I've had my first breakdown ever on my 749 today after almost 10 years of trouble free riding. About 3/4 mile from home the clutch emptied itself of fluid and the leaver came back to the bar and it stalled as I tried to pull up. The culprit I believe is the slave cylinder as fluid was weaping from the underside. It's an after market MPL tuning one which I've had on the bike for about 5 or so years. I've taken it off this evening expecting the little o ring to be in bits but it looks fine to me. It was very mucky with fluid so I guess it has been weaping for a bit but I hadn't noticed, although while out for a ride last weekend I had a lot of trouble finding neutral so I guess it's connected? Anyway when I pull on the clutch leaver fluid comes out of the little hole on the back of the slave should it come out of there? I wouldn't have thought it shouldn't as I can't see how the small hole is sealed by just being fastened to the engine casing. Anyone know if this is knackered from the inside which is why there is fluid coming out of the small hole?
Time for a new one I'm afraid. Lots of aftermarket ones around although Oberon seem to be a favourite. I would check with your nearest parts department about the cost of an OEM just in case its cheaper although I wouldn't hold your breath on that one. Andy
I have the OEM one somewhere packed with other parts in the loft so will get that re fitted for now. What's the small hole on the MPL one for anyway and why is fluid escaping from it? Is it a seal inside gone? I've emailed MPL to see what they say.
Not sure about the hole on the MOP cylinder but failure of the main piston deal is fairly common on most Dukes. Crap and gunge build up from the lube going off the chain and eventually knackers the seal. I had exactly the same prob on my SS and thought I'd fixed it by changing the seal, only to find a couple of weeks later that the fluid was black again and air was findin it's way in through a knackered master cylinder seal too! You can get rebuild kits for the latter from Modo Rapido etc. and it's relatively straightforward to fit, if a little fiddly if you need to.
Turns out the small hole on the rear of the slave is a breather hole so shouldn't have fluid coming out of it, which suggests an internal seal failure. I've contacted MPL Tunning who can supply a new seal kit for €15 but I'd need a special tool to gain access or I can return to them and for €49 Thay will repair and send back to me, so looks like I'll be returning it to them for a repair which is half the price of a new one.
The special tool they are on about is for unscrewing the front of the cylinder.If you are competent with a few tools I'm sure you could codge something together.
