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Old 06-20-2002, 02:25 AM
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Clutch Slip Fixes

Clutch Slip Fixes


Springs
Denny Zander

Out of the seven XSs in my family, three have had slipping clutches at one time or the other. This was generally encountered when the bikes were first purchased.

On the first one I did the usual replacement of the plates, fibers and springs to the tune of around $100 US.

On the second one, my dad took the time to measure his fibers. He found that they were with in spec (greater than 0.11"-2.88mm). Just for grins, I check the fibers of the clutch I had replaced. They where in spec also. We noticed that the sum of the differences from new (0.12"-3.0mm) was about 0.40".

My dad had a local machine shop punch out some 0.040" aluminum washers to use as shims behind the clutch springs. Voila! No more clutch slip. He has gone over 10K mi. since.

I installed the shims in our 3rd slipping clutch XS with the same results, no more slip.

We figure that, over time, the heating and cooling of the aluminum cases may cause stretching. I have seen this in automotive aluminum transmissions. What ever the cause, shimming could save some $$ and time.




Hoyt McKagen

Denny is absolutely correct about the use of shims. Have been shimming them for years. It's a grand cure for nearly any case of clutch slip and works well even with greatly increased power. As long as fibers are within thickness spec, won't replace them. I've put only two sets plates in clutches in decades and both cases were because of frying. The best source of those, BTW, is spark plug washers. They are most often the right diameters in and out and they can be had in various thicknesses. For the cleanest neatest job, use them from one brand plug ... not necessary to match the heat ranges!!



Sid Hansen's * WARNING *

About that tech tip fix: I tried shimming the springs at the ends that contact the star plate. WRONG! The thicknesses of the washers that I used was as specified in Denny's tech tip. Be warned that if you do this the wrong way, like I did, you will be looking for a new star plate. There is a circumferential groove that allows the posts to be counter-sunk into the star plate. As you tighten the bolts to the clutch, the washers will bend into nice half-moon shapes and WILL break the ends of the star plate with a wedging action.





Note: Aftermarket (Vesrah) springs are available in the Dennis Kirk catalog for $14.99/set.



Jaybird

If you need springs, tell your dealer to order from Parts Unlimited (a huge nationwide distributor) Part #KGS-025. They are 20% stronger than stock, look high quality and cost around $15 for a set. Cured my slip for good with no noticeable difference in clutch effort. Just FYI





Cables
Kenneth Kalafus

My H has had a clutch slip problem since I bought it about 6 months ago. Adjusting the clutch mechanism and cable free-play didn't fix it. According to the section in Clymer's on trouble shooting, any other clutch problems require clutch disassembly and new parts, so I've been living with the problem.

This past weekend, I finally decided to tackle the problem. I took apart the clutch -- friction discs and springs were on the edge of where the manual says to replace them, so I ordered new discs from Dennis Kirk ($43) and started to think about getting shims for the springs.

(aside tip -- when removing the clutch, you don't need an impact wrench or assistant to get off that 27mm clutch nut. Just put the bike in gear and press the rear brake pedal to keep the engine from turning)

So I swapped in the clutch from my SG, which I "know" works just fine and doesn't slip. Surprise! In the H, it *does* slip. What the hell is going on?

It turns out that the problem was due to the CLUTCH CABLE. The cable was very sticky, such that releasing the clutch lever didn't fully relax tension at the clutch mechanism. Since there was always a little tension on the clutch mechanism, it behaved as though the clutch lever was always pulled in a little bit, so the clutch would slip under hard acceleration.

Replacing the clutch cable ($10 plus about 20 minutes work) completely fixed the problem. If I had one of those cable lube tools, it probably would've been even easier. I wish I had known this before spending about 4 hours swapping in a different clutch and $43 for unnecessary parts (plus I still have to put the clutch back into my SG).

To test for this problem on your own bike:

Take off the cover over the clutch mechanism (the one with the two screws). Make sure your clutch has some "free play" (adjust the screw at the clutch lever, if necessary). Pull the clutch & release a few times. After eleasing, the clutch cable should relax at the clutch mechanism. Poke the cable with your finger -- if you can deflect it easily, you're okay. If the cable is very tight here, it's probably causing your clutch slip problems -- so lube or replace it.

I've seen threads before on this list in which people have had clutch slip problems, even with new discs and springs. Strengthening the spring tension by shimming the springs fixed the problem. It's possible that some of these problems were caused by sticky cables, since a strong enough clutch spring would pull hard enough to overcome a sticky cable.

I wonder if similar problem affect people's throttle cables -- potentially leading to excessively fast or inconsistent/hard to adjust idle.




Note: Clutch cables are available in the Dennis Kirk catalog for $8.99. At this price it might be worth replacing the clutch cable and saving the old one as an emergency spare for long rides.




Also see Replacing the Clutch elsewhere in the XS11 site.
 

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