400ex carb for 350x - She's A Runner!

[userj8670]

Bought an '07 400ex carb for my 350x. I have seen a 300ex intake is able to be used as well with the 400ex carb. Since I have searched and can't find an answer can someone please tell me if it's bigger than stock 350x intake?

I am aware you need to stretch the stock boots over the larger 400ex carb - but if I can find an intake that's bolt on and bigger I'd prefer to go that route...

[oldskool83]

when i had my 350x the intake was not a bolt on with the 400ex carb. I'd use a 400ex one for many reasons.

[userj8670]

when i had my 350x the intake was not a bolt on with the 400ex carb. I'd use a 400ex one for many reasons.

Thanks so much for the reply! I was hoping somebody would chime in.

I did look into the 400ex intake, however the only ones I seen were a 3 bolt pattern and the 350x head is 2 bolt pattern? Is there a a swap of some sort?

[shortline10]

I just did a 2007 400ex carb swap a week ago , about 30 seconds with the heat gun and the 400ex carb slid on the factory 350x manifold with no issues , same with the boot to air box , also the factory snorkel will need to be heated up right were the choke lever pivots for clearance .
Great mod .

[userj8670]

I just did a 2007 400ex carb swap a week ago , about 30 seconds with the heat gun and the 400ex carb slid on the factory 350x manifold with no issues , same with the boot to air box , also the factory snorkel will need to be heated up right were the choke lever pivots for clearance .
Great mod .

Thanks for the reply Shotline! Did you have to mess with the jetting or the accelerator pump?

[shortline10]

The 400ex stock jetting was spot on .

[userj8670]

Any tinkering with the accelerator pump?

[RIDE-RED 250r]

The 400ex stock jetting was spot on .

A friend of mine who is a member here bust doesn't post much came to the same conclusion with the jetting. :beer

[shortline10]

Nope , factory setting was perfect , hit the throttle as fast as I could and no hesitation !




Any tinkering with the accelerator pump?

[userj8670]

Impressive! I am throwing mine on Saturday so we shall see how it goes. I am praying and hoping I don't need to tinker and it's just bolt and go. I bought a bunch of jets just incase. I will keep you posted

[DickyDanger]

Impressive! I am throwing mine on Saturday so we shall see how it goes. I am praying and hoping I don't need to tinker and it's just bolt and go. I bought a bunch of jets just incase. I will keep you posted

any updates userj8670?

[userj8670]

any updates userj8670?

Unfortunately no - ran out of time. Got the carb in and man its a tight fit. Had to take the intake off and the put the carb on the intake and then screw the intake in which with an open end wrench was 1/8th turn at a time...but it's on!

[shortline10]

Get this going yet ?

[userj8670]

Get this going yet ?

Hey Shortline - thanks for remembering and showing interest! Unfortunately no I have no updates since last. Problem is that the bike is at Hondaline Hartmans which is 2 hours away from where I reside. Trying not to take up every weekend from his wife and kids but maybe this weekend. I promise this will be updated as soon as I have an update - will more than likely need your vast knowledge of engines to help me get this carb dialed in!

Thanks again!

[userj8670]

I just did a 2007 400ex carb swap a week ago , about 30 seconds with the heat gun and the 400ex carb slid on the factory 350x manifold with no issues , same with the boot to air box , also the factory snorkel will need to be heated up right were the choke lever pivots for clearance .
Great mod .

Forgot to ask you - how did you specifically install the carb into the intake boot. For me I had to take the intake boot off to grt the carb into the frame. Then once in the frame I put the intake on the carb and installed the 2 bolts thar mount the intake to the head. Problem was that since the carb is so big I could barely get a box wrench in there to tighten the bolts. 1/8th of a turn at a time - sure hope I don't have to mess with jetting much and go thru that every time:crazy::crazy:

[shortline10]

I heated the intake manifold up with a heat gun for a few seconds and the carburetor slid right in , never removed the manifold , same with the boot to air box .




Forgot to ask you - how did you specifically install the carb into the intake boot. For me I had to take the intake boot off to grt the carb into the frame. Then once in the frame I put the intake on the carb and installed the 2 bolts thar mount the intake to the head. Problem was that since the carb is so big I could barely get a box wrench in there to tighten the bolts. 1/8th of a turn at a time - sure hope I don't have to mess with jetting much and go thru that every time:crazy::crazy:

[userj8670]

Interesting...I don't recall having enough room to slide the carb in if I was to go that route. Seems that it hits the frame due to the limited space and size of carb...

