What Compression piston

I'm going to put a high comp. JE piston in my bike real soon with XR cam,,,,I plan on running pump gas (93 octane) what compression piston would you guys suggest,,

I am getting ready to go to a 416 and my friend is gonna do the 440, so we've been checking with shops around here on that exact same question. They say 11:1 is a good norm, 12:1 with stock cam and might have to boost the accelerator pump to feed it. We are probably gonna do 11:1 just to keep costs down.

Yeah a buddy of mine suggested the 11:1 JE piston,,JE pistons are lighter than wiseco so that should help...Also there are 3 head gaskets and dropping down to using 1 was also recomended,,more compression this way..You'll love that 416 kit if you get all the bells and whistles added with it,,,my racin buddy that has one is a real rocket ship..

Yeah I hope it's as good as I've heard, the other guys we ride with have some pretty intense bikes. One is a DS650 that has been in the shop since it was new being stroked, ported, cammed, and you name it. The other two are a Raptor and a built 250R. So we are gonna see how the 416 and 440's do against those. We've been reading a lot, and asking a lot so I hope to get a decent build that will do some talking out there. You know any specifics on your buddy's that has made it so good?

I had a little work done to mine and it goes great. I didn't want to have to run race gas and the engine man said I would not have to but.... when I run 93 it pings when it starts to wind out. If I run 110 or a strong mix of more 110 than 93 it screams!! With bald tires I can run a banshee and walk a stock 400. I am ready to see how some traction out back helps!!

Later,

Originally posted by WJW77
You know any specifics on your buddy's that has made it so good? [/B]

bored .80 over w/ 12:1 JE piston, TC racing cam, TC ported head, heavy duty valves, Flywheels been lightend, Hinson clutch basket, 38mm Lectron carb, K&N filter w/ outerwears wrap, Engine built by Rocky Ridge Racing.

Its a real handful

[400exRacerX]

My buddy has a 11:1 comp je piston and when he runs pump gas (93 octane) it pings. From what team pompton racing told me is that 10:1 is the highest comp you can go on 93 octane.

My 416 is a Wiseco 10:1 with an XR400 Web cam, and trust me, it can boogie. I couldnt make up my mind whether I wanted the Wiseco 10:1 or 11:1, but I do not want to have to bother with race fuel or pinging due to 90-ish octane pump-gas...

I have zero regrets having gone with the 10:1, and acutally, I believe the camshaft makes more of a difference on the overall power increase...choose your cam carefully, meaning, get as agressive as you can afford WITHOUT having to rebuild the internals of the engine. For example, my 416 with the cam I have ALWAYS beats my 2 friends' 430's, with 11:1 pistons & diff. cams than me.

Oh, and I didn't want to sacrafice ANY reliability -- another key reason in going with the 10:1 -- it adds a good dose of power, without putting all the stress of super-high compression on the engine's internals.

Whats the stock compression of the 400 from the factory???

[#77]

9:1