400ex Kits

[mar400ex]

What big bore kit should I get for me 400ex?

[ridesa02400EX]

get ross 440 kit from C and D

[mar400ex]

is that better than doing the 500 Kit?

[ridesa02400EX]

yes 500 kit will be super unreliable

[mar400ex]

what makes it so unreliable?

[ridesa02400EX]

i really dont know that much about it but i know that 440 is the biggest reliable size to go. a 500 kit would make the cylinder walls really really thin. unless you have to go with an aftermarket cylinder for a 500 i dont even know if a 400ex cylinder can be bored to a 500. a 500 kit would also cost tons of money im sure. considering that with a 500 probably almost non of the stock engine parts would hold up to it. i would just go with wither a 416 or a 440 high compression and a cam.

[mar400ex]

with everything that is done to your bike, since you have the 440 kit and all. does your bike beat rail pretty good in the sand? can you beat most people in drags?

[ridesa02400EX]

i have never taken my bike in the sand it goes pretty fast but not fast enough. just putting in a big bore kit wont really open up your bike that much. put a cam and high compression piston and you will see some significant gains. im am workin on doing this right now to my quad. then eventually go with porting and a carb. but make sure you have an aftermarket exhaust and airfilter before you do this stuff you dont want that stock exhaust choking your bike. oh and also make sure your bike is jetted right.

[2002400ex]

to get a 400 to a 500 it is stroked too

[shano125]

I have the Four Stroke Tech 500cc kit and it is bored and the crank is also stroked. I ran it for the first time tonight and won the pro class short track race against raptors, banshees, and yamaha 450's. I hope to have the 39mm fcr carb on it next time. But, if you want the ultimate 400ex go with the 500.

[keepitpinned]

i wouldnt go with a 500. the heat with the 500 is going to be insane