It is the bike. Almost all older YZF will have similar problems. It generates more heat. Possibly its beacause of the YPVS 9power valve) which limits the exhaust air when in idle or slow. Havent tried but maybe by replacing the YPVS with a straight flow exhaust might reduce the problem. Also try adding in a variable heat sensor that activates the fan at a slightly lower temperature..maybe at 10 degree farenhite than the actual cut in.