Need Help on Compression

[Quadguy08]

I just bought a 1988 250R and it is running on 210 pounds of presure(thats what the guy said) so because its running on race fuel I want to run on pump fuel. For the motor it has a Pro Design Cool Head w/(I dont know the cc of the dome) with a Pro Design Adjuster Plate. I was thinking if I was to put a 19cc dome w/bigger gasket would that lower the compresiion making me able to run on pump fuel and what should the timing be at?

[DPR250R]

19cc dome is still for race gas.....

You need to drop to a 21cc dome but should not rely on the dome size alone.

You need to do a compression test. The compression sould be in the 180's or lower to safely run pump gas.

[wilkin250r]

A 21cc dome should do the trick.

I'm assuming you have an aftermarket ignition? You must, if you are asking about the timing. If you have the stock ignition, there's no way to adjust it.