2003 YZ450F Valve cover hoses

Miscellaneous Motocross Engine Valve Train Yamaha YZ450F 2003

1 reply to this topic
  • Buchta179

Posted April 14, 2013 - 09:36 AM


I tore down my 450 to install new faction mx valves. Everything went well and I have put everything back together, the only problem is im missing a hose! I have the larger Breather hose, but I'm missing the smaller one. i know the larger one is an oil overflow in case the bike is laid on its side, but I don't remember what the smaller one is or what it is called, please help me!

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  • grayracer513

Posted April 14, 2013 - 02:47 PM


The smaller one is the air pressure balance hose for the oil system. It runs from the cam cover to the frame at the left side of the steering head to equalize the pressure in the oil tank with the crankcase air pressure. Just a piece of oil proof vacuum hose will work. Clamp it on.

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