'78 KZ400 clutch slipping

Hey guys, need some assistance here I think. This is a new to me bike. Went through the gunked up carbs and finally have it running fairly well. I've gone on a few couple mile rides for testing and I'm finding that I'm getting slipage in the clutch. I adjusted the clutch as per the service manual. A mechanic friend also told me to adjust the thumb wheel out and therefore turn the cable into the clutch housing. I'm not sure that made much difference although now I only notice it from mid range to high range rpm.

Are there other tips you can provide me with? Is there any adjustment I can make at the mid level adjuster part of the cable? This bike has 16k miles on it and has been taken care, so I've been told.

Thanks in advance.

Did you change the oil? If you may have slightly overfilled the oil, it can make the clutch slip. Drain a bit out, but it will take a while for the excess oil to clear out of the clutch through useage.

Also, exactly what type oil is in the bike and did the previous owner pay attention to the JASO-MA oil issues? If regular , non-JASO-MA compliant oil was used there's a good chance that is what is causing the clutch slippage. Ed

I have no idea what the PO had been using, although I hope is was the right stuff. I have changed the oil and filter and filled to spec. I use Rotella T just like I do in my CB750 which I've read is great for this bike as well.

I adjusted the clutch to manual spec (again), and now I'm not getting slippage however the clutch lever is back to how I'd not prefer it to be. Meaning that it really doesnt start engaging until pretty far out. In other words, it doesnt grab until I've let out the lever almost all the way. I guess I can learn to deal with that but if anyone can tell me how to adjust that without getting any slip that would be great.

Thanks!

It sounds to me like there is still an adjustment problem. Quite a few newbies think they are adjusting correctly, but are not, so please pardon my questions if they seem a bit too obvious.

It is very important to follow the procedure in the factory service manual to a t. Kawasaki used at least three different clutch release systems on the KZ series, so it is crucial to use the procedure for your exact year and model. Basically, the procedure starts by loosening the lever and mid-cable adjusters, then go to the engine. This is where the differences appear. On some models the procedure starts with turning the adjustment screw clockwise until contact, then backing out just a smidge (technical term there). On other models, the screw must be turned anti-clockwise until contact, then in a smidge. It really matters. Then the lock nut is tightened. Next is the mid-cable adjustment, the last is the adjuster at the lever.
If you are certain this has been done correctly and there is still a problem, it could be a badly stretched cable, or some monkey business inside the cover with the release mechanism. Another possibility is that the pressure plate springs are very tired after more than 40 years of being compressed. They are pretty cheap and relatively easy to replace.
She'll Rotella is a good choice, but it is possible that the friction plates have gotten a fatal dose of friction modifiers from the PO using an automotive oil.

yeah I've followed the FSM to a T. All checks out. It def could be the friction plates but I've never changed those before. Was looking at some videos of "how to" and it doesnt seem like rocket science, MAy keep it as is for a bit and change the plates once I get it built. Going to have the engine out in the next few months so I may do it then. THaks for your input...def a newb here but have the knowledge to follow the FSM. Could be the cable too i guess....being stretched.

Can't believe nobody has asked the basic question... Is there freeboard at the clutch arm, is there freeboard at the clutch lever on the bars?? Without both of these, the clutch will likely slip.

I may be sound stupid but what the heck is a "freeboard" on a clutch arm/clutch lever??? Freeboard = adjusting screw for the cable???

Perhaps he meant "free play"?

Rick H.

Freeboard, free play. The ability to grab the clutch arm with your fingers and confirm that there is movement, that the arm is not tight and hard against the clutch pushrod.
90 percent of clutch slippage problems are this and are rarely worn plates or weak springs.

yes I even put a little as FSM calls for 2-3mm of "free play" checked it with a mm ruler lol