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Discussion Starter · #1 ·
I've got a trx500fm1 and it's burning lots of oil. So I opened up motor and found piston covered in oil. It also had lots of play inside cylinder. What I don't understand is why when I did a compresion test I got 110psi..isn't that good?
 

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When you tested compression, the (excess) oil helps to boost the psi up. It's also likely that the oil rings on the piston are worn right out but the compression ring is just good enough to keep the engine running. Worn out valves can also cause the oil to get by and burn. Probably time to rebuild it all (or as much as you can afford) starting with a rebore & new piston.
 

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That looks pretty normal from what I can see. I would remove those valves, clean all the carbon off and replace the valve seals.
 

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Yes, valve stem seals. Often they are included with gasket sets.
Remove the valves and clean them with a wire wheel on the bench grinder.
Clean the head with what ever you like as long as it doesn't scratch or dig into the metal.
There are chemicals that help to soften up the carbon. Hope this helps.
 

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I assume you mean the connecting rod & there's usually some side to side play but not up and down.
 
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