I just bought a 1994 Polaris 425 Magnum, needed carb work ( it was overflowing gas into the oil). I put a new needle and seat in the carb and a new spark plug, air filter, cahnged the oil and it starts right up. No more gas in the oil either. Now I took it out for a ride and it was running great until it started to get heated up. The temp light never came on but it started to back fire and got really doggy. Then it died and would not start back up until I let it cool down for about half hr. I checked to make sure the anti freeze was circulating and it was, but the fan never kicked on for the radiator. I ran it in the garage and blew compressed air through the radiator to try and keep it cool with the fan not running, and it still died after it was running for about half hr. Then once it was shut off a while it started riight up again. Any ideas on what I am having problems with?