Psi

[bvmracing]

What is the PSI for a 08 bone stock 90 and 70cc DRX??
Cheers,

[Airchunk]

Does DRR list an advertised compression ratio ???
If so I can convert it to a gauge reading .

[bvmracing]

Not sure, but someone told me it is around 140.
thats were I'm at.

[Airchunk]

Well , one of the old rule of thumbs was 125 psi should run. But maybe not run good . I just built a DRR 50 ( 2-stroke ) and set it up for :
14:1 ( compression ratio like a 4 stroke )
which yields a 8.63:1 compression ratio (like as 2 stroke)
the approx gauge reading on a compression tester would be 190 psi and require 102 octane fuel.

A note about compression ratio's .
a 4-stroke compression ratio is the total swept volume of the cylinder displaced vs. what volume is left over at top dead center.

a 2-strokes compression ratio is calculated based on the swept volume above the exh port and what is left over at top dead center .

I don't see anything advertised on the DRR web site as far as compression ratio . Maybe it is printed in the owners manual under engine spec's.