl indicated on nmmcler is 1.0
amp. Al (his value the cher voltage should
bc13.5 volts [0 15.3 \‘olls.

c. Disconnect rhe balmy while rhe engine is
running, and slowly increase engine speed
unlil Zencr currcni indicated on the amme-

 

46 Electrical Systems

“Jr is 5.0 amps. Al thi‘ \‘aluc Ihe Volt-
meter should indicate 3 chcr \‘ollnge 0f
12.0 to [5.0 mm.
Nola: Test “c" should be carried out in
quickly a< pnwihle lo avoid ovcrhealing
Ihe Zener Diode.

Ii Ihe mnmcier in Icil “a" regiflen any current
in all before Ihe voltmeter indicales 110 volls,
lhcn u replncemenl Zener Diode musl be filled.

Ir |c>| “'n' is salisizlclur)’, bul in lcsl “b" n
higher anlngc than that stated IS registered on the
\‘allmcter, befnre [he nmmeler indicates 1.0 amp,
then a replaccmcm chcr Dinde must be filed.

If in text “c" the Zenel’ Diode does nol pass
51! amps \\i|hin lhe stated \‘ollage limits. it should
be replaced.

Chm-king lilo energy Ir lei- .yslcm

Tu Check out the AC coil in this syslem as
used by BSA and others, il is nece<ury |n take
the allernaior am of the Qslem. if the cngine
is a lwin um 6-voll ballericx are needed and the
hookup i} made as [allows in Ihc BSA:

1. Dificonnccl Ihc allcrnator leads,

2. Diiconnccl lhc black/wllow “in: [mm Ihc
condcnocr ill lhl: righl hand coil and connect it
lo the posiliw lcrminoi at one of lhe ballerics.
Connect the ncgnlim Icrminnl of the batter) to
the condenser.

3. Disconnect the black/white wire 1mm Ihc
alher condenser and conncci il In the positive
lerminal or Ihc >ccund bflitcry and Ihc ncgaiive
Itrminal of the condenser.

Thi. mum a supply or current normally de»
livercd by Ihc alicrnator.

Remove lhc lead from one spark plug and
Upcn and clusc Ihc breaker puino a couple of
limno. H u mark can he induced bzlncen me
loud llnd Ihc plug or |L\ ground, then the coil
and condeihcr serving lhal ping are in good shape.
If no spark‘ then modulus a knoun good coil
or Cundcnscr.

This <ame pracedurc can he fullmved with
an) hike hmmg |hi~ urrungcmgnu

Nam: Il i< \ery important to make Ihis tea
a: quickl) us punihlc since |hcse coil: are run
designed lo npcmm on no and can he olerhenlcd
and ruined.

 

llisccllnncmh .lu-rnolor ilnrns

Thcx'c arc pilrl ularly imllblc-[rcc units, but
lhc “Iring and mum in oomc models cause
problem“ unu- Contucl mlm be good. ln addi-
llon, n digln nimcmcnl in (he suilch can Causc
o clulngo ln Alternator oulpul by culling in or
am Ihl: Miriam coilx. Cmilinlnly and resistance
lam can be run uni. drop cquipnlcnl bul the
average rider mlm rely on visual inspeclion and
(lcdllcliw reasoning.

 

 

 

  
  

OVERLAP
MUS'V BE EQUAL ON BOTH
SIDES WHEN POINTS ARE
BREAKING

ng oi paint: with ruler is mailed in mm
llansier system.

/

c— Cnlrecl
@ Camacl
l IS wnm
E) On: Side

‘fl" cnnlacl

/\\Cnniamlnntion
I u(
1/ the Contact

Breakcr [wink contact conditiunsr

 

“\Ho.

 

L2“ flcqllcnlly encountered ll’OHNCS include
a Imlsc roror mined by inallflicicnl lighreaing
of lhe .xhufi nul and mo liulc clearance llclwccn
slalor palm and rnulr. Thi\ clearance \huuld he
approximaleh .007" lllake ~urc polo nurh are
ligl‘n and nnl pcmlilllng pole: lo rub on me mlnr.

Bronkvr points

\Vcan lhc allrilion cl counllc» electrical div
charge: hclwccn Illc conmch, is ll": enemy of
breaker pain“. l’nnr cnndcnscrs hnslcll flu: end
by "0| cernplelely zlhmrhing rhe currcm imluccd
in rho preee». A build |p ol melal (“Hamlet")
un um: poinl i» an in ' rioa of poor condenser
capaehy. as are pninlx which are blue from heor.

Point» are cheap and easy In replace, Don'l
\r)’ \n mu: lhcm if|hcvx|rcl1lr goncl

If you clean the palms cvcry 2,000 milci or so
uilh finl: emery clolh, or even in“ burnisll rhem
Will] a business card lelcd hcmccn lhc cloxcd
eomaeo “huncxcr you :ldjml the gap, lhey will
sunlvc much longer Ihiln ir you ignore Ihcm.

If pain“ hurn consislcnll)‘, check lhe connec-
lions or rhe hallery aml ground. Exec» \nllzlgc
dchrlCIl lu {minis us llle lcafl-rcfiflmicc palh
could be (he |roublc.

0n lwin:, where um sets of pain“ are mod
and il i» ncccxsnry to alter lhe gap or one in
match the liming on rhe olhcr. this is permieiihle.
It is honor to have a varialiun in gap lhan in
timing.

Like“ c on magaelo modck, if gap is in
.003", ii is better to let it alone than Io rc-Iimc Ihc
mag.

Dislribulon sull'cr from weakening of aulomab
ic admncc rpring< and a general ail-soaked eon-
dilian on molorcyclcfi. Ouliidc or cleaning the
unil up. all you can do is replace the spring‘ if it
l\ a high»milcag: unil. \Vlll‘l lhc Convcnllunzll
slribulor, scruflnizc Ihc hnkclim cap for mick-
ing. if poor ignilion problems can'l he laid al any
olhcr doorslcp. Thin i: really prcuy rare nllhough
cracked and broken caps aren'l. But Ihcy am
also prelly obvious.

 

 

 

Spark plugs

The spark plug is seldom worn our in scnicc
hul generally fails became of impmcd operating
candilians. Carbon formalion, lead fouling from
gasoline addilivc< and other dcslruclivc forces
cause the clcclmdc‘ ID CCMC hcing lhc cmicsl
pulh lor mrrcnl to follow.

Best advice ahoul plum is replace rnI/lEr man
repair. The accompanying illuslmliom disclose
varioru plug condilinns and causcx. A nudy ol
rhem and a eornpari n helween |hc phulos and
your bike's plug\ will do much in edueale you
on engine operaling eondilions.

   

Elnclricul Imus 47

 

     
   
 
 
  

n T. CABLE

cowggoo V1 FIG. 63 Distributor

DlSVRIEU'ION
icons

W. RoToRAnM

El.

9 CAPACITOR
councioaunzar -
szm

e) FIXED coNrAchTE

/s£cuawc. snazw

com/ac?
ANUSYER

BASE PLATE
5311mm: SCREWS

Cnnvmlinnzl dislrihulnr as used llll Nnrlnn.

   

Enllsuucliml

I)! plug: having dilllnnl heal langls.

48 Electrical Syslems

Ahmys use the plug recommended by me
munuiu urcr {or normal condilmm H II): rcc~
ommcndcd plug n clearly loo hm or too cold
{ur the cundimms )our cycle cncounlcrs, g0 m
ms nu“ slap in ma hum range. Sn |hc gap
nghl. Map in clean and ymA'll hznc m: if [he
rc~l Or |hc igniliun aplcm Is wurking‘

 

 

Mixtuv: (an vich, pluK (nu mm m cundilinns‘

 

Plug n1pluguhealrangmmixtuve land.

Cuil

Cons \uflcr from merhealmg, principally Lcnv-
ing |he ignilion on i: an invilafion (o ;\ mulled coil
fine: Ihc currenl from the ballery will flow
Ihrough (he poims and inlo |hc c ' To Check
the condilion of :\ duhious coil, substitme a known
good 0ch

Mitxur: tun Jun, nluz [on Mt lnr canditinnsv

 

fliHnulzd Illug.

 

 

Chapter 4

 

Clulchc: and lmmmksions on [he

and rcllehcl)
geneml silualion n gcncmlinn of riders ngo.

 

 

M n-

w sW mm .

 

 

;(:'

[lphfled drawing 0' Kawasaki clunky

modem
meieicyele can he mid to be highly developed
trouble flu-til“ cunlrusl [n [he

 

 

Clutch and Transmission

Cfliaway View uf “and: celluifupl clutch.

The modern unit-box is of the conmmlrmcsh
variety and grcally simplified. Clulchcs are al—
mesi nll til lhe snme pnuem, Wcl Illulli-plulc
on [he counlcnhdfl, with :ome centrifugnlly
npemled iypes on [he smellesi displacement mo-
dck. and o. lcsscr number of dry nlulli or single
plate lypcs.

Tu gel m the clutch or transmission mcans
a striprduwn nn most Inpnncw machinm and a
fair amount (if labor on the olhcrs. So it i< best
to be aware uf ihe enrly symptoms at impending
tmuhle and take corrective ucliune if possible,
helnre [he wnm uccun. The bcsl prcvcnllvc
medicine for Clulchcs is to keep mljuslmcm cor-
reel (with enough [me play m ihe lever lo
nllew enmplete disengagement), and to make gear
changes with n blip of lhrolllc inslcad of speed

" shihing. This i: clcmcnlary advicm but if not

49

rulluvtcd, some of lhe following symptoms will
bc sure Io show up

® Engine speed inerenses when throllle is
opened hut machine doesn’t
Caused by (a) insuflicicnl spring pressure
(b) worn friclion discs
(e) lack of oil if we! mm
(d) too much all ifdry yp
(e) not lullyrclming

 

50

Clutch and Transmission

tv

 
  

 

gt $9qu
{sag $71393 i

lam mndel Triumph eiulch. ‘

rtureh

""“Wurttv rittrhntttt

vim/Mme“ t-sc

rim
sprint ( "m‘

dulvh httr a ,'

 

    
   
 
  
  
      
    
 
 
 

riulrh boss

mxflyrethhtm thun
mt smit
an!

Cunk shin

 

Push

semi wit. t

pressure
Pille

nitttnit zttattgettmti n1 Yamaha 250 tunnels.

Lei“ lake Ih' leasl-<erio||s first. lack of sui-
ncient tree piuy. There should generally be w
or so mmemenl m the Outer end of Ihe han-
dlebar lever (or Va” clearance at! the inner end)
before the clutch actuating mechnnisrn begins Io
tie (\thing lo the clutch. This ettn he udjusled
m the later: where Ihe cable enlers Ihl: housing
and or it the uc|uuling uteehnnism inside the ,
homing, It is imporlam in make <ure Ihnl there
is no pressure on the rclcaie mechanism ill the
[minl of disengagement Too much free play will
reiult tn difficult gear engagement, or more pre-
cisely, nhrupl and grinding noises. Ii your selling
ui the tree ptny :idjuslmeni ehnnges one condition
for another, yuu'\e gone inn [ctr and sumething
in bcmeen is indicated,

In Briliih hikes and olhen with rod-aelunlcd j.
Clulch mechankm (see lhe Royal Enfield il~
lu<lmlinniY lhe ‘crew which ii at the end of the
pushmd passing through the mainshak mus! he
Ilnscrmwtl slightly ii there is no actuei tree play.
The clulch release cable musl be slackened cfl

 

 

Clutch and Transmission 51

Pllmily am anal
Clinch aim camplele
. anayy dim-n gm
1 Clulch Imlu
mulch we wml Cluth lnclmn disc 7.1m

’r
2
z
2
3
_ 4 mm plalc 7plales
, s 4, Clutch plan A lplzlr
, 1) Clutch plale a spins
_ a s
, a
' 7
' , a

elm mm
mm spllngs swings
Clulch plessule plill.‘

Glitch Mm mull pm

  
  

5mm Hal msrm

   

l
a {6m min

   

Clutch Mu mm
in :lo sleelbll fi’lfi‘ \ ,
l'l‘ Clulch llllel mind camplel:

l1 Clinch adluslm " “329

3 mm “mm mm pm

[winded View nl Manda 450 clutch, lyniul ul all mndels
alum 9m.

While [his ndjufimenl is made in order nol (0 ins
fluencc it. Clearance of 1,32" lo “6” at Ihc
sleeve a! Ihc housing Should be SCI and any slack
in the cable laken up m ihe handlebar adjusts
nlenk.

Insumcicnl spring pressure or worn frickion
discs are indicalcd if (h: adjuslmcnl is corrccl
and Ill: clulch still slips. parlicularly “hen spccd
shining. Analher lime at which lack of binding
pressure becomes noticeable, ii you aim in Ill: 9555
habii of speedsshilling. is in klck surung, The gin—5 "
clulch which is on the counlcmhah. as in mosl
small bikes is gcaml up In (he miimhan and

 

 

 

 

 

 

Korquc is mulliplicd. Eleiflnce M 7“" in V," at imlu and ill levu is specifitfl

In cm: of poor friction discs lherc ix lilllc
“hich can be dam- in lhc nonradiuslablc prcssurc

In! Kiwzsalli clulnll release.

   

Inluaal clutch adlustmenl nu Kawasaki. A quanemnm
Adiuslinz clutch level I!!! play at Musing nn Kawasaki. nl sclzwnulwavd is nnminal adjustment.

52 Clutch and Transmission

 

Exulnded VilVl ol llnyzl Enlleld :lulcn, typinl ul nllshrllfl»
npllalefl clutches.

SMALL
GAP HERE»

 

  
  

  

  
  

 

‘lvi:

refill

   

r”.
l

     

r l'r
mill, 1‘

ADJUSIER
’ N r mums:

m [and nlhlr armsn hikes! leuuim Ipnwxilllmly v."
alumna: ll illnu Ind Ill :Illlch release IIVH.

plum type except Ia replace [he offending pans.
In Brilixh cyclss and mhen wilh rrrljrrslnble re-
lerm- um“, you crrn lrgmen up on the screws and
shall all’ an overhzlul for male lime if you
don'l [Cl lhc slrpprng condillnn get out of hand.
Th: wcl lype clulch depend: on on [or pmper
funclloning. The dry~plulc lypc can'r stand lr.
The BMW, Ariel and such, with dry clulches r
lolcrale a small amount ol seepage from scals.
bul il Ihc)‘ become ail»soakcd, you've had EL
A Iillle or] can be burned on by slippage, which
generalee hem, they say, but gelling exactly the
righl anmllnl of heal llrls way In cure an 0in
Clutch is more apl (a be luck lhan :cience.
[1 you are hard put to local: a clutch disc [or
)our not-sn-cnmman dryrdlsc jobv you can soak
Ih: [riclinn material in SDlVCl'H (no! gasollne), .v
or carbon tetrachloride CClr, or :vcn boil it in
(I strung solulinn of delergcm lo remove rlrc
oil.
\Vilh lhc wer-plale lypc, keep ”79 oil level in
lhe chain case righl on the mark. Uae lhc r:c<

 

    
 

on sea]

as: rlnmr pressure plate is retained by lhese lnnr spring
retaining nnls [PL

 

Clutch and Transmission

nmmcndcd “eight ml. and, if in duubl m lo whul
il mould be. il is no crlme lo experiment, The
Iighlcsl oil ymr can me “ilhout problems i: rhe
hm.

