In 1955 Yamaha's first motorized product, a single cylinder street bike, was made and sold in the Japanese market. Today Yamaha is a world leader in manufacturing with an extensive line of products. In addition to motorcycles, some of their products include ATVs, golf cars and snowmobiles. The SS 440 snowmobile was produced from 1980 to 1985. It was equipped with an engine manufactured by Yamaha Motor Company.
Bore and Stroke
The bore and stroke of the engine is 66 mm by 64 mm. The engine has a displacement of 437 cc. The engine for the SS 440 is a variation on an earlier model. It is positioned in the front of the sled. The SS 440 engine was placed in a lower position for added stability. The engine is rated at 50 hp at 7,000 rpm.
Cooling and Lubrication
The engine is cooled with an axial fan. Axial fans blow air so that it flows parallel with an engine rather than in a radical direction. The engine is injection lubricated. Oil injection lubrication uses a pump driven by the engine to regulate the flow of oil. It is then injected into the engine by the intake manifolds. Oil injection systems have been used since the 1960s on two-stroke engines.
The SS 440 has a twin-cylinder engine. The compression ratio is 6:1. Compression ratio represents the volume of the cylinder and combustion chamber at the bottom of travel -- below the piston -- divided by the volume of the combustion chamber above the piston. Compression ratios are important because exceeding these ratios can destroy the engine.
The engine uses BR9ES spark plugs. They are made with a combination of aluminum oxide and ceramics. This combination dissipates heat and provides electrical insulation. The core of the plug is copper which allows a wider range of heat. The tip of the plug is nickel alloy, giving a longer life span to the plug.
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