Whilst away at the TT my clutch began to slip badly on the 999 and I managed to limp it home thinking the plates had gone... It happened after it got really hot in traffic on sunny Monday.I've taken the clutch pack out tonight and there is loads of meat left on the plates and it measures 38.5mm. So I've checked the plates for anything obvious and put it back in. The lever feels fine but i cracked the master cylinder bolt where some tiny bubbles came out and started her up. Took it for a ride and it still slips!I've checked the bearing on the pressure plate and that seems ok, although the collet that fits between it and the push rod is quite tight (I can't recall if this is normal?).It's a standard slave cylinder and I'm wondering if this may be the culprit? Maybe not returning the push rod?Any good advice welcome!
If it happened after if got very hot you may have just glazed the friction plates - give them a quick once over with some fine grit paper and swap the order of the friction plates 'round in the pack ... If the master or slave cylinder needed work then it'd be more likely to stick and be difficult to disengage rather than slip. To see if the actuating rod/pressure plate is operating properly, check it with the cover off - it's dry so no problem running the engine with it off ...... but don't stick yer fingers in when it's running! Good luck.
Air in the system would prevent it disengaging quite the opposite, is the collet as far in a possible within the pressure plate? Are all the springs present on the pressure plate? Have you removed, cleaned and repacked the clutch plates and steels in the correct order, is the gap to the top of the basket within tolerance? What about the clutch hub nut is this torqued correctly?
I had a similar prob with my 999 and it was a faulty master cylinder not allowing the fluid to expand into the reservior and acting like a sealed system. When the bike got hot the fluid expanded and operated the clutch slightly. Try bleeding the system, if fluid won't flow through the master cylinder then that's probably the problem.
If you had topped up the reservoir too much, when it gets hot the fluid expands and operates the clutch slightly, and that can cause exactly the symptoms you describe......
Had this issue on mine. It would slip mainly when hot and still do so even when packed out to max clutch pack tolerance. The fluid was not returning back fully into master cylinder fully so a quick adjustment to the screw on the master cylinder and it now works a treat.
Sounds like a brilliant design ....... a clutch that doesn't work when it gets hot! But hopefully an easy fix. What happened to good old cables?
Well after systematically checking the hydraulic system today and finding it to be working ok I went back to the clutch pack. Despite it measuring 38.5mm already I thought sod it and replaced the outer thin steal plate with a thicker plate from my old clutch pack. Took it for a test ride and no slip! It gets more a labour of love with my bike each year and I've stopped questioning why things work if they do Until next time.....
