Topic: cb750 clutch mysteries

[koendd]

So,

I'm working on a clients cb750 (K2?) which had a burned valve.
rebuild the motor and it now comes down to the clutch which was odd to begin with, when starting to disengage the clutch, it would make a grunting noise, didn't do it while going into 2nd or higher. only when in first when you would start to ride.

so I'm back at this stage and can't figure out how to correctly mount it.

it has the early style basket (no circlip to hold the outer basket in place, just a slotted washer).
Shorter style inner basket (where to plates go)
and shorter clutch springs.

so it should have 6 fiber and 6 steel plates if I'm correct?

the owner fitted new plates before, and I thought that's where his mistake was.
but after taking a fiber out, there is some play in the parts.

could there also be a difference in the pressure plate? maybe it has a later pressure plate in an early clutch pack?

[koendd]

So I have the right clutch hub (?) which is shorter and shorter clutch springs.

So i would assume I need 6/6 clutch and steel plates but then again there is some play.

[Kevin D]

I can't tell you about k2, but I was just in my K1 clutch (e10688xx) with 7 fiber and 6 steel plates. What's the fiche say for K2?

[koendd]

I can't tell you about k2, but I was just in my K1 clutch (e10688xx) with 7 fiber and 6 steel plates. What's the fiche say for K2?

was reading hondaman's book where he states the the shorter hub needs 6/6 plates.

but then again, that wasn't right on my bike so added another plate  tot 7/6 and now it sits ok.
will see how it works out..

[HondaMan]

The REAL short hub (K0 only) uses 6/6 plates, the K1-K6 use 6/7 plates (7 fiber). The later, longer ones use 7 friction plates also, but have the double-steel sprung plate in the stack, making it all taller.

The K2 should have 6 steel, 7 friction unless, like mine, it was a reworked K1 engine that ended up in a K2 frame (from Honda!). So, in a word, the K2 might have 6, or 7 friction plates. The first thing, though, that you need to check is: the thickness of the cork plates that you have there. They should be 0.140" thick when new, 0.128" totally worn out. Here's the catch: we are getting the superbike plates that are 0.128: thick brand-new from some vendors. If that happens, the clutch won't work. You need the right ones, and you can get them at PartsNmore: their #39-1052 is correct.

Here's another important thing: DO NOT use longer springs in this clutch or you WILL break the pressure plate or the lifter, or both. Use the regular springs.

When you have the right stack-up of plate thicknesses, the top aluminum plate will be slightly below the tips of the fingers of the clutch basket (less than 1mm is normal).