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

[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

[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.