My clutch was slipping today in 5th and 6th gear, mostly 6th. It happens in about the middle of the rev range when i open the throttle quickly. Im using Motul 5000 semi synthetic oil.10000 miles of use. Anyone able to explain why its happening and is there anything that can cure it?
If you've been using moto specific oils, then I'd guess you need new clutch friction plates an to check that the clutch springs are within spec. I assumed your clutch cable is not binding and you have the appropriate amount of freeplay dialed in at the lever.
Im assuming the Motul 5000 semi synth is suitable, seems to have done the job nicely so far. I have what i think is appropriate freeplay in the lever, but theres no harm in checking again and putting some oil down. I dont know how to check spring spec. I had the clutch out when i was doing the 10000 mile service and it looked good, i was careful to keep the stack in order with a cable tie. This one really has got me stumped and a bit frustrated.
If your springs are in check then you have to probably replace the plates,it's pretty easy to check them. Just remove the clutch cover and check the plates, you should find the appropriate clearances on the manual
According to the manual, the minimum thickness of each clutch lining plate is 2.65 mm. I suggest that, first of all, you make a stack of those 8 plates and make sure that its thickness is not less than 21.20 mm, i.e. 8 times 2.65. Then, if you want to do a neat job, you can measure every disc, but IMO that's not so important in your case. The length of each spring should be at least 39 mm. When I checked my springs, some of them were close to be under that limit and so I replaced 3 of them, installing the new ones equally far from each other.
Motul loses its shear stability and much of the additive package is cooked off in 5-7000 miles. Change your oil (meaning both "service it" and change the oil you use if you're going to go 10k intervals), and check your clutch as mentioned above.
I can see how you can be confused after reading my post. The engine has 10000 miles on it and i change my oil roughly every 2500 miles. My 10000 mile report thread wasnt that long ago and my bikes only done 800 miles since. I think i had a brain fart when i typed the first post.
First things first, how much slack do you have in your clutch cable? If there is zero slack, back it off until there is a little slack. As the plates wear, your slack becomes less (unless your cable is stretching or clutch arm is twisting). I've seen several burned up clutches over the years from people setting the cable too tight and not rechecking it as the clutch wore. That's one nice thing about a hydraulic clutch, but I've seen the same thing to some degree in having to bleed off excess fluid from the reservoir as the slave piston backs up due to clutch wear. If that isn't it, then pull the cover and check the plates.
Thanks Theo, Ive measured the friction plates in a stack and theyre 24.10mm and the steel plates are 11.25. All of the springs are between 39.5 and 40mm. I think the part on the end of the push rod with the thrust bearing is adjusted too far out, making it too long, so the pressure plate is being held back slightly. Ill adjust it so it has some freeplay, so it cant hold the pressure plate back with the clutch engaged. Hopefully this might cure the problem.
