Clutch Slipping

[draser]

When the revs change... do they go up or down? Does bike slow down with revs going up?

 

[dduelin]

Just had the same problem occur. (80mph 5th gear, passing a car, 75% throttle, level highway, 6am, 40°F, dew on the ground at most) I initially considered bleeding the clutch but as someone stated most clutches default closed and open under pressure.

I think it was Mark who suggested a tank of bad gas causing the knock sensor to adjust engine on the fly, of the ideas in this thread this theory makes the most since to me. I ONLY get this issue in 5th gear around 80-100 under a load (ie getting on it). It will still pull the front wheel off the ground in 1st and 2nd so I'm thinking it's not the actual clutch or fluid compression.

I wish this thread were more helpful, people trying to correct the last guy rather than build on an idea based on their experience.

I'll post again if I discover anything.

Clutches generally begin to show slipping in higher gears first because of torque multiplication of the transmission. A clutch that begins to slip in 5th as described (80 mph and passing, opened throttle) probably won't slip in gears 1, 2, 3, and maybe in 4th.

Slipping under the demand of highway loads is because the friction material and/or the clutch springs can't generate the friction coefficient they used to. If it slips in lower gears or all gears then look at the lever and hydraulics.