More than likely,there will be a lot more damage than, fried rings. I have never herd of fried rings. More likely,you've burned up the pistons. This is usually caused by either running too lean a fuel mixture and/or over reving the engine. If, and a big if, the cylinders were not damaged they might be reused,dependig on how bad the engine was overheated,and if they're not scored.Then,you have to look at where the metal went. The bearings in the base of the engine are open to the crankcase. Any tiniest bit that gets in one will ruin it.You'll find that she doesn't run very long after you just replaced the cylinders. The engine needs to be completely torn down, and inspected.Once it's repaired, the original sorce of the problem still needs to be corrected.Air leak, dirty carbs,mixture settings, clutch setting, ect.Depending on the sled, engine rebuilds are very expensive,many times costing more than the whole sled is worth.There are tons of them aroung here with blown motors,just sitting because it wasn't economical to repair. Good luck!