Engine vibration

[duckspeed]

I'm going to try and sort engine vibration on my mates 2001 model year 1150.
The vibes are very noticeable at 2000rpm and really spoil the ride.
Apparently the bike had a single piston replaced under warranty due to high oil consumption, my question is are a closely matched pair of piston fitted on production?
Could an imbalance between piston weights cause the problem we have?

 

[flatdog]

Surely if the piston is mismatched then it would vibrate at all revs?

I'd ensure the tappets/timing/injectors/plugs etc were all spot on before doing anything else.

(if straight from dealer/ manufacturer network then I would expect the replacement piston would be of a 'standard' within manufacturing specification - possibly with a mark on the crown identifiying a matching piston spec for replacement purposes)

 

[Timolgra]

Get your throttles balanced then see.

 

[Steptoe]

I'm going to try and sort engine vibration on my mates 2001 model year 1150.
The vibes are very noticeable at 2000rpm and really spoil the ride.
Apparently the bike had a single piston replaced under warranty due to high oil consumption, my question is are a closely matched pair of piston fitted on production?
Could an imbalance between piston weights cause the problem we have?

I'll ask the obvious question... was the vibration there before the piston was replaced.
And why replace the piston ? why not fit new rings ?

 

[duckspeed]

Throttle bodies balanced valve clearance correct. My mate didn't own the bike when the warranty work was performed, so we can't make a comparison.
Thanks for responses so far.

 

[flatdog]

And why replace the piston ? why not fit new rings ?

Thats probably all they did anyway. unless proof of receipts run to megabucks back in the day.

Do a compression test to check everythings fine at that level.
If the TB's etc are checked and CORRECT then it may be rider perception?
Personally If i was checking this bike as a mate, (the owner seems to be new to these) I'd take it for a proper ride and see if there is a definate issue with the motor before committing to any rectification (expensive) work.
The vibration could even be coming from the drivechain or even the tyres.
If he has had it for a while without issue, then I wouldn't be fixated with pistons.

 

[duckspeed]

I have ridden the bike and the vibration comes through the bars, seat, foot pegs and is there at specific engine speeds

 

[Robh1664]

Mine did that kind of vibe, I ballenced the throttle bodies and it's now as smooth as a BMW salesman.
I'm aware the balance has been done but maybe it's worth a second check !

 

[(RIP) trickytree]

Try a motronic reset. My 1150 ran smoother after.