Break in

[hatfield44]

I don't think you can use just compression pressure and not have a large margin of error for the compression ratio. You can determine a compression ratio range from compression pressure, but a accurate finite compression ratio will not be obtained.
I believe you can calculate the overall pressure ratio then convert it to compression ratio. You must have a little more information than just compression pressure though. I do not know how accurate this method would be though ??? ??? ???
Pressure Ratio= Pressure1/Pressure2
Compression Ratio= Volume1/Volume2
Compression Ratio = (Tempature1/Tempatrue2) *Pressure Ratio

 

[warriorgirl09]

If you know exact engine displacement (bore and stroke), as well as the size of the combustion chamber (volume in CC's of the engine when the piston is at TDC), then measure compression (in PSI with your guage) you can figure out the compression ratio.

thats what he does! cause he always asks me if it's bored over and by how much

 

[sidewayz]

So , help me if you can with some est. compression on my quad . Its bored 20 over , stock stroke , temp. - cold , and 170 lbs. of cylinder pressure .

 

[warriorgirl09]

So , help me if you can with some est. compression on my quad . Its bored 20 over , stock stroke , temp. - cold , and 170 lbs. of cylinder pressure .

i'll call him on Monday when he's back in the shop from vacation. i'll see if i can get him to figure it out for ya