this question has most likely been asked a million times, which has more power and more top speed. does the 6th gear on the 350x make it a little faster than the 400 or is it about equeal

 

The 350X engine stock produced 21HP @ 6000RPM. That was a figure that was commonly found back then and still now on a stock engine.

The 400EX engine stock is a different story. It's amazing at how many different numbers come from so many different sources. Usually the dynos will show 24HP @ 6800RPM. More power than the 350X[slightly] and comes on a little later in the powerband.

As far as speed goes, I wouldn't know. Being that your engine is still in a three wheeler frame, you have a much lighter machine. The ATC350X weighed 320lbs. dry while most numbers on the 400EX come in around 375lbs.
That, along with you having an extra gear to play with, I don't think you would have a problem staying up with a 400EX or maybe even faster than a 400EX. Just stay off the trails[img]i/expressions/face-icon-small-happy.gif[/img]

Both engines can be made much stronger, but the 350X engine can make more power for less money than the 400. The 350X/250R quad that tore through the amateur GNC races about 6 years ago was dynoed at nearly 70HP!! Not only that, but he ran the entire season with only installing rings one time. That is what you call a reliable "built" quad.

 

A stock 350x produced 27HP @ 7000 RPM and 21.70 ft.lb @ 6000 RPM...

 

everything i seen on the 400ex test's dyno's etc says 28hp and isn't the 350x like 24hp ill check that but anyways the 350x is loved because it makes it's power feel like twice what it has just like the 200x that fly's with 12hp

 

WELl ive seen my friends race on there machines and it was in the sand.....The 400 ex was way ahead especially on the start and still at about 300 feet the 350x started catching up a little but was still far behind.....THey look like they got too high of gearing!