79 KZ400 Clutch / Tranny issues

Well the good news is I got the carbs dialed in. Now, it appears my clutch and tranny need some attention.

The transmission will not shift anymore. The clutch lever will go up and down but it never engages in a gear. Just stays in neutral. Prior to yesterday it was shifting fine. Down, up and into neutral with the engine off and the clutch lever not pulled. In fact it shifted fine yesterday at one point. Than I put the cover, foot peg and shift lever on, and nothing.

Is it possible that my clutch is sticking in the engaged position? This seams likely because my clutch rod does not appear to move IN when I push on it. It also slides completely out which seams weird to me, but may be completely normal.

Anybody have any thoughts?

Would first perform clutch push-rod adjustment.
Accessed on fully assembled motorcycle through the cover plate in the sprocket cover.

Good Fortune!

The following is from manual covering Kaw large fours, but believed also applicable to KZ400.

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!

Thanks for the input. I will give this a shot as soon as I have time.

Am I correct to assume I need to drain the oil before doing this?

treitz wrote:

Thanks for the input. I will give this a shot as soon as I have time.

Am I correct to assume I need to drain the oil before doing this?

Push-rod adjustment doesn't require oil drain, and is accessed by just removing the small inspection plate cover on the left (gear-shift side) of the bike.

Accessing the clutch itself by removing the clutch cover (on the foot brake side of bike) will allow some crankcase oil to spill out unless the bike is leaned far enough over toward its left side (the kick stand side) when removing the clutch cover.
Sometimes, just having the bike supported on the kickstand leans the bike far enough over to prevent much oil from escaping when the clutch cover is removed.
But would have a catch pan underneath just in case.

To reiterate, would perform the fast-easy-quick-clean push rod adjustment before going into the actual clutch assembly.

Good Fortune!

Sometimes the shifter side cover can be insalled off center slightly, causing the shifter shaft to rub and no longer be able to travel that extra little bit to engage/dessengage gears.

pull the cover off and try shifting the bike with just the handle pushed back on the shifter rod (no cover).

Good luck.

I tried shifting it with the cover off and at one point it was shifting just fine. Than it stopped.

It feels like the shifter is traveling plenty far. As I mentioned before, the fact that I cannot push the clutch rod in by hand leads to believe the clutch is stuck in the disengaged position.

So through the left inspection cover I should be able to tell whether the clutch is stuck or whether the push rod is not engaging?

you should be able to get motor in gear without motor running without the clutch,does kz400 have external shifter linkage for shift drum under cover like 900/1000?

In looking through the manual and pictures of my bike I don't think that there is any way looking through the shift side covers will help me here.

As you can see in this picture, there is no visual way to see the the push rod from the shift side other than the inch or two that is sticking out.



If I decide to take the clutch side cover off, what am I looking for? I have attached a picture with a circle where I THINK the push rod goes, but I am not sure.

PLUMMEN wrote:

you should be able to get motor in gear without motor running without the clutch,does kz400 have external shifter linkage for shift drum under cover like 900/1000?

I know. And it WAS shifting just fine without pulling the clutch.

However, once I put the clutch cover back on and pulled the clutch lever I am assuming it disengaged the clutch and than never reengaged it.

Based on my current research and opinions I am leaning toward clutch springs as the cause.