There’s nothing quite like the scream of a two stroke engine and the smell of burning engine oil is always right there with that scream. In the world of motorsports its sound is unmistakable. Dirt bikes would see the two stroke engine utilized on early models because of the smaller size. Snowmobiles would also follow suit because of the light weight. It was only a matter of time before the ATV would make use of the technology to improve response, increase speed, and reduce weight. The first two stroke quad made it to market back in 1985. The Suzuki Motor Corporation would design and release the Quad Racer, a two stroke racing quad with a 246cc powerhouse. Although two stroke engines were appearing on earlier ATC’s from the big four manufacturers (Honda, Kawasaki, Suzuki, and Yamaha), this quad in particular would set off a revolution of racing and sport riding. The ATV brought more stability to the table with four wheels versus the three wheeled ATC’s. Engine size and power was utilized far better on quads when riders became more apt to keeping their wheels beneath them. The ATC was considered unstable and its production would eventually be outlawed, but the two stroke quad would flourish in the coming years with all the major manufacturers contributing their own version.
The two stroke engine was first invented back in 1878 but the first patented two stroke motor, a v-twin, didn’t come along until 1904. The two stroke design has certain advantages and disadvantages when compared to a four stroke engine. One stroke equals one cycle, therefore a two stroke engine completes its energy production using half the cycles of a four stroker. This is because two stroke engines have no valves. The fuel intake, fuel ignition, and exhaust emission all happen on each cycle (or revolution) of the engine. Four strokes in comparison use a camshaft and a series of valves to separate all the phases of energy production. These additional components add overall weight to the four stroke engine. The two stroke however must burn oil during its ignition phase. This accounts for the blue or grey smoke which emulates from every two stroke exhaust port. Two stroke engines require oil to be injected simultaneously with the fuel or pre-mixed in the fuel tank. Two strokes also burn more fuel versus the four stroke powerplants. Citing emissions, noise pollution, and higher fuel usage, the two stroke engine has all but been eliminated from automotive and street motorcycle market, but the lightweight simplicity and sheer horsepower per cubic centimeter of these engines allowed them to flourish in the offroad market.
In their heyday, quad manufacturers flooded the market with their own two stroke engines. Beside the big four, Honda, Kawasaki, Suzuki, and Yamaha, other big players like Polaris as well as a variety of small scale Chinese manufacturers have capitalized on two stroke power for their quad ATVs. But new, lightweight, and more efficient four strokes would eventually become the accepted powerplant for the majority of production quads. The two stroke has been completely dropped from the lineup of most manufacturers in favor of reasonably quiet, fuel efficient, technologically advanced four strokes. Sport quad riding and organized racing have also, for the most part become four stroke events. As quickly as the two stroke engine entered the atv industry, it has, for the most part, fallen by the wayside even with new advances in emission technology, including reductions in odor as well as smoke.