Bog when motor hot

4 replies to this topic
  • yz450scott

Posted June 20, 2010 - 06:29 AM


My bike has very little "YZ Bog" when I crack the throttle when I am warming up the bike, but after riding for a few minutes and the motor is hot I have a definate bog or hesitation from no throttle to 1/8 throttle. I have leaned out the pilot jet and have the fuel screw 1/2 turn out. I have tried a 38 pilot jet and played around with the fuel screw with no affect. I know none of my jets are clogged. I completely tore down the carb and thoroughly cleaned the carb and all jets.. I lowered the needle to the 3rd position (raised clip to lean it), but it is still the stock needle. I was thinking of changing the needle to the next leaner needle. I have ordered a quickshot for the AC pump to see if that helps. It is strange that the bog/ hesitation is worse when the motor is hot and also worsens when I go up in altitude..The valves are adjusted perfectly and the motor starts kick hot or cold..What are my options? Any advice at all would be great...Thanks

By the way, My bike is a 2001 YZ426 (stock head pipe with White Brothers E-series Muffler) :with only about 50 hours total on the motor..

  • grayracer513

Posted June 20, 2010 - 07:27 AM



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  • bodnar44

Posted June 20, 2010 - 04:31 PM


Test your throttle position sensor. The test steps are in the service manual 6-9 section. I bet that it is going bad.

  • MrBlahh

Posted June 20, 2010 - 04:37 PM


tps on a 2001 426?

  • grayracer513

Posted June 20, 2010 - 05:52 PM


Yes. Why not? All YZF's have them.

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