Hi everyone ... I have a stage 6 mid race cylinder with one piston ring on my yamaha slider , the piston ring it's very used and it came the time to change it .. may i change the whole piston and put 2 piston rings or may I change the piston ring only tell me info plz ... thx

In my opinion a piston doesn´t cost much, so I would change it

you get piston rings when you buy a new piston

I know they don't cost much but i can't find special rings for my stage 6 piston ... and a new piston isn't much too but i'm afraid that stage 6 has with 1 piston ring and what is available in my city to buy it's with 2 rings

If you find piston with correct piston rings for material of your cylinder than yes you can do that. But it will have some lower HP. And the qouestion is can you find piston in that dimensions...