RS250 Piston Size

[Jonnysims]

Im sure this question has been asked many times before but i couldn't find anything in the search engines!
Im rebuilding the RS and bought the aprilia piston assy 8600409, does anyone know if these are all one size or are there different sizes because the piston is way too tight to fit in the barrel, even without rings?

Any help would be much appreciated

Cheers

[keean]

AFAIK, Neither Aprilia or Suzuki supply oversize pistons. Non OEM suppliers (Pro-X, Wiseko?) supply pistons in various over sizes, although some of these have the gudgeon/wrist pin in a slightly different place as they were designed for a different bike.

Is the cylinder round, or is it too narrow in only one direction?