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Slipping Clutch


gregd
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Make sure you have freeplay in your lever and the master cylinder piston is returning completely.

Make sure you are running proper oil in the proper quantity.

Lastly, squeeze the lever and, while squeezed, crack the bleeder for a second and re-tighten.

If it still slips, it's time to open it up.

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Greg - what year and displacement is your bike? You asked if anyone had an idea about the cause; it looks like Mick, Charlie, and gazer have pretty much covered all the bases.

If you're going to crack it open and have a look remember its very important to put everything back exactly as it comes out, unless you're replacing all the parts. I write on the clutch outer pressure plate with a Sharpie marker numbering the clutch spring holes and lay out the springs on a piece of paper or cardboard with corresponding numbers so all the springs go back in the same holes. Make sure you don't flip over any of the fiber or steel plates from their original orientation and keep them in order.

That said, I would buy new springs, fiber plates, AND new steel plates...(but my bet is with Mick - your springs have gone wonky).

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You're right... its a lot of money, but now is the time to get those new steel plates too - don't cheap out and buy just the fiber plates. Get a full set of new plates - you'll be happy you did, and you won't have any problems with the clutch dragging instead of slipping.

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I didn't want to possibly derail this thread while GregD was asking questions, but now that his query seems to be almost resolved, I'd like to ask another clutch-related question, the answer to which I believe may be related to GregD's problem (hence I didn't want to create a new thread):

The clutch on my '03 250 doesn't work until I've ridden around for a minute or so after starting. When I say "doesn't work", I mean there's no clutch at all. After starting it for the first time that day, engaging the clutch, selecting a gear and releasing the clutch while stationary stalls the bike. If I put it in neutral, get it rolling and jump on before selecting a gear it's OK and I can feel the clutch returning almost immediately. After 20-30 seconds it's fine and works perfectly for the rest of the day.

What's going on? Worn plates/spring again?

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neonsurge,I had the same sort of problem as you and after speaking to some of my mates discovered that most trials bikes seem to have this little quirk. I discovered that working the clutch 3/4 times before putting into gear worked a treat. :huh: .That said, i have just ordered a full new set of plates and springs and made a big whole in my wallet, along with the money spent on copious amounts of alcohol at the manx 2 day (brilliant weekend) :) that new bike is going to have to wait a little longer than anticipated :(

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neonsurge,I had the same sort of problem as you and after speaking to some of my mates discovered that most trials bikes seem to have this little quirk.

You may be right, but this is my 3rd Beta and the first one I've owned (or ridden) that's had the problem. My old GasGas suffered with horrendous clutch drag that I never managed to completely eliminate but up until now my Betas have all been as good as gold. It's a once-a-day minor annoyance more than anything else but I tend to worry that this kind of thing is a symptom of something more sinister. I'll try pumping the clutch a few times while it's warming up like you mention and see if that helps.

Thanks for your input!

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Ron Jeremy, er... neonsurge... are you saying that you pull the clutch in, put it in gear, let the clutch out and it stalls? That sounds more like a 'buretor problem.

If it sticks or drags an excessive amount, I think you need new steel plates. The little puckers / dimples on the steel plates get worn down quickly and I think they are what reduce / eliminate the "stiction" between the fiber and the steel plates. So when the oil is cold and all the parts have mated nicely (like you in those videos...) there is tremendous stiction between the plates. Once you get them "unstuck" by having dissimilar driveline / engine lash (riding around) everything's peachy - more oil flows between the plates and the clutch starts working normally.

The other posts are also correct in that new oil has more "long-chain molecules" (read: more shear strength) and better resists being mashed out from between the plates by the force of the clutch springs.

Bottom line: (again) try new steel plates.

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Ron Jeremy, er... neonsurge... are you saying that you pull the clutch in, put it in gear, let the clutch out and it stalls?  That sounds more like a 'buretor problem.

No, what I'm experencing is the clutch failing to engage from cold. Start the bike, warm up for a couple of minutes, pull the clutch in, select a gear - bang, the bike jumps forward and stalls out. If I push it in neutral with the engine running, jump on and select a gear, the clutch starts working normally within a few seconds. This only happens from cold.

I've always used PJ1 Clutch Tuner oil in all my bikes and change it at least once a month, so I don't think that the oil's the problem. HOWEVER, shortly after I bought this particular bike the water pump seal failed and I replaced both the seal and the impeller shaft. I've had the clutch problem right from the start so I'm wondering if the pump was leaking for a while before I noticed it. Maybe I've still got moisture in the clutch?

Anyway, like I said it's a very minor annoyance rather than a real problem but if I can get to the bottom of it it'd put my paranoid mind at rest. Thanks for everyone's suggestions!

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