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Help! My bike won't run right.

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Two weekends ago I got stuck in some gnarly mud cutting the track. I killed the bike as soon as I hit the mud and just dug it out with the help of others at the track. The mud was above the swingarm, but the engine wasn't under any mud and should have been fine. The problem is, once I freed the bike it took forever and a day to start it, and once I had finally got it going it backfired and died everytime that I wasn't revving.

I've since cleaned the bike up, checked the air filter, etc...

I can start the bike up, and it'll sit just fine with the choke on. Once I turn the choke off, though, I either rev it to keep the bike going, or it backfires and dies. Everytime I let off the gas, it pops really loud and threatens to die. What could be the problem and how do I fix it?

Bike Specs: '02 CRF450R. Engine rebuilt about two years ago. I change the oil every-other ride. I maintain this bike REALLY well.

Mods: Please don't move this to a different forum. I'm wanting to ride tomorrow so I'd like to get as many views as possible.

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Always check for clogged carb vent lines. Clogged lines will cause hard starting and bogging when the motor is hot. They can also cause erratic running

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yep, the symptoms u describe and the mud sinking both point towards a plugged carburetor vent line. they generally poke out under the bike right by the front of the swingarm. they sometimes make bikes unhappy on water crossings too.

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Drain the float bowl on the carb.

Mine doesn't have a screw to drain it. Do you know of any other way besides taking out the carb?

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Mine doesn't have a screw to drain it. Do you know of any other way besides taking out the carb?

Its dosent have a big 17mm not on the very bottom of it?, it should.

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Its dosent have a big 17mm not on the very bottom of it?, it should.

I'll go look. If it does I just unscrew it, let it drain, then put it back in? I'm guessing I should turn off the gas?

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You Carb should definitly have a some place to drain the bowl. Ya definitly turn off that fuel line.

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I'll go look. If it does I just unscrew it, let it drain, then put it back in? I'm guessing I should turn off the gas?

Yes turn the gas off, unscrew the 17mm bolt and let it drain, then turn the gas on twist the throttle a couple of times and start it.

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clean the entire carb with carb cleaner..if ur bike is running erratic like zingy-- it's lean, probably b'c of the block jets...but since u also said it bogs, so it must be clogged

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K guys, here's the run down. I drained the bowl, and cleaned the vents. The vents I didn't take all the way off - I just stuck a long screw-driver up them and wiggled it around to clear the dirt out. The bowl... I just drained it like normal I guess. I rode it around the front yard and though it's better... it still pops after high revs. It'll idle if I turn the idle up a bit, but when I turn the idle down to a pretty low idle it won't hold it. Any more ideas? My dad said check the exhaust for mud that could have gotten in the header, but I'm not entirely sure if I could have gotten mud in there.

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Air Filter? have you checked that

I took my seat off the day it happened to see if my air box was completley caked... but it looked fine to me. I'll go look a little closer though...

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