what would be the speed of a stock 400ex before and after you put a 440 kit and exhaust

 

Top Speed is really not determined by engine displacement....Gearing is where topspeed comes into play...Your topspeed will probably be a little higher with the 440 kit because I think you are able to rev the engine higher...so you will get a little more RPMs out of all the gears and 5th gear than you were previsously...but if you want a much higher top speed you will need to gear it higher via sprocket changes...look for a noticiable change in acceleration though.

 

which state do you live in
PA,AR

 

no clue!

 

sorry

 

Actually not entirely true. Each engine has a power curve and upping the size will change the power curve. Think about riding a 4-wheeler up a hill on a paved road. Eventually the 4-wheeler will reach a point where the speed has topped out even though the throttle is at 3/4 or full. The engine is doing all it can (reached it's peak power). Adding a bigger engine would (in most cases) get you going a little faster before you hit the peak power.

Now forget the hill and consider flat ground, wind resistance, weight of the 4-wheeler, friction on the road all cause the ATV to reach a max speed and that's it. Add more HP and you'll get going faster. If you want the engine to rev higher just keep the throttle in the WOT position and pull in the clutch...she'll rev then.

Power curves can be different depending on how the engine is set up. Things like a high lift cam or a high duration cam can affect this.