Help me with a vibration issue...

manofsteele

manofsteele

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Alright I got my bike on the road and finally all tuned and dialed in and it runs great. When I get above 45mph I get a vibration in the front end that comes in and out, it's not a constant. I loosened and re-torqued the whole front end, it has tapered head bearings and I rechecked those also. I changed out the rim and tire and nothing has helped. I also replaced the fork oil with 10w30. I have another bike that I'm going to swap out the forks with and if that doesn't work I'm stumped. Any suggestions?
 
sounds pretty normal for these bikes, certain rpm's create resonant vibes in the bars.
 
Yeah it's a bobber and it has all the engine mounts, it's not normal vibration, it's a pretty bad shake above 45. I don't think it's wheel bearings because when I changed out the wheel it didn't go away.
 
No front Guard !

Checked out your thread on your build and i see it has no guard. These forks need to have a brace of some kind.
 
Really? A front fender would make that much difference? I think a lot of people aren't running anything in the front and don't seem to have any issues.
 
You mentioned taking you bike for a spin before installing the front Caliper. did you notice the problem then, if not it could be you haven't tightened up something in the front brakes propper since putting on the caliper
 
The tapered bearings get tightened quite a bit more than the old ball bearings would. If you are 100 percent sure that the spare wheel has perfect bearings, keep tightening the steering bearings in small increments until the shimmy goes away.
 
Not 100% on the wheel bearings, but what's the chance both sets are bad? How do you check the wheel bearings for play? Ill try tightening up the steering head some more, I currently have it torqued to factory specs 40 ftlbs. What do you recommend I torque it to?

650skull, when I drove it without the front brake I never got it passed 45mph. I also rechecked and retorqued the whole front end including the brakes.
 
Are you tightening down the large nut(s) on the steering stem? I'm not talking about the bolt that holds the upper tree to the stem. I swapped out from stock bearings to rollers and had to make adjustments over a bit of time and riding.
Sitting and running, if I give her a little rev- as the rpm's come back down I could feel a vibe through the handlebars if they were loose.
 
Never rule out the REAR wheel as a source for front end shimmy. A bad drive chain can cause a periodic vibration also.
I fought a CB1100F front end shake for quite some time. Finally found bad rear wheel bearings were the cause. Cupped tires cause shimmy also.
 
Well it's got a new chain but the tire may be suspect. I need to change it out anyways due to some sidewall splitting and I think it may be out of round, I'll check when I get home.
 
Have to add swing arm bushings to the suspect list. Uh not so much on the hardtail.
 
my hardtail did that like crazy, through the whole bike though... To the point of the chain looking like it was going to fly off it was vibrating so bad. Only at certain rpms.... My stocker 74 doesn't do it at all and is vibration free, minus normal XS vibes.
 

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