Honda ATV Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
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????
 

·
Registered
Joined
·
2,392 Posts
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
 

·
Super Moderator
Joined
·
18,227 Posts
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.
 

·
Super Moderator
Joined
·
18,227 Posts
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
 

·
Premium Member
Joined
·
6,616 Posts
You will probably have to rejet the carb.
 

·
Super Moderator
Joined
·
18,227 Posts

·
Registered
Joined
·
202 Posts
i know all about jeting but what im asking what sizes are u guys runing
 

·
Premium Member
Joined
·
6,616 Posts
I have a 450, telling you my jet sizes would be pointless. Plus I ride at high altitudes so that changes jetting completely.
 

·
Registered
Joined
·
202 Posts
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
 

·
Super Moderator
Joined
·
18,227 Posts
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.
 
1 - 16 of 16 Posts
Top