Hydralic Clutch Issues

[woods racer 34]

I have been having issues with the clutch fading once the bike gets hot. When I let it cool down for a couple of minutes the feel comes back to the lever. I have bled the clutch line numerous times exactly like the manual states only to have the same result. I have also checked out the clutch plates, basket, and all the clutch internals. Everything looks like new. Has anyone had this same issue and if so what causes this and how did you fix it? I'm thinking of replacing the seal to the slave cylinder piston to see if this fixes it. Suggestions?

[somewon]

is your fluid level staying up?

[sheriff525]

you just need to bleed it...that is what happens some times if you flip it!

[woods racer 34]

somewon,
Fluid seems to be staying full. The pull goes away when the bike heats up. I keep trying to bleed it. Very strange though that the pull comes back once the bike sits a couple minutes.

[sheriff525]

are you bleeding it from the bottom up. I had the same problem. if there is small air bubbles in the line it will still work while cold. But once it warms up the air expands enough to stop the hydraulic action. So you just have to bleed it.

[Ben Bettis]

You can also try running brake fluid in the clutch. This is what we do on the race bikes. It has a much higher boiling point than the mineral oil that comes stock. If you do run brake fluid, make sure you flush and bleed it through thoroughly, as mixing mineral oil with brake fluid will not work.

[woods racer 34]

Thanks guys for the tips. This one has really got me stumped. I'm bleeding it from the bottom up. It doesn't look like I have any bubbles when I pump the fluid in. I will definitely try running the brake fluid. Ben what do you suggest using to flush the lines?

[mudslinger]

I wouldn't use brake fluid in your hydraulic clutch system. I read that synthetic atf is good and have been using that. I used a small pump that screws onto the top of a quart oil bottle to pump from bottom.

[Ben Bettis]

blow air through the lines first, then use the brake fuid to flush the lines. Just keep bleeding the fluid through for awhile till you feel you've gotten a good steady stream coming out without air bubbles. Use at least a DOT3 brake fluid. A higher DOT has a higher boiling point. We use brake fluid on all our race bikes and have never had a fading problem in 20 minute plus motos.

[woods racer 34]

Ben,
Thanks for the tip on using DOT 4 brake fluid in the clutch line. Tried it out today and ran it hard for over an hour with zero clutch fade. Wish I tried this sooner!