In a two-stroke, the oil is mixed with the gas and the fuel works as the lubricant, running through the crankcase and the engine. Once the oil is mixed with gas, it s tough to burn cleanly. As with a chain saw, there is no crankcase full of oil, so there is more pollution as the oil burns with the gas. Creating cleaner sleds is a relatively new idea for sled manufacturers, although the mounting demand by environmentalists for them is not. This demand has many experts expecting a federal mandate.
Actions taken in Yellowstone National Park are one reason why.
In November, Yellowstone Park officials announced that snowmobiles will be phased out and banned in the 2003-2004 season as a result of the sound and emissions caused by some 50,000 that travel through the park each winter. Chuck Maguire, an assistant engineering professor at UM and an engineer with General Motors for 14 years, said if the federal government required that snowmobiles be made with four-stroke engines, it would cost the industry more to build them, but it would be done. Until then, cheaper and dirtier is how engines will be made, he said. The industry likes to complain. A two-stroke has much more horse power, which is what people always wanted, just like with a motorcycle, Huff said.