Husqvarna recommends a cutting bar of anywhere from 13 to 24 inches of length, although the standard size is 15 inches. It has seven teeth on its drive sproket and can support chains with a 0.325 inch pitch and with a drive link thickness of 0.050 inches.
The Husqvarna 51 chainsaw runs on 87 octane gasoline, or higher if it is to be run at high engine speeds, mixed with two-cycle oil at a ratio of 50 parts of gasoline to one part of oil. It can hold approximately 20 fluid ounces of fuel-oil mixture in its fuel tank at a given time.
The Electrolux ET ignition system in the Husqvarna 51 uses a single Champion RCJ 7Y spark plug. It requires a 0.020 inch gap to produce the appropriate size spark for efficient operation.
The 49 cubic centimeter single cylinder engine used in the Husqvarna 51 generates 3.1 horsepower when running at 9,000 revolutions per minute, which is its maximum speed when under load. Conversely, it idles at only 2,500 rpm. The engine has a cylinder bore of 1.73 inches and a piston stroke of 1.26 inches.