The 42 Special uses a two-cycle single-cylinder engine rated at 2.1 horsepower. The cylinder is bored to 1.65 inches in diameter with a total volume of 2.6 cubic inches. This cylinder supports a single piston that operates at a maximum speed of 14,500 revolutions per minute and is designed to idle at 2,700 rpm with a stroke of 1.18 inches.
Ignition and Fuel Systems
The 42 Special uses a model HDA98 Walbro brand carburetor to control the flow of fuel into the engine from the fuel tank. The fuel tank holds 1.1 pints of fuel, while the bar oil tank holds 0.57 pints of bar oil. Oil is delivered to the guide bar from an automatic oil pump at a rate of 3 to 7 milliliters per minute with the engine running at 8,500 rpm. This saw uses two-cycle engine oil for air-cooled engines mixed with gasoline at a ratio of 1 part oil per 33 parts gasoline. Husqvarna recommends using gasoline with an octane rating of at least 90 to reduce the risk of thermal damage to the engine.
