Quick Question

[Deerslayer89]

My piston is stamped 66.42, is this a 66.50 .20 oversized?
Sorry for the stupid question. :-/

 

[scotj77]

that is a strange size. you sure it doens't say 66.47....

 

[Deerslayer89]

As sure as the pic. I should probly mention its a Namura piston, i need new rings.

 

[scotj77]

I guess that's their version of a 66.50 piston. if you are replacing the piston i would have a shop check out the cylinder and see if you can get away with a new weisco 66.5 or if you need to go to a 66.75. you should be lookin at about 60 bucks for a bore and champfer job. make sure they champfer the ports though. this is where they round off the edges of the ports so that the rings don't snag. if they don't do it your piston will get distroyed. or you can just send it to kenoconnorracing and have them do it all for ya.. he will even supply the correct piston.

 

[yfz914]

ya might wanna go with a wiseco ..X2^^^

 

[royalt67]

Yeah, that is probably actual size which would fit in a 66.50mm bore with about .003" clearance. .08mm~.003"

 

[Blaster200boy]

Have the Machine check out your cylinder and they can tell you exactly what oversize to get. but its very wise that you give them the new piston to check out. If its a 66.50, that means its a .50mm over. If the machine shop tells you to get the next size up, it would .75mm over. I would highly recommend using a Wiseco Piston. The cast ones are crap. Plus, Wiseco are cheaper too.