400ex carb on 350x...

[smokinp]

hey.ive been looking around on the site and cant seem to find the right answer.is the 400ex carb a direct bolt on to the 350x and is it really worth the bother.the reason I ask is because I am in the process of building a 350x and need a carb...thank you for your opinion.

[ATCnut]

400ex carb has a accelerator pump. I have heard that they really help starting the cold blooded 350X. Kasey is going to put one on his 350X, I have been waiting for a report.

[HRC1]

I got one going on too, 12:1 piston, megacycle cam, ported head, i'll post about it when i fig out how to mount the thing, i dont think it will fit the stock boot, it's 4 mm bigger and i dont think it will squeeze in there. should be dont in a couple of weeks

[RacerRichie]

I'd also like to hear if it works I've been looking around thinking too///

[BIGCRIP28]

i think NOS_350X put one on his. maybe contact him.

[NOS_350X]

Yup i got one on my X, both the intakeboot and boot to the airbox will strech over it, but you do need to get larger hose clamps. I'm still working on getting the jetting, i'm having major problems with that. During fast accleration it floods out. And it wont rev up completly, i'm workin on it tho. When i do there will be a full report on it.

[smokinp]

thanks for the input guys,keep us updated...

[83185s]

sounds like you need to just go down on the jetting??any cool mods i can do for a 200x ..like a biiger carb?? what would work without much trouble besides a xr200??i plan on one day geting an xr 200 cam and carb but is there anything else that would drastically change the power of a 200x?

[MTS]

Yup i got one on my X, both the intakeboot and boot to the airbox will strech over it, but you do need to get larger hose clamps. I'm still working on getting the jetting, i'm having major problems with that. During fast accleration it floods out. And it wont rev up completly, i'm workin on it tho. When i do there will be a full report on it.
fast exceleration flood- probly becuse of the accelerator pump is givin er too much....set up for a 400 right, i would find out if you can adjust it.

[NOS_350X]

I belive the acclerator pump is flooding it out, i'm goiing to try to disconnect it. Like i said ill keep you guys up dated, its been a week since ive touched it because it started to piss me off so much.

[Blown 331]

I belive the acclerator pump is flooding it out, i'm goiing to try to disconnect it. Like i said ill keep you guys up dated, its been a week since ive touched it because it started to piss me off so much.

Did you ever get this worked out? Other than new hose clamps will it fit right on? What about the throttle cable?

I just got a 350X last week and it pops on decell, every once in awhile I'll get a lean miss under steady throttle. I was going to richen it up on the needle and see what happened but the screws that bolt to the slide are in bad shape and I haven't got them out yet. It has a 138 main jet with a K&N and a DG exhaust, I'm thinking of just bumping the main up, maybe to a 142 or so? What is the stock 350X main? It has the air box lid on. I know my 400EX and 450R picked up major power by ditching the air box lid but I've heard the 350X's aren't as restricted. Is it worth taking off the lid and how much of a jetting change would I need to make to compesate?
My cousin has 2 400EX carbs laying around so I was thinking of trying one of those. Just looking for some opinions on this.

[200xman]

Did you ever get this worked out? Other than new hose clamps will it fit right on? What about the throttle cable?

I just got a 350X last week and it pops on decell, every once in awhile I'll get a lean miss under steady throttle. I was going to richen it up on the needle and see what happened but the screws that bolt to the slide are in bad shape and I haven't got them out yet. It has a 138 main jet with a K&N and a DG exhaust, I'm thinking of just bumping the main up, maybe to a 142 or so? What is the stock 350X main? It has the air box lid on. I know my 400EX and 450R picked up major power by ditching the air box lid but I've heard the 350X's aren't as restricted. Is it worth taking off the lid and how much of a jetting change would I need to make to compesate?
My cousin has 2 400EX carbs laying around so I was thinking of trying one of those. Just looking for some opinions on this.

The stock main is a 138. I had about the same setup on mine and it ran great with a 142 and the clip moved down 1 notch on the needle.

[OldSchoolin86]

The stock main is a 138. I had about the same setup on mine and it ran great with a 142 and the clip moved down 1 notch on the needle.
Stock on mine was a 148.

[NOS_350X]

Sorry about not keeping you guys updated.

Since that post i have done ALOT of major engine work to mine.

The throttle cable you can use your stock one. Its just a little tight fit to actualy get the carb on.

Heres the list of mods ive done.

Airbox elimanator
K&n
400ex carb
huge porting and polishing
12:1 with no base gasket
400ex headpipe, With whitebros eseries
Lightened flywheel
2 number hottter on the plug
VP110, or VP *2, or aviation gas
and a 215 main jet,
I havent done a cam yet strictly for the fact i havent found a jet bigger than 210.


On the stock engine i just couldnt get it to run quite properly with the 400 carb. I got it close but from a dead idle it would cough. I kept the needle clip at the center postion. And ran a 148 or 150 main on a stock engine with DG and no airbox lid.
On all my bikes ive noticed a deacent powergain by removing the airboxlid. about 2 sizes jumped up on the main jet.

[NOS_350X]

The stock main on a 350x is a 138
and 142 for a 400ex

[OldSchoolin86]

The stock main on a 350x is a 138
and 142 for a 400ex
They must have had different sizes for different years because my 400ex came with a 148.

[NOS_350X]

They must have had different sizes for different years because my 400ex came with a 148.

Yes that is true, but i dont know what years have what sizes. I know the first year was a 140.

[Blown 331]

NOS-350X, that thing sounds pretty mean. I have an article where they used a head from an 79-81 XR500 on a 500cc 350X. The XR head has bigger ports than the 350X head. If you want a copy send me your email.

[NOS_350X]

Please send it my way. Ive looked into putting a 500 head onto it but nothing is even close to lining up. I was told that the Ft500 had even bigger valves than the XR and that was a mod that the XR guys did (put on the ft head).

[Blown 331]

Please send it my way. Ive looked into putting a 500 head onto it but nothing is even close to lining up. I was told that the Ft500 had even bigger valves than the XR and that was a mod that the XR guys did (put on the ft head).

I've actually got 3 XL500's and I guess 2 are parts bikes (though I want to get one more running). And I have a spare 350X motor so I can check out if they'll fit. If you PM me your email address I'll send the article. I tried to attach it to the email feature in the forum but it wouldn't work.

[NOS_350X]

Ya thats what it was, Xl 500. Email is Basslake@aol.com If you think it can be done, what would you sell one of the heads for?

[Blown 331]

I sent the ariticle to ya. It really doesn't list any modifications that need to be made so I'm under the assumption it's a bolt on. It's not much of a how to article but still cool to read. And it gives a number to call if you have any questions. I'm not sure I want to sell a head. I'm actually looking for another one. Of the two I have I pulled all the valves out and put them in a zip lock bag. They are at my dads in the shed but I can't find them! That's all I need to get one more running. The engine is sitting there with a fresh bore and a 10.25 Wiseco. Just a head usually brings $100 to $150 on ebay. Personally I can't see spending that when all I have to do is find that bag and I'll have 8 valves!

[NOS_350X]

I got the article and read it. Didnt tell me much. But made it sound like a bolt on item.