it has a aftermarket aluminum airbox,he is jetted to run with that box.he is using a k&n with a prefilter also..

 

Mine is stock and i hit 69 mph no mods at all with my garmin gps

 

adjusting the throttle cable can give you 5mph's if it is all the way in

 

Yeah dude, i donno about 5, maybe like 3 or so....5mph is alot for jist adjusting the throttle cable

 

http://www.kg4vpv.com/~ncliborne/400ex.htm[L=400ex gearing calculator]

 

I have k and n and white bros e slip on pipe on 01 400 ex with stock sprockets jets and tires and get about 65 with wheel lift in 1 2 and 3 as well

 

I've never hit top end, 57 across choppy sand at night was as fast as I've had mine before we ran out of room. Mine is all stock '05.

 

my 2004 400ex tops out at 70mph, its got a edlebrock carb, k&n filter and HMF exhaust, and open air box, no idea if it has engine upgrades bought it used

 

Supposedly..... Just by swapping out sprockets you can get a factory 400ex into the high 70s low 80s but it takes a while to get there. Need a real long road. I never tried it so I dont know for sure.

 

your not gonna get a 400ex to go 80, my 400ex will do a max of 68-70mph if i have it topped out and i have a full exhaust system uni air filter with k&n power lid and 155 main jet sitting on 20" tires my brothers 450r will just do 80 and it has hotcams and a high compression piston