I've got a stock bore 11:1 compression wiseco piston and I need to know what the compression spec should be. I know stock is about 182psi, but I need to know for the higher compression. Thanks guys.

 

I a perfect world 1:1 compression is 14.7 so 11:1 should be 161.7

 

Yeah I thought about that one, but the equation didnt seem to hold up to the info I had. The manual says 181 psi @ sea level so I was thinking it would be in the low 200 range.

Wiseco couldnt tell me, they guessed in the 220-230 range. Then they told me stock was in the 147 area and any subsequent engine configuration would be the same because of the decompression mechanism, but since mine is gone it doesnt apply either.

Maybe I'll just have to stick with the leakdown and go from there. I'm suprised no one has this info lying around somewhere, its a pretty common compression for this bike.

Thanks Hugh the help is appreciated.

 

My 12.5:1 is 200 psi, no decompression mechanism.

 

Not many have checked cranking compression because of the auto decompression.If head work has beed done unshourding the valves will loose a little also. I will check my 13.5 when I go back together all freshened up.
Maddog who did your intake and manual decompression setup? Looks famaliar?

 

UBETRUN, thanks that gives me a decent benchmark. Now I have an idea as to what range I'm looking at.

Scholle, good points. I'd appreciate the numbers when you get around to it. I'm sure I'll be going higher comp before too long so these numbers will help in the future as well as now. Barker did my head and intake and I had him throw the decomp on since he was already in there.