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Bad vibration

Posted: Sun Oct 21, 2007 6:21 pm
by Northern ANdy
It always vibrated abit through the bars, but just lately at 6krpm its quite severe and leaves the hand numb after 10 minutes. I have thought about bar end weights, but I'd also like to know where this new vibe is coming from. My theory so far is just to wait until something (perhaps crankshaft) snaps in two and then i'll know it was that - or whatever it is that breaks. I know its not speed related, and I know its deffinitely not gearbox related, it doesn't go away if you vary the load either. So just wondered if anyone has a suggestion.

Re: Bad vibration

Posted: Sun Oct 21, 2007 9:58 pm
by zimm
carb balance

Re: Bad vibration

Posted: Mon Oct 22, 2007 3:32 pm
by Northern ANdy
only did them 2000miles ago, do they go out that quick?

Re: Bad vibration

Posted: Mon Oct 22, 2007 7:45 pm
by RedexRobB
Dunno if they go that quick but its worth a try, if you got gauges all it will cost you is a few hours time.

Re: Bad vibration

Posted: Mon Oct 22, 2007 9:35 pm
by Northern ANdy
RobB wrote:Dunno if they go that quick but its worth a try, if you got gauges all it will cost you is a few hours time.
yeah I've got the gauges, its the time I cannot spare.

Re: Bad vibration

Posted: Mon Oct 22, 2007 10:39 pm
by RedexRobB
stay up late and do it middle of the night neighbours wont mind :D

Re: Bad vibration

Posted: Thu Nov 08, 2007 9:01 pm
by Northern ANdy
eeeeeeeeeeeee well I've stuck the vac gauges on it, no better.

Re: Bad vibration

Posted: Thu Nov 08, 2007 9:14 pm
by RedexRobB
lost a wheel balancing weight off the front? What rpm does it do it at? Sounds painful but rev the bike on standstill at the rpm it comes in at and see if you get it, should know then if its engine or chassis related.

Out of interest, where the carbs out by much at all?

Re: Bad vibration

Posted: Fri Nov 09, 2007 4:40 pm
by Northern ANdy
6k rpm its at is resonant frequency, at 5.5k rpm its fine, at 6.75k rpm its fine, its not the wheels because its not related to road speed, only engine rpm. erm I think the left pair of carbs where pulling 1.5psi more vacuum than the right pair, could've been the other way round. But only the centre adjustment was out, 1 & 2 read the same, 3 & 4 read the same, but 2 and 3, and 1 and 4 read differently

Re: Bad vibration

Posted: Fri Nov 09, 2007 5:50 pm
by RedexRobB
Okies, everything tight? Handlebar isnt loose any nut or bolts, engine bolts etc?

Re: Bad vibration

Posted: Fri Nov 09, 2007 8:32 pm
by Northern ANdy
have yet to go round it with a fine toothed comb in honesty. The whole thing vibrates, tank, pegs etc

Re: Bad vibration

Posted: Fri Nov 09, 2007 10:44 pm
by masterofinsanity
could be the tyre out of shape? wheel balancing? lost a weight??

Re: Bad vibration

Posted: Sat Nov 10, 2007 8:07 am
by rover220
masterofinsanity wrote:could be the tyre out of shape? wheel balancing? lost a weight??
unilkey as it doenst happen at a set road speed, only a set rev range. however, its always worth checking these bits.

Re: Bad vibration

Posted: Sat Nov 10, 2007 10:42 am
by Northern ANdy
masterofinsanity wrote:could be the tyre out of shape? wheel balancing? lost a weight??
its not anything to do with the chassis, Its stayed through this set of tyres just like it was in the last lot. It is an engine related vibe

Re: Bad vibration

Posted: Mon Nov 12, 2007 9:37 pm
by carsounds_dan
checked your tensioner?
could be the camchain shaking about or air stuck underneath your pistons? try an oil change?
cheers
dan