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400 EXC Won't Idle

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My 2002 400 EXC won't start or idle correctly.:cry: I had the carb. gone over and cleaned. Did not help. After I get the bike started, it sputters/runs rough on the low end/low rpm's and won't idle - it dies. :cry: It seems to run better when warmed up and at the higher rpm's but still won't idle/runs rough at low rpm's. Also, it starts easier when warm/hot. Any help would be appreciated. :cry:

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Is this a new condition, or something that has happened since day one? To me it sounds like a lean condition since it wants to run better when it's hot. Possible causes...

Air leak

Cold temperatures

Misadjusted fuel screw

Dirty pilot jet

Also check your valve adjustment and compression.

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it is a new condition. The bike has sat around for a bit. I am trying to fix it for a friend so I don't know all the history. The carb was just professionally cleaned. Screw is out 1 1/2 turns, and the pilot was clean but I went ahead and replaced it with a new one. It's a #170. The bike is in my garage at 55f and still won't start easily. The valves are my next check. I am beginning to suspect that they are tight....

thanks!

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170 pilot?? Pilot should be a #48, main is a 170ish. I suspect your pilot is plugged. Remove it and hold it up to the light, options are:

1: A clear sharp light thru the hole? = OK

2: Blurry light?? = water in the gas, you can clean it and have it plug again

3: No light? = not going to start or idle well.

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opps, you're right. I meant the main. I will check the pilot again - more carefully. I changed out the fuel but it could be water. thanks for the advice.

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