My 2000 250 sherco has developed piston slap, I fitted a 99 sherco barrel and piston just to confirm this and the noise ceased.

Question is should I fit a new B size piston which the 2000 model has, or move up to C size? The Ryan Young maintainance guide recommends in cases of bore wear replace with the next piston size up! It doesn't mention if the barrel need hoanning to fit the C size, will the .00038" increace of a C size piston seize the barrel if fitted or is it nothing to worry about?

Do you still see the crosshatch honing lining tru out the whole barrel.

Otherwise you first need yr barrel checked for roundness etc before that you can order any piston sice.

Un other tip. When you have it checked/measured, ask for a cleanup of the crosshatched honing pattern. This will help yr new rings to seat nicely and reduces blow by with the new rings.

And to avoid any misinfomation. Yes, a nicasil cilinder can be honed. But you only need a few microns.

I would suggest that you take the piston and the cylinder to a good machinist and have them measured. The clearances are listed in the Sherco Manual. Fit the new piston to the cylinder per the given tolerances. I would suggest that you obtain both a "B" and a "C" piston and have the machinist determine which one fits properly.

Wayne

Thanks for your replies guys most informative. Has anybody experienced piston slap on the early shercos? and if so how did you cure it? new piston or upsized!!!!!!!!!!!!

I had really bad piston slap on an "02" that I did some trading for, RYP sent me 3 pistons, B, C and D. Ended up using the C and sent the others back. The new piston took away all of the piston slap.

Wayne

Whatever piston you obtain, check that the skirt is the same as your old piston and has a cutaway on the inlet side.

I understand the 2006 motors do not have such a cutaway, but the Sherco part number is the same as the earlier piston(doh!). I had recently obtained an A piston, but luckily I noticed the lack of cutaway before fitting.

It might be worth requesting the dealer check before despatch.

Sherco Bultaco Graham Jarvis Replica Picton Knock

Hi there i have a Sherco bultaco Graham Jarvis Replica 2000 modle 250 cc when i open the throttle half way and then let it close there seems to be a knock that comes from the piston/cylnder area. The fly wheele has a little play in it i think its my main bearings it only does this knock when it is warm.its driving me insain. What could it be? every opinion counts.

I had piston slap on my 02 290

I had piston slap on my 02 290