compression

[edge91]

Im going to build a 426 this winter, and add a fcr carb. The question is what compression piston should i get, i race mx. i thought i read JE 12:1. the dealer here says they don't offer it they have a 11:1 or 13:1. Would it be that big of a gain to go to a 13:1, should i find a 12:1 (any suggestions), or would there not be that noticable of a difference, between them and the 11:1 be enough, any advice would be appreciated

[ghak99]

If you have the cash to afford race fuel all the time, and can spend the few extra bucks to make the 13:1 reliable I would say why not go all out it it is a race quad!

[BSTURDIVANT]

If you just race then get the 13 to 1- it makes much more power!

[TC426EX]

If you go 13:1 you will definitely want to look into adding a heavy duty rod like the sparks or carillo. 12:1 is pushing it on the 400ex motor, and I wouldnt feel safe running a 13:1 without a heavy duty rod for real. This will add alot of reliability to the motor which it needs. Keep in mind that compression is not an entirely good thing. It is great because the higher the compression, the more and stronger power you will be putting out. On the flipside, if you go way up on the compression and dont add a heavy duty rod to it youre looking at doing some serious damage if it throws the rod. Also, when something blows on the motor, it will blow way harder with more compression... By all means, go with the 13:1, I know a couple racers with 13:1 440 kits, but they wouldnt be caught dead without a heavy duty rod in them thats for sure....