wr426 leaky valve stem seal.

1 reply to this topic
  • rhysieboyy

Posted May 04, 2011 - 02:17 AM


hey guys,havent rode my bike since i rebuilt my rear suspension and put a new fmf exhaust on it which was about 2months ago and hadnt rid it for 2months previous to that either.ive started it once a week just to keep her running and that.but ive noticed the last couple times ive started her up that she has being blowing smoke when cold,i spoke to my foreman at work and he reckons its just a leaky valve stem seal as it goes away once warm.is this something to be worried about or can i leave it?if you were in my position (1st year apprentice diesel mechanic on 7.50hr)would you pull it down and rebuild the head or leave it?also i have ridden but only for 20mins around the yard when really bored,she will stall and not start again,im not running lights or anything so is it possible that the electrical system is overheating or something causing no spark?or is that just a stupid idea?

thanks in advance,

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  • Pooley

Posted May 04, 2011 - 10:33 AM


I had smoke on cold startup for over a year until this winter and a complete engine teardown and inspection due to other issues...turning the bike into a submarine specifically, which is not recommended. The bike would only burn oil if it sat for a few days or more, and would not burn oil once warm. Just check your oil often to make sure it doesn't run low.

Changing the valve guide seals isn't difficult, but I had help from a friend who knew what he was doing. I had the engine out of the bike, but not sure if it can be done in the frame. If you don't have a spring compression tool, you can get by with a second person to carefully compress the spring and then drop in the seals. A complete seal-kit from Moose is something like $100, and will save money over individual seals if you were to buy them all.

The stalling and not starting again is a separate issue I would suspect. You may want to check your valve clearances. When trying to restart it, try both the hotstart, and then the choke to see how it responds while kicking. This should tell you if the carb needs adjusting. The FMF pipe is significantly different from the stock pipe and I know I had to go up a size on the pilot. You may be too lean on the pilot to start when hot. If the "not restarting" issue is new only since switching to the FMF, I would go through the process to determine the appropriate pilot jet first, and if that doesn't net results pull the carb and clean it. Clean the carb while it is off anyway actually :thumbsup:.


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