Should I purchase an over size piston ring as a replacement for a 1982 YZ80 Yamaha...

G

Gabe H

New member
...Dirt Bike? I have a 1982 YZ80J dirt bike that has some major compression issues due to what I presume to be a worn out piston ring. There is no damage to the cylinder and the piston is also undamaged. I'm not sure if I should purchase the standard size piston ring or the first over size piston ring (.25mm) in order to compensate for any cylinder erosion. I also am not sure whether or not the piston ring could wear at the cylinder causing me to have to replace it with an over size ring or if a standard one will do.

This question isn't limited to this bike in particular but rather the general rule of thumb for replacing piston rings on an unbored cylinder.
 
You can't put an oversize ring in a standard bore, it wont fit.

You need to take the cylinder and piston to a mechanic with the tools to measure your cylinder. He will tell you if you can get by with a new piston and ring or if you need to bore the cylinder and get an oversize piston and ring.

Answer is not limited to your bike but applies to every motorcycle you will ever own.
 
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