troubles with 99 yz400f

6 replies to this topic
  • burelybean

Posted April 09, 2006 - 04:26 PM


I have a 99 yz400f, the bike is overheating within a minute or two of initial startup. When riding the bike loses all tourge and has just enough to pull the bike. Have not the slightest step to take next any ideas would be appreciated

  • One Louder

Posted April 09, 2006 - 07:54 PM


is the coolant flowing? Is it all boiling out or is it leaking out? How long do you let it idle? From what i've experienced and read these bikes run hot.

  • millzy555

Posted April 09, 2006 - 08:35 PM


could be a broken head gasket, causing it to overheat and leak coolant

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  • dirtbike_newb

Posted April 09, 2006 - 08:37 PM


I just got a 99 yz400 and I've rode it hard and it hasn't had any coolant issues yet.

  • burelybean

Posted April 10, 2006 - 01:54 AM


the bike is maintaing a consistent coolant level and the coolant is warming up it just cannot keep up with the heat from the engine and the loss of tourque i am presuming is part of the same problem

  • obxnc

Posted April 10, 2006 - 07:11 AM


If the water and oil levels are good and there is no sign of either one moving into the others home, I would check the water pump impeller.. If it is not pumping, it is not cooling..

  • tom nolan

Posted April 13, 2006 - 07:51 AM


If the bottom of the radiators are cooler than the top when the bike is standing still and idling, than the water pump impeller is not turning. You should be able to see the fluid moving across the top of the right radiator with the cap off.

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