400ex runs like crap

[spiresbuilt]

i got a 400 off my buddy he said he thought it was out of time, well i went to put it in time and it wasnt out. Theres no throttle response and backfiring. you have to hold it half throttle to get it to run, so i change the plug it was soaking wet with fuel, i changed it with a new one and it fired perfect and reved up perfect for like a minute and returned to runnin like crap. i pulled the plug it was soaked also plus while it was runnnin it started smoking wasnt oil smoke it was rawl fuel. i done it again with another plug and got the same story. its flooding itself out its like it got pleanty of fuel and barely enough spark to burn it. possibly the coil? any suggestions would be appreciated. thanks justin

[Scro]

Sounds like it's jetted too rich on the pilot and/or needle.

[aDviSol2y]

What mods do you have if any? Take the carb apart and check what sized the jets are. Let us know.

[spiresbuilt]

I don't think the jet is to big. Only reason is because it ran fine for almost a year the way it is. the motor is a 416 i recently helped him put a new piston and rings in it. i dont know what size cam but i know its aftermarket its got all kinds of engraves numbers and things on it, as does the flywheel has a different timing mark then just using the "t". I may ask him if he rejetted it but im almost 100 percent sure he didn't. Anyways thanks for replying more help is appreciated. Justin

[aDviSol2y]

Well if you just put a 416 and a cam without re-jetting, then you def. need to re-jet.

[jcs003]

check float bowl height. clean the carb thoroughly also.

[TRXRacer1]

Originally posted by jcs003
check float bowl height. How do you adjust the bowl height???:p

[jcs003]

Originally posted by TRXRacer1
How do you adjust the bowl height???:p

find something better to do stalker. if you know it all we wll leave it up to you. grow up.

[TRXRacer1]

Originally posted by jcs003
find something better to do stalker. if you know it all we wll leave it up to you. grow up. Anyone that knows this carb will know why your advice is so funny.

[jcs003]

Originally posted by TRXRacer1
Anyone that knows this carb will know why your advice is so funny.

so you are implieng the carb doesnt use float bowls???:p

[TRXRacer1]

Originally posted by jcs003
so you are implieng the carb doesnt use float bowls???:p I can tell you for fact it does not use float bowls. It has 1 float bowl and a set of non adjustable floats. Look, it's okay to be a little behind. We all came here to learn at one point or another. There's just no need to act like you know what you're talking about when you don't. Bad info screws up people like the OP who was looking for help.

[gncc025]

If you rebuilt it during cold months the jetting may be off because of the warmer weather. I rejetted my YFZ in january and when may came it ran like ****.

[JOHNDOE83]

Actually you can adjust the floats on any carb....if you know what you are doing.

[f4iracer]

you could probaly try to rig the float, but you these are non adjustable float.

you can't easily just make an adjustment to the float on a 400ex carb it's standard.