250F 06 Wr250f runs bad

Hey everyone, I picked up a 2006 WR250F today and it runs pretty bad. It is a completely stock bike except the rear fender is a YZ fender. I can choke the bike and the idle speeds up and it sounds good. When I let off on the choke it will idle rough and doesn't want to take any throttle. Once I get the bike revved up it backfires a ton on decel. I rode the bike and it hesitates and spits and sputters. I think it may have an air leak somewhere? I pulled the air filter and the bottom of the box had an ounce or 2 of water in it. The filter was a little ratty so I ordered a new one. My hot start cable was really loose so I adjusted that but haven't ran it. I'll probably mess with it a little more tomorrow and if I don't have results I'll pull the carb and clean it. Any suggestions on what I should check?
 
Hey Jake.....if your not sure how old the gas is, drain all the gas and put fresh in, since there was water in the air box, I'd for sure pull off the carb and clean it out real well, check/set the float level, and reinstall, probably wouldn't be a bad idea to just change out the plug also. If your still having problems I'd check/adjust the valve clearance also.....give an update on how it goes.
 
Plugged Pilot and starting jets.
Replace the air filter.
Put in fresh gas.
Adjust the fuel screw under the carb.
Replace the exhaust gasket where it meets the head as it is leaking.
Check valve clearances.
Replace the spark plug.
OHM test the coil.

Paw Paw
 
Pulled the carb and cleaned it out. Pretty clean, there was a small jet in the bottom of the bowl that seemed to have some goop in it. Bike ran better after that, took it for a ride and it would run good until top end and then it would fall flat on its face. Got back and checked for air leaks with some WD-40. Couldn't find anything. I noticed when I revved the bike it took a little time to fall back to idle. I unplugged the TPS and it fell back to idle like normal. So I took it for a ride and it ran pretty good, it was pull wheelies without effort. Brought the bike home and it sat for a few hours then I washed it up. I started the bike and choked it until it was warm. Turned the choke off and gave it some gas and it instantly died. Went through that 3 or 4 times so I finally left the choke on to pull it into my garage. The header was glowing bright red after that. So I let it sit for a minute and cool off a bit and fired it back up. Idle adjustment is hardly effective, with it turned all the way up it speeds up a little, and turned all the way down it will die. At idle I'll turn the throttle super slow and it still bogs and dies. If I start the bike and it is above idle it will rev up fine, but once I get down to idle it won't take any throttle. I did notice that the PO drilled 3 half inch holes or so in the baffle of the exhaust. Checked my jets and I have a 168 main, then a 68 and 42 pilot or leak jet. I'm not sure which one is pilot and which is leak jets.
This week I'll get a new air filter, plug, do my valve lash, and replace the header gasket. Might end up cleaning my carb again just to be sure.
 
Pulled the carb and cleaned it out. Pretty clean, there was a small jet in the bottom of the bowl that seemed to have some goop in it. Bike ran better after that, took it for a ride and it would run good until top end and then it would fall flat on its face. Got back and checked for air leaks with some WD-40. Couldn't find anything. I noticed when I revved the bike it took a little time to fall back to idle. I unplugged the TPS and it fell back to idle like normal. So I took it for a ride and it ran pretty good, it was pull wheelies without effort. Brought the bike home and it sat for a few hours then I washed it up. I started the bike and choked it until it was warm. Turned the choke off and gave it some gas and it instantly died. Went through that 3 or 4 times so I finally left the choke on to pull it into my garage. The header was glowing bright red after that. So I let it sit for a minute and cool off a bit and fired it back up. Idle adjustment is hardly effective, with it turned all the way up it speeds up a little, and turned all the way down it will die. At idle I'll turn the throttle super slow and it still bogs and dies. If I start the bike and it is above idle it will rev up fine, but once I get down to idle it won't take any throttle. I did notice that the PO drilled 3 half inch holes or so in the baffle of the exhaust. Checked my jets and I have a 168 main, then a 68 and 42 pilot or leak jet. I'm not sure which one is pilot and which is leak jets.
This week I'll get a new air filter, plug, do my valve lash, and replace the header gasket. Might end up cleaning my carb again just to be sure.

It may have an air leak, one clue there is that the idle screw is not affecting the idle. I think I would look at the tps also as it seemed to make a positive change when you disconnected it, is it adjusted correctly, does it sweep from low to high voltage with no drop outs? It may not be a bad idea to go thru the carb again if none of these things turn up anything. But I would definately fix everything else that you know is wrong first then go from there. Such as air filter header gasket etc.
 
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Plug, airfilter, and header gasket are on order. Tomorrow after school I will pull the carb once more and put some fresh fuel in her. I'm going to see if I can find a free manual or carb specs for the bike so I can set everything to stock. Forgot to mention I pulled my plug before I cleaned the carb and it was black didn't look lean at all, looked rich if anything.
 
Will do. Also, I just learned this bike has emissions crap called AIS (Air Injection System) It injects air into the exhaust to burn off leftover fuel in the exhaust. I will be removing that as well to get rid of the annoying popping on deceleration.
 
Will do. Also, I just learned this bike has emissions crap called AIS (Air Injection System) It injects air into the exhaust to burn off leftover fuel in the exhaust. I will be removing that as well to get rid of the annoying popping on deceleration.

there should be a check or Reed valve in the AIS to prevent air from rushing in on decel that's probably bad, but yeah....pull it completely off, that shit should never be on a dirt bike
 
Ok, the pilot jet still seems to be clogged. The leak jet is what meters the fuel going through the accelerator pump and is located in the bottom of the float bowl. If clogged as you stated it will create w very lean condition when you twist the throttle. Remove it and clean it.
When you put on a new oiled air filter, it will have a great effect on you carb as it will make the bike run a bit richer as without it you are still running lean.
Adjust the fuel screw under the carb to about 2-2 1/2 out from seated.
Adjust the float level.
You may need to go to a 45 pilot jet.

Paw Paw
 
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