10 replies to this topic

[manwithtool]

We finished a trial on Sunday, and my son stayed and had another 20 minutes practice. But came back complaining of vibration thru the handlebars. He insists he did nothing unusual !! but 14 yr olds say that alot !

Anyway, it does seem to be vibrating a bit more than I'd expect. Seems to be running fine no misfire. I wipped the stator cover off and there doesn't seem to be any play in the mains bearing. I haven't looked at the clutch side yet, but if that was worn I'd assume it would suck in gearbox oil and smoke alot. And I'm guessing a main bearing wouldn't go just like that ? could it be a big end ? I recently (5 trials ago or more) replaced the piston and rings and top end. No play in big end then.

Anyone got any clue what might have caused a sudden increase in vibration ?? anything appreciated !!

Cheers
Martin

[manwithtool]

Just an update...
I called MRS and spoke to a helpful chap who said it is most likely to be the rear bash plate bolt come undone....So I'll be checking that tonight. be nice if it was that simple....although bolting a bash plate on is never much fun !

cheers

[B40RT]

A slack engine mounting bolt (even half a turn) can cause vibration.

[manwithtool]

B40RT, on Sep 21 2009, 10:52 PM, said:

A slack engine mounting bolt (even half a turn) can cause vibration.

I hope so because the bash plate looks ok. I know there's a bracket from the barrel to the frame under the tank. I had to remove this to replace the piston, the allen bolts into the frame were a pig to remove, so maybe there were done up tight for a reason...I'll see if they have come undone tomorrow night....I'll check all bolts !!

[Kramit]

Front motor mt. bolt is my guess

[manwithtool]

Well I had a look the other night and the bolt going thru the bracket on the rear of thebarrel was loose. Too late to start the bike up...But hopefully this will cure it.

Cheers for all the help !

[manwithtool]

B*gger.... Vibration is still there. I have been informed that a loose or wobbly flywheel might be the cause....I'll take alook at this tongiht hopefully with a dial gauge. I checked bfore and there was no play, but I didn;t try and "wobble " it.

I'll also go over all engine mounting bolts with a spanner rather than just check with my fingers. Trial on Sunday so I hope it's a quick and easy fix !

[trialsnutterman]

Yeah defiantly check all bolts will a spanner socket, don't forget the swingarm axle hidden under the plastic caps.

[manwithtool]

Well, I went round and tightned up all bolts, bash plate bolts although not loose I could tighten them about 1 turn. Same for the Front engine mount. However I think I have made a big mistake by startin the bike up on the bike stand....on it's wheels it doesn't seem to vibrate too bad...Anyone else care to confirm that a bike will vibrate alot more on a solid stand ?

fingers crossed !! I suspect it was the bolt at the rear of the barrel not helped by the others not being that tight.

Cheers for all the help and advice !

[copemech]

manwithtool, on Sep 28 2009, 06:59 PM, said:

Well, I went round and tightned up all bolts, bash plate bolts although not loose I could tighten them about 1 turn. Same for the Front engine mount. However I think I have made a big mistake by startin the bike up on the bike stand....on it's wheels it doesn't seem to vibrate too bad...Anyone else care to confirm that a bike will vibrate alot more on a solid stand ?

fingers crossed !! I suspect it was the bolt at the rear of the barrel not helped by the others not being that tight.

Cheers for all the help and advice !

Sounds normal for that to me, I think you have it fixed!

[manwithtool]

Yep all fixed....I suspect it was the bolt on the back of the barrel.

Cheers all....

But I have had anther problem....But I'll start another post..

Cheers