I need instructions on how to change my piston ring on my 1993 yz 125. thank you.

What is the compression after putting the piston in? seems like carb problem, was it cleaned out when you changed piston?

I would be checking compression it may not be visible score on cylinder but it does not take much to loose compression on small bore motor with one piston ring and 11 years old

If you have never stripped down an engine get expert help .Piston rings are very fragile and can be snapped very easily .They also fit in there correct place on the piston by a small pin in the ring slot and you will neen a piston ring shimming assembly kit to keep the pistons in the correct position while you slide them into the cylinders .

only reason would be your running too lean. which causes more heat, which causes pre-gnition and pinging. Also if timing is off you create more pressure which in turn causes more heat

the retail value in good condition is approx $1,500. meaning it looks good, runs good, good tires, breaks,chain and sprokets. but with the extras you have and the after market up grades, i would start with a little higher price.

change the rings anyway then you know if its them,cheap and easy to replace

• If a hole in the piston then install new piston and rings. Next, clean the carbon off the head and install a new head gasket.
• If cylinder wall is scared the piston has seized up. Pull the cylinder off and take it to the dealer. Have them bore the cylinder and return it along with a new oversize piston and rings.
• While at the parts counter, get a new stock spark plug and a supply of Yamalube Two Stroke Motor Oil. You need to add 4 ounces per gallon when filling up. This will be a 32/1 gas to oil ratio. NEVER ride the bike without at least the needed 32/1 mix.

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