Hi My first post so please be gentle! (I haven't had a need to ask anything about my Monster before as it has run pretty well over the years!) But I was riding it the other night and the clutch simply disappeared. Nothing from the lever at all, no pressure, no clutch, nothing! I managed to get home without a clutch through sheer luck and good fortune I think. Anyway, my first instinct was the master cylinder was gone and I think this is not repairable as it looks like a sealed unit. I purchased a new one and put it on. Still no pressure and unable to bleed the line. I started the engine and left it running and tried the bleeding again and hey presto, it came back. I managed to bleed the clutch and it seemed fine. I was riding it this morning and after so many miles, it seem to 'pop' again and I lost all pressure. I stopped and refilled the reservoir and bleed it again but it was not perfect. So a couple of questions... 1. Why does the engine need to be running to get any pressure with the clutch? 2. What might be wrong with it? Someone told me it could be the slave cylinder seals?? (I did notice some slight drops of oil in the vicinity of the slave cylinder this morning so I'm think there might be some validity in the defective seals!) 3. What fluid should I use in this system? Brake oil? Synthetic or non-synthetic? Can I simply replace the slave cylinder? Would this resolve the problem with the seals (if that is the problem)? Your help would be greatly received. Donald
Slave cylinders are usually the first culprits. You dont need the engine on to keep pressure. Clutches are a pain to bleed, I haven't needed to do so on my S2R but on the SC it took me ages to get pressure, still dont know why it took so long.I just used normal dot4 fluid I seem to remember, whatever the standard stuff was. Is it an 800 or 1000?
Thanks. I have a full new slave cylinder on its way as I didn't want to mess about with seals. And its the 1000 model. The engine definitely has some sort of say in the pressure - rightly or wrongly! Even when I'm riding it I can feel the pressure 'coming and going'. I suspect this is because of something wrong with the seals in the slave cylinder, so hopefully that will sort it out. I had another mate who was telling me the difference between synthetic oils and non-synthetic, and the useage of them. Apparently, non-synthetic oils (mineral oils?) have a low(er) boiling point so if the fluid passes close to say the exhaust, there is a chance it could boil and lose pressure. (Is he talking bollox)
OK, I replaced the slave cylinder and set off on a run. The clutch seemed absolutely perfect but there was always something in the back of my mind that this was the lull before the storm. And true enough, it was. After about maybe 5 miles, the clutch lost all pressure again. Luckily, I had taken some oil and my bleed spanner with me. So I stopped and bled the system. What I noticed was a lot of slivery, almost molten metal liquid coming out of the the bleed screw. After a few air bubbles, the clutch got some pressure again and I was off, clutch feeling a lot better. At first I thought it might just be that I had not bled the system properly, but again, after a couple of miles, the clutch lost all pressure again. I gave up! I took it to MD Racing in Walton where Mike examined the problem and quickly came up with the diagnosis. Within the clutch there is a clutch rod (not sure I'm using the right terminology here!) and apparently the bearing on this rod has seized, which makes the rod spin and essentially drills into the slave cylinder. This explains the silvery liquid that oozes from the bleed screw! There is an updated slave cylinder now that has a pin in this rod to stop this behaviour. The pin stops the rod spinning in this environment! So there you go, lesson learned. And about £150 of trial and error (new master and slave cylinder) and it was neither! I have no idea about the cost of this repair but I've no doubt I'll find out soon!
