400ex carb on 300ex

[kmath91478]

I want to put a 400ex carb on my 300, but I need the 400 rubber piece to attach it. if anyone has one laying around, i would like to purchase it. thank you

[NV300ex]

hey do a search theres tons of info on this mod.. i'd been doing same thing as well.. first u dont need another intake rubber.. take ur own n heat it with a heat gun and slip it onto the 400ex carb.. it'll be snugged but it works.

[SET THE STAGE]

you shouldn't even need to heat it up. it just takes a little force to get it in there haha

[NV300ex]

why couldn't u lube the inner side of the tube with some white grease.. to make it that much easier to slip it on the carb?

[01exrider 281]

Is this of any benifit to a stock 300. I have a pipe, jet kit, and filter. But, I just want to know if it is worth it.

[honda300EXtreme]

when i first added the 400ex carb, my motor was relativley stock, i had a hmf muffler and wb header, and 11:1 piston, and a well vented air box,

i can honestly say it was the best improvment for the money at the time, i would recomend it, you can find them all day long on here for around 50 bucks

[kmath91478]

thanks alot everyone. i'm gonna try the heating it up trick. also, i'm looking for front tires, relatively cheap. i don't want to buy brand new yet until this winter. thanks again

[01exrider 281]

so the 400 carb bolts right up.

[SET THE STAGE]

yes. it's just sort of tricky to get it in the boot

you'll have to rejet, too. if you have a pipe, filter, stuff like that, though, it shouldn't be far off from the stock 400's jetting.

[forgiven]

Do you lose a lot of low end doing that? I have the 400 carb and I put a 330 kit on for my wife and it is nice but what would be the characteristics of the change? More mid and top and a little less bottom?

I also have a K&N clampon with open airbox lid, and a full Yoshi pipe. Runs really good for a 300 but always looking for more.

My buddy who is also my mechanic friend doesn't want to do it because he doesn't think it would be good for it. Help me convince him.

[NV300ex]

My buddy who is also my mechanic friend doesn't want to do it because he doesn't think it would be good for it. Help me convince him.

this is easy.. its ur bike not his.. so no need to convince him of it.
also if you must, think of it this way.. correct me if im wrong anybody, but when u goto a different exhaust your freein up the motor to exhaust better, same way with bigger carbs. more juice the better it'll be, i dont think it'll be overly done to the point it just sucks everything away from your motor, not with a 400ex carb. :blah: the way i see it im surprised he dont carry on about smaller tires either.
usually somebody thats against better mods for your stuff is against everything else, thinking a k&n filter is bad idea, bigger pipe or headers is wrong.. geesh mod the bike out and say this is the way to do things lolol
i had an old timer tell me what the heck are you doing, ur messin it all up. heck im makin it a better bike thats what im doing.

[01exrider 281]

I agree with the fact that it is his bike. If you were gonna do something stupid then I could see him your buddy saying that. But you are adding my fuel and air for more power and performance. So there is no convincing.

[forgiven]

I understand it is mine. He is a sharp guy trust me. That is why I am asking. Usually when you move up in carb size you lose low end and gain mid to top. I was wondering what everyones experience was with this so I can make a better decision myself.

Just to put it into a frame of reference, FST asked the same question when I mentioned putting the 400ex carb on so I figured it was legitimate.

Would really like to hear from those who have done it and how the bike responded to it. I am looking for something more than it rocked or it was great. Specifically where did the power come on and where did you lose power.

Thanks

[01exrider 281]

Yea I am now curious to how much it actually does. Maybe the next goodie for the beast.

[SET THE STAGE]

unfortunately, my bike came it on there so i don't know what it was like before. however, i've compared mine to my uncle's 300 and my cousin's 250x and my low-end is RIDICULOUS compared to theirs. granted, mine has more stuff and smaller tires, it still has so much more power in the low-end than theirs. i really don't think it'll hurt it that much if any.

not to bash your friend, but i know how an engine works and considering that you're freeing up your exhaust with a bigger pipe and have a high-flowing filter, a (slightly) bigger carburetor would be nothing but beneficial especially on a 4-stroke. now if you did a 6mm jump on a 2-stroke, i could see that hurting it's performance.

it's worth a shot. if it doesn't help much now, it will on the long run if you were to ever get a cam or big bore kit.

[JohnT_98300EX]

My atv experience is new, I haven't been playing with them long. However over most of my life I have messed with high performance street and street/strip cars, trucks, and motorcycles. (on a real world budget) There are basic internal combustion principles. First and foremost balance is needed. For instance,install a header gives you sound, unless you modify the intake to make use of the new exhaust.
As for installing a bigger carb that principle definitely applies plus big air and fuel flow is most helpful at high rpm. To much carb that works great at high rpm can actually crush your low to mid range throttle response.
For my application I can't see needing it. Top end horsepower is not my goal.I want brutal, arm stretching torque with instant throttle response so I'm sticking with the 300 carb. Is it stock? Not any more. Does it run better than before? Yes.