how many cc would a 12:1 piston add to my trx250

 

none, compression does not change the CC, you have to change the size of the piston or size of the stroke in order to increase your CC

 

notta 1!

 

I don't understand why you think that a higher compression piston would add cc's.
Perhaps you are confusing higher compression with over-size. Both are readily available from the after market.

 

do you maybe mean combustion chamber ccs? like if i put a 21 cc dome in my coolhead instead of a 19? in that case you would actually be losing ccs which in turn adds compression! thats just my thought maybe im just going crazy!

 

every 10 over you bore cylinder will give you about 2 more ccs.

 

I agree with the guy who said that you can only change your cc's if you change the bore and/or stroke. The compression ratio has nothing to do with cc's

 

think of it this way! a flat top piston could hold only so much fuel and ait in a certian area (measured in ccs) now put a dome on the piston therre is less area in the combustion chamber so if you add a high compression piston (which most have a large dome) it takes up more area and leaves less ccs for the fuel/ air to go and in turn provides more compression! with a higher compression p[iston you lose ccs in that aspect but when it comes to displacememnt of a morot (bore and stroke) it has nothing to do with it! does anyone understand what im trying to prove?

 

Sorry, but that is a totally different thing. You CAN NOT change the size of an engine by changing the compression ratio.

 

Sorry, but I didnt finish reading your message before I replied. You are right about what your trying to say. When you increase compression ratio, the air/fuel mixture gets squeezed even more, and creates more power, but in some respects you must increase octane so you dont ping. Most high horesepower engines have high compression ratio.