400ex Carb On a 300ex

[300XFST4602]

Ok i am thinking about doing this , is it a good idea , and woudl i just have to use the stock 400ex jets?

[ghak99]

If your motor can handle more air and fuel then yes it will give you more throttle responce and top speed. I would only do it if your head is ported and you have a good exhaust system. You will need to rejet it properly. One of my friends recently put one on his 250x and once he got the jetting figured out it ran all right. As soon as I get a pipe I am putting mine on as well. You will need different carb to air box boot and the 400ex throttle cable. Most people use the 350x air boot.
Hope this helps.

[300expower]

i've done it without any problems for the air boot, only takes me 1hour to get this thing in place:mad: but it fits well!
need the 400ex cable and i use 400ex kn jet kit, with kn filter, i run 142 in quebec. no problem! great response, go for it it's the biggest mod i made for the price, 150 canadian!

[Diedrich]

just buy ya a good carb, cable, and 350x airboot..the airboots are on ebay all the time..jet it right and it should do good..with the mods you got it should help out

I have a 400ex carb for sale...:D

[Dunlap]

How much for the carb Rico?

[300XFST4602]

So I will have to get a new air boot if I get a 400ex carb????

[Out_Sider]

no, u dont have to get a new boot, but it is easier to get on, and i think it allows more air

[465Stroker]

Stock airboot will work fine if you heat it up a little. The 350X airboot will let the carb mount and breath a little easier. You can use the 300EX cable without any problems too. Jetting we had for a 330cc motor and 2" x 4" hole in the rear of the airbox lid was 160 Main jet with a stock 400ex needle, pilot, and 3 turns out on the fuel screw. You will not notice a difference unless you at least have a slightly higher compression piston, bigger cam, and a good exhaust. If it is a stock motor you would most likely not see any gains.

Originally posted by Mickey Dunlap
How much for the carb Rico?

Well someone else bought it from me last night. I was askin $75, I think that sounds reasonable..:confused: or am I a crook..:(

[465Stroker]

Mickey - How many do ya need? I have 2 plus about 2 other that I have robbed parts off of in the past. PM me if ya need any.

[Dunlap]

Thats O.K.,I like the 400ex carbs and I try to buy all I can for projects I build.

[ZRacer]

Originally posted by Rico
Well someone else bought it from me last night. I was askin $75, I think that sounds reasonable..:confused: or am I a crook..:(

Rico, You crook!

[465Stroker]

Yeh - I sold it to Rico for $15.00!! :o

[ZRacer]

He bought mine for $10.00, and tried to get me down to $5.00:eek:

[Pappy]

there ya go mickey...between 465stroker and zracer you have some carbs for less then $15:devil: you two wanna play poker sometime:confused: :blah:

[Dunlap]

I pay $50 for good used ones. I don't mine people making money its good for the economy.

As for Harlen and Ricks responses the pic says it all......:mad: