Clutch not releasing properly / dragging

[Hman]

Hi, I've got a bit of a conundrum to which the search function returns no results, or I'm blind and missing the answers.

I bought my '79 750 with a completely rebuilt engine which is running in good condition, but the clutch does not seem to work properly. Setting the clutch so that you've got a couple of mm of free play results in not being able to select gears/return to neutral while stationary. To get the clutch to release I have to adjust it so that the clutch is pulled in partly. This results in a slipping clutch however when I pile the power on.

To me it seems as if the clutch lever doesn't allow enough travel to pull the clutch all the way. I also highly doubt that the clutch lever is a standard unit.

Any suggestions as to what can be done? Is it maybe as simple as looking for a lever which would give me more travel? Or could there be something wrong with the clutch.

[7981GS]

Missing a fiber and steel plate?

Daniel

[Hman]

Have not opened her up yet, can only do it over a long week-end or holiday as I use it to get to work and back.

Might missing plates cause this?

[koolaid_kid]

A picture of the clutch lever might help us determine if it is aftermarket or not.
Since it is your DD, I would approach it in this manner.
First, I would disassemble, clean and lube the clutch release mechanism. It is on the left side of the engine, btw. This will require the removal of the clutch cable on the bottom. At the same time, I would completely remove the clutch cable and examine it. If none of the inner strands are broken, clean and lube the cable. (If any of the strands are broken, this could cause the cable to stretch which could be causing the issue.) This will only take a couple of hours, so you could do in one evening.
If this does not fix the issue, then I would remove the clutch cover and buff the glaze off the fiber and the steel plates. Be sure and mic the fibers while they are out. If they are still in spec, reassemble the clutch and, using a new clutch cover gasket, put it all back together and test again.

[Hman]

I've tried 2 cables, both new, same problem persists. Mechanism is clean.
Clutch action is smooth and medium weight as it should be.

Here's a blurry pic of the lever, my phone's AF is dead.


20111111_001.jpg by HmanSA, on Flickr

[Jonzilla]

My clutch has a very small window of either doing what you're talking about or being too tight and slipping at high rpm's. I would just screw out the cable like a quarter turn at a time and test it before turning more. If you get it too tight the clutch will slip but if you get it too loose (may be too loose now) it's hard to go to neutral while stopped. Find the window in between.

[Hman]

Hmmm, I wil try this approach. The times I adjusted it I'd go for a couple of turns, will try small increments tomorrow and see what happens.

[Hman]

So I adjusted the cable in smaller steps and after some tweaking found a small window in which the clutch works properly.

Bad news is my rear tire died yesterday. A big piece of rubber came of exposing the belting. Luckily it happened at low speed and about 1km from my house.

[keman]

Glad to hear you got the clutch sorted out. Too bad about the tire.

[Normk]

The problem of a small window of release range in a clutch is something I've seem a few times. I think the term "small window" which Jonzilla coined really nails the description, hats off for that.

Another possibility is that the clutch may have wear grooves in the basket or hub. These grooves can catch the plates and prevent them from sliding on the hub splines or basket grooves and so cause the clutch to drag more than it should. This often requires more release clearance in order to achieve enough plate separation for a release.

We used to file or grind minor grooving but one needs to consider that too much side clearance will create other issues so, at some point, the basket or hub may become unserviceable. It is also worthy of consideration that the surfaces need not be perfect although that is ideal. One may choose to live with some grooving which does not cause severe symptoms rather than to remove too much material.

Can't bring to mind an image of the clutch release lever so may be off base here, but the end of the lever or cam which contacts the release bearing insert may be worn flat or a groove/depression worn into the insert. These kinds of wear can "catch" when the release mechanism is moved, resulting in a poor release.

The other posts have very valid suggestions so you may wish to make a list and work through the easiest first. The reason I suggest a list is having forgotten one possibility and having had to go back in later.
(Groan)

[blowerbike]

adjust the worm gear 1st and then the handlebar lever to fine tune.

[ramrod400]

My clutch started dragging and I thought is was because of changing type of oil and/or cold weather, but after adjusting on it for what seem to be hours I must have hit the window? I'm glad I read this cause I thought it was a fluke.

[chuck hahn]

If it returns where it is set at now, then I would take a look inside. See if the ridges on the inside of the clutch basket that the fibers fit in have grooves worn in them.