i have a 1998 300ex fourtrax it is piped jetted and has an k&n air filter. I am wanting to race next year (flat track) i live in a rather small community so we dont have classes for the quads [img]i/expressions/face-icon-small-sad.gif[/img]. so i was wondering what i could do to atleast keep up w/ a 400 prefferably a 450.

THanks, Paul Frailey

 

ANYONE?

 

I owned a 300ex for many years. Good little ATV. If I remember correctly it is not a full 300cc...More like 280 or something like that. Answer is bigger carb, bore cylinder and bigger cam. Back in the late 90's and early 2000's Dirt Wheels and 4-Wheel ATV did some articles with these kinds of mods. I would Google the subject or go the web sight for these mags and look in the archives.

My 300ex had a White Brothers pipe, K&N filter and was rejeted and still could not keep up (on the top end) with my brother in laws little 230 Suzuki Quad Sport that had a pipe, K&N, bigger carb and cam. You're looking at some pretty serious mods to keep up with a 400 or 450.

 

well i was thinking about purchasing a 330 big bore kit, stage 2 cam, oversized valves, and port and polish it. Do you think that would do the trick?

 

Yes, higher compression piston and up the rev limiter (there are aftermarket kits for the limiter). The motor can take more rpm than what the stock limiter allows. You will more than likely have a problem with the clutch. It's not made to take a lot of extra power. A full aftermarket clutch kit won't be to far away if you ride hard with more ponies.

After all that the front end might be a little to willing to come off the ground. Extend the swing back swing arm. Crap this gets expensive. Perhaps someone else on the forum will have more specific info.

Good luck![img]i/expressions/face-icon-small-wink.gif[/img]

 

I love my 300ex but I know that it'll never keep up with a 400/450 with an average rider.
That's when I break out the 250R. [img]i/expressions/face-icon-small-happy.gif[/img]