excessive vibration

[Anonymous]

Hey all. Went for a highway cruise last night (my first with this bike). I had a very uncomfortable vibration on the handlebar on the throttle side. Within half an hour my throttle hand was numb. I have noticed the vibration at lower rpms but it was never really a problem. The cluch hand is no problem. Any suggestions? Also...halfway through my ride my tach quit on my. Due to the vibration?? Dont know.

[vstan905]

What kind of bike, year and model? I can't help with the vibration on just one side oter than check you riser bolts. As far as the tach, pull the cable and see if it broke.

[Jethro]

My throttle hand goes numb all the time. These old air cooled motors with a 40lb crank are buzzy! Your clutch hand doesn't usually get as numb becasue you are moving it around more, but your throttle hand stays pretty much glued to the grip. About the tach, again, my bike is pretty buzzy and my tach hasn't quit. Probably need a new cable (hopefully).

[Anonymous]

Sorry for leaving this out. Its an 82 GS650L. As for the throttle hand going numb all the time. I'm pretty sure thats not normal. Certainly shouldnt happen during a half hour ride. Never used to happen with my last bike which was an air cooled 86 450 Honda. Have noticed that the left side mirror image is smooth but the right side image vibrates. I'll try tightening a few things down again and see what happens.

[Hoomgar]

It could be that your carbs are out of sync. That will make it vibrate nasty. So will a twisted crank. Let's hope it's just carbs. Not much else I know of that causes serious vibration like you describe.

[earlfor]

Re: excessive vibration

The two most common causes of high frequency vibration are the carburetors being out of synch and the chain and/or sprockets being worn beyond specs.
Stiff links/binding pins mean the chain should be replaced. Also, its better to run a chain too loose than it is too tight. A tight chain is guaranteed to cause vibration, whether old or new.

I have an 83 1100E with a bore kit and an 1150E. Neither of them vibrate and I've never had numb hands from them if they are properly tuned and set up

Earl.

Hey all. Went for a highway cruise last night (my first with this bike). I had a very uncomfortable vibration on the handlebar on the throttle side. Within half an hour my throttle hand was numb. I have noticed the vibration at lower rpms but it was never really a problem. The cluch hand is no problem. Any suggestions? Also...halfway through my ride my tach quit on my. Due to the vibration?? Dont know.

[Anonymous]

Never knew the carb sych could cause that much vibration... time to do a carb synch now that you mention it.

What about tire balancing/bent wheels? My 81 650G was vibrating like crazy until I got new tires put on. What a difference. Found out I had a slightly bent wheel in the process, but a tire balance made a monumental difference for me.

[Anonymous]

I Have a new rear tire and the front tire is in good shape. The vibration is only on the one side. I just tightened the riser bolts and a few other things but havent taken it out for a test ride yet....will report later. As for the chain and sprockets....its a shaft drive. Hope it proves to be nothing serious. Thanks for all the suggestions. This forum is great.

[earlfor]

If the vibration is only on one side. it is almost certainly a synch imbalance
An unbalanced tire would cause both sides to vibrate. also, an unbalanced tire is a low frequency vibration. Synch is hi freq.

E.

I Have a new rear tire and the front tire is in good shape. The vibration is only on the one side. I just tightened the riser bolts and a few other things but havent taken it out for a test ride yet....will report later. As for the chain and sprockets....its a shaft drive. Hope it proves to be nothing serious. Thanks for all the suggestions. This forum is great.

[Hoomgar]

Yup, carb sync. Give it a good sync dood and I'll bet she smoothes right out.

[duaneage]

Check the motor mounts, maybe one is loose and the engine is riding strange.

[bwringer]

It's common for the throttle hand to feel more vibration -- the handlebar is more free to vibrate since the twistgrip tube has to be slightly loose to function.

On the clutch side, the grip is affixed firmly to the handlebar and can help damp out vibration.

I agree you should start with a good carb sync. However, you may need to add bar end weights and/or fill the handlebar with lead bird shot to change the handlebar's resonant frequency.

I just filled my GS850's handlebar (shorter than stock) with #7.5 lead bird shot (they were out of #6), and it does seem to make a big difference. We'll see how it goes on the road to Asheville next week.

The shot comes in 25 pound bags for less than $20 at any hunting-oriented sporting goods store. This is enough to fill several handlebars.

More than you'd ever want to know about handlebar vibration and treatments:

http://www.manicsalamander.com/bar_end_faq.htm