3 Cvar grinding “hen shifting

This symptom generally stems from clulch
sourcfl ralhcr (hull Immmis‘ion problem. The
prime pussibilily is failurc lo release rully, Too

(ABLE

     

\ tug A
M” } LEVEL Bum
SCREW 5(REW

Lucaliuns of Llulch afljuslmenl pninls in MA twins—F
is the screw lain and G the Incknul.

   

'®@ k], , ’ »'
a???

m

Exploded ViEW nf Royal Infield lransmissinn.

    

 

n |l\c Cluu‘h Cub]: i\‘ the men
Cm down on the m: puy of

much free p
prohuhlc cm.
xhclcvcr,
Again. he sure |hc adjuumcm mcchanixm m lhc
cm A) correct The poim “here prcxsurc i< 1U“
rclcaxcd «hm-Id IV: lvctwccn :2 ma 1 mm of me
udjuuing mm 0n pu\hrod»rclcasc clumhm,

 

   

011:”!qu M Shin mechamsm Iln Nnndz autnmalit EIIIIE"
models—ml In n! ma level muvemznt dismgazes clutch,
nalam nl mmmm nhangas gear. nisunsninnnlchange mechanism in BMW nu.

 

 
  
    
 

 

 

v- G
._t o.
5:; En
‘” 3
en. t.
it; tug
0V «V
o o
- -c
n i.
._. m

 

Transmissions 5.)

m I};
C N
(A («A
win Vt”
1, I]!
h: L:
a _
ulfl $V
U U
'u
i: "E
N v

 

V%+

 

;
§_

 

— Main Shah

 

 

 

 

 

 

 

 

 

+

 

 

 

 

 

 

 

 

 

 

 

 

1 [6+ '9
@2174? mm

 

'Countei Shaft

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—L&

t. A
a m A
a} m a
0" v V
.,, A
5o 5 :13
3'33 ; e.
3.2 5’; 3‘3’;
m? 3 DE
33 Ex
Vv m

+ E%%E%}%Jiii

 

 

 

m ’3 ..
N N ti
V V V
A A t.
m a: E
V V 3
EA LA U?
34/ 3": 9;;
03 0“,: 'E—
«:2 .5: {2"
:5.“ v

inerilnw M Yamaha ZED Arspnfl transmission.

Too much oil. or loo heavy an oil will cause
cluich tintg and keep the dim spinning. if the
condilion clean up when Ihe hike hm been run
for a few miles and Warmx up. suspect either of
lhcsc two fneton,

Uneven clutch spring pressure. causing parnal
non-disengngcmcnl. n prc‘cnl whethgr cold or hot
and tegnrdiett of fldjllumcnl. Sonic L‘Iulch tpringt
can bc individttniiy :idjmlcd and are prone u) this
\on of mulfunclion.

If n clutch hm been previously overhauled.
there me other items to think (\bOHL In mnny
clulche<, such its R0 1 Enficld. clinch \prings are
fitted ullcrnmcly. wank and strong. and in the
models with ntijutting (Crch. the strong springs

 

mun be behind the screws. Any miscuc here can
mute lrouhlct

Ridcn who tttijmt the KCICW‘ in the pmttiic
plale am“ In L’ikc tin “cur can mcrdo it ttntt
coil-hind \hc ipringxt which came» drag and poor
rclcmingv

TKANS‘IISSIONS

The mmt common complaint aboul tinmmtt.
\iom is (illiicllixy in engaging i. t . , m Oppomd
It) “gear grinn- " |hi~ i\ in the irammiMiOn and
i\ related |o Ilic shill tntchitnimt and \pzicillg at
gun. A< Hontht ridch thaw. iinding neutral in
home of (hi: smaller dhplilccmcnl modck is, al

 

 

     
   
      
   
  

\

mil-mi
j >122leva

 

o6 Clutch and Transmission

,Maimxle
diam." eellar

    

 
 

Main-me . _
ball~lwanng shim

/Serund amen mi-

Low driven gear

   

Eulhux Enmnanlms, Vamahl MRI.

\ _Shifler-]1ELd‘

/ \
/ ‘\DI
/ /

 

veaxle

 

Bea! nailing i3 zcbumpllsnen by (muslin: still halls inln
inlelnallyrhlnachlfl gear in small Vzmaha.

<>

Mun-mm sum in llama mnsmissinn slaps lumping
nulalgm.

    

umcs, prcuy frustrating The spacing helween rhe
gem which musl be engaged lo achieve neutral
is close and 1h: shift lever and claw muvemem
are more or less "geared up" for easy aciion, so a
small amounr of pedal nclion is hard in oblain.

When a gearbox gels older, :1 similar silualion
oxisu because of wear on shift forks, pins and
spacers. In addilion, hard usage bends forks. II
all adds up lo sloppy linkage and imprecise move-
mcnl inside |he box, so you overrun one gear am!
impinge on the next pairing.

There is no adjuslnienl possible in me modern
gearbox linkage, so if you are having real trouble

    

Simple and eflecliv: gill clings mum! is :mulnylfl ill
Vamlhl J-spud m.

 

 

 

Trunsmissiuns 57

PRIMARY PINION

  

  
 
  
      
 

PINION
2|

 
   
 

25
2nd ...'r
(—

  

 

  

I5

        

      

{D

Std TOP

MAIN AXLE

2nd

    

LOW

  
   
  
 
  

DRIVE AXLE
PRIMARY GEAR

I

  

" ‘3rd . In .
3’ i lGEAR WHEEL

14

 
  
    

S!
DRIVE SPROCKET
inllllaw in Vamzha 4sneefl \ransmissinn a! I25“ mudlL

finding a gear, it means a strip-down to gel at 1h:
linkage and/or spacers, broken ratchet spring, as.

 
   

A close perusal of the accompanying illusiralinns ¢< b
of various gearboxes will make Ihc operations clear ~‘® ),7 Q; n
and dcmonslralc Ihc need for internal repairs‘ ( 4g humm-
m 7%;

  

Shiftor mm
“mm pin
_Clmn;:n- lewr

rA:

   
 
      

nmzry molinn is comma inm lineav mnlinn hy shilm
cam plate. may in plan. “upper yin and change Iml
Czn accnunl In! jumping nut a! gear amt diflicull enme- Innzxufl cam maves shill m u: change gem in mm
menl. 4-5pm.

58 Clutch and Transmission

 

 

 

 

 

 

 

, K
'\

 

 

 

 

 

 

 

 

 

 

 

 

 

nut tngngemtnt ls hy tapered dogs in Suzuki 3-sn22d.

3 Trannnliuiun jumps out or near

Thi< means dtilerent things with difierent hoxen.
in the annnete camlnnI-mcsh lranomifiiono where
geura are engaged by coupling uirh dowele. either
the gear is not being shovcd far enough into mesh
or the dovlek ore “om ofi. ln hoxee which ute
plungers nnd bnlls for lecnting. the apring, enn he
mo we'tk. or engagement i< not being forced.
Worn earn plalm in BSA buxm :th up this tiny.

\vbrn xpacer‘, particularly in Honda beret, are
responslhlc for the most complnints. There in a
particular problem nirh Hondn Recent! gear
spacert and n thtcler one is ntnllnhle from Honda
IO COHEN Ihc condition.

Wnrn or bent ohifl forks nre also a prime Cause.
pnrriculnrly in srnnll ditplneement htlrea which may
hnte been ridden by inexperienced youngsters.

 

Kickstmer mechanism nl small tltsplaremznl Suzukls,

 

Jamming (he Cogs into mesh when Ihe Clutch is
mnladjusted accounts {or a lot of it. In Hondns,
too. the shift drum limil apring can loie temiou
and create Irouble.

® Trnnsmiesion won'l shill

You are in for a strip—down anyway. but iI
might be good lo know what Io look for.

II the clutch opemles but (he shift lever won‘t
move any gear, the pawl of the shift arrn or the
Shining fork is broken. Or. in the small displace-
ment bike, the dowels on Ihe end of the drum
which engage the shirt levcr may he sheared err.
This is rare, but it can happen. In addition, in
various hikes, the numerous pins which provide
the fulcrum points for linkage can break.

ll you can get the box into one gear or more,
depending on the type, then the problem lies in
the engagement of the other gearfi: broken dowel
pins. clutchdogs, etc. In the Honda. the enumer-
shait ficcund gear is mun“); the firfil sutpeet he-
cauoe it takes more of a beating.

cent a m»; DUW‘

   

‘13.

VVWa'l S'W‘l'ig tom

Broken SM“ liver Swill! n! Wm vlwl in pins can HMS:
yrnhlems in Sulnki box.

 

 

 

Trmlsm issiuns

 

fliszssmhlld [cars in Narnia 45" box.

In ihc Rmnl Enficld and such boxes whcrc lhc
ratchet playx‘ such an lllipormnl mrL a weak or
broken mlchci spring can permit me shiitcr m
slide righl paei a couple of gem and lend you [0
mspm the moral.

Seldom arc gear (cclh chewed up. pm when
breaknuc doc: occur‘ ihc rcsulmnl growling and
howling or malfunction is prclly Din/mus,

 

wm portion ii 1rium|lh hnx i3 layshzli pinion par.

Dmin lhc gczlrhox and examine the oil [or him
of nlclfll. Poke your liulc linger inm lhc sump
and run ll nmund lhc inslllc of lhc Cass: adjacent
Io ihc hole for Ihc drain plug. If Ihcre are bits of
melal, he prepared.

6: Jamming kick Mark-r

The llrsl loolh on lhc kick smrlcr scalar bears
|hc hrllnl oi service hccausc ii is lhc engagement
paint and if one: fouled, ii is more llkcly in con-
unuc to be aimed up. The mom can be ground
all if lhi‘ l: (he only problem, rallml’ lhnn m»
placing lh: whole scclol’. If Ihc pinion lcclh are
lmd, lhc sinner seldom Jams, slippage is me symp»
mm.

 

Elal Lhanglng mlchanism nl Suzuki 3-Sncedl

60 Clutch and Trunsm ission

59,“:

    
  
  
 

r“i:\' Crank :ns¢(L)

   

6“»an / @J Kick-WW“
gnu“ Wes “Muir-r

h > “,r
A "“‘n / Kick-n71!" rehiner:
’ bani":

vald‘

chk-staml mechlnism, Vamzhl antfl MF-Z.

 

@ Slipping ki slal'll'r rmchel pawl (in Briliih cycles) is to be suspected.

If the engine does nol spin ever In response in it the reiurn spring breaks and the pedal docsn'l
a kick, and [here nre grinding noiree. worn out or flip up, it should be replaced at once. Secure it in
broken secrcr or pinion gun can bi.- suspcclcd. piece while operaling ihc machine Accidental
If lh: starter doesn‘i mm to engage, a worn engagementcan mean big trouble.

Chapter 5

Carburetors and Tuning

The cnrhllrclor is, if no! [he hcan, m Icml the
lung 0! [he molorqclcl II ix linkcrcd uuh luo
much and nol kept clean enough by num ri-lcn
Them arc (ml) 4 it“ mechanic» who llndurvhnd
carbllrclion cnullgh lo nllcr the I my acuin -
and improu: pcrl’ormancu, ya uuarly c "body
mkc» lhu lihcrl) m .uaulnulala, Cumcqucmly,
most czlrhurclor lrollhlc can he [mead ID Ihe lam
"ulrlc up" or [he km Iimc sonlcbndy fiddled Wllh
|hc cllrhllrcwr.

A good undemnnllrng ur each carburulnr'e
nruchanlcal mmhod of coping vli|h an cllginc'\
Varied dcmands for m 'r mixlum will help pm
you on [he righl [ruck for lrluuhlwhoollnn \Vc
ulll renew each of rho popular carlmrcmrs ln rm-
Ierm‘ med hy Ihc manufacturers. Follow Ahc
Ihinking of the ucugncr and you mll heucr under—
slanu ulu-n- and how Irouhlc can crop up,

Amal carbllrcmn haw alwnyfi been in the fore-
mm or nlolorcyclc fllcl syslcme. New, pmhahly
the Kclhin is used on more indixldllnl cycles hul
[he Amal i< [ound in every corner of the world.
Olhcr c1lrhllrc|nr< or rm slillcdhroulc lypc owe
allegiance m Amal They use difl'crcnl mclhods
ro aualu m: :unu- cnd~ in mun. cum, bu: lh:
:inlpll'cily nr opcrmion and use of service are all

l due lo this cancepl.

     

 

   

 

 

g
Warn HlmIUl slid:

causes pmhlams in

tuninl Amal
Earhumnls.

 

GEVERAL CHIHURETOR
TROUBLESHOOTING

Thcrc 'er two poixihlc [milk in ullrlnlrction,
cilhcr richness or weakncsx of mixture.

[In rations ul‘ ml...“

5,) Black smoke ln cxnaml
ruul \pru ng 0m of carbumnr
Your-“rakes, cighl umking
Q) Tua-umkcx, [our making
Hull'y,1unlp) running
Somy spark plug

   

 

India-Xian; of uunknm
m Spllling hllc in carburcror
Emuic alomd’llnning

I; Ovcrhcnling

(9 Englnc rum bcucr il mmulu is nol wide
0an 0r choke i: parliully cloml.

If ricnum or wcakncw is pmcm check if
Cllmcd by:

u. Fuel Iced. Check mar 1m and puwagc‘ are
clunm filler gmlzc lu float chllmhcr banjo con-
ncclion n nol choked wuh foreign runner. and
(hen: :lmplc flow of fuel. Be sure rum i: no
flooding.

 
 
 

 

 

 

 

 

Eavhuratnl is usually Iinkered w' lull much and um
ken! clean annulh Dy avuaz: liflu. Experts such as
Mik! Eanalile flflvucale mainlalnin: Vactory specificalinns.

