What yr. 400ex carb fit the 350x

[dreadhed]

I was wondering what year of the 400ex carb will fit the 350x. Will I need to change the intake?

[Jason Hall]

As far as I know all 400ex carbs are the same. You don't have to change the intake boot, but you should open it up to the same size as the 400 carb. The 350x intake port is also smaller than the 400 carbs inner bore, so to really get the carb swap to make total sense the intake port & intake should be enlarged. I had my 350x apart when I decided to put the ex carb on, so I opened everything up then. It sure woke my 350x up.

[NOS_350X]

The statement above sounds good to me. The only thing that you realy MUST change is the intake tube from the frame to the airbox must be removed.

[dreadhed]

I should have the head port enlaged? And when you say the intake should be enlarged do you mean the valve or the intake that goes into the motor? I know they are dumb questions but I want to make sure I under stand.

What kind of filter should I use runing a airbox like that?
Thanks for the help guys.

[Jason Hall]

What I did with mine was took the rubber carb boot off the head. I then warmed the rubber intake with a heat gun, pushed the 400 carb into the intake. Thats when I noticed the intake would restrict the carb down. So I used a small 80 grit sand paper disc in my die grinder & opened the intake boot up until it was the same size as the 400 carb inner bore. I then mated the rubber intake boot up to the cylinder head & scratched the new intake bore onto the head & used my die grinder to open the intake port of the head to the same size as the boot.

[dreadhed]

Right on that helps alot. I have never grinded on the intake port of the head. Should I pay someone to do it or is it some thing pretty easy? Did you have to take the head off to do this?

[Jason Hall]

If you have never used a die grinder before I would recommend you take it to someone who will do it for you. You really need to pull the head off to do it. Do you really want to put the carb on bad enough to pull the head? If you send me the parts I would do it for you. I still have the carb that was on my 350x to size it right.

[dogger]

also if your shopping for a good carb to swap to the fcr 39mm is alsome. comes stock on the yfz450 and is good for great power especially with a cam and exhaust.