Clutch Klutz... (xj750)

I developed a strange problem on my 1981 XJ750. I had been riding about 20 minutes and I pulled on the clutch lever to shift down to stop. The clutch lever had no resistance but the clutch was still engaged. I thought it might be a broken clutch cable, so I stopped the bike (still in gear) and got off to inspect. The clutch cable was NOT broken. I checked the shifting lever on the outside of the clutch (it's called the "push lever assembly") and the lever would go up and down - I could move it with my fingers. Keep in mind - the clutch is still engaged. I had no way to open the clutch plates so I could shift. I was about 20 miles from home so I put it into first gear, and started the bike while it was in first gear. I was able to shift gears without the clutch and I made it home. However, when I got home, the clutch was working. So I went for another ride and the same thing happened about 30 miles out - no clutch lever resistance, but the clutch was fully engaged. So I limped home again.

I'm going to tear into the clutch this weekend and see if I can find anything. But it seems like a strange problem. Any ideas what is going on?

Thanks,
-Rustee Gold
Seca - XJ750

 

If you can move that lever on the engine by hand, then you are definitely not disengaging the clutch. After having mine apart and seeing it works, I really can't see how it would stop working and then start again. If the lever is aligned properly and torqued down, you really have no choice but to open up the side cover and look. Helpful tip, lay the bike on its left side and you can open up without draining the oil. Order a new gasket and clutch shaft seal from chacal while you're at it.

 

that shaft has a gear down in there that mates with another to push the throw out bearing. a few C clips hold the gear on the shaft. these could be the problem.
and then you went for another ride !

 

see red circles
this is a 550 clutch butsame idea the shaft with gear engages the pull rod with splines (ribs) and pulls it out compressing springs in the clutch. if you can move that lever with out much resistance the 2 parts are not meshing

 

I removed the clutch cover tonight and everything looked fine. But I did notice something that was probably the problem. The crankshaft nut was loose. I spun it off with my fingrts. Infact the locking washer that is supposed to be bent to keep it in place was not bent... I've owned this bike for 2 years and put 21000 miles on it. I bought it from the original owner who never opened the clutch. The washer appears to never have been bent. So as near as I can tell, this bike has been driven 80,000 miles like that.

I hate to jump to conclusions and I can't understand why this loose nut would cause the symptoms I was experiencing, but everything else looks good.

 

crankshaft nut? got a photo?

you are talking about the large nut that holds the clutch center onto the input shaft?

 

Yes. The large nut that holds the clutch basket onto the center shaft. I assumed that was the crankshaft but I wasn't sure by looking at the diagram.

 

that being loose would cause the problem as whole basket would move outward

 

Yup, that makes sense. When you pull the clutch in, it pulls that rod outwards to pull on the pressure plate. If the whole basket can move or it is riding further out then that pull rod isn't going to do anything. Glad you found that, I imagine bad things can happen to the clutch boss and splined shaft if left loose.

 

I have a confession to make. I re-examined the nut and the lock washer in the daylight this morning and I CAN see marks on the washer that look like it WAS bent over at one time. (see picture). My records show that I DID remove the cover abut 8,000 miles ago to inspect the clutch discs - however I do not remember taking the basket off nor do I remember taking that nut off. But... evidence indicates that the washer was bent at some point.

As always - thanks for your help.

-Rustee

 

Rustee -
Glad you found that. Don't feel bad, I also have bouts of CRS syndrome.