White Bros. Revbox for 400EX

[EXerHonda400]

I want to buy a revbox from white bros., but i was wondering besides the obvious 9200 to 10200 RPM increase what kind of horsepower increase am i looking at??

[trailburner]

none, a stock 400ex motor stops making power at about 8000 rpm, in the mid 8000 the stock rev-limiter should start kicking in,making the motor rev any higher than that is kinda useless:ermm: ,now if you have major motor mods done thats different, & if your battery does not have a full charge it will not start[major pain in the *****!!!] the only resone i have one on mine is it was on it when i bought it........

[Glamis400ex]

ditto....couldnt have said it better trailburner

Glamis

[F-16Guy]

Yeah, don't bother waisting your money. I saw no power gain, and it was a pain to start unless the battery was hot. There have been lots of posts about this, but the one that explained it best basically said this: The WB box is essentially an XR250 box. It has a anti-kickback circuit that keeps it from producing spark unless the engine is turned over at or above a certain speed. This keeps the kickstarter from kicking you in the back of the leg on an XR250. If your battery isn't smokin' hot, it won't turn over a modified 400ex fast enough. If your bike's stock, you'll never get past the stock 9200 rpm limiter, anyway. Use that money to buy bars or an air filter.... something you can actually use. If you really have to have one, mine's for sale..... anyone?

[Glamis400ex]

yeah, mine came with one also when I bought the quad used. I keep it for back up in case the stocker craps out if I'm at the dunes.

Glamis