I am thinking about hopping up my 2000 400ex but not sure how big to go.I do not want to have to rely on race fuel all the time.I have allready put on powercore 4,k&n,stage 2 jet kit.I use this atv for all around use-dunes,trails and some motocross racing.Could someone point me in the right direction and give me their thoughts on say 416 vs 440 and what else is needed for complete package-cam,carb change etc.also what did you spend to do these mods?I also have done complete suspension,clutch.

 

I would first get a good cam, either a web cam or a GT thunder cam. Next, I would bore to a 416, and get a 11:1 piston, you can still run 92 octane with this compression. I wouldn't get a carb until you got a port and polish. If I were you I would contact GT Thunder and they will help explain your options. (330) 674-7122.

Prices!

Cam 150
Piston- 100
Bore-40
port-50 to 250

 

ok, i see there are two similar post dealing with this topic now...so ill stick to this one...first of all, ive seen a true 400, a 416, a 426, and a 435(440), all run and race, each other aswell as other quads....in my opinion, its all with preference......i picked the 416 because to me it was the most enjoyable...however, the 440 is super nice too, but i would go more with it for woods riding...it has allot of torquey power...HOWEVER, if you line these quads up, the true 400 usually gets pretty much pulled off the line and left...the 416 and 426 are pretty much dead even, both high reving bikes with nice torque also but has allot more mid and top than the 440..in a nice drag, the 440 will jump off on top of the 416 and 426, but ive seen with my own eyes the other two come back and beat the 440....not going to say the 440 isnt reliable, but i know it cant be as reliable as the 416 and 426...hope this helped any!

 

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