The size of a standard G3L piston is 2.7182" (69.042mm) to 2.7192 (69.067mm)...
Oversizes are +.020" and +.040"....There are no pistons listed over those sizes so a +.060" if available, would be an after market piston such as Hepolite...
When reboring, the bore to piston clearance should be measured at the bottom of the piston skirt at 90 degrees to the gudgeon pin axis (the front and rear thrust faces of the piston...)
Clearance for std. and oversize pistons is .0034" (.086mm) to .0054" (.137mm). Measurements should be made with the components at room temperature...
Mail me off forum for additional information...Ian
try at Peter Classic Bikes by sending him an email ( he purchases Pistons from a big Italian factory)
try the Matchless club in Holland Onderdelen fonds.
