I have an on-going issue with my girlfriends 02 500R.

Problem: The bike has a wierd vibration/wobble. The best way to describe it is there is a vibration that starts on the left clip-on then moves across the triples to the right clip-on then back across to the left again. Then it repeats. It is worse around 45mph, but it is alwaynoticable over 35mph. It seems to be worse on decell. If I let go of the bars, it will wobble worse and worse until it breaks out into a tank-slapper.

The bike: We bought the bike new in 03'. It has been dropped several times. Never at speed, mostly in parking lots. Tires are Perelli Sport Demons, stock sizes.

What I have tried: I checked front and rear brake rotors and rims for bends/wobbles. I took both front and rear tire in to a tire shop and had them rebalanced. I have loosened the front forks in the triples, then retorqued. I have checked the alignment of the rear wheel. I checked front and rear wheel bearings. I checked the steering head bearings to seeif they were loose (by just lifting the front and wiggling them. No slop that I could feel).

I consider myself a very good techincal/mechanical troubleshooter/problem-solver, but this one's got me stumped. I am running out of ideas, and getting very frustrated. If anyone has had any experience with this, or has a friend with experience with this. Or even an idea of what to check. It would be greatly appreciated.

Please Help us!

Thanks,

BB

 

Has the bike been stored for an extended period of time? If so, the tires may have developed a "flat spot" where they rested on the ground. I think the only cure is to ride it alot ... or replace the tires.

 

hmm, you checked tires, rims, fork straightness, steering head. And still the same wobble. Are the front rebounds equal?

 

"...worse on decel..." DING!
This is very common when your front tire is worn, cupped, or as Zephod pointed out, stored for a long time.
Is this the original stock tire that came on the bike? If so, it's probably time to replace it. The high profile of that stock tire seem especially susceptible to cupping, which is notorious for causing this condition.
If the front tire is fairly new, I'd take it back to the shop that installed it and ask them if they use a computer "spin" balancer, or if they use a "static" balancer. If they insist that a static balancer is just as good as a spin balancer, take it to a real shop and ask them to rebalance the tire and be prepared to pay 15-$25.
There is always the chance that it could be one of the previous excellent suggestions, but the bar-swapping on decel with your hands off the bars is usually a strong indicator of a worn or cupped front tire.
Good luck and let us know how it goes.
Peace!
-CCinC

 

Both tires are Perelli Sport Demons (stock sizes). They are both like newwith only about 1000 miles on them. They don't show any signs of cupping or uneven wear. Just the normal flat-spot down the center of the rear tire. They have not set for long at all. I am not sure how the tire shop balances them, but they are a reputable shop that I have taken my bike tires to for years without a problem. I took both wheels back to them, and they re-balanced them, and found the rear to be slightly off. Unforunatly this did not cure the issue.

I am confident that the tires are not the issue here. And short of replacing both tires, I have done everything I can to rule them out.

Thank you, for all of your input. I appreciate it.

Any more ideas?

Any one else?

 

What are the "front rebounds"?

 

Rebounds being the spring pressure on the fork springs. How you set sag numbers. A low oil level in one leg compared to the other leg will also cause uncertain handling issues.

 

I ran across this when I was looking around for help with my wiring issue....sounds like it might be of use:

http://gpz500s.foobuzz.com/info/how-...ing-the-forks/

 

I just checked this. The forks are perfectly parrallel. Great info though. Thanks!

 

I ordered a Repair Manual yesterday (a Kawasaki manual, not a Haynes, or Clymer). Will it tell me how to check these things?

Is there a way to set the sag on these bikes? I didn't think that the forks on these bikes were ajustable...