carb problems

5 replies to this topic
  • yz450f05

Posted October 07, 2006 - 02:24 PM


well i just bought a power now and put it in my yz450 like 3 or 4 months ago and while i was doing that something changes so i took it to my local Yamaha dealer and they didn't fix it and now my bike has a problem with lean pop and when your riding and go into a spot where your on the gas then not it has like a fast idle...Can anyone help me out?

  • Fastest1

Posted October 08, 2006 - 08:18 AM


Are you referring to a hanging idle? When you let off the gas it hangs briefly and then comes down as if mechanically stuck momentarily? Try turning the fuel screw out to lessen the popping. The motor will need to be at operating temp and go out in 1/4 turn increments.

  • yz450f05

Posted October 09, 2006 - 05:48 AM


well when i let off the gas it holds a fast idle for a good 30 seconds or more, but the idle sounds like the choke is on but its not

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  • grayracer513

Posted October 09, 2006 - 07:40 AM


That's what he said, a hanging idle. Do as he suggested and back the fuel mixture screw out in quarter turn increments. If it isn't fixed by the time that it's 2 1/2 turns out from seated, look elsewhere.

Hanging idles are caused by lean mixture, an air leak in the intake, or tight intake valves. In your case, since you say that the problem surfaced after you installed the Power Now, it's possible you did something wrong in attaching it to the carb or in reassembling the carb to the bike.

  • yz450f05

Posted October 10, 2006 - 04:41 PM


alright thanks ill try turning the fuel screw out if that does not work i just put my factory 4 exhaust on what jet from the jet kit should i put in?

  • Fastest1

Posted October 11, 2006 - 04:19 AM


Do they have a jetting recommendation for their pipe? Another way to check for an air leak if there is one, is spray wd40 or similar product on the carb boots while the bike is idling on the stand, if the idle changes, you have found your leak. Generally the power now shouldnt need a jet change but weather changes will always require fuel screw adjustments for optimum performance.

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