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2003 cr125r

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Hello, I am in the process of installing a new piston and rings on my daughters 2003 CR125. When I took it apart last night I was shocked to only see the top ring on the piston. The lower ring is nowhere to be found. It looks like it may have been that way for awhile because wear on the piston is noticeable in the groove the ring should have been in. I did not drop it down in the engine, got any ideas, has anyone seen this before?:banana:

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CR 125 are only using pistons with one ring. So I guess that someone has previously installed a wrong piston. You would find alot of damage if there was a second ring which broke. Check the crankcase, cylinder, if everything looks nice, just install a proper piston and you are ready to go.

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ok, the piston has some damage but the cylinder itself looks surprisingly good so I am thinking that all I need to due is hone the cylinder and replace the piston and ring and put it back together. I am almost positive that nothing fell down into the engine because I used a towel stuffed under the piston to make sure nothing fell down into the engine I have also used a flashlight and moved the crank, no noise, nothing binding. Thanks for your help.

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If you have taken the engine off a bike, then you could even flush the crankcase with the premix. If the engine is in the bike, then just try to look as best as you can. Although I would bet that there was no second ring, it just could not hide anywhere easily. Replace the piston with a suitable one :banana: It must have only one ring.

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