Clutch slips when applying throttle

1976 KZ 750. The bike takes off just fine, and last time I had the clutc cover off the clutch pads were all good. Th only time the clutch slips is when I am really giving it to it and the bike hits 4k. the rpms shoot up so I let off the gas a lttle and they return to normal. I'm thinking its time for new springs. Any thoughts?

Have you adjusted the clutch cable carefully following the procedure in the factory (not aftermarket) shop manual?

What kind of oil is in the engine?

Probably springs, but the wrong oil can make the clutch slip. If it is 5-30 or 10-30 car oil, it probably has Moly in it and that makes the clutch slip.

Would perform clutch push-rod adjustment.
Insufficient gap may be preventing full engagement.

Good Fortune!

I use 10 w-30 motorcycle oil so I doubt its that, and I have about 1/4 inch pay in clutch lever so it should be engaging all the way.

springs...Z1 ent enterprises....new cable and gasket wont hurt.....since the flat rate shipping...good time to do an oil and filter....at least get two more filters..all fits in a small box...three to five days...one hour swap....cheap and good service.....least thats what id did...all better


9 outta 10 springs....oh and do the cable and pushrod to the handle like the book says...i'm still [palying with mine...like a new guitar string they stretch a bit when new....i leave the pushrod adjuster a half turn back out from just light seaying, lock nut tight it on the pushrod and almost all my slack at the cable turnbukle with almost no turns out at the bar....then as i ride the handle bar thread can have plenty of threads to take out later...

KZCool wrote: ... I have about 1/4 inch pay in clutch lever so it should be engaging all the way.

Nope -- also requires push-rod adjustment.

Good Fortune!

Clutch push rod adjustment -- Need and Purpose
[This is a 1 minute job from start to finish, maybe 2 minutes the first time.]

The FSM covering Z1 and KZ900 includes a periodic maintenance chart requiring clutch push rod adjustment at 2000 mile (3000 km) intervals and explains the need therefor in separate text, which explanation is quoted verbatim as follows:

Besides cable stretch, clutch plate wear also causes the clutch to go out of adjustment, with a decrease in push rod play. Due to this wear, the push rod gradually moves closer to the clutch release lever (at the lower end of the clutch cable) until it touches the adjusting screw. When the rod is touching the screw and therefore has no play, the clutch will not engage fully and clutch slippage will occur. Note that the clutch push rod does not necessaily have play just because the clutch hand lever has play, and so hand lever play alone cannot be used to determine whether or not the clutch requires adjustment.


The FSM covering '77-'79 KZ1000's includes a periodic maintenance chart requiring clutch adjustment at 5000 km intervals, and explains the need therefor in slightly different language, which explanation is quoted verbatim as follows:

Clutch plate wear also causes the clutch to go out of adjustment. This wear causes the play between the push rod and the adjusting screw to gradually diminish until the push rod touches the adjusting screw. When this play is lost, the clutch will not engage fully, causing the clutch to slip.
NOTE: Even though the proper amount of play exists at the clutch lever, clutch lever play alone cannot be used to determine whether or not the clutch requires adjustment.

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end of excerpt

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While the clutch may indeed be worn out with plates needing replacement, it isn't uncommon to overlook or be unaware of the clutch pushrod adjustment feature, especially without a manual. It is worrisome to see anyone of unknown experience, without a manual or failing to consult a manual, proceed with clutch disassembly and plate replacement, without first being aware of and considering the clutch pushrod adjustment.

Where both (1) clutch cable slack adjustment is perfect, and (2) clutch pushrod adjustment is perfect, and the clutch still slips, suspicion is certainly toward the plates being worn and needing replacement. But other things can also cause slippage, even with proper adjustments and good plates, such as glazed plates or improper oil being used in the crankcase.

Good Fortune!

I have a manual and set the push rod adjustment as descibed when I first installed it. However I didnt know that the slack in the lever didnt directly correlate with space between the adjuster and pushrod. Thanks for the heads up.

Good Fortune!

:blink: wow Patton, you are pretty good with MS Paint.

Well I found out why my clutch was slipping. one of the bolts holding the springs in was backing out and ended up exploding out the side of my case . fun day let me tell you. Just came back across this forum after a while and thought it was a good story :laugh: