400EX horsepower

[300EX KING]

How many horses does a stock 400ex put out?

28.3 i think i read that somewhere.

[300EX KING]

If you think about it, if a 400ex has about 28 horsepower, and a 300ex has about 17 and you get a really quality pipe that gives you 4-7 horsepower that brings the 300 to 24 horsepower, then add a filter and open the air box lid ,thats anothere 2 horses. so now the 300 is up to 26. Thats not far at all to the 400. And all you did was a pipe and a air filter. So the 400 isnt that much more powerful than the 300....... Oh and if you think that i made up the pipe that gives 4-7 horsepower i didnt, the White Brothers e-series pro meg gives 4-7.

sorry but a pipe does not bring 4-7 hp LOL what a joke

[FullBore52]

Nope, not on a fourstroke....maybe port it along with the pipe...the ports suck for a 250x...much less a 300ex..(282ex actually)

[300EX KING]

The White Brothers E-series Pro Meg gives 4-7 horsepower, look it up in Dennis Kirk

[Wheelie]

Don't believe everything you read. A full system and filter on a 300ex MIGHT bring it up to 19 or 20hp peak. It might gain 3-5hp in the mid range, which is where most four stroke pipe shine.

I've owned a 300ex with a full system and K&N filter. It wasn't even close to the power output of my 400 when it was stock.

BTW-A stock 400ex puts out between 25-28hp.

[airheadedduner]

A stock 400 puts out around 28rwhp......which is about the same as an 88' 250r.

[rhino99]

Even if a pipe, etc did add that much hp, you still have crappy suspension, a small bike, etc, not to mention that you could just add that stuff to a 400 and it will be twice the hp again!

[Nausty]

Is the 28hp with or without the air box lid? What about throttle adjustment? I know when I adjusted the throttle it made a huge differance in acceleration and power. I got a grin the first time I nailed the throttle listening to the motor and no air box lid. I dunno but it kinda reminds me of the sound my dads pos f150 makes when it goes into passing gear, yet nothing happens.

[Scott]

I have a 300ex with the mods you describe, and it's no where near a 400ex. And no a pipe will not add 4-7hp to a 300ex. Adding 7hp to an 18hp engine is almost a 40% increase. There's no way changing a metal pipe is going to do that.


2000 300EX
K&N with outerwear
DG head pipe feeding a 4" SuperTrapp w/ 12 discs
125 Main Jet
No airbox mods. Yet...

[TheChknhwk]

The stock HP of the 400 ex is closer to 26hp peak. I installed a K&N filter, no lid w/a prefilter & the dyno jet kit w/a 160 main jet. I am running stock exhaust at about 1000' above sea level. I noticed a near phenominal torque/performance improvement in 2nd & 3rd gear and a general over all throttle response improvement. It's K&N's ATV power up kit & I say it was well worth the 140 bones. My dad is already getting one as soon as he's done w/his break in period on his new 02'. Follow the link below for some before & after dyno charts of the 400ex & some other popular quads out there. The big increase on this kit is that it picks up 5lb/ft of torque at 4500rpm. I tried to get dyno jet to send me the dyno charts for the 400ex w/various pipes on it, but they refused due to a conflict of interests they say - the *******Z!

http://dynojet.com/newgraphs.shtml

Happy Riding ~ Hawk