400ex not revvin up help

[Myrtle150]

Hey guys...while i was at the track today Id been ridin for about 25 minutes and all of a sudden my 400 started boggin and wouldnt rev up. I let it cool for a few minutes, rode it for a while and it started doin it again. Its not overheating or anything because i wasnt even ridin it hard....and i also noticed if i kept the rpms low for a few minutes and slowly started revvin it up it would be fine. .....could the main jet be loose? i havnt had it apart yet.......thanks

[EvilJester400EX]

Check your air filter to see if it's loose, this happened to me once. If that's not the problem, check your airbox boot.

[ReconRider25]

try drygas is gastank? also check the choke...i forgot this and it did that cuz it was only on half....:rolleyes: :p

[660RaptorRider]

check your boots and make sure they are still on. Mine came off a few times at the track.

[cals400ex]

check to see if the mainjet fell out. also, it is possible that the two little skrews holding the slide (where needle goes) down came out.

[660RaptorRider]

also gas is on the right :blah:

[Myrtle150]

lol..yea i know where the gas is. I went out and tore it apart today, adjusted the valves, put a new plug and jets in and it seems to be runnin fine now...thanks

[660RaptorRider]

good. whats all involved with adjustin the valves. what tools do i need and what other things would i need.

[cals400ex]

here is what you need to do:

http://www.exriders.com/techarticles/valves.html