1999 Yamaha WR 400 Won't idle

2 replies to this topic
  • rcf2

Posted June 21, 2009 - 09:46 AM


I just picked this bike up, it had been sitting outside for over 2 years. So ya the carb was completely gunked up. I went through the whole bike, new oil and filter, cleaned the air filter, changed the plug, rinsed out the gas tank, put in a inline fuel filter, and took the carb apart and cleaned it twice, including all jets the 2 diaframs and every hole and orface I could see. put it all back together and using the technique I learned from this sight, it fired right up and idles with the choke on.But the second you turn the choke off it stalls. Now It runs great giving it gas, no missing, it just back fires a little when you let off the gas. It has a 170 main jet with a white brothers E series exaust. I could not find the air fuel adjustment screw on this carb. Am I just over looking it or does it not have one? Any info would be appreciated.

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  • ncampion

Posted June 21, 2009 - 10:48 AM


It's on the bottom of the float bowl in a recessed hole just in front of the main jet access plug. When you cleaned the carb, if you failed to remove and clean this screw, that is probably why it won't idle. There are pictures on this site of the screw if you do a search.

  • William1

Posted June 21, 2009 - 01:02 PM


Also, replace the pilot jet, cleaning is usually pointless.


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