taurine side effects

CARBURETED TWO-STROKE ENGINES

Carbureted two-stroke cycle engines are characterized by high levels of unburned hydrocarbons, carbon monoxide, and particulate emissions.

Unburned fuel = Red | Burned fuel = Yellow | Air = Blue


High hydrocarbon emissions

High hydrocarbon emissions from carbureted two-stroke engines result from the scavenging process. Scavenging refers to the process by which the burned exhaust gasses are flushed from the engine. In a conventional “carbureted” two-stroke engine, fuel mixed with air enters the cylinder when the piston uncovers the transfer ports. This new air/fuel charge is used to force or “scavenge” the combustion products from the previous cycle out of the cylinder. Unfortunately, the exhaust ports are also open at this time, allowing 30%-40% of the unburned fuel to be lost directly into the exhaust stream. At idle conditions the losses can be as high as 70%.

High carbon monoxide emissions

High carbon monoxide emissions result from the rich air to fuel ratio typically seen in these engines. High residual gas fractions within the cylinder lead to an environment in which consistent ignition is difficult. In order to improve combustion stability, rich air/fuel mixtures are typically used. This excess of fuel leads to incomplete combustion and high carbon monoxide levels.

High particulate matter emissions

High particulate emissions result from the unstable combustion and excessive lubrication typically found in small two stroke engines. Also, in a typical 2-stroke, the oil mixes with the fuel at the carburetor. As the air/fuel/oil mixture transfers into the crankcase, the fuel dissolves the oil. This action reduces the amount of oil deposited on the cylinder wall (or other critical components) as it is essentially washed out of the engine by the fuel.

How does CEI clean engines? >>