This site uses cookies to help us provide quality services. Using our services, you consent to the use of cookies.

[Forum] Help with 1996 Honda Benly CD50 engine

Frank: I have a couple of the new(ish) 12V CDi Benly engines. I need some help with some crankshaft tolerances. Anyone here that has experience with these engines? Frank
Kleesbees: Hi Frank, What tolerances do you wish to know. If it is regarding the big-end you can use the same as the 6 Volt models.
Frank: Thanks for your answer. My problem (on both my Benly engines) is, that the clutch is grabby, meaning they don't fully disengage when I pull the clutch. It is dragging slightly when riding, shifting from gear to gear, and also if you just push it by hand with the clutch lever pulled. I have bought a new clutch plate and even got my hands on this pricey kit from ( ). None of it makes a difference. I have, of course, played around with the clutch adjusting mechanism, but to no avail. When doing some other repair, I noticed that there was quite a bit of play - maybe as much as 1-2 mm on the big-end (see image)
cd50 bigend play
Now, since different clutch basket doesn't seem to do anything, I started thinking, that maybe this play makes it impossible to push the little metal rod that disengages the clutch in as far as it should, but rather pushes the whole crankshaft? I have a Workshop Manual of a MadAss 50CC which is using an engine that seems identical to mine. Here I find these data:
cd50 bigend values
Am I correct in assuming the play I'm experiencing is too much, and should only be up to 0,6 mm? If yes, how to I fix it? Where is the play 'created'? The bearings seem fine. I have some Takegawa spacers or shims, designed to reduce this play. I'm a little unsure though, where I should add them. (These or similar: ) I can add that the engines started riding in Japan, and then got exported to Sri Lanka where I'm sure they have gone many miles. I have had 3 years of trouble-free riding though.
Wim: You can reduce axial space on axles with putting in the right shim rings. Gr. Wim.
Kleesbees: From the way you describe the problem I think it has nothing to do with the axial tolerance. If you already adjusted the screw it is lickelly that there is another problem. I have some old C310 and C320 models with much more play than 1-2mm and clutch work there too. Maybe there is a problem with the clutch not being able to be pushed in so the clutch plates are disabled. The copper bush in the primary gear can be worn, clutch plate wrong assembled, is the oilthrough installed? Is the problem only since you imported the bikes? Or did it appear later on? A bent shifting axle and gearshift spindle can also cause bad shifting.
Frank: Thank you for the replys - appreciate it. The problem has pretty much always been there, but has worsened somewhat over the 3 years. The gearshifting is pretty smooth. The grabbing is especially felt, when I ride at higher speeds, approaching a 90 degree turn and thus having to shift down from 4th to 2nd. The only thing in the clutch that could be worn (out) is the copper bush. I assume you mean #4: ? The rest of the clutch should be fine, as the kit i mentioned before, is already assembled and the rest of the assembly is very straight forward. I'm not sure what you mean by "oilthrough" - can you point to it in the fiche?
Kleesbees: indeed number 4 is the copper or brass bush. The oilthrough is number 15 on the partslist page from CMS. Furthermore check if your collar (number 11 on the cms page) has the right thickness. It sometimes happen that that is thinner then original over the years. Hope you will find the problem. Mostly it is the search for the wrong part which has worn out over the years, but a nice puzzle.

Feel free to post a comment if you want to add something to the discussion!

Please log in or register for free to comment!