61

62 Carburetors and Tuning

b. An leeks. Them mny he m Ihc conncclion
ro lhe engine or due ro mum .nler ynhe slcme
guide clenrnnee.

c. nerecrue or worn porn. Emmplcx are n
lame fining rhroule ynlve. worn nccdlc ler. lame
leu.

d. Air elenner choked up.

o An nir elenner hmlnfl been removed.

Calllr rnmrola

Sec rhnr rhere ls o minimum of brrcklroh when
rhe cemroh nre «cl lurch and llldl nuy rnoyemenr
or rho hnndlehnr (10w nor enure lhe rhroule Io
open; |hi~ i~ done hy rhe ndruuer» on lhe ion of
the enrhurelor. See mm the rhroule shuts down
ireely.

I’m-1 {cell

Same lmer model munh rrnd orhen nre ruled
wuh u filler gnuze m rhe lnler re Ihc noru chrrmher.
To remove lhe liher grurze unzcreuv Ihc hemo boll;
lhe bunjo crm men he renuned nnd rho hirer
gnuee “illulrzmn irnm Ihc needle willing.

Eu ~llru rh.u rln- hirer gnu/e h uudmnrged nnd
free from nil iorergn mnuer Te cheek irrel flaw.
belore rcpllelng lhc luuuo. mm on lucl ldp
momcnmrin and sec rhru iuel gushes mil.

Fhmiling

Thix may be due |0 a norn needle or n leaky
lloru. hm 15 more llkcl} due lo impurhim (grit.
null. 015,) in lhc Iank: \u oleun mll Ihc lloul
chnmber pcnodicalh' lill lhe Imuhlc comer. ll
lhc rrouhle pcrfilsh, the (link minl he drrnned rrnd
clenned eul.

Fixing carlmrclor nnd air leaks

Erriulc «lmvrunnlng o onen czul~cd by mr
leaky \u \‘crlly |hcrc nro nnne nr Ihc poiru oi
rumcluuem lo ihe eyhuder or lnlcl rune. Check by
memo ol :ln orlenn rind ehnunme by uen nnrhers
11nd lhe equal Iighxcning of flange mm. 0n lmer
model Aumh n \(‘ullng ring ix ruled inrn lhc rue
urchnrem lnge or rhe eurlmrelor ln old muchinca
idol mu lor rnr Isak: enmed hy .r norn rhroule
or uorn inlc| ynlre guidu.

 

[hu'kfiring in (-xhulhl

Muy be enmed by loo nenk n pilot mixlulc
when [he Illrolllc h clmcd or ueurly cloxcd. Alxn
u mr he cumcd Il)‘ hm rich n pilm mirrure nnd
dn leuh in |hc C‘dminl \yucm. The reason in
euher eneo u rher lhc mlUiIrc has nol fired in |hc
erhndcr und hm lircd in rhe hol exhnusl header
or uurlller. ll rhe hanging Imppcm when ”10
rhroule n irurly vlidc open |hc lreuhle wrll he
Ign on, nor cnrhurolion.

 

 

lav-row (- l'url ennuunplitm

ll lhi: crumol he corrccred by normnl adjlm-
nreru, lr my be due lo flooding earned by in
pllrilim lroru rho muL lodging on lhe flunl needle
will prcvcming ur val": lmm closing.

ll mny nlso be earned by n urn-n 110m needle
valve. High cumumplion wilI be apparcnl it ill:
needle jel has word. It may be remedied or im—
proved by lowering lhe needle in [he rhroule, bur
iI il Czulnol he, rhc only remedy is ID gel :1 new
needle lei.

There :er meny orher came: or high fuel can-
rumprion n0| cunncclcd vlilh rhe cnrburelor.

 

Three variable pa“! ul Amal: (A) (Mum: slup smw
murals ulh spud; (Bl pilul ail smw cnnlrnls ml: and
lnw speed mixlullz (Cl maul in canlmls "We! speed
range.

 

 

Air fillers

These may affect Ihe jel tellln' If a carhurercr
is so! with an air filler and [he cnglnc k run wilh~
out one, rake care not to overhear lhc engine due
lo we weak a mixlurc. Testing will} the choke hill
indicnle it .1 larger main jer and hlghcr needle
pnsirion are required,

 

Eflccl oi ullilurlr on cnrlmrclor

Increased allilude lends Io produce a rich mi).-
rure. The greater lhc allilude. Ihe smaller (be
main jel required. Carburemr: are sel by Ihe
Izclory ‘uilahle for allliudes up to 3.000 feel (ap-
proximnlcly). Carburclorfi ufied conslnnlly for
nlliludcs of 3,000 to 6,000 feel Should have a re-
duction in main jet size of 5%, and Iherenl’lcr {or
every 3,000 (cal in exec“ al' 6,000 feel allllude
[urlher reduction: of 4‘7: should be made.

No adjuslmenl can compensate for losl power
due Ia rarified air,

AMAL CARBCRETORS

.‘Ionohloc-R. ~TT-Gl’

The supply of air Io Ihc engine is comrolled by
a lhrollle slide which carries a lilper needle oper-
uling in Ihe needle jel, The needle is secured in
Ihe lhroule slide by a spring clip filling in one of
five grooves and rhe mixing srrengrh lhmughcul a
large proponion of the throttle rnnge is comrolled
by the posirlon o! ihis needle in me slide nnd by
[he size at [he iel in “thh ll work, There is,
however, a reslricling or main jel nl Ihe bollom of
‘he needle jet and Ihe size 0! this conlmls [he mix-
lure slrenglh at the largest lhrollle openings:

A! Very small ihroule openings fuel and air are
led Io Ihe engine lhrough a separare pilul syslem,
which has an Outlet ar rhe engine side of rhe
Ihmllle The air supply Is this piloI sysrem is con-
rrolled by lhe pilol air sereu, and Ihe slow running
of the engine can he udjusred by means of xhii
screw and il slop which holds the lhrollle open 15
very small amounl,

The lhrullle slide is cul away a! Ihe hack and
rhe shape of rhis curnuny ennrrols rhe nuxrure a!
lhrolrle openings slighlly wider rhan that required
for slow running. There is n compensating System
[0 prevent undue enriching of lhe mixlure wrlh
increasing engine speed, lhis sysiern con<isllng or
n primary choke surrounding rhe upper end or rhe
needle jel through uhich nir is drawn In rncrensing
quanlilies as the depression in Ihe main choke in-
creases. This air supply and rhe supply m the
pilot sysrem are taken from the sepdrule duels in
the main air inlake [0 [he carburetor so Illa! J"
Ihe air passing to Ihe engine can he fillered by
filling an air cleaner lo Ihe main carburetor air
inlake.

 

A "ml C urbu rotors 63

  
    
  
  
   

Clip and nuns
Admin-mm 7117
mm. ’waIn

"mam: Her-4m e

Spin. \

 

in Ilmr

nun nu nun.

n... Seal 'thln rum»,

("luv-Ila Iviy \

7|an A" 5n...

Threw: Sup

mm nr/

5%\ . w. n.

\ ... en...

Amzl Monuhlunl

Two smllll holes in the needle jel. al a level jusl
below the italic level in (he llcull Chamber, permil
fuel In [low lnIn Ihe primary choke Vlhcn |he
engine is no: running or uhen n is running ni
very low speeds. lhus forming n uell of fuel which
will be drawn inln rhe engine on srarring or ne-
celcrnling from low speeds. AI niodernrely high
engine speeds the lmcl of fuel in (he llrxll Chdnlher
lnlls sllghlly and in cunsequcme up more fuel
llcwfi Ihrough lhe cw“ holes in Ihe needle icl so
lhal rhc [nel hell remains empty unril rhc engine
slows down or steps,

A hnndlebur-cumralled mr filide is prmlded lo
enrich lhe mixrure remporarrly when required.

Tuning Illc carlIurclur

The lhmlllc upcning M which each runing polnl
is mm! eflcclivc is \hovln under TUNlNG SE-
QUENCE. I! <hould be remembered, hm‘lflcr,

6:1-

Curburclors llllll Tuning

 
 
   

  

‘ “WW"lllllullllllllfl

Amal TT was develnpefl lnr mad lacing.

 

Am] type 21 used m mung Mes.

 

 

Amal lul, type.

am a chllngc of «wing at any pninl will have
\mnc cllacl on ma mung required at olhcr poinls.
For inflame, ll Change of n ll jcl will have some
file“ on [he mixlul'c a|rcnglh m half Ihrolllc,
uhlch, humeverl i\ mainly CummIIed by the needle
pmlflon Slmllarly an allcrmian lo Ihc lhmulc
cum my llfl'u‘l hmh |hc ncchc pmilion
rcqulrcd and m: lldluslmcm of ll]: pilol llir scrcw
l‘ur lhi: lemon il S necesml’y m lune the carbu»
rclur ln u dcfinilc ~cqucncc m folluvlw:

(I) Muin jcl. The fin should be chasen which
gi\é~ mlnimllm speed m lull |hro|llc wilh Ihc air
mnlml \lidc npcn If we diflcrenl sizes of jel
gm lhc mm :pccd lhc Imgcr should be chosen
{or :nfcly l is dungcmm 10 run wilh mu weak
a miKlurc m full lhrolllc.

Fl, The pilm llir sore“ \hnnld be sel lo give
good ldhng. Nulc mm lhc pl|0| m i» Alclachnble
and sixes am available. If [he pilol nir adjusling
\L‘YCW nccdx In Ilc xcrcucd uul Ia“ (hnn half a
um. lhc Luger ~ch pilol jcl should he med, if |he
mr mom need~ k) be Screwsd oul morn: (Inn 273
mm, m the «mllIlcr size of pilot icL

   

 

 
 

 

 

 

@ The lhrolllc \‘ill\‘C should he sclccled with
llll: large“ llmollnl of cub-may which “ill prcl'cm
spilling ul’ nlisfiring when opening inc rhrolrle
slowly {rum lhe idling p0\lli0n.

The lime“ posillnn of ill: taper needle
should be found cunxislcm willl good nCcclcrmion
wilh the air slide “lllc open.

@ The pilot air screw should he chcckcd lo
improve idling ii posiihle. When \clting lhl.‘ ad-
iusimenl oi lhe pilol air screw l , hould he done
in Conjunction wilh lhc lhroule slop. Noll: lhnl

 

mm: 70 '4 0994
mm 4215

3. '/s vol/4 OPEN
rNRor‘rLE cur Aw"

 

 

 

 

 

 

 

 

 

e. '/. ro 3/: OPEN
NEEDLE Posmorl

I. a,‘ 10 FULL 09m
mm JEY 5le

“mill: sequent! la! all Amls.

Amul Carburetors 65

lhc currccl selling Hf lhc zlir \crcw is [he one which
givcx ll’lc iaslesl idling speed ior a given posilien
ul lhe lhrnule <|0pe li rhe idling speed is rhen
undesirably [ml i| ciln hc sluvlcd down by un-
screwing lhc lhrolilc imp a fraclinn of :1 mm ll
will he noted [km of (he four points In which
adjuumenn nre normally mauleipllol nir screw,
lhrolllc cumwaya n It poillinn and mzlin jcl
hizcilhc firsr and lhird du nol require changi g
of any pans of (he carburelur. Asulming lhnl ll-le
chrburelor has Ill: slnndard selling in snil lhc
panicular lypc of engine any small adjusrmenrs
ueensiened lry nlmospheric eendiiinns, changes in
qunliiy ui ruel. cm. can usually be covered h§
adjuslmenl oi ilre pilol nir screw and raising or
lowering lhe lnper needle one nolch. If. however
ihe machine is used nl very high aliiludes or wil
a very restricted air cleaner 3 smallnr main i.
will he necessary, The following lilhlc gives ll‘
reduciion in min in size required all difl'ercl
llllluldes.

 

ALTITUDE ((1.) anLcnox
3.000 5%
6.000 9%
9.000 13%

12.000 17%

In rlie case of Carburetors for engines rllrlninl
on alcohol iuel considerably larger jets are neede.
ln rnosl cases a #113 needle iel will he require:
and lhe main jcl size will need In he increasei
by an nniounl varying from 5092 lo 150% ac
cording to ll'lc grade of fuel used. Ii lhc engine is
run on iuel ennraining a small praporlian ol
alcohol added [0 lhe iuel, a rough and ready
guide is lhal rhc main iel should be increased 1%
[or every 1% oi alcohol in the fuel.

Synchronizing Iwo carburelors

When selling lhe slow running on machines
lined wilh lWo carburerors, ihe following pruee.
durc is recommended.

® See lhai both rhroulc slides are open the
same dmounl for any given posilion of ”re lwisl
grip. This is mosl easily checked hy looking into
lhe air inlnkcs while slowly opening and closing
the lhrolllci wilh Ihc air slidns Widn opnn. Make
sure lhnl rhe highesr poinl or lhc culavlay on rhe
lhroule valve rezrchci ll‘le lap of lhe horc simul-
lnneously in holh carhurelors. li necessary adjust
one or bolh mid-cable adjusters in [he lhrnule
Cahlcsu

@ Repear rhis procedure ior lhe nir slides.

@ Slan rhe engine and lei it run at u {N idle
unril ihoroughly warm, Open lhc air slides lully
and remove ihc high lension lead and walerproof
plug cap from lhe riglnhnnd snarl plug. opening
rhe rhroule ii necessary lo keep lhe engine running
on on: cylinder,

 

 

66 Carburetors and Tuning

@ Adjust the throttle stop on the left-hand
Carburetor to hold the throttle jutt wide enough
open to keep the engine running with the twist
grip shut.

@l Adju“ the pilot air screw on the left-hand
carburetor to give the maximum speed for this
throttle position.

@ Slow down the engine as tar as possible by
adjusting the throttle stop and reset the pilot air
screw it necessary to give the maximum speed tor
lht: new throttle position. Repeat until the engine is
running as last as possible on the smallest possible
throttle opening.

(3 Replace the right-hand plug cap and lead
and remove the left-hand ones.

(9 Repeat steps (9, ® and (g on the right-
hztnd carburetor.

.3.) Replace the lett-hand plug cap and lead.
The engine should now be running steadily at a
fast idle.

@ Slow the engine down by unscrewing each
throttle stop equally. it running beeomes lumpy,
adjust cach pilot air screw an equal amount. If
necessary, slow engine dostn iurther by unscrew-
ing cach throttle stop equally but do not try to
get too stow an idle with a hot engine, otherwise
it will be liable to stop when only partly warmed
up.

Dismantling and ronssonttrling (Munobloc)

After removing the carburetor, the procedure
tor dismantling is the same uhethcr for single or
twin except that the twin carburetor cables are
connected at. junction boxes. Removal of the Cablt:
nipples lrom the junction boxes is quite simple and
straightforward alter the single cables have been
disconnected {mm the lever and twist grip.

