Clutch (?) problem

[roryjohnson]

Dear all

(first a quick introduction: I'm a non mechanical city dweller, fell in love with R65 at first sight 2 years ago, bought a 1980 model from a kindly old man from the internet, only to find that everything was wrong with it, just got it back from the mechanic, very happy until...)

Driving two days ago, stopped at traffic light, bike in first gear, clutch in, with no warning  I feel the bike begin to pull forward despite holding the clutch. In the course of a minute this got worse, a friction noise came from engine/ gearbox, and a minute later the bikes stalled. I can put it in neutral and start the engine, but as soon as I change to first gear it stalls despite holding clutch lever. The lever does not feel different from before. Bike is now un-ridable.

A) is this likely to be clutch problem?

B) can you give me an idea of the seriousness/ time/ cost of fixing problems like this?

Thanks in advance for any help or advice guys.

PS this is a brilliant forum, it has helped me so much during my so far difficult R65 existence.
Best

Rory Johnson

[Bob_Roller]

I would look at the clutch cable to see if it has frayed at the cable ends .

Check the free play of the clutch lever at the handlebar, there should be 2-3 mm or about an eighth on an inch free play before you start moving the cable .

Second, I would look at the arm that the clutch cable attaches to at the back of the transmission, there's an adjustment bolt that adjusts the clutch on the center of the arm, check to see it's loose .

[tvrla]

Good suggestions!

It doesn't sound like a clutch problem - instead something in the release mechanism. All easily checked without tearing anything apart.

[nhmaf]

It could be that the piston/throwout bearing assembly is damaged, but the first - and easiest- thing to check is the clutch cable (both ends) as Bob suggests.  

If the throwout assembly is damaged (it lives at the back of the transmission under that little black rubber accordion boot that a bolt on the clutch arm pushes into) that could cause this, but sometimes it is just a bolt that falls out/loosens back there.

If you can post pics that would help, but we do our best to help, and have good imagination skills..
 

[Barry]

The lever does not feel different from before.

That's a bit of a worry as it implies there is no increased free play at the handlebar lever.

This is only one possibility but you should eliminate it before doing anything else. I would look carefully at the clutch operating arm on the back of the gearbox. On your 1980 model the arm pivots on a pin which is held in place by a circlip. It has been known for this clip to fall out which allows the pin to also drop out and can lead to breaking one of the pivot posts cast into the gearbox cover. That is a not a nice problem to have. If the pin has already come out of one of the posts it could give the symptoms you are experiencing. If the pin has started to come out DO NOT ATTEMPT TO OPERATE THE CLUTCH LEVER until it is correctly fitted again.  

One of the problems with this circlip is you can't see if it's installed correctly because it doesn't fit in a groove on one end of the pin as you might imagine but between the inside of the top pivot post and the operating arm. This makes it virtually invisible unless you know exactly what you are looking for. A safer solution is to replace the pivot pin with a plain shanked bolt and self locking nut.

So you know what to look for the clip #11 is more properly called an E clip and looks like this.

[roryjohnson]

Dear All
First, thank you so much for taking the time to consider my problem.

I went back to the bike today. I must say the handle DOES feel loose now. When I moved it, the clutch arm on the engine cover also moved. I did notice the cable looks frayed, althoughi don't know if it was always like that. Pictures attached, not sure if they're helpful. I took images of the lever arm room from all angle.

PS Barry I only got your message about not moving the handle after getting home.

Best
Rory

[roryjohnson]

Photo

[roryjohnson]

Photo

[Barry]

Rory

The pivot pin looks fine in your photo. It hasn't moved so that's not the cause. Worth being aware of that pin though on the early bikes.

So it's possibly the frayed cable or loose cable adjusters - an easy fix and sounds like you need a new cable anyway. I would do a clutch adjustment and see if the correct amount of play is then maintained.

If that doesn't do it I would investigate the clutch pushrod or release bearing #1 and #4 in the diagram above. The pushrod has a hardened end which can wear through and the radial needle bearing is not the best design as the rollers have no choice but to skid do to the difference in peripheral speed from one end of the roller to the other. The design was changed for the later 81 on bikes.