Piston to Wall Clearance ?

[Leonard Ray]

I have a 86 Mariner Magnum 150hp that I had to bore two cycliners out. The pistons are .020 WSM pistons.What is the proper piston to wall clearance. The pistons did not came with any paper work.

 

[Faztbullet]

Re: Piston to Wall Clearance ?

Have the cylinders finished @ 3.145... I usually bore my customers blocks a thousand under size and finished hone out to final size. The pistons are tapered and the shirt is the big end, so it should measure right around 3.140-3.142 due to the moly coating may be thicker in some places but dont worry as as the coating will be gone is several hours. You need not worry on about side wall clearance as this is a 2 stroke but to set you at ease it will be about .002-.003...