(C Remove the throttle and air slides from the
body by unscrewing the mixing chamber top cap.
then wihdraw the slides and throttle needle.

(73 Remove the needle retaining spring clip.
compress the slide return, then push the cable
nipple dovln and out of the slide.

@ To release the air slide. compress the spring
anti slip the nipple out or the bottom oi the slide.

@ Unscrew three slotted screw: and withdraw
the float chamber cover and remove the float
spindle bush and the float. Thcn withdraw the
triangular section noat needle.

@ Unwrtw the banjo bolt which secures the
luel pipe banjo connector to the tloat needle seat-
ing block and withdraw the banjo, filter and junc-
tion washers. Unscrew the needle seating block.
Unacrcw the ticklcr body; then withdraw the
ticklcr and spring.

@ Remove the air screw and throttle stop
screw, than the main jet cover nut [rum the bottom
of the body. Unscrew the main jet, main jet
holder and needle jet. To release the jet. block

seertoa gt
‘ Nam transstees l
assets in l

v—eAs swam mg" utter m

 

Alb—u

 

VILDY tttt
mast-e:

 

Fuel flow in Amal 0P. '.

winter! the main jet holder, until a (cw threads
are engaged. then tap it with a hide mallet. This
will release the jet block through the carburetor l
body. '

@ Unscrew the pilot jet center, and unscrew the
pilot jet. All that remains to be removed then is
the hexagonal locating peg, the end of which can
be seen protruding within the mixing chamber.

Thoroughly clean all parts in solvent or carbure-
tor cleaner. Deposits on the carburetor body are
best removed by a light grade wire brush. it is
advisable to wash the parts several times each in
a clean quantity of solvent to avoid particles ol
dtrt remaining. Allow the parts to drain, prefera-
bly using a jet or compressed air to ensure that all
holes and drilling: are free from blockage.

Apart from one or two points that are men-
tioned below, reassembly is a reversal of the above
instructions.

no not refit any paper washer. it is advisable to
purchase replacement washers before removing
the carburetor.

When replacing the jet block, ensure that the
paper washer is in position; align the location slot
in the jet block with the locating peg in tht: car-
huretor housing and drive the block home.

—1

Flnilll)‘. nulc |hil| rhe llear xpindlc hieh fin on
rhe oulsldc end or rhe spindle. and lhai rhe lluai
presillrc pad n npperruen so rhar the deal needle
rcslx en n, Flnal level e mdrkcd by a «mull pip
on llear coxcr.

Insprrling lln‘ mlmpnnrms

The puns liable lo show vicar ilflcr Con~idcrilh|c
mileage are |hc lhreule \'ilI\c shdl‘. inning cham»
her and Ihc air xlldc.

@ Inspcu rhe lhrerrle \ixlvc «lull: lor ficcuivc
Scoring |0 ”it from urea and check the euem of
near ml lhc rear \lidc lace. ll hear is apparenr.
lhc \Iidc xhould be rcncwcdr In Ihix caxcl be sure
re replace lhc slide wilh rhe corrccl degree ol
culuual (smmpcd on my: of wlidc).

® Emminc the air mm: for cxccwivc “our
and cheek rhal ii i) nm aerually ‘om through ar
any pain, Check rhe [u of mu air valve in Ihc iei
block. Ensure rhal rhe air valve \pnng in nervice-
able by impeering 1h: coils lor “car.

@ Impccl Ihc Ihrollle rerurn wring for em.
ciency and cheek rhar ir hm nor lesr compressive
srrenglh.

@ Check [he needle jet [or wear or possib]:
scoring and earelulh- examine Ihc lapcrcd end of
[he nccdll: for iimilnr \igm.

@ Eulmin: (h: flunl needle for cfl‘iciency by
inserting il inlo Ihe im‘crlcd flonl nccdlc >03“ng
block, pouring a small amounl of gasoline inlo
lhe apenure. surrounding lhe needle and checking
ii for leakage

 

LINE TO BE LEVEL
WITH BASE OFCIRCLE
Mounting DI Amzl EP on BSA Snilfile.

Anml Carburetors 67

p, Be «urn ihar lhc lloai dncx inn luilk ny
shaking i| re xcc rl n eenrarm 1m) luel. Do nol
auempl l0 repair a Llumdgcd Hear, A nevi one
can he pllrchaacd [or a mull eon,

~ (5h ihe giuulinc lilier, uhieh lie over lhc
needle us ing hide-l. {or any powlhlc damage [0
lhe nre»h. . mic lhzu rlre filler hm nnl purlcd
[rum in ~upporling errueiure line enabling rhe
ginohnc m humus unfilrered.
a“ When lcplacing czlrhllrcmrr do fit“ over.
ughlcn ihe nun and thin narp lh: herlv.

 

   

   

 

.Ul \L CP-2

Thn i» rhe neueu Amal. lr follow rhe mmc
principles as preliom model: but ihe loedrion ol
rhe pilor lcl hm been changed.

The remore noai houl which n a learure el lhis
model i\ mourned hclvlccn rhe |wo Cilrhurclors
Spilfirc

 

vlhl‘n filled to :| [Win \llch as the BS
Mk, II.

 
 
 
 
 
 
 
 
 
 
 
   
 

Finding hie! level using clnl plaslle (unlinmal av.

 

68

Carburetors "ml 'I‘unilg

111: pnmwn of 1110 11m chamber rclmhc 10
[he um curhurcmn |~ udmimhlc h) meani of \hc
rod» rm “hmh .r r~ \mpcndml [mm m lnp mmlm-
in; The gm Imel m rm chumhvr r: 1ndica1ed
h) r. nmed 11m 011 111: uulmlc oi 1111» bod} 11nd
1n pmmomng 1h: fluzu chamber 11m 1rnr~ ihould
bu on 11 1m-1 111111 (he luuml mum of Ar c1rclllm’
\cnhud mark on (he crxrhurcmr J1r ju plugs
11m {0110“ mg rlluummn \\ 111 mm- 11m cluur 10
\nu mu )m. 11111 pmhuhly r1011 lhzn mm 11m
11m chamber in 11113 pomrmr 111: \han pipm
cmmucnng 11 unh each 111 (he nun curburcwn
.m- s1rmgh1.

 

RING

The Bing Curhurclur r» kmmn pnnmpnll)‘ .rr
1hn munlr} mar».- 11 r» fined 10 1111111 models.
1r 1; cfiwnuull) 1m Ihc M11111. Hch are du’cuium
for dimizcmhl) and arumunrm:

g; mama-1 1mm air finer 1mm Iramnu
\iufi hmmng and remme rm- filler. Clean {he
111m :lemenl \«hcn nccmm by 1.1mm; mu
[he dml (And rcplucc 1| cu \ 3.000 nu‘lm

Nmu' When immlhng 11m Mr r111: remsmber
|he Incanng pm and make :1 crxrrccl m. Upon
remmul of upper engine huuzi cover. 11h cm
the mm \crccn. cmn 11 “am gmnnc and m
11 “1111 oil

9 For rcmmnl 11ml Clcaning of [he cnrhllrflor,
11mm“ 1h: knurled ring on [up and pull \hroule
51111;» upward and mu,

. 1mm pan

Feud fur Idlmg mlxmrc

. ldhng jel

P111;

. Con1rn1 cahlc N11. mum Spnng

. JcInccdlc Imlnlur

. 111mm: 31111:

Air mm: mm

. Cmnpcnxrmm
Ier needle
Neudlc jcl

 

 

 

nir Iced

 

HoqufimgleH

Tmnma cahle aflfustmanl ll handllhal.

1:. Mam jc1
1; Plug

14. Priming human

15 Flual 110111

16. Hum

17. Dnmpcrring

1» Has: finmg

19V Idling mixmrc adjuuingscreu
20' 11mm» mlw mp 5cm“

 

Eulaway 0! Ring Eavhulnln! uslfl an BMW. lflznkifibilinn
of pan: is in text.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   

"Hum: cable adjustment :1 calhumar.

 

. :1 MM all paving-x and 1m and rmucni-
M.» pilih pmpcrl) ciwml mm prmhlcd mm mm
gihkch lnr prc 'Imrmn mlyuximcni. «m rhc
“um; mixtun‘ dimming xcrcw rum m “mi lhun
hack ii oul our: and a mu mm

(D '1“ mm Ilic idling mail mm (WM grip In
mm W,» p0\iiinil mm «mm mmulc mm“- ml
hurh Cruhunzinrx [m i plu)‘ of m",

   

[ll-ILL OIK'I'O

Th: Dcll 0m cmbumur is fined
lulmn MAM» :riul “mum nu» rm Ann!
10 ”IA! hcilnling [0r iniurmuiiun zrml scn it:

[0 mos!
Rum

JIKOY

 

The \hleL‘rFurupcun v xium of (he mmrni
Ami arc um! on 1mm mmmc, c,
’ihm an» munobluc carburcxom '1 he main in

 

 

[Mon 6‘)

is I mml

   

||hc mi n] lbs in: i jcl [wk and il i~
ziumiiw mm \1)!\Lll‘\\il\gI)!c¥l|ilill]flhu]|. The
iklliiigj ism cdun (htlighlJmns‘\Iilcilhmc
m.» pilni iii sure“ 11» lhlUch \uhc nccnllc
ix lumml ccccnir .n ma Ihrmllc \.\l\c Lind
[minim nuccnilrlc Micr unwrcmng n..- mixing

   

 

 

 

 

‘27 \25 \25 ~21. ‘23

De‘l om: carhumulr (I) Tinned "rm nezdle, l2) ”flared needll, 13) tickle! maimnl lilIK, (4) final clam!" cum, [5)
mm chamhzr cum screw, lei pin! uninn wash", (7i licklu spring (a) gas filter, (a) luckier, um gas nip: uninri, rm my:

 

washer, ilzi pin: uninn nut, (1:0 air slid: spring, 1141mm“: siidz cum nut, (IS! canle adjusting screw. um um»

filming straw Iacknul, [17) (Nam: slide WV", [18’ Hi! cDmmi slifll, HS] lhrntlle spring, (1m unwed new: annnnl
mg rim. (1|) lhrnulz slids, Ill) ring Elamn screw, 123) ring damn. {141 carhurelnr mm, M! side, (zip Ihrpm: stun suew
Incknul, 115) nilnl air smw spring, (17) nllnl air smw, rm mrnule stun screw, [19) mm chamber umnn washer. (In)

slaw running in, (31) main in. (an aim nhamhzr uninn nlug, (33) needlz ‘

 

{34] final chamber uuian wash", (35) air

inlet. [35) llnal chimhzl, [37) flail chamhfl cave! Wash". (35’ final needle Illai n: Saving, (39) final.

 

 

 

Carburetors and Tuning

70

L_xo<

3: ”a: .12:
:2 ”.2 I .3:
33 mu 5 I ”mean

we 3 m0

m0

 
  

S \u 3. 3 ‘m

59: 2 5—5.. mm 35:? 912.2. s; E 56‘ m: 9.51?

 

 

 

chanthcr top. 13y conlprc<\lng the tpring tlte
Ihmlllc cable “ill ht: Ircctl [mm the I’CCC» in Iht:
throttle mite itntl the tpting l'cSlillg oit the needle
clip end he rcmmctl. The needle clip hccurtn
the pmitittn oi the needle.

1he nthin jet, itlling jet. throttle v to \ltlp
screw 11nd the pilot all \Cl’cllt itrt: RICI‘L‘Wil‘lc {rum
the right-hand side of the ct Ivllrclor Lifter rc-
movnl of the CL“ t:r.

Acccs: (or cleaning and repairing the float
ehnnther pnrtt it ohtntned .titcr tinsch\\ing the
mo M 5 wrong and ramming the llmtl chamber
mp.

thulclnn are ittljtlslcd M Iht: work fur hrcilkr
ing in. After approximately 1,500 to 2.1100 km
(1.1101) ntilesl they hnlc to be ntlj|l~|ctl as follows:
For the 2922 SB 12 carburetor (for Ih: 453
mode

ntntn Jcl

itlling jcl

 

 

   

 

 

105 (Solexl
40 (Solex)
needle pthiliml 2nd In 3rd notctt from top
pilot nir :crcw /z m I turn slack from light
For the 291.1 SB 14 Carburetor (tor the 450
model):
main jet
idling jct

109 (Solex)
40 (Solcx)
needle position 2nd to 3rd notch from top
pilot air tcrow V2 to l tttrn slack from tight
For the 2926 SB 12 carburetor (for the 455
model):
main jet
idling jet
nccdle poeition
pilol oir screw

120 (Solex)

60 (Sulcx)

2nd to 3rd notch from top
1/; to i turn

More recently carburetor 2922 SBD II has been
imploycd for [he 453, 473, and 473.04 models:
main jet 85 (Sulex)
idling jet 45 (Solex)
needle posilion 3rd to 2ntl notch from top
Carllllmlor Z924 SBD 12 and later still 2924
SBD 17B carburetor for the 450, 470. and
474.04 models:
2924 SBD 12
90 (Solcx) 88 (Soch)
idling jet 45 (Solex) so (Solcx)
needle position 3rd to 2nd notch from top
Carburetor 2926 SBD 153 for (he 455/05, 475,
and 475.04 models:

2924 SBD 173
main jet

main jet 91(Solex)
idling jet so (Solex)
needle pn 31d In 1nd notch from top

 

(The pilot atr screw setting is the Same at [or
the SB carburetors.)

Thic adjustment applies to gasoline ot 72 octane

grade (regular). The adiuslmenl has to he checked
tor other kinds 0! fuel.

When reselling the carburetor after running in,
the throttle valve needle position has to be checked.
After unscrewing the main jet bolt and the idling

 

Keilu'u 71

let the \'i|ltlt: or the trio jt:l\ hm to he checked.
The throttle toltc \lop wrcw ttmuld he slltckcnctl.
The pilot itir tetct» ohmlltl he tiuhteuett nnd then
tluctened its preterihetl .r\llt:r ttttrtinu. tlte engine
ltllmg speed hut in he :Itljlhtcd with the throttle
tttlte \lUP ~crt:\\'t The throttle enhlc play hm to
he token up uith the cubic bolt end its posilion
secured with the nut.

KEIIIIN

liondn IV the big tncr or Keihln cttrhuretort
"Milt in lupun. Bath the tilde throttle and crinr
ttnnt tncttunt lute; tire usctl. The tilde throttle
tipes nre fitted to all models up to the 450. which
hm tun chrhurcton.

\ dovtndrnit ntndel is found on the Honda 50
Model 100102. Aecontpnnying lllu<ualions make
the lunctiun: clear.

