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yz125 help

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I have a 2000yz125 and yesterday i was riding out of the power band and then i started to nail on the throttle all the way to 6th gear and i noticed i was blowing smoke then it was deaccelerating and all of a suddon it shut off and cant get in to start now.I cleaned my plug and let it hang out of the motor and it is getting spark.Could it still be that the plug is fowled?

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I went a head and did a compression test and it was only showin 40PSI!!!!

So puled the top end and i was toled that it was sleved but am not sure?Also what all should i replace when doing the top end?I am going to post some pictures and was hoping you could tell me if it is sleaved?If it is how do I remove it so i can install a new sleave.By the way this is my first top end job so sorry for all the question.Thanks

http://img228.imageshack.us/img228/379/p1010500gr1.jpg

http://img88.imageshack.us/img88/3223/p1010503il4.jpg

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That bike does not have a sleeve from the factory. So unless someone sleeved it, you're going to have a Nikasil coating.

Does a magnet stick to the cylinder bore? If it does, you have a sleeve.

A top-end includes piston, rings, wrist-pin and needling bearing, circlips, and gaskets. This should run you about $100.

Also, while you have the engine apart, make sure there is no up and down movement in the rod.

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Yes a magnet stuck to the cylinder bore so it must be sleved.How do I take it out and were can I get a new one?Is there only one size in sleves or am I going to have to measure it?

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If the bore is still stock size, you can have someone bore the sleeve and install a larger piston.

Contact Steve at Moto814.com here: http://moto814.com/contact.html

He'll tell you more about the options you have and do the work for you.

While you're at it, I'd recommend getting a porting job from him too, I've heard great things about his work.

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40 psi is very low and not enough to get a 2 stroke to start. It's hard to see if the cylinder is scratched or grooved (I didn't see any) and it does looked like it has been sleeved. You might just need a light hone and new piston/rings and reassemble. :thumbsup:

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As long as you have no bad scratches in the cylinder and it mics out OK, then go ahead w/ the new parts. Hone only enough to break the glaze on the cylinder walls. I like to go into the cylinder in 1 direction and reverse the drill on the way back out. Go down slowly for 4-5 seconds and back out the same speed. Assemble the new parts w/ a dab of oil except the ring and cylinder (allows for quicker seating of the new ring and no glazing) and allow a full warm up before riding off into the sunset! :thumbsup:

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How do i find out what size piston I have?Now that i dont need a new sleave I am going to need to put the same size piston in.I think it is the stock size but i am not sure.

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Once you take it apart, the old piston will tell you what size it is.

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Im going to do it right and just get a new sleave.Can you tell me how to remove the sleave,were can i buy a sleave?Also were on the piston does it say what size it is?

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Doing it 'right' shouldn't include a new sleeve. You can't replace it, a machine shop has to. If you have deep scratches or gouges then you might need a rebore. That's allowed w/ a sleeved cylinder. :thumbsup:

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Im going to do it right and just get a new sleave.Can you tell me how to remove the sleave,were can i buy a sleave?Also were on the piston does it say what size it is?

I really think you should take it your cylinder to a trusted dealer and have them take a look at it for you, give you some advice, and take it from there..

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I cleaned the cylinder with gas today and you cant even feel what looks like scratches.

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