Does this piston look stock to you??

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Does this piston look stock to you??

Post by lizardfungus200 » 06:45 pm Feb 10 2019

,Just trying to get an idea of how many hours are on this bike. 2000 kdx200. It had and still has really good compression, looking pretty clean except for some little things. The guy who owned it was an engineer and it truly was his wife's bike.

The black **** on the piston is because it burns tranny oil. I confirmed this with UV dye, will pull the motor and pressurize the transmission while I spray soap and bubbles in the crankcase to locate the leak, I will probably document it too. If it is the crank seals, I am considering removing the lip and replace them without splitting the motor and use some type of special glue to secure them in. Has anyone ever done this procedure without splitting the cases?

Thanks for your help guys, I plan on plating it and riding the pch someday!
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Re: Does this piston look stock to you??

Post by Julien D » 07:39 pm Feb 10 2019

Welcome to KDXRIDER

Yeah that looks stock to me. Should be a letter code stamped on top. I have seen someone cut the lips off and drill and tap for some stops to hold the seals in. If you have a leaky crank seal, though, it is quite likely the bearings are worn. Would be worth checking before making any decision on the mods.

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Re: Does this piston look stock to you??

Post by SS109 » 08:15 pm Feb 10 2019

The piston is toast. That transmission oil is getting past the rings and burning.

As to doing crank seals without splitting the cases in stock form, no. I do remember a member here, after splitting his cases, having the lips machined off and he made plates to retain the seals. This would allow him to do future crank seal replacement without splitting the cases.
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Re: Does this piston look stock to you??

Post by KDXGarage » 08:20 pm Feb 10 2019

Why would one do the seals and not the bearings, assuming one did replace the seals one time without splitting the cases. forum member doakley participating in National Enduro series: (current class standing, 4th!)
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Re: Does this piston look stock to you??

Post by rexemouse » 01:29 pm Feb 11 2019

Machining the lips off can be done, but I don't think it can be done cleanly or correctly without removing the crank. Most will argue that its not necessary because if the seals are worn, then it probably needs bearings anyways. But it is nice to have the option off freshening up the seals if your in there for something else, or if the seal leaks or fails prematurely. This usually stems from poor assembly, but does happen, and sucks to split cases if it does.

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