High Comp Pistons

[SHANE03EX]

If I put a high comp piston in my 400ex, like 11:1, could I still run premium pump gas or would I have to swich to something else? Also is I couldn't run pump gas what is the highest compression I could run with premium pump gas?

[ridesa02400EX]

ive heard that the highest to go with pump gas is 11:1 but i heard it doenst run as good as it should with pump gas. most people run either race gas or a race gas/pumpgas mix with an 11:1. i think its a 10.8:1 that is still really good and runs better on pump gas then 11:1

[SHANE03EX]

Thanks for the input. I am a newbie and appreciate it.

[SHANE03EX]

The reason I started the thread was because I am thinking of putting a 416 kit in my 03 400ex and now my question is what is the best complete 416 kit on the market and about how much is it. I can install it myself, except for the boring, so dont include labor cost.

[JD400exrider]

Depending on the cam you go with your looking around 300 bucks maybe a little more for Piston, Hot cam and gaskets. Give C&D a call they sell allot of the 416 set ups. Good prices and good people to deal with.

[QuadJunkies]

I have 11;1 and dont have to run race fuel:huh

[go_chrisg]

well it will still run premium with an 11:1 compression but you'll get more out of your normal gas with the 10:8

[QuadJunkies]

Originally posted by SHANE03EX
If I put a high comp piston in my 400ex, like 11:1, could I still run premium pump gas or would I have to swich to something else? Also is I couldn't run pump gas what is the highest compression I could run with premium pump gas? this is what I learned when putting a Hi Comp piston on the Predator.. Unless your bumping the Comp up alot, there is no need to run race gas simply cause your not changing timing curve(I think thats how he put it:o ) for instance,we put a vortex CDI on the PRedaotr that had a big change in curve(HPD mapped) with that combo, you may detonate......but anyhow, by just changing your piston to a 11:1 you will be fine,everyone has there own opinions on what is better, I went with what 3/3 racing Companies reccomended as the best in over all gains......;) Hope this helps some......

[RED121572]

I had a 11.1 in my Honda and didnt run race gas. It now has a 12.5.1 and I choose to run straight race gas all the time.