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YAMA1978

She's burning away

7 posts in this topic

Spring is finally here for us in Canada and i started up the beast (2000 yz426) and to my amazement it vomited large quantities of thick grey-blue smoke, I had the neighbourhood kids running in fear it was so bad. Anyways i figured it was my valve oil seals because it smoked a bit last season on start-up. This will be my second time replacing the exhaust valve oil seals in the past 2 years they seem to be over heating and burning up i think :thumbsup: . The carbs good and valve clearances are in spec. timing according to the cams is good although from the appearance of the valve faces and exhaust id say it was a little on the rich side. I ride mostly trails so im thinking i need to open the throttle up more to clean out the carbon. I use 94 octane fuel because anything lower than that makes pinging.This is a cheap repair but very time consuming, any help would be apprieciated. :thumbsup:

P.S. I know there is a valve missing.... :confused:

valves

piston

exhaust port

intake port

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I heard that a bad air filter like the k&n wears out valves and seals faster. So it could be your air filter. Just my 2 cents

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I dont know what is wrong with your bike but I do know that if you use the macro option on your digital camera that it will take better close ups. Also, turn off the flash and just use a flashlight to illuminate what you are trying to take a picture of. On most digital cameras pressing down on the d pad will turn macro on. It should show a picture of a flower if it is on. (d pad is the little circle or the 4 buttons that you use to scroll through the menu) You can normally turn off the flash by pressing up on the d pad until there is a picture of a lightning bolt crossed out displayed.

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The pix of your engine look fine....? I was always under the impression that valve seals fail when you aren't using enough oil or not changing the oil enough. Oil seals dry out and crack, in the old days (big gas guzzling V-8s) a little top-end oil, like Miracle Oil, keeps the oil seals nice and happy. Now a days I use only fully synthetic oil to keep everything happy.

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Sorry about the pics, i just looked at my own post with my computer at work and man they suck. They looked so much better on my computer at home.

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Well according to my speacilist the only thing which can cause the valve seals to wear out is: heat, lack of lubication, and poor quality. Usually overheating is the biggest cause, either not enough oil or not enough coolant flow. Check to see if there are any cooling system problems and make sure the oil circulates well. Hope that helps.

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