99 yz400f problem!!

3 replies to this topic
  • bodybagz66r

Posted June 22, 2010 - 04:47 PM


The bike started earlier but when i would give it gas it would backfire and shut off on accel. past the quarter throttle mark. Bike ran perfectly fine before i put it away 5 days ago, long story short i removed the airfilter to clean and found it had no guide on it. It was just mounted to the airbox via the bolt so i decided to clean it while i replaced the clutch. Anyways i wanted to take it for a ride w/ the new clutch before i cleaned the filter so i threw it back in there (mind its not that dirty) anyways now it wont start. Could if be that it needs that guide? I just dont understand why it ran perfect before! im dripping with sweat and tired!! sorry if i rambled need help please!!

  • 09speeddemon

Posted June 22, 2010 - 09:42 PM


To me it sounds like you need to clean your Carb, A lot of times what happens when they sit they will start and run then when you shut them down something breaks loose in the carb and plugs up one of the jets or the floats get stuck.
Hope this helps

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  • grayracer513

Posted June 22, 2010 - 10:47 PM


Change the spark plug and don't ride it in the dirt until you get the filter cage.

  • DGXR

Posted June 23, 2010 - 02:01 PM


The bike will run without an air filter element but it's not a good idea, esp in the dirt. When you say the air filter "had no guide" do you mean the whole cage is missing from inside the foam element? Or is it just missing the tab/spike thing that lines up the filter assembly inside the airbox? The filter could shift around without the spike so like grayracer said, get a complete cage and make sure it's all mounted square and tight before riding it off road.

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