sputtering after 1/4 throttle

[Shrk352]

last week at a track my airfilter fell off and my 02' 400ex stalled and woulndt restart. I then took apart the carb cleaned everything put it back together and got a new twinair airfilter. It ran great for about 20 min with no problems, then all of the sudden it started sputtering but only past 1/4 throttle. it will run fine untill I get past about 1/4 throttle. could it be that my main jet is cloged, Im not sure what it would be exactly. thanks.

[bwamos]

Sputtering/Spitting would be a rich condition. Stuttering/Bogging would be a lean condition.

Try smacking your float bowl a couple times. From the cleaning your float could be stuck. Happens to mine almost every time I clean it. I just give it a tap with the back of a screwdriver (plastic handle). Then I pick up the ATV by the grab bar to where the rear wheels are about a foot off of the ground and drop it about 5 times.. and I'm set. But, that's my machine.. lol. Hey, it works.. lol.

But make sure that you remembered to turn your choke off first. ;)

Did you have a K&N before, and now a TwinAir? If so TwinAir's don't breathe quite as much.. so you'd need to adjust your needle 1 notch up on the clip, and probably drop your main too.

[wvspeedfreak]

Also,check to make sure your main jet hasn't fallen out.I have seen it happen.

[bwamos]

Yes...

Very good point.. happens more than you think.. lol. Esp. since he just cleaned it.

I'd almost put money on that one. Symptoms and timing fit perfectly.

[Shrk352]

thanks for all the tips guys ill try beating on my carb and if that doesnt work I guess Ill rip it all apart again, I had the stock filter before and now just got the twin air. thanks again.

[Shrk352]

ohh and its sputtering and boggining/stalling if I dont let off the throttle. feels like I have the choke on but its not.

[Iliketogofast]

It appears as if you have an age old problem. It's been around for as long as I can remember. I'm afraid you have a four stroke. The only cure is to go out and buy a zinger right now.

[Shrk352]

hahah you sound just like my Yamaha loving friends who are saying my problem is that I have a Honda.:rolleyes:

[Iliketogofast]

Yeah but the problem is they are wrong and I am right. Yamahas suck too. :D Juuust kidding. I had to get it in though.