Atljimirtg wrew til in pilot controls idling
nlixlllrct Turning to the right creates a richer

mixture. It) the lclt, a leaner mixture.

Screw 12) Conlrok idle speed. Turning to
the right increases speed, to the heir reduces it.
Idle opucd ohctuld be 300—1000 RPM.

 

 

_. Fuel mum

w an rat/sen 53>

 

 

Keinin downdlait lyp: ls used an “and: 100-101

 

 

72 Carburetors and Tuning

 

 

 

 

 

 

 

lurl llnw in Keihin simmi lypz.

Opel-mien

\thn choke IQ“)! is pushed up in full shill
pmliiun. ihe choke [2) colllc< down. The relief
links (3) rnnrilh new in ~hnl lhc window (5) by
me spring (4). When lhc lhmlllc who (1) ii
npened about 1,4. incl Sprays oul irorn ilic pilol
onller (a) and rhe needle jel (7) (due to vacuum)
llnd all |Iic same unit lhc relief valve (3) is npcncd
(dolled pan (8) ) properly [0 allow air now lhmugh
1h: Window (5) lo give most ndequnlc mixlure
(er slufling. AIicr rhe engine i: sinned, \ncnunr
increase», opening (he relior vnhe (3) widely lo
iced ndeqnnre n wire in rhe cnol engine, The re-
1ch Valve (3) opening will \‘ziry. cmrmpomling lo
lhc lhmulc \fllVe (1) opening (9).

Funcxiun at each pm
(9 Main jcl (10)

The primary funciion oi Ihe main jel is lo
annual fuel flow for proper nlixlulc a! high
spend.

@ Air jol (5)

To prevenl loo rich :1 mixlure at high speed
(lhrolllc wide open) or loo loan a mixture nl slow
speed, air i< ‘upplied in thc nccdlc jcl which
conlrols th‘ unmunl.

@ Needle ier (4)

Ai full lhnlllli: and ill nlcdium specd [he needle
in once more norm ro comm] fuel nirer con-
lml by (he ninin jcl. ll is ndpmerl ni Ihc Same
mic {is this jel needle.

@ lei needle (7)

The fundion of Ihc nccdle i: In control n ix-
lurc mlin rn medium rhrnnle opening (belween
Hi and V: mm) in Conjunction with [he needle
in explained above. ‘l’he jet needle. having a

 

 

 

 

 

long taper, is titted in a suspended state on the
center hole oi the throttle iahe, the tapered
end inserted in the ncetllt: jets Therefore it moves
up and doun according to the throttle \‘altc,
its taper responsible tor udcquntc mixture ra to.
The needle Can be adjusted to four positions,
first position (highest) giving lcanest mixture
and tourth position gi\ ing richest mixture.

@ Throttle Valve [6)

The throttle valve controls the amount of air suc«
oned by the engine and has the important Iunction
or controlltng nti\turc. 'there a cutaway on the
air suction side or the throttle \‘dlt'c. By chang-
ing the size oi the cutaway, negatiie pressure on
the needle jet can be varied to change the amount of
flow to change Iht: mixture ratio. The range of this
function is betuecn idling and around H [mm
nutciicctit hate ‘1’: turn,

@ Slow jut (13)

The slow jet control: flow at fuel at idling
state. By a loner opening at the throttle a
taporized mixture is made by air coming through
the orifice oi the itir bleed.

(a Air scren (II)

'lhc :tir screw cantmls the amount of air ilow~
ing in the idle isle“) slstem. lt controls uir to
be mixed with Iuttl \thich passes through the
slow jet to get adequate mixture “hich is Iorczd
trom the end or the slow jet.

in making pretintinart . justntents. engine re
pair or replacing Worn parts. be certain that

(D each part or the engine is properly adjusted,

@ the Carburetor is checked ior atr leakage,

@ all worn parts are replaced with new parts,

 

 

High speed atljthtment

For the lull throttle position (full to half open)
adjustment is made in the main jet. To determine
rich or lean mixture. the tollouing procedure is
used.

(D \Vhile running at full throttle, close the
choke a little; this creates a rich mixture. II the
speed increases. replace the main jct with the next
larger size and check again, using same procedure.

C2) It the speed decreases when closing the
choke, the main jet is suitable, or too large. To
determine if the jet is suitable or too large, replace
jet with next smaller size. It the speed decreases
and then speed increases by closing the choke, it
indicates that the original jet is the proper one.
Replace original iet ior hest periotmance.

Intermediate speed adjustment

For the throttle opening to to 1/2, the mixture
is regulated by the height or the throttle cutaway
and jet ntedle. Intermediate speed control is
more precise since the cutaway will attect any
speed under to throttle opening. Fuel consump
tion is most economical when the jet needle s
leaned out ID the left as much as possible without

Keihin 73

 

MittsUttK float level ill Keihilt.

causing a loss in acceleration in the intermediate
speed range.
(9 Jet needle
3. If black Smoke comes out of the exhaust
at intermediate speed. thl: mixture is too rich,
Lean out the misture by turning needle to the
lens
h. it you to the engine “braking“ while
accelerating or running at constant speed, turn
jet needle to the right.
(2) Cutztvtay or throttle valve
The higher the punched rnarlt, the “crtkcr the
mixture and \‘ice \ersa.

Idle spot-d adjustment

From 1/4 throttle to idling. the mixture is reg-
ulated by the air Screw and the throttle valve
Cutawa).

(D Air screw

The mixture is regulated by the air screw while
idling; a turn to the right makes the mitture
richer; a turn to the left makes it leaner. After
adjusting. check for engine- misses by tlightly
opening the throttle. II there is a miss, re-ndjust
tor hetter perrormance,

® Cutaway of throttle valve

At almost it throttle opening. mixture regu-
lation is sometimes difficult. In such a CLtSL‘ lake
higher Cutaway number: it mixture is [Oct rich
and Vice versa adjust the air screw again,

Arljuslmrnl of "oat position (carburetor
remoted from ~engine)

® Place the carburetor uptide down This is
not the correct float position or the regular Iuel
level since the spring in the float valve is retracted
due to the thrust from the float valve end on the
float arm by the weight at the flat“ itself.

@ Tilt tht: carburetor So that the float pin (4)
std): in upper post on and itoat (l) in luwer
position; hold this position just before the float

 

74 ( Irlmrelnrs and Tuning

nnn (3) lenvc< rhe float valve end (2) (leaving
nuinl i: aheul 7o= [mm upsilll: down pmilion).
neynnd a margin el 50’ m 70", lhe final value (2)
(10% "0| l‘CII’IICI.

:9 Meanure lhe heighl dillerenec hemeen lhe
inner end 0( |hc enrlrurelnr (5) and carhurerar
hmly is), There i< no dimenlu uilh perlermnnee
ii lhe accuracy of H10 flonl poxilmn day within
0.5 mm (.02") up and down. it dmnred lrern Ihi:
nrneunl. udjual lhc ileal arm <3) hy bending wirh
special care in Ihe prezerihed 0.5 mm.

liElllIN-IIONDA 430

A pair of e '\ (consmm uncuurnl carburetors of
lhc 5(3ch (\pc 1m: u<cll on lhc Hnnlln 450. \\'ilh
[his e \ upe, ihe lhmule slidl: i‘ nor uc|uu|cd
dirccll) lu ihe rhle, Ivui h} negnlixe nrewire nnnslnnr vzlncily ulhuillni: are used nn unnrla asni
nhn rhe pmon uhich inrnu rhe slide The ren-
rurl is [hm changed according to demand and
rhe primmy'chomlnry venlurl rclzllionship bl:-
comcs very smooth.

 

 

 

Venmri

The portion of rhe carburetor lmdy uhere air
emcrs’ and u- squeennl h) the lhmule is called
rhe l‘cmuri and in ir lhe air [low rnle become: \ /
higher. Thu change in rnre i: nccnnrpanied h) ‘-
n change in nrmure and ii “Ian: R an opening in
rhe ude (or llnnmu) nr rhe \‘cnluri sccnon “hen:

{—
4—
luel can he inunduccd, u uill be sucked along
by rhe nirslrcum. To heuer vaporize (he (ucl
llroplcla suchJ up nr lhis nnrnr, nu arr hleed
isuxed. -,

Air Mun-d

Air bleed is gmphicull) illuslrdlcd hy lhe cum-
mon rorla Hm“. [I yuu place Mm“ in your
moulh and inscn it into a glass of “aler and
suck, you 3 r n zlead) ilnu nr uaier. it you re-
mme )Our muulh from lhl: end of lhc \(ruvl lh:
\\a|cr \\l11 llnu haeh .nm [11: glass. ll you make
a hOIL' in lhe Slrim. air mixes with the warm
and you gel bubbles “hich ‘hrm liule lendency

lo mum in the glass when you remme )0"! y
rnuurh. u )oll enuld make an opening in rhe
5m“ and inrraduee nnmher alm“ 30 mm ”1:: I f
submergcd juncuon of lhu “air bleed" and lhe
"main Jul“ <lra\\a vim under “men flu: bubbles in '
|hc main jet" \xould be even smaller and more
plenlirul lhan previously This is “air bleed." I
(D Air 5) m '7
1
ll
(al m) (c) I‘

 

lllllslminn nl PIISSM! than in "minted I": ll! Vlnluli.

 

Air pasxcd ihrough lhe air cleaner in raken from
Ihe air imakc (2) rhrough (I) nnd (15).

When lhe amounl of nir required by |hc engine
is small, rlre vacuum nirlan (15) is generally
Iovlcrcd and forum it prima
milling rhe [10M rah: in rhe

 
 

venluri, lhus main-
nluri, Illusmtinn n1 zir nleerl princlnle.

 

 

 

  

/SAJ
/,

 

 

 

 

 

 

 

cuuway ti litinin muslin! velocity tarhuretnt.

With an increase 01 air volume Ihc flow rate in
Ihe narrow venturi portion (1) becomes faslcr
Khan that of the air intake (2); [bus the pressure
of Ihe venluri portion (I) becomes lower than
lhnl of the air intake (2) (i.c., becomes negative
pressure). The diherence in the pressure is lmns<
milled as the pressure diflerence in between the
upper and lower surlaces or the vacuum pislon at
porlion (a) and portion (b) and [he force to pull
up the vacuum piston is actuated.

The vacuum piston (16) is pulled up in a
value proportionate to the llow speed, and the
vcmuri area is increased.

Further, as the englnc reaches high speed, the
vacuum piston rises up to the top and lorms a
secondary vcnluri sectional Surface which is suf«
ficienl to maintain maximum output.

@ Fuel syelem
a. Flow system
The amount oi luel which passes through the
main jel is controlled at slow in through the pilot

jeL Simultaneously, the luel is mixed with air
hunt the slow air jet at the air bleed. The mixrure
jets from the pilot outlet H2) and bypass (13)
near the periphery 01 the \hrolllc valve. On the
pilot outlet (12) the pilot screw which regulates
the mixlure is provided.
b. Main system

A part at the luel which passes through the
main jet is directed into the slow system as ex-
plained above. However, the other main parlion
oi lhc Incl is mixed with air irom the air yet within
Ihe air bleed oi the needle jcl holder, and jets-
out {min the needle 5:1. When the vacuum piston
is fully closed (when it works as the primary
venturi) or when the vacuum piston is hull closed,
the tapered porlion of (he jcl needle installed an
the vacuum piston squeezes Il-le iuel in order to
prevent excessive iuel passage lrom the needle jcl.

@ Float eharnlser
The Iuel coming from [he luel Innk enters the
floal charnher through passage iron the iuel tank,

' 76 Carburelors and Tun in g

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fuel flow mmugn c,v cmumnr at various mum:
nnlmnfis‘

5mm

 

 

 

float rnhc seni and mm valve. The Herd (11) i:
flonicd up accordingly. The final \dh‘c (6) ie
lined b3. rhe nun: arrn (7), and when rhe flout
val“: (6) Common Ihc fludl \zllvc .-al (5), [he
inel imldc rhe float chamber (9} ii mod, and the
fuel lcxcr i< lmwrcd. The final (I!) i\ also
lowered accordinnly and rhe flex“ \‘nlu: (a) leave:
rhe floiu Valve mu (5); rhui, rhe fuel cnlcrfi in|o
rhe flu.“ chamber (m. H) rcpcaling rh e openi-
rinns, n Conslum lnel level can he rnninu ed. The
pumon of me nenl who (6) nhich comucfi the
lien. nrnr 17) ii prm'ldml wirh n eprin Furlhcr,
when rhe merercycie ix inclined m for gn mailer
niche lo the floal vahc 5cm, lnei ererrlcm, nnd
lhe luel enrer, rhe qlimlcr; [hm |hc memow line
(8) ha: been provided [0 nmim' i the :pccific
ruei low]. When rhe fuel leicl re_ hes n >pccific
iercl, lhc overflow line pcrmik lhe iuel lo be
dischargcd.

@ Clmkc

When srnrring engine in cold weather, ii is nec-
emry n» prmide a rich mixmrc and [or this
purpesc n choke \alve (3) has been provided
\Vhen lhe choke |e\cr (17) is med, the choke
(3) cloxcs and nir flow ix milcd.

Howewr, if the opemien ii improper, macs;
fuel is red Io lhe engine. For [his Icawn, a relief
valve (18) is provided on Ihe choke vnlre 13).
The relief \ah'e (18) open: and closes by the
negalivc plesmrc, and makes rhc mixlure wilablc
m n celd engine.

 

 

 

   
   

 

 

Vacuum piston and in mill: (m) in Klillin E,V maul].

thhhflundu 450 77

fl
g g

Film in and 3an ill 0' E V cavhurelnr.

l1

MJ\
§ mm: JEY HOLDER
Main in, Hull: ill hold”, and null! i=1.

?

GASKEY i

VALVE 5m VALVE

Flam Mull! Valli! nompnnlnls in C V Illuflzl.

k;

\Tl //

 

 

Dnzrflinn nl mint Valve in choke in ON madel.

ii

 

78 Carburetors and Tuning

Curllurelor flincllnlls

® Idling

\Vhen idlingi [he lhrollle Valve (15) i‘ in an
almosl closed posilioni and [he fuel is jailed from
rhe pilot ourler (12). Accordingly, rhe mixlure
regulation is pcriormcd a! [he pilol screw. When
(he piloi screw is lurnerl in. me mixiure becomes
lean and becomes rich when Ihe screw is Iurned
oul. Screw lhe needle fully in and back oil unlll
rhe besr cng‘nc speed is ohmined wilh a closed
lhrollle,

(.5 Lou and rruising speeds

The iuel is mainly ieired from rhe bypass (13)
because rhe rhrorrle valve (15) is opened at a
specific level. Accordingly, lhe mixrure adjusr-
rnenr is sel by rhc inside dinrnerer of rho slow jel.

