bore size

[roadkill]

what size piston will i need to get if it has a 67.5mm in it with .015 clearance between the piston and cylinder with relatively low scoring. i found out i needed a new top end when i heard knocking and took off the head and found that much clearance. and i was wondering if wsm pistons are any good

 

[phragle]

thats way to much clearance. For example a wiseco usually runs around .003 clearance. Time for a new bore and piston.

 

[Wildcard2]

You need to bore and gone it and get a 67.75 piston.

 

[roadkill]

ok so what bore is that in thousandths and how many bores can i get out of my cylinder with what size it is now

 

[hotrodaj_2]

Every .25mm equals .010 not sure of your the exact bore size. If cylinder is not beat up to bad, bore .25mm larger (or .010 whichever is easier for you). Get a piston to match,67.75mm looks like. Imo do not buy WSM pistons. From what I know they are a cast piston. Cast = Bad. Pay the extra money and get a forged piston. The make is'nt important, just get forged. It's money well spent.

 

[roadkill]

ok thanks for the help

 

[phragle]

take it to a shop, they order the piston, bore it slightly undersize and then hone it to final dimension/clearance needed by measurng the new piston as the new piston will vary slightly in size.