The engine is a two-cylinder, four-cycle, air cooled, overhead-valve, V-type engine. It has three major component assemblies: cylinder, crankcase and gearcase.

Cylinder assemblies include cylinder head, valves, rocker arms and piston. Cylinders mount on the engine crankcase in a 45 degree "V," with both connecting rods connected to a single crank pin.

The reciprocating, linear motion of the piston in the cylinder is converted to circular motion in the crankcase. The built-up crankshaft consists of an off-center crank pin interposed between two counterweighted flywheels which rotate on two end shafts (pinion and sprocket shafts) supported by antifriction roller bearings. The lower end of the rear

3°BTC (1/64 in. BTC) 35°BTC (7/16 in. BTC) 038-.043 in.

170 ft-lbs

.003 in. maximum at rim 001 in. maximum

cylinder connecting rod is torKed to tit around tne singie-end front cylinder connecting rod, allowing a single connecting rod-crankpin connection to the flywheel.

Flywheel rotation is clockwise (viewing engine from right side). Using the front cylinder firing position as a starting point, the rear cylinder fires at 315 degrees rotation (360 degrees minus the 45 degrees between cylinders). The front fires in an additional 405 degrees (360 degrees plus the 45 degrees between cylinders), completing the 720 degrees of flywheel rotation necessary for the four piston strokes.

The gearcase is located on the right side of the crankcase and houses a gear train which operates and times the valves, and crankcase breather. The rotary crankcase breather valve is located between crankcase and gearcase compartments and functions to relieve crankcase pressure caused by down-stroke of pistons, and controls the flow of oil in the lubrication system. Air exausted from crankcase is fed into carburetor air intake system.

A single cam shaft with four cam lobes is gear driven. The engine valves are opened and closed through the mechanical linkage of tappets, push rods and rocker arms. Tappets serve to transmit the cam action to the valve linkage. Hydraulic lifters installed in the tappets automatically compensate for heat expansion to maintain a no-lash fit of parts. Valve and breather timing are obtained by meshing gearcase gears with timing marks aligned.

Ignition spark is produced by the operation of an electronic ignition system. Both spark plugs fire each crankshaft revolution. However, the spark in one cylinder occurs ineffectually during its exhaust stroke.

Most other engine components function similar to usual internal combustion engine design. For further description of part function, see pertinent manual sections.


For 1979 and earlier models use a good quality leaded "Premium" grade gasoline (94 pump octane or higher). For 1980 models, use a good quality, leaded or unleaded, "Premium" grade gasoline (94 pump octane or higher). "Pump octane" is the octane number usually shown on the gas pump.

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