[400exrider15]

I'd like to know what to look for in my 400ex when i go to open it up in January to re-do the head. I wanna know what a bad piston looks like in a 400ex. Im gonna think about putting a High compression piston in it. but it would have to be JE though. I havnt had much luck with Wiseco...

 

[TRX2fiveO]

Wiseco is all I have put in my quad and I haven't had any issues. JE is good CP, and Namura are good too. Pistons fail due to improper assembly, running too lean, lack of lubrication ect. I reccomend the 426 kit it's a good all around install. 440 kits are good if you race alot but trail riding I would go with the lesser.

 

[400exrider15]

I mean, if I had the money, I would spend it on the Big bore, but i can only afford about $180 this winter to get it all done.

 

[TRX2fiveO]

A standard bore Wiseco Kit is around 250 georgies. but it comes with everything for a top end rebuild. If you do it correctly you won't have any issues with the wiseco brand.

 

[Redracer]

I agree with Moose!