[400ex piston] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

Pages:1

400ex piston
(Click here to view the original thread with full colors/images)

Posted by: Penler

sry bout the noob questions guys, but when it says on .40 over, wat does it mean, is this high performance and do i need to change sleeve or just install the piston....

Posted by: 440exking

Get the sleeve bore over to .40 over then put it back together.

Posted by: Penler

how much would this cost, and how much more horsepower would i get? is it worth it? what about reliability

Posted by: underpowered

.40 over is = to 1mm, so the piston you have would make your quad a 406. you sill see som eperformance gain, ecspecially if you have a higher compression piston like 11:1. as far as reliability, it wont really change with such a small increase in displacement.

Posted by: Penler

ok so i want to get a .40 over 11:1 high comp piston? who should i get it from wiseco or je

Posted by: underpowered

i have always liked JE, but i am running wiseco now with no problems. it is up to you but i say most people will tell you to run JE

Posted by: Penler

alright and with this i can run normal pump gas? do i need premium? and how much horsepower will i gain is it worth the money...

Posted by: underpowered

you would need to run premium.
Horspower really varies depending on other mods, who built the motor, ho many hours on the motor, tolerances, ect.... to put it simply, it will be worth it and you will get a noticable gain.