need help with diagnosing very strong vibration

hi, noticed today and friday when using the bike that its got a really deep distinct rumbley vibration coming up through the rider seat and can feel it through my knees on the tank.

It seems really bad at 3-4k revs, havent riden any harder as just in commuting traffic on work journeys. Its aways been quite vibey, but the past few days its really bad, and when I started it on choke, you could even hear the vibes coming up through the frame to the tank etc, so its doing it when stationary as well.

Ive had a quick look for anything loose, but nothing obvious, I had the forks out for new oil 2 weekends ago, but surely that would be causing this???

Oil level was 3/4 full, and changed oil and filter on saturday, old oil had only done about 2K since last oil change a year ago.

I know its a bit of a stab in the dark here, but maybe others have had this and can say, try this, or so and so is on its way out.

Thanks, Lee

[TamSV]

Does it still do it at 4k revs when stationary in neutral or do you need to be moving to feel it?

not sure tam, will be going outside in a mo to see if there is anything loose, and will rev it up to answer your question....

[DarrenSV650S]

It's the CRANK! Welll I don't know that actually. But mine got very viby just before the crank gave up. But hopefully it's not that on yours

right..... just been outside, bike vibrates wether in gear or neutral, does it when stationary or when riding along. Reved it upto 5k, still done it.

Ive looked for loose engine mount bolts, losse exhaust, loose anything, couldnt find anything wrong. wondered if the frame was cracked, or headstock, cant see anything obvious.

It does have very slight cam chain rattle, but its had that for the 3 years Ive owned it. I did put my ear to the tank while it was running, but all you can hear is the engine running as normal, but amplified through the tank. Held my hand on either side of the engine while its running, and can feel it, but it revs up ok with no extra noises, just the feel of the excess vibration.

Im stumped???

Originally Posted by DarrenSV650S

It's the CRANK! Welll I don't know that actually. But mine got very viby just before the crank gave up. But hopefully it's not that on yours

im a little worried its the engine, as nothing external seems obvious.

[maviczap]

Hope its not something like a engine bearing on the way out

Does the vibe keep proportion with the revs?
ie more revs more vibes?
If it happens when the bikes stationary then you can be certain the only moving part is the motor, both plugs firing?

would be just my luck, had to scrap my car due to engine fault, as it was uneconomic to get it fixed.

Originally Posted by Owenski

Does the vibe keep proportion with the revs?
ie more revs more vibes?
If it happens when the bikes stationary then you can be certain the only moving part is the motor, both plugs firing?

same strong vibe whatever the revs, first noticed it when starting it on choke friday, then again today, so 3K on its strong. both plugs are firing, when off choke when its warm it ticks over fairly quiet and got its even cycle of both cylinders as normal.