stock bore JE

[Nate408]

Any of you guys run the stock bore JE piston? I believe is 10.5:1. I was originally going with a 426 11.1:1 JE with a stage 2 hotcam until i got the cylinder off decided against boring that thin. Ill probably get the stock bore or 406. also be running cometic gaskets, hmf slip on, k&n, etc.
thanks,
Nate408

[Nate408]

anyone?

[2001400exrider]

y dont u go 406 llike u said with 11:1 comp?

[H_W]

Originally posted by 2001400exrider
y dont u go 406 llike u said with 11:1 comp?

There would not be much difference between the stock bore and the 406. I have the stock bore JE piston and I love it. With my current setup, I can consistantly outrun stock raptors and sometimes piped ones.

[Norris3710]

i think its a great setup je 10;1 and a cam

[Norris3710]

i think its a great setup je 10;1 and a cam

[2001400exrider]

i dont understand the differnt compressions... 10:1 and 11:1 whats beter and why? how can a pistion have more compression then another!

[Norris3710]

I know more the compression the better! but with a higher compression piston you must run race fuel!

[2001400exrider]

Originally posted by Norris3710
I know more the compression the better! but with a higher compression piston you must run race fuel!

such as? would that include 11:1 for running race fuel? whats the highest compression u can go without running race fuel? i can get 94 octane thats the highest i can get around here.

[Norris3710]

my buddy runs his on 93 with no prob and he has 11;1 weisco thats the highest i would go personally

[boricua]

for simplicity, say a 10:1 compression ratio takes 10cm and compresses it to 1cm, that gives you "x" amount of pressure in that 1cm space....now lets increase the 10cm to 11cm...and then compress it to 1cm, now that you've compressed 11cm of "whatever" into a smaller 1cm, the pressure that has built up inside is high, higher than with 10cm or anything less than 11cm for that matter. picture a balloon inflated only half way, then pop it....now filled another balloon, same size, half way and squeeze it enough to build pressure inside just before it pops, then pop it....the one squeezed will pop louder and with more force.....

remember, this is just for simplicity....a high compression piston doesnt draw more air and fuel, it only compresses the same amount of air and fuel more, creating a more powerful combusiton.

draw back is when air and fuel is compressed it gets hot, the more you compress it the hotter it gets, eventually pre-igniting, before the spark plug goes off. the most common way to avoid that is to use higher octane fuel. this will allow you to run much higher comp. ratios. much like anything else, there is a limit....

[2001400exrider]

so wats safest to go 10:1? and wat octane is required for that? just reg 87??

[H_W]

Originally posted by 2001400exrider
so wats safest to go 10:1? and wat octane is required for that? just reg 87??

The 400ex owner's manual says to run 92 octane, and that's with the stock compression. You can go with 11:1 and still use pump gas.

[400exrider707]

Originally posted by H_W
The 400ex owner's manual says to run 92 octane, and that's with the stock compression. You can go with 11:1 and still use pump gas.

Putting anything over 87 in a stock EX is a waste of money and actually just makes it harder to start. I have a wiseco 11:1 in mine and run 93, although the wiseco's compression ratios are off cause they were meant for the XR. You could run 93 on a 12:1 wiseco.

[Plante400]

Originally posted by H_W
There would not be much difference between the stock bore and the 406. I have the stock bore JE piston and I love it. With my current setup, I can consistantly outrun stock raptors and sometimes piped ones.

thats a load of bs or the raptor riders suck

my 440 wont beat a raptor in a road drag. not after we get off the line anyway

[Norris3710]

my 400ex will outrun a raptor no problem and i have stk bore 10;1

[2muchquad]

93 octane is fine for a ex with 12.1 or under with a stock cam.with compression ratios there is usually more than meets the eye.one must take into account valve overlap,cam duration etc.a 11.1 wiseco may actually only be 10.2 or so.theres no written rule on advertised compression ratios.sorry for rumbling on:rolleyes:

[shamisc]

Originally posted by Plante400
thats a load of bs or the raptor riders suck

my 440 wont beat a raptor in a road drag. not after we get off the line anyway

Sounds like to me you suck as a rider. Not trying to flame, but my 400 would outrun a Raptor when I had a cam and a pipe. My 440 outruns 686 and 727 Raptors. You must be having issues with your 440! What compression ratio are you running at what brand?