A little off the top

[oynot400]

I have a Ross 88mm piston (426) with 11:1 compressoion. I want to get it closer to 10.5:1 so I can run straight pump gas with it. Does anyone know how much to mill off to get the compression down there?
Thanks, :)

[RAPTORAZ]

My 416 has a Ross 10.8:1 piston, and it runs fine on 91 octane. Getting a thicker head gasket would be the easiest way to lose some compression.

[YZROOSTINYA]

running a ex head gasket will get you 10.5 :1 and the XR head gasket will get you 10.8:1

[OCCRA288]

if you mill the head you will gain compression by making the chamber shorter. Run a thicker head gasket and you will lose compression by making the chamber taller.

[YZROOSTINYA]

he meant off the piston

[oynot400]

I will have to check the price on a new ex head gasket. That sounds like the way to go.
Thanks guys! :D

[YZROOSTINYA]

there like 15-25 bucks

[nakomis0]

I heard milling the cylinder .20 will get jump your compression up 1.

So sounds to me to get the comp u want, you need a gasket .10 bigger than the one you currently have.

[F-16Guy]

I just bought a stock 400ex head gasket off service honda for under $13.

[cals400ex]

my local dealer said that some people double the gaskets up to lower the compression. i don't know if this is a good thing to do or not, just something they said people do.