300ex vs 400ex

[300ex__tyler]

i was wondering if theres anything i can do to my 300ex to at least keep up with my step brothers 400ex. ikno i can get a big bore kit but would it keep up with it?

[01boneless]

with a big bore will help but its kinda like a 450r vs 400ex thing lol

[Tyler01]

Big Bore Kit
-Exhaust
-400ex carb
-Gearing

[wilkin250r]

The problem you will soon find is if you increase the motor, you start finding the limits of the suspension real quick, because the suspension on the 400EX is much better. If you don't believe me, just measure the front shock lengths on them.

A professional 330 kit complete with cam, head porting, and oversized valves should easily keep up with a 400EX. In fact, you'll probably even be able to beat the 400 in a drag race. But that stuff isn't cheap. You can get a cheap 330 kit for like $300, and it will indeed be a decent increase, but I don't think that alone will do it. You'll have to combine it with a cam ($200) and depending upon the cam, might require hardened rocker arms ($100) and head porting with oversized valves ($450), and that's just inside the motor itself. You'll probably also need an aftermarket hi-rev CDI ($100) and probably a bigger carb. But the carb can be cheap because you can use a 400EX carb, and they can be found on ebay for like $25

The head porting is a real key, because the stock 300EX head and valves are really restrictive, they're almost too small for the stock bore, let alone a 330 kit that's trying to rev even higher because of an aftermarket camshaft.

And like I said, now that you have a serious motor in there, you're going to find the suspension severely lacking. That's hundreds to upgrade to even a cheap set, thousands to upgrade to a really nice set.

[Tyler01]

Me personally i would put 400ex shocks and a-arms on it with a raptor 660 shock on back cuz you will be able to hit jumps and suck much harder and faster than a stock suspention.

But if your working on a budget go with this and you should be fast
-Exhaust
-Air filter/400ex carb

If you got alot of money then go with the=
-330ex kit
-Cam
-Valves
-Port and Polish

[Speed37]

well, what do u want to beat him at? A drag or a trial race? Cause if you want to beat him in a drag, just buy a bigger quad. To much money in too small of a quad. Plus after you put all the stuff into that engine, your gonna be running gas thats like 6 dollars+ per gallon. Just upgrade to a bigger quad.

[400exrip]

If you want to build a bad National 300ex go with Curtis Sparks National kit it has the sparks pipe,35mm FCR carb,ported head, oversized intake and exhaust valves, multi angle valve job,mx cam, heavy duty valve spring kit,hardfaced rocker arms, Sparks 14:1 piston,and Sparks CDI.

And then you would have to run vp112 gas that is $80.00 for 5 gallons.

But a bigbore kit and a port job should put you beside a 400ex with a pipe.

[HondaPohl]

All the money you will dump into the 300 you might as well go buy a used 400 or 450!

[400exrip]

Oh yeah I am learning that now!

Done went and spent a LOT of money on a 400ex for the TT National Races

Could have done built a 450r and ran it for 3 more years, now have a 400ex that i ain't gonna run but 1 year. then switch to the 450's