03 YZ450 Leaking Coolant on Cylinder

4 replies to this topic
  • twyz250

Posted February 08, 2009 - 03:26 PM


I have an 03 YZ 450 and it blows radiator fluid out of a small hole above the exhaust(Brake side). The hole is about the diameter of your little finger. At first I thought it was a radiator leak and after the bike cooled I noticed a small drip from that hole in the cylinder. The fluid never ran down the cylinder and was burned off by the exhaust and what didn't burn was misted into the radiator on the right side (side with the cap). Please help.

  • honyam83

Posted February 08, 2009 - 04:56 PM


It is the hole where your decompression unit would bolt up. they went to the auto decomp in 03 but left the hole. There are several threads about it. Just search this forum. Use key words "decompression" "plug" "leak". Good luck with your problem I hope that you get it plugged up soon. Honyam

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  • grayracer513

Posted February 08, 2009 - 05:53 PM


That was engine oil:


  • honyam83

Posted February 08, 2009 - 06:01 PM


Yep grays right sorry about that.

  • twyz250

Posted February 20, 2009 - 08:07 PM


I installed the after market plug, works great!!! Thanks for the very important info and $$$ savings. The info on this board is priceless.
Thanks again.

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