We have a few winches working at higher elevations in Colorado, and we have not received any complaint from the users. However, air density decreases approximately 3% per 1000 feet (305 m) of elevation, thus at 8500 feet (2593 m), the air is approximately 25% less dense than at sea level. This means there is less air entering the carburetor, altering the air/gas (petrol) mix ratio. This is equally true for 2-cycle and 4-cycle engines. The only way to retain the horsepower is to increase the amount of air (altering porting and carburetor size). Many shops specialize in this work for snowmobiles that work at high elevation. Running a standard engine (2- or 4-stroke) at high elevation will result in improper combustion and plug fouling. The common remedy is to change the gas (petrol) jet to a smaller one; and a local HondaTM dealer can probably fit the winch with the proper jet. But there will definitely be a significant loss of power; a portion of the power loss will be offset by the lower weight of objects at high altitude (lower gravitational pull). However, working with 1 or 2 pulleys will compensate the power loss. But again, we had no complaints so far.