Actual size of a 65mm piston

[Coupelx]

getting parts ready for the topend after it gets back from porting but im having real trouble figuring out exactly what pistons are in it as there are no identifying marks. when i check them with my digital caliper the bores come out something like 64.8mm while the pisons come out slightly smaller. I am thinking of just going with a 65mm piston and call it a day but wanted to make sure its actually 65mm or is the bore 65mm and the piston slightly smaller?

 

This is exactly why i hate buying someone elses shit never know what exactly they did

 

ill check the bores again tomorrow morning and post the actual measurements.

[FireHead]

getting parts ready for the topend after it gets back from porting but im having real trouble figuring out exactly what pistons are in it as there are no identifying marks. when i check them with my digital caliper the bores come out something like 64.8mm while the pisons come out slightly smaller. I am thinking of just going with a 65mm piston and call it a day but wanted to make sure its actually 65mm or is the bore 65mm and the piston slightly smaller?

 

This is exactly why i hate buying someone elses shit never know what exactly they did

 

ill check the bores again tomorrow morning and post the actual measurements.

The piston will actually be 65mm if that is was it is supposed to be. You can't accurately measure a bore with a pair of calipers as the measuring edges wind up bridging inside bore. You need a bore gauge, ID micrometer, or a set of telescoping bore tools to accurately measure a bore. In any case the bore should be larger than OD of the piston by an amount that is dicatated by the engine design, bore type (nikasil, chrome, iron, etc.), ring type, and piston composition. :geek:

[Coupelx]

thanks!

[blowit]

getting parts ready for the topend after it gets back from porting but im having real trouble figuring out exactly what pistons are in it as there are no identifying marks. when i check them with my digital caliper the bores come out something like 64.8mm while the pisons come out slightly smaller. I am thinking of just going with a 65mm piston and call it a day but wanted to make sure its actually 65mm or is the bore 65mm and the piston slightly smaller?

 

This is exactly why i hate buying someone elses shit never know what exactly they did

 

ill check the bores again tomorrow morning and post the actual measurements.

 

 

I highly recommend some better measuring tools or have it done by a shop or this will come around and bite you in the ass! Clearances are not negotiable and set for a reason. Piston breakage and cold or hot seizures will result. Know your clearance!

 

Brandon

Edited November 29, 2007 by blowit

[FireHead]

I highly recommend some better measuring tools or have it done by a shop or this will come around and bite you in the ass! Clearances are not negotiable and set for a reason. Piston breakage and cold or hot seizures will result. Know your clearance!

 

Brandon

Word. You dn't want to have your piston to bore clearnce to be like fucking an open window (figuratively speaking) or vice versa. :biggrin: