If the engines were the same as our old ski-doos (yes, Rotax), they were very prone to overheating. Even on a ski-doo. As soon as springtime would come these engines would get so hot that I was pouring snow on the engine head! Or else, you had to wait a good 30 minutes before being able to restart them!
I remember on a springtime day when the engine stopped right in the middle of our lake about two miles from home. Of course, it was ice, not water... but it was about 50 degrees out there with 2-3 feet of ice beneath the track. I was riding an Olympic 300 model 1972 that was already 10-12 years old at the time.
After a 30 minute break and with some ice/snow on the top of the engine, I was able to restart it. Phewww...
Benji.