Boring Sizes......

[Blaster30]

How does the boring number go because i just had my cylinder bored 1 size over stock or factory and wanted to know whats the size because it seems as if my stock and new piston r the same size....

 

[Quadrider10]

.10 i think.................

 

[Triple_B]

Boring sizes are in increments of .010" (10 Thousandths of an Inch), or in increments of 00.25mm . This is about the same width as one hair on your head (unless your bald). Sizes go from 66.00mm (stock) , 66.25mm (.010), 66.75mm (.020), 67.00mm (.030), 67.25mm (.040), 67.50mm (.050), 67.75mm (.060), 68.00mm (.070), 68.25mm (.080), and 68.50mm (.090). You will not be able to tell the difference between a stock cylinder bored over, due to the insanely small amount of material taken off. But, do NOT use an incorrect sized piston for any cylinder. Although it may LOOK like it fits, it really doesn't. If yours is bored .010, you will need a 66.25 piston

 

[slickerthanyou]

Bore sizes are like this, stock bore 66.00mm, then you have 66.25, 66.50, 66.75, 67.00( 1 mm over stock), 67.25, 67.50, 67.75, 68.00(2mm over stock), 68.25. The pistons are actually smaller than the sizes above, Only real way to tell what size your bore is--is to measure it, or have it measured!

EDIT: Triple B is a faster typer!!!

 

[Larry's Shee]

To add to the answer, the bore would be say 66.25mm and the piston would be ABOUT 66.22mm, or ABOUT .03mm piston to cylinder clearance. Don't forget to gap your rings!!

 

[Blaster30]

thanks to you guys i now can finally finish rebuilding my motor nd ride like the wind for christ sake