Clutch Engagment

Hi everyone,
I have a '76 KZ750B with a clutch issue.
I start the bike pull the clutch, shift into first and it lunges and cuts out. The last time I rode the bike everything worked fine, other than the carbs needing some tuning the tire is losing air faster than it should. Life got in the way and the bike sat for about 3 months. That's when the problem started. I adjusted the clutch to the shop manuals spec. but still the issue. I thought maybe the clutch plates were stuck due to sitting for so long. I pulled, honed, oiled and reinstalled with still the same result. Other than that I have not worked on this bike. Bought it over the summer and haven't had the time to get familiar with the KZ.

I'd appreciate your thoughts.

-toast




the skateboard is just a template, though I humor the thought.

If the clutch is not releasing, it may be the throw out assembly. The one on my 750 twin failed a long time ago. It's attached to the side cover. Make sure it moves freely as you work the lever arm.

What kind of oil are you running?

Is the steel ball in place at the end of the rod?

I'm running 10w-40. Hmm the steel ball? That is a good question. Since I haven't pulled the rod I figured it would still be in place. Do you have any suggestions on checking that other than pulling the engine apart? The manual says not to pull the rod as it will drop the bearing. Looking at it now I might as well check the external shift mechanism. Please excuse my absent mindedness, I am learning most of this as I go.

I feel the lever pull when I squeeze the clutch. Everything feels and sound right.

Kungfutoast wrote: I'm running 10w-40.

...but, is it API or JASO-MA oil? Please share specifics.

Sorry my bad, API. This was my first oil change on this bike. I do not know what the previous owner used.

Well, there's your problem! You're dealing with a wet clutch and the "friction modifiers" in API oils are not good for the plates. Get yourself a gal of Rotella-T 15-40W, for ~$17, from Wally. It's listed as Diesel, but JASO-MA cert and will work fine in your bike. Just need to give the bike a couple extra mins, when dead cold, to get the oil up to temp.

Thanks. I'll change to this oil and report back if that resolves the issue. I hope it's that easy.

-toast

How long did you run w/the API oil?

We can only hope... but it could also be something else, that is being masked by the oil. Hard to say.

Please also look into the ball bearing thing...

The oil is fresh from when I pulled the plates last week. I am still going to look into the bearing and shift mechanism just to be sure. So I'm on the same page, the bearing you're referring to is the one in the photo below.

The oil is not your problem. Your symptom is the clutch won't disengage (drags). If anything, the API oil will cause the clutch to not engage (slip).
If you feel resistance at the cable, the ball is also probably there. The lever would have lots of free play if the ball was missing.
Remove the cover and check 2 things. First, when you pull the clutch, you should be able to see the clutch hub move. It's not much, but it will move outward. Next, remove the clutch plates and inspect the "fingers" of the clutch basket for grooves. The fiber plate tabs wear notches or grooves in the basket fingers. The plates get caught in these grooves and will not release. You can remove the grooves by lightly filling each finger of the clutch basket.
Good luck.

Thanks for the input MDZ. I ran through everything you suggested. It's been a while so let's recap.

I am having a clutch disengagement issue. It won't happen! Apologies for the misleading title of my post.

The clutch release unit is fine and in working order. There is tension when I make adjustments at any of the many points. Lever, midway adjustment nut and clutch adjustment screw. See attached images.

I inspected the clutch basket. There is movement when I pull the Clutch lever. It's not much but what I would expect there to be. I removed the plates and inspected them. I am new but they appear to be fine. No burn marks from friction, or any build up of material. I went ahead and honed them as suggested from a few friends. Also oiled them before reinstall. (oil used Rotella-T 15-40)

I check the basket fingers and there is no visible wear. Even gave it a finger job. Everything felt good.

I pulled the push rod and bearing out and those look good too.... This is where I am at a blank. A friend just came to take a look and his response was not great. Slow step back "that's about all I know" He suggested I pull the whole clutch and reinstall. Or go to a mechanic. Not very excited about that idea.

If anyone has further suggestions or insight I'd appreciate the thoughts.