Buying New Piston

[Jonn]

When buying a replacement piston,in this case for my 225,not re bored,do I order a 70mm piston,and it will be slightly smaller to suit,or do I have to order the smaller size to fit the bore?

[dave411]

Order the same size as your cylinder size.If you have a 70.00 mm bore,then a 70.00 mm piston should fit.Talk to whoever is supplying the piston.

[rosscla]

Ideally you want a piston to match your bore with the correct clearance. You could put any standard 225 piston in but depending on the actual size or the bore wear you might get some piston slap which can encourage breakage or further uneven wear resulting in needing a rebore and an oversize.

A standard ’70’ mm piston will probably be somewhere around 69.95 - 69.99 mm when measured, some of them are graded like this A, B, C etc.

Get your bore accurately measured and specify a piston to suit.