Forum

[TvR]

No solution as yet. I ran it downhill at speeds up to 50mph and had a nice smooth ride, unless I blipped the throttle ... so I conclude its a problem in the motor not the chassis. At least, that's my thinking at the moment. Will have to wait till the new year now as I'm away in Tasmania from tomorrow.

Appreciate everyone's input, I will take a fresh look when I return.

Have a good Christmas one and all.
Cheers, Trevor

[RoSy]

This is how I used to cure vibration on the bikes iv'e owned and nine times out of ten it has worked, put bike on centre stand, place a car jack beneath the engine protect the sump if needed, just jack up until the weight of the engine is on the jack, you do not want the bike to lift at all, then loosen every single engine/frame bolt, remove head steady bolt. Once you are satisfied every bolt is loose try and wiggle the engine or very slightly jack the engine one or two mm it will not move much, if you can slide the bolts back and forth thats where the engine needs to be ,the object is to find a neutral position for the engine so when it's all tightened back up the engine isn't solely resting on one particular point. Tighten the head steady last and try to keep an equi distance around the bracket/bolts so as the bracket is not hard up against a bolt. On these big lumpy singles it doesn't take much for the engine to bind against the frame, try to imagined the engine sitting/floating evenly with a gap around every mounting bolt hole. Don't forget to torque all bolts to required amounts.

[ric]

Was anything changed on or added to the bike around the time this started?
I once swapped out a very heavy pair of OEM mirrors on an 865 air cooled Triumph for lightweight alloy bar ends and the bike picked up vibrations in the bars as well as elsewhere on the bike. The vibration had always been there but dampened out by the original equipment.

[Revband]

A worn or loose petrol tank mounting or something touching under the tank can cause this, before a major engine strip check it carefully.

[binary]

That was a good idea running down the hill at 50 MPH with the engine at idle. Any frame vibrations would have shown up as the engine has no input. The vibrations started again the moment you accelerated the motor from idle. This indicates like you said that the vibration is likely coming from the engine. Two possible things are the bearings or for some reason that seems impossible the crank has come out of true. You would not think that it could be any thing else from inside the engine.

[Dennis C]

This type of engine will always create vibration, it's how the vibration manifests itself that can be the problem, it is possible that the engine itself is not vibrating any more than it was, it may be that something else has changed amplifying the problem, from the op's description it was never in doubt that it was coming from the engine and I don't feel that coasting down a hill?. Would prove very much.

[Scalyback]

Pop her on it and rev the engine a few times, trust me, it'll be a good night!

[Alan R]

OOhh---- Scaly !!

[binary]

Dennis C. You have to be willing to try different things to try to prove where a vibration is coming from. If nothing else at least you can cross it off the list of trial and error.

[Bullet Whisperer]

If you have a centre stand, put it on that and rev the engine - slight backwards movement is ok, but if it rocks from side to side and 'waddles' backwards, it could spell worn main bearings.