Motorcycle Racing Forum

Motorcycle Talk => Wrenching => Topic started by: EX#996 on June 11, 2004, 09:48:35 AM

Title: SV Clutch problems
Post by: EX#996 on June 11, 2004, 09:48:35 AM
We are having a problem with our superbike motor and the clutch slipping. It would start slipping when the motor would reach 7 to 8 grand.  Basically when the torque of the engine started to peak, it started to slip.  Any ideas or suggestions?  Here are some specifics.

700cc motor
Barnett clutch
83hp with stock carbs (some day we may be able to afford flat slides)

Some of the suggestions to fix the problem have been:

* Is there Amzoil in the motor now?  If so, go back to Spectro Blue as the higher hp combinations will overpower the clutch with the wrong oil.  It also seems that if the oil is above the halfway point in the window with the bike perfectly level clutch slipping will occur.
* New plates, I use the Barnett Kevlar plates and keep them very fresh
* New plates, stock metal plates. I replace metals if there is any evidence at all of warpage
* Run the oil level slightly below the upper mark. If you have the oil control block off plate installed you should be ok as far as pickup.
* The book says the internal push rod adj should be bottomed out and them backed off 1/4 turn. I suspect this is not enough clearance for a race bike. I back off 1/2 turn. You should be able to spin the push rod freely with your fingers.

Any ideas or suggestions would be appreciated.

Thanks!

Dawn  
Title: Re: SV Clutch problems
Post by: tshort on June 11, 2004, 10:04:51 AM
I'd detune the motor (by rejetting?), down to around 71 hp or so - maybe less - and then the clutch won't slip so much.  Also, ride below 7000 rpm, if that's where the slippage starts.  This should fix *all* your problems. 8)  Hope this helps, Dawn.
Title: Re: SV Clutch problems
Post by: tzracer on June 11, 2004, 01:59:37 PM
What clutch springs are you using?
Title: Re: SV Clutch problems
Post by: Dawn on June 11, 2004, 02:50:27 PM
Barnett Springs
Title: Re: SV Clutch problems
Post by: motomadness on June 12, 2004, 09:55:09 AM
Do you have a new clutch cable?  If not, does the old one move smoothly through it's range of motion?  I had a problem last year where my clutch was dragging because the external lever arm would drag on the case near the bottom end of the travel causing the clutch to slip.  Eventually, the slipping would increase and I would have to replace my clutch.  Moral: make sure the entire path of the cable is unimpeded.
Title: Re: SV Clutch problems
Post by: KBOlsen on June 12, 2004, 07:59:43 PM
John says that the Barnett kit comes in two versions - one with an extra steel/fiber, and a "standard" version with the "stock" number of fibers/steels.  Does yours have the extras?  Was the secondary spring left in when it was installed?  If so, take it out.  

When you take them apart, the outer pressure plate is marked to go in a particular spot - if not installed correctly this may cause slippage.

First things that came to mind from Mr. Cummings.
Title: Re: SV Clutch problems
Post by: Super Dave on June 13, 2004, 05:32:05 AM
QuoteBarnett clutch

This is usually where I've had problems.

They seem to work fine cold, but when they get warmer, they slip.  You have to do all the adjustment on them when they are hot...or they slip.

I always use OEM fiber plates.