[99trx400ex]

im looking to get a 426 big bore kit for my 400ex but have a few questions........ is there goin to be a significant power increase, like is this really something worth doing?? will it be ok to still run premium pump gas or will i have to mix it with fuel additives?? im also not sure about what compression to choose either and if i do go to a 426 are there any other upgrades i should make? and ive heard stay away from je pistons and wiseco is the way to go but that just may be opinions not really based on quality.

 

[TRX2fiveO]

Anytime you increase the C/R of an engine the performance will greatly improve You will see a noticable difference with the 426 kit. as far as fuel is concerned I am running 12:1 and run only 108 race fuel. when you increase the size of the bore and up the C/R they do recomend you run a minimum of 108 octane. I haven't heard anything bad about JE piston Kits personally but piston failure is mostly the installer's fault IMO their pistons are built to the same specs as Wiseco and from the same material. JE builds alot of pistons for the auto race world just like Wiseco. It's all going to depend on how YOU build it. Take your time have your machine work done by someone who knows what to do, what questions to ask and what to look for. just make sure youcarry the piston, rings and Jug to them and have everything bore matched. .060 over on a piston may actually be .062 so make sure you had them everything so you won't have any issues...Good Luck

 

[Billy250X]

Agree^^^^^^^^!!!