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Powervalve question (with pic)

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Just picked up an 02 yz125 and here is how it came..

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Decided to rip it apart and look everything over...

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Looked in the exhaust port and noticed that only one of the powervalves is back, then other one is near the piston. My question is do the powervalves work together or do they work separately. I just thought it was a little fishy that both powervalves weren't together. The top end and cylinder have less than 3 hours on them so I'm assuming the powervalves aren't dirty or stuck. Sorry for the newbie question but this is my first 2 stroke so I'm learning.

Sorry for the bad pics, but if you look you can see how one is father back.

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The 02 125 definitely has two powervalves, and looking at the diagram for that year it appears to be the same design as my 06. Assuming this is the case, they are designed to always move together.

My guess is one of the valves has come lose from its spring or its pin has dropped out and is rattling around in the compartment (hopefully).

Take off the valve cover and your answer will be there. Send a pic of what you see.

http://www.cheapcycl...semblies/186987

Edited by rjpjnk

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The 02 125 definitely has two powervalves, and looking at the diagram for that year it appears to be the same design as my 06. Assuming this is the case, they are designed to always move together.

My guess is one of the valves has come lose from its spring or its pin has dropped out and is rattling around in the compartment (hopefully).

Take off the valve cover and your answer will be there. Send a pic of what you see.

http://www.cheapcycl...semblies/186987

Thanks. Is it as simple as taking the motor out of the frame and popping off the powervalve cover, or do I need to do anything with the linkage on the right side of the motor? Anything is helpful since this is the first time I've ever had to deal with powervalves.

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I would rather not take the top end off since I don't have any gaskets and I really don't wanna deal with the headache, but I guess there is no easy way at getting to the powervalves though.

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I would rather not take the top end off since I don't have any gaskets and I really don't wanna deal with the headache, but I guess there is no easy way at getting to the powervalves though.

You could probably unbolt the engine and swing it up a bit in front to access the cover, but it would be a better choice to take the top end off.

Here's my thinking. You just bought this bike and do not know its history, and clearly it has at least one significant problem so far (the lose valve). The best advice I can give you is to download the free online service manual, take the top end apart and learn about 2 strokes as you go. It is really pretty easy to work on if you have any mechanical know-how, and I already know you do because you noticed the powervalve problem ;-)

Go for it!

EDIT: You can easily reuse the gaskets if they are in good shape. I have. But if you go for the teardown you will inspect piston, cylinder, head and bearings, and even if you reuse the piston I'd still replace the ring. There is only one and it costs about 9 bucks. A small price to pay for like new compression.

Edited by rjpjnk

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