clutch slipping - should I go with regular or race replacement?

I'm pretty sure my clutch is slippin. I had always suspected it, but now since I have the 615 kit installed, I really think it is. The bike is fast and accelerates well with controlled application of throttle, but if I'm going near WFO and it gets into the powerband, it gets louder and gets to redline faster, but the bike doesn't really move faster.

I searched for "slipping clutch" and saw a thread where a guy was reccomended to get a stock replacement vs the "street racer" setup EBC has. I guess maybe that still applies here?

The bike isn't a race bike, but it isn't exactly stock either, and I feel tempted to put in the 'best' stuff because it really isn't much of a price difference. However, I don't want it unstreetable or more annoying than it is beneficial. I am the type of person who would try a burnout and picking the front wheel up here and there, though..

Here is what denniskirk has to offer:

clutch plate selection at Dennis Kirk

Post edited by: steell, at: 2006/07/26 19:48

first adjust your cable to see if thats the problem, if it doesnt help, take the clutch apart and mic the parts to see if some/all are out of spec, if so, and if you have strong hands like me, go with an APE "extra plate" clutch kit with heavy duty springs. they will take abuse(aka "fun" :evil: )
that is if they make them, im not sure now that i think about it, i think just the middle weights and big bikes, if they dont make em, and your friction plates are ok, see if the aftermarket springs will swap in

Post edited by: 77KZ650, at: 2006/07/26 18:55

use the aftermarket plates with stock style springs,your left arm will thank you!:whistle:

Try following through the troubleshooting section in the manual for clutch slippage before you spend any dough. You might find half an hour of adjusting will save you beer money.

wireman wrote:

use the aftermarket plates with stock style springs,your left arm will thank you!:whistle:

Done that. Yeah, it was easier on the left arm, but it slipped like crazy at highway speeds. I put in brand new stock springs too. It would only grab fully with the recommended aftermarket springs, and they were a BITCH on the left arm!

I called three different speed shops, and they confirmed the same thing. They each said almost the exact same thing "get the stock clutch, everything else is a waste of money". So I sprung for a stock set of disks and even used my old stock springs. The bike shifted so nicely with no slippage that all the money and time I wasted on the "performance" clutch didn't even bother me.

I have yet to feel a nicer, smoother, lighter clutch among all of my friends' bikes (although my buddy's KZ400 comes very close!).

This was on a 1981 gpz550.
Now if the bike is putting out more torque than stock, I can't say what will happen.

Post edited by: loudhvx, at: 2006/07/27 02:01

get a set of clutch springs. they sag first and create slipping. very simple fix
less than 5 dollars for EBC brand-maybe a gasket and oil change also at the time you take the clutch cover off

Hmm that sounds like a good idea, trippivot. Worth a shot either way. I was even wondering how much oil would run out if I had the bike all the way over on the side stand and did it that way, heh. It should be due before too long anyway though.

Lou, when you say "stock" clutch disks, do you mean stock spec (or someone who markets them as OEM spec) or literally "genuine kawasaki" clutch disks?

It's not an adjument thing, the cable was new put on by me when I got the bike, and I can loosen it up till it has all the play it needs and then some, but as soon as the clutch cable pulls taunt, the clutch slips. It would say to me that it is in the clutch itself, with disengagment happening so quickly. When I start out, I can let the lever out literally almost all the way before it even grabs at all.

the way you just described your clutch,,you have it to tight. it disengages when the lever is pulled in..it engages(holds)when the lever is let out. if the bike starts moving when releasing the lever and its at the end of the travel, the clutch plates will slip under a load, the clutch should be adjusted to where its at full holding power before the lever is all the way back out,,hope that helps you some

I would agree with Trippivot and the tuning shops you have spoken to, use genuine Kawasaki plates only and some aftermarket springs. The EBC springs are about 10% heavier than stock. If you don't mind a really heavy lever action (I don't) then Kibblewhite do some "red" racing springs (they aren't actually red) that are about 30% heavier and will cope with about 150hp.

stock is the best

Trav wrote:

Lou, when you say "stock" clutch disks, do you mean stock spec (or someone who markets them as OEM spec) or literally "genuine kawasaki" clutch disks?
.

I mean from the dealer,genuine Kawasaki, oem disks. I tried to use brand new stock springs with aftermarket disks and it slipped a lot! The aftermarket disks only grabbed with aftermarket springs which were way too heavy for rush hour traffic.

My motor is stock 550 with a jet kit and Kerker.

Lorcan wrote:

I would agree with Trippivot and the tuning shops you have spoken to, use genuine Kawasaki plates only and some aftermarket springs. The EBC springs are about 10% heavier than stock. If you don't mind a really heavy lever action (I don't) then Kibblewhite do some "red" racing springs (they aren't actually red) that are about 30% heavier and will cope with about 150hp.

Just curious, what do you use for a clutch, Lorcan? What handles 230+hp?

After the clutch in my Seca Turbo exploded, I went with a Barnett clutch & springs (it was $20 cheaper than the Yammy parts!) It held really well for a long time, but eventually started to slip right before I got rid of the bike.

Trav, if you're going to pull your clutch plates and inspect them, you might consider hitting the steels with some sandpaper if they're glazed.