[RIDE-RED 250r]

Although I haven't been down this road myself with the wife's 350x, I know of a couple people who have and they found stock 400ex jetting to be about spot on. I would start there or to be safe, 1 size richer on both circuits.

[Dirtcrasher]

Yep, larger jets for more fuel/larger air outlet and the heat gun does the trick.....

If you have another silencer, such as the SuperTrapp with no airbox lid and it adds allot more air, and fuel.

If you take the lid off, I'd bump the pilot 2X more and the Main jet about 3X larger.

[userj8670]

I have a full supertrapp (including the header....yes they made one) with a uni filter and a stock 86 motor. The main is a148 as of current

[kazander]

I have done this to 3 different ones. I found it easier to pull the intake and lightly grind the inside with a dremel to fit. Then I use a 400ex air tube, modified at the airbox, modify the airbox to fit the air tube and run the 400ex air filter. Jetting on 2 was spot on. 3rd bike has a midrange cam and I had to go up on main. On the side of the carb with the cable there is a v shaped piece that you can open up the v until it contacts the lever sooner to help kill any dead spots.

[userj8670]

Yep, larger jets for more fuel/larger air outlet and the heat gun does the trick.....

If you have another silencer, such as the SuperTrapp with no airbox lid and it adds allot more air, and fuel.

If you take the lid off, I'd bump the pilot 2X more and the Main jet about 3X larger.

Thanks DC. I'm gonna try and fire it for the first time this weekend so we will see how she runs...I'm stoked

[Crazyktmmatt]

I think mine is a hair lean so far. Ive only rode it 10 min at most tho. Kinda hesitates. I havea 400ex header and 450r muffler. I'll have to screw with it more when it warms up.

[userj8670]

Ok - as promised we now have a runner! That motor is a bear to kick over wow does she have some compression ...and it's stock! That being said she runs only with the choke on . Of you tske the choke off she will eventually die out. I didn't mess with jetting or any adjustments due to time. I believe the pilot is off as when rev'd up it will not return to idle right away... also it will not rev up allthe way...cuts out a bit. I have also included 3 short videos so you can hear and see what she is doing. I appreciate any help!

https://www.youtube.com/watch?v=7OSJZI6K3SA


https://www.youtube.com/watch?v=vkuWErbZ5Nw


https://www.youtube.com/watch?v=s-xn1yJtZVM

[Crazyktmmatt]

Adjust the decompression cable. It will be easier to kick then.

[shortline10]

Sounds like the air fuel mix screw needs adjusted ?????
Adjust the idle high enough were it wont stall out with the choke off and turn the screw in and out were it has the highest point of idle , then see if it will idle down correctly . Note don't have the idle set so high that you cant here the difference when adjusting . Should be some were near 1-2.5 turns out if the jetting is close .




Ok - as promised we now have a runner! That motor is a bear to kick over wow does she have some compression ...and it's stock! That being said she runs only with the choke on . Of you tske the choke off she will eventually die out. I didn't mess with jetting or any adjustments due to time. I believe the pilot is off as when rev'd up it will not return to idle right away... also it will not rev up allthe way...cuts out a bit. I have also included 3 short videos so you can hear and see what she is doing. I appreciate any help!

https://www.youtube.com/watch?v=7OSJZI6K3SA


https://www.youtube.com/watch?v=vkuWErbZ5Nw


https://www.youtube.com/watch?v=s-xn1yJtZVM

[userj8670]

Sounds like the air fuel mix screw needs adjusted ?????
Adjust the idle high enough were it wont stall out with the choke off and turn the screw in and out were it has the highest point of idle , then see if it will idle down correctly . Note don't have the idle set so high that you cant here the difference when adjusting . Should be some were near 1-2.5 turns out if the jetting is close .

Thanks for the repose shortline- was very eager to see what you had to advise. I am going to tinker with the air fuel screw before I start tearing into the carb but ultimately I do think a larger pilot is in order.

As to the idle I did actually tinker with thar for a minute. I rotated the idle screw clockwise until it wouldn't go any further any it made no difference (ran only with half choke )...yeah I am clueless on that one. Note I didn't go the other way though with the idle screw... yet...

[atcmatt]

From my limited experience I would say it sounds like it needs a larger pilot jet. Just been through the whole getting thing with mine and found a larger pilot was the go with moving the clip down one groove also.