YZF750 Clutch slip

DaddyA · Post by **DaddyA** » Sun Nov 23, 2014 4:02 pm

Afternoon fellas,

Been out for a short run today, clutch started to slip (not the first time this has happened). It seems the slave cylinder gets hot and I believe the fluid expands causing the slip.

it doesn't happen when cold, and if I bleed the clutch when it happens it works properly. All the seals have been done, and new braided line fitted.

Anyone else had this issue? Or know of a fix.

Currently running round with a hose and 8mm spanner!

Cheers in advance.

faststeve · Post by **faststeve** » Mon Nov 24, 2014 12:31 am

check the seals on the master cylinder ,and return hole in master cylinder is clear , have you changed the levers , wrong ones can cause the cylinders to not return properly and keep pressure up , slave cylinder getting hot may be the clutch rod spining under constant pressure ,, bad news

DaddyA · Post by **DaddyA** » Mon Nov 24, 2014 4:27 pm

Cheers Steve,

All seals were replaced. I'm sure all was as it should be when I changed the seals. I'll check again over winter.

It does have different levers? Doesn't always happen.

I'll probably look to change the friction plates as the bike was stood for quite a few years.

Bad new? In what way?

Thanks again.

faststeve · Post by **faststeve** » Mon Nov 24, 2014 5:23 pm

Wrong levers can stop the piston fully returning and hold pressure, only needs to be a little and each time it holds a bit more, had it on a front brake once when I mistakenly reinstalled a yzf lever on my exup, all was fine till the brakes finally locked on as I was moving it around the garage, a few pulls while maneuvering and it was solid, back to the right one when I realised and back to normal, it's bad news if the pushrod is spinning wildly under pressure to the point it heats the slave, it will be red hot and damage something for sure, I'd lay money on the lever change, especially as you have to let the pressure off by opening the bleed valve, or on an outside chance the master cylinder seals in backwards, not much else can go wrong really.

DaddyA · Post by **DaddyA** » Wed Nov 26, 2014 5:25 pm

Cheers again Steve,

I'll have a good look now it's off the road. It seems the lever is working as it should but I'll check anyway.

I believe it had a EBC clutch in, not sure if that would have an effect - bike was sat for 10yrs so I'll replace that anyway.

If I get it sorted I'll post it up (if)!

Thanks again.

faststeve · Post by **faststeve** » Wed Nov 26, 2014 11:59 pm

E b c clutch is fine, got to be a problem with the master cylinder, either the different lever or the cylinder itself, from the symptoms you describe it can't be anything else, it's not letting the pressure off properly and each stroke of the lever puts a bit more on until the clutch is held open just enough to slip, you let the pressure off at the bleed valve and it's fine for a while,