The fan is thermostatically controlled by a temperature sensor near the right upper side of the cylinder coupled in the cooling system hose. If the sensor fails, it is relatively easy to bypass the sensor to keep the fan on all the time until the sensor can be replaced. I placed some large white spots on my fan blades (which are black) so I can easily tell when the fan is running. Trials bikes are remarkably sophisticated (hydraulic clutches, dual external suspension damping adjustments, small yet powerful twin caliper brakes etc.) and it still amazes me how they can fit all the parts in such a small, light package, as most of the new bikes weigh less than 170 pounds. Jon

NOTE. JIM SNELL, the official Gas Gas parts importer, advises that a constantly running fan is usually a sign of low coolant in the cooling system.