Did you let the sled warm up first? Maybe a cold siezure? My guess is you probably siezed a piston for some reason, a lot of times they will start up again. Most of the time you dont burn a hole in your piston, the side of the piston hits the cylinder wall. This happened to me when my oil cable broke and motor was not getting oil. You should pull your head and check your cylinder walls. Sometimes if its a light siezure and didn't score your wall too bad you can clean up the aluminum with muractic acid. The esiest way to remove aluminum from the wall of a nikasil plated cylinder is with muriatic acid. Be very careful! The acid eats aluminum very quickly! You must be very cautious when using it near cylinder ports...it can eat the aluminum at the edges of the ports. It can also eat aluminum through any nicks or holes in the plating. use a cotton tipped swap to apply the acid precisely where you want it on the nikasil liner. If it causes bubbles, then it is eating aluminum from the surface of the nikasil. Leave it on for about 20 seconds and then wipe off thouroughly. Repeat the process two or three times to be sure you have removed all of the aluminum from the plated cylinder wall. Then rinse the cylinder very thouroughly with water to make sure there is no remaining acid. Then drench the cylinder in WD-40. Then a little work with a scotchbrite pad. Then a final cleaning and ... viola! Ready for assembly, good as new. Depending on how bad it is you may want to stick new pistons in there.
If it scored the wall pretty deep you will need to replate cylinder.
Find out why you siezed, too lean?, no oil?, overheat?, detonation? Cold Seizure?
Could also be electrical prob but usually electrical problems dont just restart.