The Kohler Company in 1920 started out selling engine generators for rural farms and households. In the late 1940s, Kohler expanded its product line with stand-alone engines for industrial and agricultural machinery, and in the 1980s and 1990s further expanded into engines for commercial and consumer yard and garden equipment. The Kohler CV491 and CV491S engines are part of a totally redesigned line of Kohler engines first launched in the 1990s.
The difference between the CV491 and CV491S is that the 491S is equipped with a 12-volt electric starter in place of a manual-pull recoil starter. Otherwise, the two engines are identical. The "C" in the engines’ model designation stands for the Command Series, the "V" means it is a vertical shaft engine and the "491" is the displacement in cubic centimeters. The "S" suffix on the 491S designates an electric start engine.
The engines’ nameplate also has a 5-digit specification number designating which of several dozen varieties your engine is among. Kohler made minor variations of the basic engine to match these engines to specific equipment manufacturers’ specifications. There also will be a 10-digit serial number with the first two digits designating year of manufacture and the other eight digits designating your engine’s place in the production sequence for that year.
The CV491 and 491S are single-cylinder, overhead valve, air-cooled gasoline engines producing 17.5 horsepower from a 29.9 cubic inch displacement. They have a 3.6-inch bore, a 3.03-inch stroke and an 8.5:1 compression ratio, producing 28 ft. per pound of torque at 2,400 rpm. Some varieties of these engines are equipped to run on propane rather than gasoline. The engines’ crankcase holds 2 quarts of oil and they are equipped with a replaceable full-flow oil filter. An optional oil monitor either shuts down the engine or activates a warning light when oil pressure drops too low. The engines have a replaceable high-density paper air filter with an optional oil foam air precleaner that surrounds the paper element.
The gasoline engines are equipped with a float-type, fixed-jet carburetor. Some varieties are equipped with an engine-driven mechanical fuel pump while others rely on gravity fuel feed. Propane engines have a fixed-jet propane carburetor and dry gas regulator fed from a pressurized fuel bottle. The CV491 and 491S have a full-pressure pumped lubrication system. Fuel is ignited by a spark plug powered by an electronically-timed flywheel magneto ignition system. Some of these engines are equipped with Kohler’s optional Emission Sentry pollution control system.