Engine cutting out.

[bigb426ex]

I have a 400ex and on my last XC race it was part MX and whenever I was going uphill on the MX track with some jumps in it after I landed the engine started cutting out on me. I had to drop it down to 2nd and it give it all throttle to get rid of it cutting out. This is the only time it seems to do this when I'm jumping on an incline. The boot on the carb is still on real good and the air filter is secured as well so nothing was in there. Had a full tank of gas too. Not sure what the problem is?
Thanks in advance:D

[duke416ex]

Mine does this occasionally when I do a lot of jumping. I figure it needs a good carb cleaning, and did you take the air fuel screw out to make sure there was no water in it?

[OldYellow]

Mine does the exact same thing. I wish i could figure it out.

[cals400ex]

what year 400ex do you have? what mods and what jetting are you running?

[2muchquad]

well from the symptoms you guys have mentioned,on a mx bike i would say try to adjust your float level,im not sure if they are preset on the 400ex,i know some quads they are.its worth looking into:)

[cals400ex]

Originally posted by 2muchquad
well from the symptoms you guys have mentioned,on a mx bike i would say try to adjust your float level,im not sure if they are preset on the 400ex,i know some quads they are.its worth looking into:)


the reason i asked is because they changed the float pin in 01. my buddy had very similar problems with his 00. he replaced the part with the new one and never had a problem. i am better rich jetting may also cause this problem. i believe the floats are preset from the factory and are not adjustable on the 400ex if i remember correctly.

[bigb426ex]

I have a 2001. I'll double-check tonight on my jetting. I bumped mine up to a 426 and still running a stock carb.