Okay i am looking at putting in a stock bore high comp piston in my 04 400ex. I cant decied wether to go with the 11.1:1 or the 12.1:1 or the 12.5:1 piston. Also what brand is better, wiseco or JE? If someone out there has a high comp piston in there 400ex what size and brand are you running, and have you had any probs with it? Thanks for your input ahead of time.

 

i am partial to the ross pistons. they are near identical to je, but lighter. you can also purchase a lighter piston pin, which i have, to go with this piston. i would get the 10.8:1 or 11:1 unless you plan on replacing the head studs along with the stock rod. you woudl also need to run race fuel wtih much mroe than 11:1.

 

You can't go wrong with the Ross, or the JE

 

Ross if you have the money, JE if you dont. Hey, Venom Racing uses JE piston's in their 700hp Vipers, so they cant be that bad. [img]i/expressions/face-icon-small-wink.gif[/img]

 

off the shelf ross and je pistons for the 400ex are both around $120.

 

Thanks for the info guys. I think im going to go with the JE stock bore 12:1 high comp piston. And i plan on running race fuel. Not a prob i get a discount, 114 octain only cost me $2.50 a gallon. How come no one really said anything about wiseco? I thought they were good pistons. Guess not. But that's what most of my buddies run. Have yall had bad experences with the wiseco?

 

Anyone .........

 

no bad experience with wiseco but i have read that the compression ratios are closer with the je and ross pistons.

 

ok, in everyones opinion what would be better, a 11:1 or a 12:1 high comp piston standard bore with the stock rod. Also cals400ex why would i have to replace the head studs and the stock rod. A couple of my buddies are running a 12:1 piston bored .20 over with the stock rod and the stock head studs and have not had any probs yet, they just have to run race fuel. Thanks.

 

i would replace the rod forsure with over 12:1. the stock rod had been known for failure. i have even seen it fail at 11:1. the head studs have tendency to pull out. i probably wouldn't replace those unless they start pulling out. you will know when that happens because you will start having head gasket leaks. i like the 11:1 for reliability. i don't know how much quicker it would actually be with the 12:1. it may help,it may not help much. just make sure you get the race fuel with over 11:1.