1999 wr 400 no idle

4 replies to this topic
  • rvinvents

Posted March 01, 2009 - 10:04 AM


my 1999 wr 400 was running fine during my last ride, i brought it home and changed the oil. then went to go for a ride in the desert a bit higher altitude and it was rainy that day. anyhow the bike fired 1st kick but when i turned the choke off it would not idle it has always ran great at this location before the bike seemed to run normal except for the no idle condition, what would cause this overnight change, i know its probably the carb but which part. i am no carb expert i could work on 2 stroke carbs but 4 stroke carbs look kind of scary. ps when i got home the same symptoms were still present no idle without choke on. is it the air screw, idle jet, or acc pump?

  • tntmo

Posted March 01, 2009 - 11:34 AM


You just need to pull the carb out and take it apart and clean it. If the bike sits for more than a month or two the fuel will start to gum up the small air and fuel passages. I had to clean the carb three times on my buddies 400 before it idled correctly.

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  • rvinvents

Posted March 01, 2009 - 12:42 PM


thanks it only sat for two days though?

  • William1

Posted March 01, 2009 - 02:13 PM


Pull the pilot jet. If it is not spotless, replace (do not bother to try to clean) it. Check the fuel screw, ensure the spring, washer and oring is there and in good shape. Confirm the number of turns is less than three from fully closed.

  • rvinvents

Posted March 01, 2009 - 05:55 PM


thanks i will check it out, ps is the a manual on the carb somewhere on this site?


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