Ross’ 1975 CB750

[Galactica]

So having the gasket on order, I decided to open up the transmission cover.  Mine is a #3 cross head not Allen head.  Tight as can be.  Dang.  Now I’m thinking the worst.  Splitting cases and sourcing transmissions/parts.

[kilowop]

Having occasionally had similar situation arise, I was advised to push it over a cliff and declare it stolen.

[hardrockminer]

That would be JIS crosshead?  I use impact screwdrivers if they are tight.

[Steve G.]

  I’m assuming you mean Ohillips head rather than cross head Ross?
  Your entire motorcycle is fastened together with JIS head screwdriver heads. I strongly suggest getting all 3 different sized heads at Princess  Auto. You may need to buy a multi head tip mini box.

   Vessel JIS screwdrivers are the best made .

[Galactica]

Ya, it’s JIS. Thought I’d push some buttons. 

The screw was staked at the factory and you can see it hasn’t moved.  I thought it would be too good to be true.  So I’ll get the gasket and ride it a bit more maybe, to try a get a definitive diagnosis.  But I’m pretty sure I’m looking for a transmission or parts there of.

[Twisted_Twin]

A trick from the Bevel Ducati guys that I found when I was trying to get the clutch in my 860 to stop slipping (it worked) .

Those clutch plates probably sat dry and stuck together for a long time.

Before spending a pile of money on transmission parts, I'd try pulling the clutch friction discs out and soaking them overnight in some ATF.

Transmission fluid has friction modifiers in it that are specifically for wet clutches. Engine oil doesn't have this and since it's a unit engine....

Won't cost much and beats tearing down the transmission.

[Steve G.]

  JASO MA and JASO MA2 rated engine oils both have specific additives for wet clutch operation, and longer chain molecules for gearbox operation.

  Ross, are you concerned that you may have a bent shifter fork?

[Galactica]

Could be a bent shifter fork.  Most likely if a fork is bent, it’s because the dogs and ears are worn, then the gears slip apart and bend the fork.  One problem causing the other, I’m thinking.

[Steve G.]

 Splitting the cases should not be taken lightly!!

[Galactica]

Shawn, the clutch has been working fine.  It’s possible that it is to blame.  That would be an easy fix.  It doesn’t slip so much as chunk and juddder, and not all the time.  When I get the transmission cover gasket, I’ll ride it some more.  It could well be the clutch.  That would be my hope, but I’ll do some research in the meantime.

Steve, splitting the cases is the last resort.  I’ll certainly exhaust all other options first.