HELP!! sputtering when i accelarate

[trillbill400]

I have an 04 400ex that is sputtering when i give it gas almost like it isnt getting enough fuel. The bike had an aftermarket pipe on it when i got it but it cracked, i got my hands on a stock pipe and put it on this is when the problem started. i pulled the carb and it had been jetted the main jet was a 165 i rebuilt the carb and went back to stock jets but that did not help still doing the same thing any advice would be appricated!

[TheAwesomehonda]

So let me get it straight the whole bike is stock correct?

[trillbill400]

well i do have a k&n air filter and an aftermarket oil pan and thats it.

[TheAwesomehonda]

Hmm well then I don't really know I would just put on a 42 pilot and maybe check the needle position and the a/f screw.

[trillbill400]

thanks i will check those things out and let ya know!

[trillbill400]

What is the stock needle position? I checked my plug it was black so i figure it was running rich, lowered the needle to the 2nd slot still having the same prob!

[Stickman400]

3rd notch on the needle, but the needle has nothing to do with how rich or lean it is, that just helps your throttle response.

[trillbill400]

thanks that is good to know i have been researching online and seeing all sorts of things!

[cheater13]

It could be something that the other guys said about the carb jetting but this happened to mine too. I could go, then slam on the gas and it sputtered and shut off. Found out my fuel line was kinked because it was too long. We cut off a little bit and it ran just fine.

[russellsroost31]

sounds to me like the main jet fell out ive had it happen twice
the 2nd time it happened it almost killed me

[TheAwesomehonda]

Originally posted by russellsroost31
sounds to me like the main jet fell out ive had it happen twice
the 2nd time it happened it almost killed me How does your main jet falling out almost kill you :huh :huh

[trillbill400]

thanks again everyone who is trying to help me with my problem! checked my fuel line and no kink, pulled my carb all jets are intact and rebuilt carb! i noticed a weak spark when i grounded my spark plug ( thin and yellow ) i read that the spark should be fat and blue! gonna change my plug tomorrow mabye that will fix it!

[russellsroost31]

because i was racing at summit when it happened
it was in pratice and i did a race start for pratice and i sould tell somthing was wrong so when i came around to the doublle i hit the throttle and it bogged out and i was already commited so i cased it hard and about thru me off the bike infront of another rider
so then i had to go back to the trailor, strip the bike of all plastics and gas tank to get to the carb, take the carb off and put the jet back in, put the bike back toghter to only have my one buddy come running back yelling that we r up so then i had to get all my gear on and back up to the line to only take 3rd

[TheAwesomehonda]

Originally posted by russellsroost31
because i was racing at summit when it happened
it was in pratice and i did a race start for pratice and i sould tell somthing was wrong so when i came around to the doublle i hit the throttle and it bogged out and i was already commited so i cased it hard and about thru me off the bike infront of another rider
so then i had to go back to the trailor, strip the bike of all plastics and gas tank to get to the carb, take the carb off and put the jet back in, put the bike back toghter to only have my one buddy come running back yelling that we r up so then i had to get all my gear on and back up to the line to only take 3rd Ok I got it. Man thats got to be fun taring it down and fixing it before the next moto.

[ansimation]

This sounds exactly like what is happening to me. Not sure what to do here so if you solve it hopefully that will give me an idea where to take it. I've already cleaned the carb twice, adjusted a/f, same thing. idles fine and everything and rides okay in 1st gear or even second until you really start to get on it, then it starts crackling and popping like it's starving for fuel. I just put a new float in the carb as well.

[Kwadrider04]

Possibly go up a few sizes on main jet? Just an option

[ansimation]

I really don't know much about it, or even what's in it now. A marine mechanic buddy of mine is the one who has been helping me with it but even he's stumped.

What size main jet would you guys suggest for a 426ex, 10.5:1 wiesco, stage 2 hotcam, after market exhaust not sure which brand though, came with the bike. I have a uni filter also. Maybe I can go get a jet kit tomorrow if it's something that Honda might have handy.

[CJM]

They usually sell jets at the dealer.

Buy the following 42 pilot jet, you need to remove the carb bowl to put this in. Then buy the following main jets: 160-175. If you can get increments of two thats good, but increments of 5 will also work.

Chances are your gonna wind up at 170ish main, 42 pilot and the fuel/air screw 2.5 turns out.

Check this FAQ thread for posts on how to tune/jet: http://www.exriders.com/vbb/showthread.php?s=&threadid=464998