Z400 troubles

[4trax250x81]

This last weekend when i raced my z400 i had a few problems. I got a good jump off the line and everything seemed good until after one of the longer straightaways, it just shut off. I had the clutch in and it was still rolling when it shut off. After i got it refired it ran good in the low and top range but in the mid it just sputtered. I just bought the quad from someone and it was my first time racing it, the guy before me didnt get it out yet this year. Do the problems have something to do with the needle position on the carb or bad gas? Would it shut off because of either of those problems? Its not the stock carb, its a Keihin FCR 39. Thanks for the help in advance!!

[PeeWee21]

Sounds like you have a clogged jet. My suggestion is to take the carb off and give it a thorough cleaning.

[4trax250x81]

Thanks for the reply. I took the carb off, took it all apart and gave it a good cleaning, but it didnt help the problem. It shuts off after straightaways unless i give it a little gas while i have the clutch in otherwise it shuts off. Could it be something with the jetting or the needle position?? Any help is appericated!!

[HondaRacer300ex]

Maybe your idle is too low?

[YFZ450Ridr]

ok this might sound dumb, but check to see if your choke is on. its happened to me and its just enough to mess somthing up. also it could be bad gas, my dads old warrior did that once, and we drained the gas in the tank and carb and it solved the problem. also maby check to make sure the filter and plug are in good condition.

[RidrKFX]

that same thing happend to me on my ZL500 (snowmobile) it did that on a long straight and like i got it running after a while and it pulled hard in the low and high end. It didnt run right, untill i found that there was a small hole in one of my pistons. That might be the same with you. But i dont know because this was a snowmobile with 2 pistons and the z is with 1. But what you described was the same thing that happend to me.