IMO you are really cranking for unported 906s. Compression helps. But more headflow should really add power with everything else you've got going on, the heads are the weak point for sure. Stock valves or 2.14/1.81s?
Also, assuming you've got something like 6 cc valve notches I think 12.6:1 compression is a high estimate. You'd need a 65 CC combustion chamber which on a 906 would be milled until the step pad was gone, although people have done that.
A rough guess is that around .100 has been milled off, the step pad is almost gone.
The valves are 2.14/1.81s.
I talked with Hughes after getting 200psi cylinder pressure and this is the answer:
I went ahead and did some calculations.
Based on the altitudes listed below (choose yours) here is what I estimate your compression ratio to be.
At sea level to 500ft above you would be approx. 12.5:1
750 to 1500 ft above sea level you would be approx. 13:1
2000 to 3000 ft above sea level you would be approx. 13.6:1
3500 to 4500 ft above sea level you would be approx. 14:1
Good luck,
Kevin
My elevation is 600 ft.
Cam is installed (and dialed in) centerline at zero, after Hughes instructions.
It might be a high estimate, but I know it's too high for pump gas.
