I have owned this 1986 KLR600 for about 15 years and it has been converted and used for trail riding. It has about 9000 miles on it and has never had any major issues. The last time out in 85 degree weather the bike started to overheat and then started to backfire and lose power. When it cooled down it was OK until it overheated again. I have keep the anti-freeze changed every few years and it currently looks like new in the radiator. The thermostate and pump appear to be working since the water gets hot in the radiator and the anti-freeze appears to be moving when you look in the radiator with the cap removed. The fan also turns on and off automatically. Any input on how to resolve this issue would be appreciated.