Clutches for beginners

[Fast4fun]

I hate to bore people with newbie questions but I'm curious about the mechanics of my bike. What are the first signs of clutch slippage? For instance, while heading down a straight away, as the engine approaches peak power/torque and the bike approaching 135-140 i notice that the bike doesn't want to accelerate. It totally plateau's. I know the wind resistance is growing exponentially and that the rate of acceleration naturally slows but I'm talking about more than that. Comparable bikes continued to accellerate past me. Is this an early sign of clutch slippage? Also, would a slightly warped clutch affect HP #'s on a dyno?   What other signs should I be looking for?  I noticed all of this after a few very full weekends of racing where I'm pretty hard on the clutch off the line.

[Super Dave]

If it won't pull any more R's, that sounds more like a gearing problem...too tall. 

Clutch slippage is that.  You're trying to accelerate, and the R's go faster than your ground speed.  Like you're on a wet area that the tire spins on.

[tzracer]

What is the tach doing while the bike is not accelerating? If the speed is not increasing and the tach keeps rising, the clutch is slipping.

[Jeff]

What you describe sounds more like a gearing problem or flat spot in the jetting/mapping.

The only times I've felt a clutch slip is off  the start and then out of the corners.  And one good twist on a slipping clutch will completely eat it...

Clutch life really depends on the rider.  I've gone through as few as 1 per season and as many as 3...

[aberg12012]

+1 on what everyone else has said here.  If your clutch slips, you won't be asking yourself "gee, I wonder if my clutch is slipping."  You'll be cursing and spitting "oh crap, my clutch isn't grabbing..."  You pretty much can't mistake it.  Toward the end of last summer I notticed the brand new clutch I just put in at the beginning of the season is starting to slip... It happens when I'm going down a straight and pre-load the shifter, and blip the throttle for an up-shift.  As soon as the tranny clicks into the next gear I nottice the motor is accelerating slightly faster than I am.  But the bike quickly catches up with no loss in top speed.  What your describing sounds more like a jetting/mapping or some other problem with the motor that it dosn't want to produce enough power to go any faster.

[Super Dave]

It happens when I'm going down a straight and pre-load the shifter, and blip the throttle for an up-shift.  As soon as the tranny clicks into the next gear I nottice the motor is accelerating slightly faster than I am. 

Just to note, preloading a shifter is really hard on the shift forks.  You've got a 100HP pushing against those little steel forks.

[aberg12012]

Actually, to be more accurate, I'm a little more lazy with shifting... So I usually don't put any force on the lever untill after I've already started backing off the throttle.  Dave, is my "lazy" method of blip shifting a safer method in your experience?  

Obviously this isn't something thats going to make my very slow lap times improve anyway... lol

[Super Dave]

Well, to shift while the HP of the bike is loading the gears...

I can cause problems.  When you'll have to pay for them is the question.

An electronic shifter cuts the power for a moment, enough that it unloads the trans and allows the shift easily.  Lettin' off unloads the trans and allows the easy shift.  Same idea, one is an OEM unit in your right hand...the other costs money.

Basically, you shift and let off that tiny bit at the same time.  If you shift then let off, you've got some load on the gears.  If you let off then shift, it can have back torque on the gears.

That make more sense?

[Fast4fun]

Thanks for all the info, it helps alot. I'm still not sure what caused the plateau but I was no where near the redline. BTW it rides just fine on the street. I was able to get in a good 30 minutes today just outside of Chicago. Not bad for xmas eve. Happy holidays to all.

[Z-man]

When your clutch plates go, your bike will continue to run through the RPMs but not that much happens with respect to gaining speed.  For me when my clutch went the tach went through the rpms like lightning but now much happened in the way of movement forward.

Z

[cbirk]

Iengine approaches peak power/torque and the bike approaching 135-140 i notice that the bike doesn't want to accelerate. It totally plateau's.

Thats EXACTLY when my R1 would slip. It sounded like Excitebike on NES, it would plateau.  I changed the discs and it cured it. Although the R1 did have a diaphragm spring for the clutch which was weaker.