400ex motor/carb setup

[jsracing2]

Ive got a 417 kit, stage 2 hotcams, minor port/polish work, LRD slip on, Open airbox. What carb/ jetting would anyone recommend? I know there are similar setup out there.

[CJM]

450R carb is a common mod, you will either have to make an adapter to fit it on the EX boot for the airbox or shave the airbox boot down with a dremel.

[slightlybent47]

NO! NO! NO!
I’m tired of herring about all the adapters and especially using a dremel tool to shave something out.

There is a much easier way.

First off the 450 carb will fit the head boot just fine without any modifications.
After you remove the stock carb all you have to do is spray a little wd-40 on the inside of the head boot and slip it right on. You do have to change the clamp to a bigger clamp because the 450 carb is a little bigger then the stock one but it will still go on just fine.

Now when you put the air box back on you will find that it just about ¾” of an inch short from reaching the carb. All that’s needed here is a short extension. To accomplish this and not spend much money or have to order something special, all you need is a 2”x2” rubber hose to extend the boot so it will reach the carb.
It will look like this when your done.
http://i55.tinypic.com/4k8ifa.jpg

[slightlybent47]

If you modify or change the head boot in any way and you want to put the stock carb back on. Then you will have to buy another boot to replace the one you modified.
But by doing it my way you can go back to the stock carb very easy and you don’t have to replace anything.