enging missing at 1/4 throttle???

[hsr]

ok here's the deal, when i start my quad and go to warm it up i let it idle for a little bit then i lightly tap the throttle etc... but when i get right around 1/4 throttle the thing bogs out and sometimes will shut right off. I have about 5 hrs on my new motor , with a fresh new top end and the carb has been rejetted properly. I dont know what it could be. The other day i noticed that the air boot that runs from my airbox to my carb was partly disconnected up by the carb and i was wondering if something could have gotten in there and clogged up one of my jets. I took the carb apart but didn't see anything to obvious. Can even the smallest piece of microscopic dirt be doing this? Would my valves be causing this?? I am lost....please help!!! And oh yeah i was thinking maybe an exhaust leak b/c i do have one on my supertrapp ids2 but its way back where the header connects to the silencer, any help would be appreciated...thanx

[TheX1992]

what did you do on your rebuild? it sounds like your needle jet (or pilot jet i forget which one) needs to be changed. if you bored it or did anything to it other than stock you might have to change the jetting. look in the book what jet it is.

[KY Woods Rider]

I'm going to assume that everything in the motor is alright (correct jetting, timing, no air leaks, no electrical problems, etc) and that the motor is warmed up fully (they'll all miss if you give a cold motor too much throttle). It sounds like you may have a piece of trash caught in the needle jet; no, not the needle, the needle jet. You cannot see this jet just by taking off the float bowl and looking, it is in the lower portion of the carb where the needle bottoms out. It is above the main jet though, so you won't see it. You may be able to see it if you remove the needle and shine a flashlight into the carb and look where the needle goes into the lower part of the carb, but you probably won't be able to see well enough to tell if it is clogged.

My Foreman 450 did the same thing a few days ago (it seemed like you shut off the gas as soon as you got to 1/4 throttle), but I let it warm it fully and then took it around the yard a few times. I got lucky and after a few times of quickly going to about 3/4 throttle, the trash got sucked on through and it's been doing fine since. If that doesn't help your quad and you can't find any other problem, then you may have to completely pull the carb apart and check out the needle jet.