Nola: Thi: iniidc diamelel’ is somelimes indi-
cnled by number, Lind fur inslnnce, if lhe number
is #38, ll means ihnl the inside diameter is 0.38
mm.

@ Medium speed

The opening or rhe lhrollle valve (15) becomes
larger, rhe vacrrurn pislon (16) sinrrs rising, and
rhe iuel slans ro jer lrorn Ihc nccdlc jsi; however,
lhe jclling value is regulaied by lhc jcl needle.
Accordingly, the mixrure ndjusimem is perlormed
by rhe serring posirien of rhe jel needle ro rhe
vacuum pisron (16).

@ lligll speed

Boih lhc ihroule valve (15) and ihe \‘acuum
pisron (16) are fully opened, and accordingly. rhe
jel ncndle's CDndilion is [hill in which [he jel
needle is moslly lined up; rhus, ihe fuel is jailed
our from rhe necdlc jcl. The mixture adjuslmenl
is set :n ma main jei.

@ Floal level ndjuslmenl

ll is dilTchlll lo measure [he heighl of Ike fuel
level ilscll’: thus, lhe fuel level is decidcd by [he
heighr of rhe ilnni. Plzicing rhe carburernr verti-
cally as shown and lighrly hiring and lowering Ihe
nonr (ll) by linger, delermine rhe posilion where
ihe l‘loar valve (6) head conrncrs slighdy rhe floar
arm (7) or Clearance of aboul 0 mm is lefl be-
lvlccn (hem. and [hen measure "H wilh a level
gage, If “H" is no! Ihe mlcd Value, adjust il by
bending thc llonr arm (7) carefully.

N010: \thn checking ihc Conlncl of (he lion:
Valve (6) ilnil ll'lC l'lonl {inn (7), il musl be done
very carclully, because rhe spring is conrained in
(he flank \‘nlve (6) Lind if this valve head ii
pushed, rhe spring is gone inn) lhe inside oi rhe
floal valve.

cnrlmiernr cleaning and adjnsriuenr—
Honda 450

ll lhe carbureror is conraminared or improperly
adjusred, lhe engine efficiency is noriceably
loaered. For example, if rhe mixmre is roo lean,
rhe engine overhculs, and ii roo rich, engine opera~

rion may become heavy and deiecrive. When
iuel overflows, ir may cause fire. For rhese rea-
sons, lire carburetor musi be disassembled. in.
speered, cleaned and adjusied periodically.

(D Remove bolh lei! and righl air cleaner case.

Ce) Ramovc Ihc 6 mm hex head ball and air
cleaner connecung lhe lube larch bell. rake ofi rhe
lcl‘i and right air cleaner covers.

 

 

 

rim iml an ill! mini".

Starter
full open

Slarter
perfectly
closed

«A - air prime-e

‘ fuel passage

 

H enmiu lul\lllre pasiagr‘

,,St.trtt-r l’luneei-

 

 

 

 

 

starter jet

 
      

jt-t not-dir-

Keillin-Ilmttla 450 79

    
    

VIM 2( )SL‘ Carbu rt~tnr

(I|l|l4‘l lltl‘ItHlt' hilt,

   
 
 
  
 
 
  
 
 
  

lnll‘l port

 

 

 

 

 

 

\oir iet

 

’\ float
valve

 

ma in jet

Schmztlc Ill czthutltor used nll Yamaha 150.

@ Loosen the throttle cable adjusting holt and

nut, remove the throttle wire from the Carbul’clm’r

(9 Loeten the carburetor helt, remove the car-

hurctors.

C5) Disassemble and clean carburetors with

gasoline.

© Use compressed air to clean the individual

nozzles, and after cleaning reassemble, reinstall,
and adjust.

(3 Idling adjustment

a. Turn the screw stop (1) to adjutt so that
both left and right exhausts are equal. When
the stop screw it) is returned, if the rotation
cannot be lowered. loosen the lock nu! (2)r
and tighten the cable adjuster (3) by one
more turn.

b. For either right or lett, open or close the
pilot screw (4) slowly from the preterit pofi»
lion and find the position where the engine
speed becomes the highest. ll tightened, the

mixture becomfl loan. H 10 filmed, the mix—
Iruc become: rich. The adjusting should be
performed within : 'A lo ‘/4 [mm
c. Rcudjust the dill'crcncc of exhaust strength
between the left and right which occurred
with the adjustment performed in accordance
Wllh the instruction in (it) above, with the
stop screw (1) in accordance with the in<
situation (a) above.
(I. Repeating adjustments (a) through (c)
ubote, adjust the carburetors so (hit! the
proper speed and exhaust ureugth are ob-
taincd from both left and right carburetors.
® Throttle valve adjustment
Adjust the throttle anvc so Ihal bclh side
throttles operate equally, Touch bnlh throttle
arms with the fingers from beneath the carburetor
and move the throttle grip it little to see it both
levers start moving at the same time. If not.
loosen the lock rm! (2) and adjusl with the cable
adjuster (3).

 

80 Carburetors and Tuning

 

 

 

 

 

 

 

 

 

 

4——— Passage of Air

 

 

4——Passage of Fuel

 

 

   

 

 

 

 

 

I
i
I
Jet needle ':
I
Inlet Purl i From l
—— l ‘ ‘ Atmosphell ISlarier
* r, T l lFully Opened
m» i i
‘ -T‘;?*'Fully Closed
‘ r r ui :5
_ i i ' 1 ' § aI er Plunger
A_lr_J<i i ... Breather
Oil Level 1 ‘ '
l ‘ 1
: l l
A'ir Breaihing m miner ‘ ‘
Hing Hole \Alr Breathing Hole :fl‘
0' Pilot Jel
3 Pilot lei W
Main Jet in” “H Needle m

A..-... Passage of mixture Gas

Cutaway nl Mikuni :arhuvelur with Marie: an Inn mndel Vamaha.

)IIKUNI

Mrllini "lrhurclurs Arc \xidcl) med 0n Japanese
nmlurqclm. \xilh annnlu nnd SuzuLi as Ihc
large“ Clmomcrs. Thc elriel elur clermic \\hich
llixlinguishc: rlre Mlkuni is an air \cnl pipe and
un merilew pipc so lieu |hc engine urll be less
like!) In fill nun mu iuel in Cm: oi u sulck
Ilccdle \al\ C.

 

 

 

Mikflni used on Yamaha ‘25.

A nprerd Mikuni upernliun n as (allow:

)1.

Arr rezlchea |hc cnrlurrcler lhrullgh me air
cleaner and nir cleaner luhc end is indnclcd into
”it engine [mm (ll ihmugh die Ihrollle valve.
'1lus ilir Hm» crenres n Vacuum Around rlre jcl
necdlc (2) and fuel in me «on; chamber is
pnmcd up mmllgh rne nuiin jc| (3i. Fan of the
nir lnlcn Ihmugh inc uir jcl (-l) cmcn lire needle
Jet 15) mini five holes (6) lncmcd zlmund inc
nccdlc jcl .lnd creates bubbles in die ruel passing
lhe needle JCL Air nous under the inreulc valve
nl high epccd so dun bubbling iucl coming from
llrc needle jcl is uleniized and mixed will. the
all.

 

channel

Slow clrnuncl

When lire engine is idling |hc lhrotllc valve
is lowered almosl lo the honour hul air is luken
Illrallgh inc llir inlcl (7) insullcd for engine
idling Air cmcring rrunr die air inlet is merered
by lhe prlul nir udjusling screu (8) ilnd primes
up l’ucl through me pilot gel (9) A richer

 

 

Au vent and nverflow lain! an Mikuni an sateluards tnr
twn~strnke enline.

fuel/air mixture than that mixed in the main
channel is supplied through the outlet (10) to
the engine, The fuel/air mixing ratio in the slow
channel is controlled by the pilot air ndjusting
screw. To adjust, turn the pilot air odjtming
screw to the bottam and then back the screw cm
1.0 turn, which is the standard setting.

Slarler device or choice

When the starter (choke) lever located on the
handlebar toward the rider ii activated, fuel will
be primed up through the Starter jet (It) by
vacuum in the crankcase The fuel will mix with
air in the float chamber (13) which enters from
the air bleed hole (12). The mixture jets {ram
(14) and mixes again with air coming from (15),
and the new mixture jets into the main bore
through the hole located in front of the throttle
valve The mixture jets from the outlet in the
main Channel and enters the engine.

Disnssemhly
Q) Remove four fitting screws with a small

Miklmi 81

Phillips screwdriver and <eparale the {loan cham.
her from the mixing chamber.

@ The {lam can be removed from the mixing
chamber body by rcmmi 2 me float pin.

Q) Remove the main jet v~iih a 6 mm wrench,
Remote the needle jet. with an 8 mm wrench.
Remove the needle valve seat with an 8 mm
wrench. Remove the pilot jet with a small screw-
driver Assembly i\‘ the reverse oi the above
sequence.

 

(g Turn the throttle valve Slop screw in so en»
gine RPM incrcnscs.

@ Turn the pilot nir ncljnqing «crew in <0 cn-
gine RPM dccrcmcs. Turn the screw in until the
engine runs (At the slowest Vpccd.

(.9 After finding the lowest RPM, fix the screw
:1 huh: before the lowext RPM. The engine RPM
is still high nt thifi stage.

(9 Turn the thrultle vnlve slap screw out and
engine RPM decrcnsck. Fit the screw 3| the spot
just before the engine Slaps, nhich ihculd be about
1,200 RPM. Measure With a rc\oltttion Counter,

(3) Turn the pilot air adjusting screw in and
out within ~23 at a turn and find the position

 

Main channel Ill Mikltni.

82 Carburetors and Tuning
“here |he en n: run: mog| :momhly The ad~
juumcm i‘ lini~hcdi

mjm. .. [or \nrious ,peed,

High qua-(1e

The mi\lurc [mic is ndjuned by [he main jet
M ‘3 m mu iluenle openingx ll me engine run;
more mmmhly “hen (h: ihmule is lumcd hack
xlighfll {mm mile opcn u lndicale‘ the fuel
nnunre n lczm If u _ m: le drop: “hen lhc
|hr0||lc l\ clmml a I 'hll} il Indicates [he fuel mix-
ml: is ienn. n‘ engine RPM drops “hen Ihc
Ihmulc xi clmud slighfly iI indicates that the fuel
mmurc is COII’CCI or 100 rich. 12w 3 larger mlm~
bered main jet “hen Ihc [ucl miluurc is loo lean,

 

 

VII-(Hum .pml-

The nnxmre is eommlled by the Jet needle
poslllun and ihmule \Ilhc emnwny in u lo M
Ihrmllc openings.

a Adjusting “ilh m needle.

There are five groove: in the upper pan of (he
]C| needle. and they are counlcd from in: |op m
me bollom: fim. second. etc.

 

 

$an channll III Mlkuni.

@999

Thralll: valve onzminn, Mikuni.

 

Lean

Rid"

 

iyuinil in Mail: and clifl. Miklllli.

1mm: um cutaway, Mill-mi.

 

 

 

Removing mum a! flux cnamher, Milunit

Remuvlm neldll Vllve, Mikuni.

 

leuvlng main jet, Mituni.

Mikum' 83

 

Removing pilnl ill. Miklllli.

If exhaust fumes me while in color, ll Indiculcfi
1hr: fuel mixture is too rich. Lower the jcl needle
by one groove: Ihal is, lil lhc clip in the second
gear from the lop. Third groovc is slandard set-
ting.

If engine RPM is not smoulh While riding and il
reeis M if engine brak: is being applied it indicntes
the fuel mixture is too lean. Raise the jet nccdlc
hy one gram

b. Adjusting with throttle vnive cutnwny.

A larger numbered Culaway increases air now,
giving a lcancr mixlurc. and a xmallcr numbered
Culuwny dccrcnscs nir flow. giving n richer mixture.

Adjusting by cutaway. however, uflects engine
pzrformancc ni Sluvl speeds below 1/i throttle
opening. Do not change Ihe throuie vuive culnway
unless there is an urgcnl necessity.

   

 

 

84

Cttrbttrplors and Tuning

Loss speeds

Fuel mixture is adjusted by the pilot air ad.
justing screw and throttle valve stop screw or
throttle openings between Va and vs throttle
openings. See adjusting idling seerinn above.

Owrflow

Fuel overflow is cnused h} a damaged nont.
imperfect contact of the needle valve and valve
seat, worn needle valve. clogged carburetor iuel
Channel, etc.

As the needle valve repeatedly contacts the
valve seat ID keep the fuel level correcl, tht: tip of
Ihe needle valve is ztpt to wear. if the needle
valve is worn, there will he a gap between the valve
seat and needle valve even when the float tongue
pushes the needle Valve. Fuel will flow into the
carburetor continuously and overflow. Check in
Vee if the needle Valve contacts the valve seat
properly when disassembling the carburetor. Re-
place the needle valve if needed. To check,
remove the float chamber anti push the float with
a finger until the tongue pushes the needle valve.
Turn on the iutzl cock. If fuel flow into the
Carburetor. the needle Valve it worn. Hole: in
the main jet, needle jet, etc.. should he cleaned
when the carburetur is disassembled. Clean them
with compressed air. Do not use wire, etc., to
clean the holes in these parts.

LINKERT/SCIIEBLER

The linkert Schcblcr enrhuretors used tor so
mam tears on lndian nnd hig Harley—Dnvidson
models nre simple nnd emeient. They are also
easy to adjust and are designed to he adjusted on
the read like tuning u motor scooter, which is a
Very productive method,

The Linton is u side drdfl carhuretor with fixed
\enlurl and n throttle butterfly. There art: adjust-
nhle low speed nnd high speed jets and an idling
speed screw which changes the position oi the
butterfly on the t_v e med on 61" and 74“ models.
The 55" hns t r ed version which eliminates
the low speed ndiusung control knob and uses an
idling mixture screw. and a throttle stop screw.

 

 

Atljrtstlttt-nt (61”. '4")

If 30“ nre starting uith an engine which runs
\att‘lztclurily l"|l| not a: well .t\ it might. ztnd
Carburctiun scemfi lo bl: the problem. lire it up
nnd bring it to operating temperature. Then set
the throttle stop lltlllng speed screw), to achieve
ubuttt 2550—900 kl’“, Snark cunlrol ~hould be
retarded.

Screw the luurtpecd needle in until lhc engine
Rumbles and almost die». Then turn the adjuster
out H turn. Reset the throttle stop screw to
desired idling speed.

