How much of a pain is putting a new piston in? I'm thinking specifically about how to determine whether I need an A or B spec piston, which I'm guessing I can only determine by measuring the cylinder bore?

Then there's the question of whether to hone the cylinder.

Anyway, never done a two stroke top end, looking for any advice.

Chrome bore or liner?

Not sure, it's a 300 sherco.

These cylinders are made by S3.

The bore is electroplated with nickel silicon carbide, then honed with a diamond hone to achieve the desired piston/bore clearence.

Are you replacing the piston as a matter of course, or do you consider there is some wear, is there piston slap?

It is quite normal for a well looked after trials bike to go for at least 10 years on the same piston (and rings), not like a motocross bike.

If your piston is an A and there is no piston slap (rattle) then replace with an A.

If you have considerable noise from the top end, you can use a B piston in the A cylinder. There are only minute fractions of a mm difference between the A and B in the lower piston skirt diameters. I have done this in the past with success.

No need to hone the cylinder unless you need to clear light surface damage.

Bye, Peter B.

Defo a chrome bore. Honing in the conventional sense isnt done on nikasil bores, more deglazing. If there are deep scores you will need it replated.

 

Only way to tell is to measure it, and to so this properly you will need a bore guage.

Got it. Thanks for the info.

Hi, my understanding is that a light hone (etching) of the bore aids the bending in of the new rings.

Cheers Taff

Oops, that should read bedding in.

Taff