KX250 cutting out. Help!

hey guys. My 2003 KX250 is cutting out at high revs. It runs well til it's warmed up it seems. Then it dies like it ran outta gas, just flat out quits. Checked the plug and it's good. Cleaned the carb and checked all the setting (float height etc). Rode it again and got into 2nd and at full throttle it started to cut out. When it dies it starts right back up. As I use her for hillclimbing I'm always in 2nd wide open. Could this be an electrical issue? I was reading about the stator, could this be the problem?
 
I think you are running out of gas?
Petcock internals clean? Are you running a fuel filter? Remove it if you are.
No inline filter. Straight stock fuel hose. I'll check the petcock and clean it.
gas cap vent, plug wire, loose ground under tank, kill button
Clean out vent cap (running a shortie hose) checked plug wire, I am running a deadmans killswitch. Checked the quick disconnect to the coil and its corroded as fuck. Possibly the problem?
 
Sometimes it is hard to tell if it is running out of fuel or running rich up top. That needs attention anyway, so good find.
How do you tell it it's running too rich up top? My plug isn't wet or black. It doesn't really bog out. It almost sounds to me like it's too lean up top. What's lean up top sound like?
 
like your piston is seizing. if it is really lean it just acts, well, like it ran out of gas, on its face, dead, catches back on as you roll the throttle back. Usually when someone tells someone that a bike that misses on top end has a main jet that is too small I cringe a little for them. I can believe that an air leak etc can cause some problems, but as the weather warms up your jetting should be leaned out to prevent the richness that comes with less oxygen in the air around you. If yours all of a sudden NEEDS a bigger main jet, you have to track down the reason and not just swap jets in my opinion. If you do a throttle chop test it may tell you that your jetting that was fine for colder weather is now too rich for the current conditions, but i think if i were you i would want to test it with the fuel a little bit freer flowing.
 
like your piston is seizing. if it is really lean it just acts, well, like it ran out of gas, on its face, dead, catches back on as you roll the throttle back. Usually when someone tells someone that a bike that misses on top end has a main jet that is too small I cringe a little for them. I can believe that an air leak etc can cause some problems, but as the weather warms up your jetting should be leaned out to prevent the richness that comes with less oxygen in the air around you. If yours all of a sudden NEEDS a bigger main jet, you have to track down the reason and not just swap jets in my opinion. If you do a throttle chop test it may tell you that your jetting that was fine for colder weather is now too rich for the current conditions, but i think if i were you i would want to test it with the fuel a little bit freer flowing.
The air leak would probably be in the reed boot you think?
 
The air leak would probably be in the reed boot you think?
That is a good place to start. base gasket area as well. i am not convinced in the least that yours has a leak though. usually an erratic idle comes along with it. i was just addressing a lean condition that may go beyond your fuel tap.
 
That is a good place to start. base gasket area as well. i am not convinced in the least that yours has a leak though. usually an erratic idle comes along with it. i was just addressing a lean condition that may go beyond your fuel tap.
Alright. Awesome. Thanks a lot man! I'll do some more testing
 
did you try it since you cleaned off that screen?
I ran it but I'm in the suburbs and my neighbors hate dirt bikes so I couldn't really run her wide open. I hit wide open once or twice and it sounded better. Not cutting out. But I'll have to run it up some hills to tell
 
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