 

dorleyhttidsttn calhuutnl. ll) high speed needle, (I) luv!
sund needle, m throttle lever. m thta c stop screw, (5)
chute hm. l5) choke disc.

The high speed adjustment should be carried
out with the engine under load, but it can be matte
on the stand where the engine's ability to respond
to sudden increase in throttle opening is the test.

Set the spark to advanced position and blip the
throttle. opening it up suddenly. accelerating to
high speed and closing it abruptly. Screw the high.
speed jet needle in until the engine hesitates and
dies or backfires. Then tcrew the control out
gradually, blip g the throttle until the condition
clears up. This is ordinarily about I/s turn, but in
old cnrhurclors it could be anything.
the high-speed jet. it will prolon-
0 reset the idle to desired speed.

0n-lhe.rnnd adjustment is made by turning the
high-speed needle control back and {0th until
the best acceleration characteristics from about 30
mph up to 50 mph are round.

 

 

Atljttottttt-ttt (no )

The tame general idea is used for the 55"
model, but slttrl by screwing in both the idling
screw and the high-speed needle adiustment fully
home and backing 011' IV; ulrnt. Fire up the en-
gine and get it to operating temperature, with
cholst: open.

Sci the idling speed at a moderately rast idle.
Screw the idling ndjustment in until the engine
(others. then hack it of! enough to make the engine

   

 

. .spted jet is turned in gradually hile
iccelernling the engine from idle to high
speed. When it begins to stumble and hackfire,

 

   

 

lenilh caibunlni, (I) Earhurew hndy, (1) mixing cham-
hll lap, (3) cable adjuslar, l4) adjuslar Incknul. (5) lhmllll
sll'ill, l5) slid: swing, (7) lap lo Bully scrzw. ll] slulel sllfll,
(9i lnrnllll slap screw, lln) slnp screw sprinl. (II) clamp
ml and hall, (11) pin: screw, liar zmulsiall lllhl. (la) main
‘ 5) slaw rlillilirl! ill. (15) "all, [I7] final hinge WI,
rll washer, ll!) ilnal hnwl, I20) ilnal hawl screw. (zll
Ind pipz, (22) lininll hall, (1:) mm washer, (24) mm wash".
(25) lillll zaull. (25) inlake adanlnl. [17)_ aflanlni screw,
(18! shakepmal washel, (29! while! cunnlullon. (3m Ihrnlll:
cahla, (31] ariaplur lu head, (32) “a". g, (31) air filler.

 

   

lurn (he nccdlc buck oul le enough to enable
[he engine to “lake ii." You can check lhis on lhc
marl by acceleraling from 30 m 50 mph

The big problem wilh many or rhere carburelors
ii warpage 0f lire flange earned h) improper hell

 

 

Zerrr'llr 85

ligh|cnmg in llrc hands or pan owner: or me-
enanie~ Air leakage ix lhc rcsull and all the
middling in the world won'r lrring lhcm inlo
adjname l. ca vlllh an all m fillerl willr
gnmiinc. ., \quir! inel in lhc flzlngc hilxc wilh
Ihc cnginc idling. ll lire engine spend: up, you've
gol an an leak.

   

 

Overhauling

Dlaasscmhling and cIcunlng or any of Ihcxc
carhurcmn follows an obvious pilllcrn, with alien-
lion lo be paid lo the following poinls on roe
asvemhiy;

(r) Be nire lhc venluri i\ installed properly willr
lhc main jcl vlcll lspmy nozzle) projecling ioro ill
and lhr: small :pring placed under il.

(9 Tire neppell w her below lire low speed
nccdlc spring k cril' nl. If left onl, loo much air
can hc \‘Cnlcd pas! lhc needle and me mixture wiIl
he loo lean and make low ‘pccd difficnll lo adjusl.

© Floai level is approximalely W irem lop
of flonl ro lop ol howl. Bend are floal lever
carefully bclwccn IhC final and the lulerum piar
prclcrahly wilh rne float removed from lhc bowl
lo avoid bending llrc small prong‘ wlrielr eonlnel
the needle headr

 

 

ZE 1TH

Zcmlh MX carburelors 1er used on some
Triumph mudck. Tni "n slide-llrrenle lype. The
accompanying illnslralien will make Ihr: disposi—
llon of pans clear.

There iv an flmll licklcr, bul prcsxing down Ihc
plunger (xi (0 mo limil or ii; lravel will provide
(1 rich miVlurc [or Ma Q when Cold. The meter-
ing hole in lhc plunger mrllm wllh an air pamge
in [he holly and fuel in drawn lhmugh lhc \Iow-
running jcl (l5), Arrer a slum limc :30 ‘econlh
or so) open in: lhrolllc w lhc lull cxlcm lo mum
Ihc plunger In in normal posilion.

 

 

86 Carburetors and Tuning

TUNING

If the lrlltll were known, mus! moloreyclc cn-
ginc Irnuhlci <tcm from inept inning. Because
lhl: cycle engine is so <irnple in formal end \0
accmsiblm nenrly every rider, nl enc lime or an-
other, undertaker lo "lunc il up."

Thi: isn‘t hall, in facl il is comlrlcndzllory. But
lou few of lhem :lllcmpl lo find out unylhing
nheni Ihc [”0ch helere Ihcy begin. No good
rncehnnic cvl:r pic-hr up n (crcvldrivcr in nngcr
unch he ha) llCCcS§ lo lhc right int‘urmallon :lboul
lhe nrnchine he is approaching. Aninlcnn \hollld
hc us cunicicnllnus

Timing: nntxixlx 0/ «diluting lilo variable: :0 I’m!
”My man! faculty .rprci'fimll'mlr, as lnr m $lrccl
biker nrc conccrncd. kncing i; nnexher mnucr,
which dncsn'l concern us here.

Thl: l0|lr>slmkc \ariablc< are (1) Valve liming,
{2) valve clearance. [3) fuel/air rlllio. (4) spark
liming, <5) peinl nnil plug gap.

Tho-stroke mechanic: have men less to worry
nhenl: enrbnrerien, ~pnrl: liming. points, and
ping.

So inning is no hig uenl, i[ you gn nl it logically.

(D Scl lhc vnh-e/lnppel (rnckcr nrnr, liiler,
etc.) Clearance. Thk is )pcclficll viith engine cold
in nlmun nil Clt‘cx “Cold" ~imply mczlm lhnl lhe
engine should he npprnximnlely Ihc ~zlme lcmpcr-
nlllr: in file rcxl of [he hike, Ihc frzlmci clc. In
other words, don'l adjuxl lh: VleVCS if [he cnglnr,
or me all in Ihc engine, i< warmer l0 lhc touch
[him any olhcr pnrt,

Letting il \ll ol'crnighl is lhc rnle followed by
most shop», hlll whatever lime il lflkCS ID cool
down i: the amounl Io allow, Clcztnlncc< Specified
with engine nnnn arc marked nllh nn zlslclisk (.)_

The liczl way In gag: lhe clearance is by go
and no-go. If clearance ix \pccificd 1a .008",
don‘t check it with n .008” fcclcr gage. Use a
.007", which should slide lhrough lhc spaccv and
ll .009" which should nol. The anSI important
ihing k to he hire you have lhc lappcl, pllshrod.
rocker arm (or nhnlcver i; applicable lo lllc lypc
01’ \‘(lch llzlin In your machinc) on lllc heel of lhc
cnm, nnrl nel iliglnly nnxo lhc quiexcning lamp or
Ihc lobe inc”. This means lhul you should have
the pislon at top dead center on the comprcmion
nrnke, not lhc exhaust alrcke, At this peinl you
czln acl both inlcl and exhaust valve Clearance.

This do“ not hold lrll: wilh Ihc Triumph Iwim
:md Mlllchlcu \inglcs, howcvcr. On the Triumph,
zcl clcnrnncc nn lh: lnlnkl: vnhe of nnc cylinder
vihcn the inlakc valve en lhe nlher cylinder in
tnlly epen, lhen repent vlilh ihc cxhausl valves in
lhc same manner. 0n the Malchlcw, romlc lhc
engine url|il lhc piunn i\‘ at TDC on Compression/
ignilion. ann lhc engine bzlck until plny is just
mkcn enl ol inlnkc plnhmd rind scl exhaust vnlvc
Cltarilncc, Then lum lhc engine forward unlil pals!

 

TDC and play is Inkcn out ni exhau<l pushrod
and ‘CI inlnkc valve Clearance.

(9 Adjust the poinl gap. Use a pair of fecler
gage» in the same Way in for the Valve‘. Paint:
are on spring lension and llley can easily be forced
open with the e.

® Scl the ignilion slnlic liming.

(D Reeheck ihc point gap, iun to he sure.

@ Chcck lhe nulanmlic :ldvnncc wilh a timing
Iighl.

(9 Clean. ndjim, or replnce the spark plug.

(9 Mnke sure the throttle is opening fully when
lhe |Wi\l grip l\ wide open.

® Start the engincl warm il up, adiml lhe ldlc
apncll rerevl to give a madcralcly {an idle. Screw
the pilol needle (<lavl speed scrcvl) in unlil [he
engine slilrh lo slumhlc and back il all 1/; Io 1/.
rum. Twin the lhrolllc npcn abruplly. lf il

 

 

Establishing tun and “Mar wilh slul ruler,

lalzl BSA models have crankcase nllll (I) flefln! llmil n1
automalin Illunce.

 

J

 

 

 

   

 

 

 

 

 

 

 

 

 

Tuning 87
AME].

MDDEl rum: PDINTS M ”M“ m
ifl~7§w Pixi: m .012 ms £03
200cc can .920 m4 mo nu
ma: Arrow 1. leader .nan ms — —
150-500” sinxles .m mu .nu me ms
500:: Min mm nus-ma .012 ms ms
550:: {win .m .m .mz mu m
Innocc 1545152 .01 1120 015 .nm .001
"mm Hun 1953159 .ma-m ms .m m

U,\I\\'
mm:

mm nuns PUINTS In, in.
n in ma .015 ms .003
a 505 .024 ,ms .nns ms
11 so .024 .015 me ,m
n 59; .au ms .006 ms

BSA

Mom PLUGS Palms m mm: Exit.
75“: Bugle Slifl"! .02" Jul Jun Jul!
Izs-Isv-nscc Banlam .m .015
mu: ML 1212 mma .020 m ,nlz .012
150»: :15 lass-'5: .0er ms ,m we
asnu Ba] .azn .DIZ .m .00:
5mm as: .m on .003 .003
500:» was MD .012 .005 ms
500:: n1 IssI-‘sz .nzn .nu ma .nm
snow A50 min 1962-‘64 .azs .015 me ‘am
550:: All) .nzn .n12 mu .m
550»: mm .uzn .012 ms .nw
65m A55 .025 .ms ms nu)
550cc ma ms .m .m m
500” ‘50” .023 .Dli .WH .n1n
5mm ASDZW ‘nza .DI5 m .nm
550»: 515525 .023 ,ms ms .0":
55m ABSZL .m .015 ms mu
55W: mu .m ms ,nna me
can»: 1155:? .023 ,ms .003 mu
441cc Endurn ms .015 .ona .nm

HARLEY-Dummy
mm:

Mum PlllES Palms m m
'55 anu .m 1122 .am no:
u 3.1 ms .uzz ms .007
am mm 193“? .nzs n22 .nm .002
74 mm 194w: ms .021 Nydnuli:
I25-I65-I75 .1120 ms

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

88 Carburetors and Tuning
canvas KAWASAKI
M0021 nuns PISINTS MflDEl 7 7 PLUGS 000115
24 11112 2500: .025 .015 05111 .025 .015
1! 250m: Trials .025 ,016 BS-HTRI .flZG .015
YES 2500» Tlizls .025 ,015 10001 .024 015
24 005 .020 .015 125051 .025 .015
25m: 5.1011: 01.2011 04m .025 .015 17551 .025 .015
I 75v“ .015 .D‘ 5
25041 .025 .015
Hosm
MDDEl 01055 Palms 1mm E
xh.
50.5505 001 .025 .014 .004 .004
907590 .025 .014 .002 .004
1250: man. 002 .025 .014 .004 004
15050 1000. 1:55 .025 .014 .000 .004
125cc mud, 00125 ,025 ,014 .004 005
16001: mud. 00150 ,025 .014 .004 005
250:» mm. 0072 .025 014 .004 .004
3000: mm. 0017 .025 .014 .004 .004
450:» mud, 00450 .025 .014 .012 .1712
[\‘DIN
A *7 7‘ 1mm
0mm PLUGS PflINTS 0.1. [m
500:» 30.5” .020 .015 .005 .001
1500: 45" .020 ,015 .005 00:
1200130000 14" 1. 00” .020 .015 .005 .000
25000 Brave .025 .018 .003 .004
43052 (win .025 .015 .003 .003
1200: single .025 .015 .003 .00:
5mm: win an .025 .025 .003 .003
\mcmnss & 4.1.5.
11100515
Mum PLUGS 00101: M m
ZSUEE .02“ Jul Nil‘ Nil'
350:!) .020 .DIZ Nil" NH'
50005 .020 .012 1111‘
5000: .012 .005 .005
500:: .012 .005 .005
500:» .012 .005 .005
50005 .012 .005 .005
55000 .012 .005 .005
Nokrox
7 77 7 77 1400515
010021 51005 001m: m.
400:» .020 .012 NII 101
50050 .020 .012 ,004 .005
50050 (will Inn .015 Jll'lZ .005
55050 (win .020 .015 .002 .005
750:: (win .020 .015 .005 .005
EDDEI: Will .02“ .flIZ .002 .005

 

 

 

 

 

Tuning: 89
PAhllHK
7 7 mm:
MUDEL PLUGS PDINIS M mu.
15m .nzn .014 NH ml
35m mu n14 Nn Nil
5mm .nzn Mir Nil‘
650:: Mo Nvl‘ Nil‘
kmu Fm In I:

7 7 7 7 mm? 77

Menu nuns PDINTS

250m: Clusaflev

 

 

 

 

Mluminulll Hun)
I. [X

 

 

 

 

 

.m .015 mm M4

:50»: 3qu mo ms rm Nil

5001:: mm .nzn ms Nil Nil

mm a mu: m“ 320 .ms Nil Nil

750 Intzvnlnm flZD ‘DIS no: .005
Suxnrnx

7 77' IAPPUS

mam nuns Palms I" m.

5mm :7 sa .nm .012 ms ms
TRII “1‘”

7 1mm

mom nuns Pmms M m

Sllndlvd TN ,010 DIS ‘01“ Jim

suns ms x um .1110 .015 mm mm

150cc 3! .nzn ‘mz .nm .nnz

svncc ST .010 D12 .001 .001

5011:: “D", Tile! Inn .01" V012 1102 .004

55m: av, rbim, mu nu ma on ma am

350“ JTA Twwa-an: .020 .015 ‘0‘“ .0”?

son»: an sum (win .nzn ms .nm .nIn

SWCE "EDA Yip! Inn .02“ .015 .0111 .0114

5mm “DUES Tigzv Inn .010 “15 M71 .004

55m Him 51 ass-'51 mu ms m m

m mm 1955‘s: .nzn ms .nnz ma

non liw 1w 1955152 .nzn .ms ‘nnz .nna

TIZU Bunnmll: WES-'61 .01" .ms .001 004

H Thunduhild WES-'54 .020 .015 002 004

ms mm was-'54 .nzn ms on mm

mm Bunnavilll mass: MD .nls ouz nnd
VELocx'n:

7 "7 777 7 7777 7 77 i7 VEEF

MMJEL PLUGS PMNTS IM. Exh.

200cc twirl [E .020 .012 ‘004 .1103

350:: mm .020 .012 .0115 .005

m .mz nus .nns

sun»: on

 

 

 

 

 

 

   

  

90 Curlmrelors and Tuning
KIONTISA SUZUKI
MnDEl nuns puma: ‘unnu 7 nuns ' Poms
175cc Impala 3|:le an me All muflzls ,nza .nu
175cc [nduw .mz ms .97 _ ,
11mm Impala Class .012 .nm
25m Summon .012 .012 Vxxcma
mun mes Palms
V _ Inunc: Rapid: .ms .011
” ”“5 mama: Bllck snaaaw .m .m
MDflEl muss —
9m 1, 2, 4. z er .025 ms
125:: um I. 12; .025 ms . 7 YAMAHA
15m 3": 015 1115 Mum nuns Poms
2min: 5!, EE, 1 SE .025 1115 7
250:» .025 .015 All mnflzls .014 .0”
slumbles. nchcn (h: nIiMurc «many. Then rmcx
idle weed as )0“ mm 1., Thix ~hould mm (he
hikc run as “all m m condhiun “ill allow
. A T
To go any {unhcr man Ih .chcck Ih: appropnr Dg’éfigwc “HER GWGE
me heading m [he carburcmr chapter for the liner 3

palms of mmudum carburclnr tuning.
[r you have a Iqurokc. ignore |hc \‘ah'c
unung bu and proceed 9 Ihmugh @

FIXED CONTACT PLATE SECURING

SCREW

)/

 
     

\ .. 0 r
O-OI2 —O‘OIS SCREW DRIVER

Chapter 6

Frame and Running Gear

Trollblc: Kuociulcd “i111 lhc frame and running
gcr'ir gcncrzll ihm» up a\ excemle rire “car. pool
«Carin inlcrmr hrilklns. or llnlmmlni.v of mu silv
pcnuon. /\|~o lo hr,- rncluded umlcr rho gcncrdl
heading lmllld he ihc cchch of mo much or Inn
lilllc c din luminn.

 

 

 

.llnun-runl Iin- “var

lrupropcr lnfldllon r: rhc pnncipnl Cline ol fires:
overloulhng o rho \cuond ollonder.

liyou do nor \'e lhc owner'» munuul for the
cyclc lor m crnc lhc owner'» nurnuul huh Io
xilpply [he irrlornnnion bucdlm: mine Iixpiincsc
priulcr lclr rho inlormulion oull hcro is n rule of
lhunrb gulllc (L) mmmmm inllnuon,

 

T|l<|. SIZE Fnoxr REM!
2.25 22 28
2 50 20 26
2.75 16 22
3.00 17 22
3.25 17 21
3.50 fir lip 15 16

Them stunnldrd~ would he {or Ihc 1igh|cxl hike
and lighlon ridcr As )0“ odd w ighl you nuru
incrcmc premlre. Generally lhc liuhren hike lo
bc flucd wllh euch <izc life goes \Dnlclhlng liLc
Ihi>1

Sill; \VEIGHT
2.25 150
2 50 175
175 225
3.00 275
3.25 325
3.50 350

For mry 25 pounds of imladm weighl ovcr
Ihcse slanddrds, add a pound of air lo from and
rear. For every 25 pound: you weigh over 150,
add n pound, lronr end rcnr. If you are going to
cnrry u pinwngcr, iidd nhmu 5 pounck lo rhc rear
and n couple [0 Ike lronr. For nnlnincd high
specd riding. higher pressures Ihlm normnl nro
required.

Thi< will prevent you ironr mining lircs by
under-inflation and will Luann: fairly decenl hzll'l'
dling. To gel exnclly lho righ| canihinulion for
)‘uur cycle is u mailer of Ina! nnd error. however.

The \ympmms of undor-rnilnrion nrc exce“
lire Wezlr m lhc sidcfi or the lrcud (plm, of counc,
mushy slecring. poor hnnclling. elm).

91

 

Balance mark an ill: shwld h: adjacent in HIV: sum.

ol-er.innnliorr results in excecr wear in lhc
Ccmcr oi lhe rreud. hurd. jolling ridrn clc.

Mnulignmenr will lll~u cume lire n . Chuck
lhe zillgnilleill or me \Vhech “ilh n lung uruighl-
odge. porhculurh ii lhe chnrn hm becn replaced
or lhc rcnr wheel removed ror any reason.

 

 

 

Wheel-In g

Louxc or hcnl \pukc\ Cdn pull n rim our of true
:md 10“ of rldtrs Whip o|ll lhc old xpukc wrench
nnd go ro \mrk Yull cnn do u, hul lhe hen
:ld\icc i: in Ink: 1h: Wheel in winchody who has
plcmy of chpzricnce. Ench spoke hum be Iighlencd
or Ioowncd d [raclion of a mm 11! a lime and ii
la n riruoccnmrning process. The Iym is opl lo
pull lhe whecl om oi round while trying lo curc
lateral dcflcclion.

 

lh-m or slifl' flooring

in uddruon lo lovl from lire prenurc, which
\ccm\ prcuy obvious. heavy sleering can be lroccd
in bad \lccnng hcud hcn lngs or incurrccl adjun-
mcm of the control.

L‘nor-rlnin or unhhly plan-ring

Worn hearings in the nor-ring head or in Ihc
from wheel an: lhc hm choices in ihh case. In
the cam: 0f non»;ldjlls|ublc hearings. rcplziccnlcm
i~ lhc nmuml coune Anolhcr pambillly is that
Ihe |irc i~ nol properly mud on d - rim. not run.
ning mic. Thi) luucr condilion will ‘how up in
handlchilr oscillmicn in slow mud,

 

Hullumillg of slhpl-Iniun

ln rho high nrilcnge hike Ihk con be due [0
rnrigued springs, bul more lhnn likely u is cuuotd

 

 

mee and Running Gear

92

um" ha 5pm suscvm 5mm dam W
x /

      
   

western/m dzmpev mck 5W9

anl W (nu my:

5mm; dampu phu A
Sleur;:rh;ev;1'c a

 

s-qu damn! Spurn]
Slmnq :wev Sphng nu
S1eenqcz'w 5: gm

31mm: damn" nulawaY. Nnnda 45a, lynical ul ulna!
mudzls.

 
  

. SIEERING Mann A
van: mum

  

Removing stealing sum, flnwnwam, Nnnflzv

by lack of ml in the from {om hhd 'Dr fmlurc or
[he hhock unil in Ihc mar.

The oil in from mm should be replaced at
10,000 miles or ~L‘monnll}. n Ihix is not done.
gumming and dutcnordlion of the oil eah rcsnh in
pour mien. chr cushion uni|> should be rc-
placed as a "nil

Although ~s ndle OH" is Ihc Icrm used by
runny Inclurics m dcxcnbmg the oil 10 he used in
fork), any good luhncmng all can he med SAE
30 n gcncm y lhc grads in summer or in elimam
“hem \vinlcr nempemuue Llucm] drop below so)
in [he daytime. 1n |he winter in rough climzncs.

 

 

anl hnkz adiuslmanl. Yflumfm. In: dull!!! '
in: indicates pnsilinn u! In: my: Iem when
mnywnm

 

 

ADJUS‘IER NUT

Rn! Make adiuslmznl. Tlillmuh. Hymn lin: flnwinl ul
lava! shnw: nnsiliun when limngs are worn.

Ran cuihlm i» U use
RcrlboM'l , "

mm m: on non mun uni

Milli» u

   
 
  
 

my
pay m li ul

  

Fiul 29 in mm mm m iil ml

nwlnniml cum / acivrinnnnln /

Frame and Running Gear 93

Ram mi in mm pip

Real mm mm me

Renl Culllnn wmq innm

Fln'lfial,"wu‘1llblll

mm

7.

E1055 slclinn oi (Ill cushion assembly, Manda 450, iyplcal
oi nlhel mnfleli.

rm ran ow En n n

m. onncm

 

i, do” no sin.»
m in 5-0»—

  

 

 

 

 
       
   
 

MAUJ

4W cum" 5,

 

ham Fall 7D

 

ois lPerane

l
JSUlflOLSgnA

   

 

I Ilomlgwmeylf'un‘hw
’7 lawman
L bum, Lanai" ' ’

Front inlk cushinll. Manda 450. typical al other mndlli.

SAE 10 can be sllbfillxulcd. For some ridcn yea!-
round :0 ucighl IS mlisfaclory. Il doesn'l cos|
much lo upcrimcnl and me handling of lhc bike
can bc lnilomd n groin dczll lo your liking by
changing ihc oil. Sonic lucchnnic~ \uggcsl lhc inc
of non-dclcrgcni. or low dclcrgcm inch as Valvu-
linco

Dragging iirakus

Exlcmnlly, lack 0! (rec play 'n (he bmkc pcdlll
or hand lcvci ulll cause dragging brakes. lnicrn-
ally. wcnk rclllrn <pring> or rusted cm and lcvcl’
shafts can prcmnl hill rclmc|ion. The ~ympl0m\
may nol be >0 seven: as |o incluclc poor perform-
ance, ycl Ihcrc can be enough (1mg lo Cause cx~
Cemve bmkc lining vicar. The obvious symplom
is hot wheel hubs.

Scraping sound lmin brakes

This n due Io worn-out brake linings. a biokcn
shoe, or broken pnoi.

Lining replacement lime

This comes when lining lhickncn ii half~rc~
duced. Ai ibis poinl lhc ndjllslmcm is prcily “ell
lakcn up in mos! bikes. \thn half lhc adjuxlmcnl
has been Until, ii li a good idcn i0 bcgin thinking

nboui rcplacmg lhc shoei, bccallsc the brakes lmc
qllil: n bil oinil’ccllvcnco whcn hol, Moxl munch
have lining nicouning npprnxiniaicly 1i" lhick
when fresh.

Chain uliining

This slams from :i IotHighl candi|ioni ll ~hould
be a “liming Io Ihc ridcr because CKCC\S tension
camc‘ chain and sprockel wcai plus vicar on

 

Remnving mini lurk can: lot when nmovfll, BSA.

 

  
  
 

  
 

‘ L)»
[TRAILiNG
filo E __

SM: alianxlmull lnr llnnl hiakls, BSA.
l

 

Ems: Sealinn Ill lea! huh. Hand: 450.

    

Class section M llulll huh, lllllid: 450.
(min dilvmfl alleclirm

 

Eliaill maslev link. Be sill: rinsed end is ill dirlcliuli nl
relation.

94 Frame and Running Gear

 

   
  
   
 
 

  
  

Slmching chain (a Ililrminl Imollnl Di Vlur.

bushings and hcarings in the lninsmission case,
which leads in slrippcd gears and all sons of good
lhingsr

   
      
   
  
  
   
   
    
     
 
   
  

Chain flopping

Rnitling, slapping sounds . gni - excess slack.
This i< as had as loo (ighl a chain as far as
spreekei wear is conccrmd and Ihe inlermillcm
shocks to the rc‘l of the drive Imin don’t do it
any good either.

Chain adjuslmenl

Proper chain adjustment usually calls for w
to 3,1" of slllck halfway hclwccn sprockets with
the machine on its wheels, unladon.

Clmin lips

Oil [be oh 'n onoe a week, alter every wash job,
and aficr riding in the min. Use a mcdium weigh!
oil wilh Molykotc or some ximilar molybdenum
disulfid: nddiliv A worn chain can wear the
sprockets by ng up and down. A worn sproekcx
can ruin a chain. Replace the whole set when
vicar i< idem. To dcicrminc if a chain is worn,
rcmnvc il and hold ir out parallel to the ground to
check , dcwnys dcllcclion.
Wear of up to 1/. inch per foot is permissible
inasmuch as this can bc lolcmlcd before [he sur—
race-hardening oi the he gs is worn through.
To check it ill: chain is serviceable, remove il,
clean it thoroughly in solvcnl, Drive a nail in a
flat surface. hook 1| link of the chain over il. and
slrclch it om as iighl cu possible Here are the
Iolcranms for various chains [0 be measured
against a ruler.

5,9" pilch
10352".

1/2" pitch—23 pitches equals 11w; maxi-
mum: 11%

w pitch
9330".

When installing Ihc chain, be sure the open end
of Ihc master link ii away from the dircclion of
rotation.

 
     

  
      
 
   
 
 
 
    
    
 
   

 

16 pilchcs equals 10"; maximum:

 

24 pitches equals 9"; maximum:

 

S

OHIlION'S

 

by OOEE RITCH

/« comprohonws- Gmde to assist the mmorcycle owner or mechanic to
I03!” :hc ork‘chvc unu adorn he begins any disassembly. It w
(warm you (C wpomt the mural: :0 mm you wm know what to look
«or as you arc dmassemblmg the UM. There‘ove‘ n will usuauy save
urns and mom-,y m making any repair,

\n as:
y yepmr shop wxm testing eqmpment. Included are some gimme
m Intak- mc (manic and gct mo ongmc‘ stained
1 :5 Omar m orgamzed around (he famihar unlts of the molorcynle.
‘mrrstrcke and [worstroke cngmes, fiucl system electrical sysVem,
name anude aiso arc valuanlc lunlng ups Wthh cannot be
c, .n, m any shop manual.

Hhm'ml’i‘d w-m Act) by ‘3ch phoms. cxplodco views of the mechanr
"3‘ 4n: Mammal unns pus u sr‘k‘Cthfl 0" wmng dragramfi Var (he more
my mods‘s of n‘

 

 

m there wm be umes when a motorcyc‘e is slalleu far

 

 

vow

 

 

   

~ cydes

 

CHILTON BOOKS

A nn-sm 310mm Campan}

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