Craftsman tools appeared in 1927, also in 1948, Sears introduced an whole line of yard and garden equipment, such as rotary lawn mowers; chain saws came soon afterwards. Few of those earliest Craftsman chain saws still exist, and should you happen to have one, you can be sure the engine specifications, including the gas-oil mix ratio, then differ from contemporary models. If you can not locate the manual, you might have to experiment to find the proper fuel mixture.
Two-Cycle Engines
The two-cycle engine that runs a chain saw is an internal combustion engine, but it is not the exact same sort of engine that runs an automobile. The ignition of gas in a combustion chamber drives a piston that forces the engine crankshaft, however, the movement of the piston is not as sophisticated, producing one rotation of the crankshaft with each cycle. A two-cycle engine doesn’t have a crankcase to hold petroleum, so to properly lubricate the piston, you must add oil into the gasoline. Since this oil is burned along with the gas, it is important to use the appropriate ratio to ensure adequate lubrication without adding too much oil, which burns less efficiently than gasoline.
The Wrong Oil Mixture
As the piston moves up and down in the cylinder to produce the power to get a Craftsman chain saw, it generates friction against the sides of the cylinder, which add to the heat present in the chamber from combustion. Without sufficient oil in the gasoline, the metal parts of the piston and cylinder soften and fuse, and the engine seizes. That typically means the end of the engine. No such risk exists when the petroleum ratio is too large. The worst that can happen is that the engine burns too much oil, causing smoking and poor performance.
Fuel Ratios Through the Years
Many contemporary Craftsman chain saws are manufactured by Poulan and function smoothly with a 50:1 fuel-oil mix. Models sold earlier 2010, like the 18-inch, 50 cc model from 2006 or the 18-inch 42 cc model from 1997, need a 40:1 mix. Still earlier models take a richer oil mix. By way of instance, the 35 cc model sold from 1974 to 1976 requires a 32:1 fuel-oil mix. If you don’t have the manual to your saw and don’t know its age, you can not readily know the proper fuel mix, even though its safe to say the older it is, the more oil it takes.
Locating the Appropriate Ratio
If you don’t know the appropriate ratio to your own saw, the best method to locate it is to begin with the maximum oil ratio it is very likely to need, which is 32:1. To accomplish this ratio, then add 4 oz of oil into each 1 gallon of gasoline. In the event the engine smokes too or doesn’t perform well, reduce the ratio to 40:1 by adding 3.2 oz of oil to each 1 gallon of gasoline. If the engine is intended to operate on the thinner oil mix, it is going to perform better. Don’t combine the oil any thinner than this unless you are sure the engine is created for a 50:1 mix, or you might mess up your chain saw.