[3o0ex622]

i wanted to no if a 400ex carb will be ok on my 300ex but its not bored it got a cobra exhuast system and its got a stock carb jettted stage 2 with k&n air filter and i want to no if it would be good idea to swap the carbs but no jetting the 400ex carb????

 

[300ex power by monster]

just get a stock 40ex carb with 400ex jets in it u should be fine and Chang that k&n filter it lets to much dust and mud and sand particles into ur head
get a uni air filter unless u have a pre-filter

 

[TRX2fiveO]

400EX will work but you will need to stretch the air intake hose side to get it on. I would use a heat gun or hair dryer to get it hot and pliable. I am going to put one on my 250X later.

 

[3o0ex622]

thanks ....how much of a dif u think it will make

 

[TRX2fiveO]

well a stock 250x/300ex carb is 36mm a 400ex carb is 38mm you will have better flow. it will make a noticeable difference, I have heard it will.

thanks ....how much of a dif u think it will make

 

[Redracer]

You will probably have to rejet the carb.

 

[TRX2fiveO]

Without a doubt!!! I forgot that info thanks buddy

You will probably have to rejet the carb.

 

[Bickford]

what do u mean re-jet re-jet with what kinda jets

 

[mud99]

what do u mean re-jet re-jet with what kinda jets

EXriders.com, your Honda 400EX, 300EX, 250r, and 250EX resource...

 

[Bickford]

i know all about jeting but what im asking what sizes are u guys runing

 

[Redracer]

I have a 450, telling you my jet sizes would be pointless. Plus I ride at high altitudes so that changes jetting completely.

 

[Bickford]

true no i was wondering what there runing in the 400ex carb on a 300ex they say u have to rejet just trying to figer out what i would need they gave a forum but that just tells me about smaller and bigger jet i just wanted to know the numbers i need thanks tho

 

[mud99]

You can call these people and they can set you up.
Dynojet Jet Kits - Offering Motorcycle Jet Kits & ATV Jet Kits

 

[Bickford]

thanks
that should work

 

[TRX2fiveO]

Well If I'm correct the stock jet on a 300ex would be somewhere around 120 for altitudes below 3000 ft. a 400ex is around 138 to 140 below 3000ft. putting that carb on a lightly tuned 300 would be too much fuel.

 

[mud99]

The stock jets in my 400 are 38 and 148.