RE: [ST] Engine buzz and balance shafts

["Dan Wallander" <triumph99@xxxxxxxxxxxxx>]

The St's does have a balance shaft.  This came up a couple of years ago
and, while the shaft is adjustable I do not see how the balance shaft could
suddenly be out of balance as it is gear driven and the engine would have
to be removed and the cases split for the shaft to be moved to another
position.  If the bike has always had excessive vibration, then the shaft
might not be in it's proper place.  

It is possible to check the position of the balance shaft, but you will
need to remove the clutch cover (requires new gasket) and a plug in the
side of the engine case (requires a new plug).  (this is for the original
engine, but most likely hasn't changed for the new engine)

It is more likely that you need to do a tune up.  Check your valve
clearances and more important, make sure the throttle bodies are properly
balanced.  Unbalanced throttle bodies can create this vibration you have
described and their tolerance on our bikes is fairly small.  There are
other things that can cause vibration too.  If the vibration occurs
whenever the engine is running, try the tune up.  If the vibration occurs
only when the bike is moving or gets worse when the bike is moving, you may
have a cupped front tire, wheel bearings that need attention or replacement
and don't forget the moving parts in the rear tire too.

I would get a proper tune up first.  You've got to do that periodically
anyway, then start looking for other causes if that doesn't solve your
problem.

Dan.

Dan Wallander
Albuquerque, New Mexico
www.danwallander.com 
Triumph Sprint ST :: BMW R90/6
TSRA-VP, ABC, IBA, AMA,HSTA


>
> So, my questions to you guys:
>
>   - Does the ST ('03 model) have balance shafts?  (I would assume so, but
> you never know)
>   - Has anyone tried adjusting them to smooth out the engine?
>   - How do you adjust the balance shafts on our engines?
>
> Thanks!
>   - Dave
>




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