white smoke wr450

2 replies to this topic
  • littleyorgee

Posted June 11, 2013 - 03:00 PM


I got white smoke and oil coming out of the breather hose on the top of the head. There isn't any coming out of the muffler though. the bike still seems to run fine though im not willing to ride it until i figure out/fix what is wrong. im not sure if this is important or not but the only way to start the bike is to kick it over with the hot start. the electric start won't get it going. the bike is an 03

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  • Krannie McKranface

Posted June 11, 2013 - 06:42 PM


It sounds like normal maintenence will solve that problem

Valve lash and shim
Replace the pilot jet and air jet
Get a new air cleaner

  • grayracer513

Posted June 12, 2013 - 10:13 AM


Depends on the volume of the "blow-by" you see. It's always normal for air to move in and out of the crankcase vent on a single, parallel twin, or boxer engine because the piston(s) pump just as much air on their undersides as with their crowns. When the engine gets really hot, there will naturally be some oil smoke that goes with it. When the engine gets run hard, oil will find its way into the tube and then drool out. That's normal, too, to a degree.

As the rings age and loose their seal, combustion gasses will escape from the combustion chamber into the crankcase and cause a net outflow that's greater than normal. That can't be solved by any routine maintenance; only new rings will fix it, and there can be wear considerations with the cylinder and piston as well. The categorically accurate way to evaluate your next move is to have a leak down test run on the bike to check the condition of the rings, etc.


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