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  2. Yamaha YZ250 - Wikipedia

    en.wikipedia.org/wiki/Yamaha_YZ250

    The original YZ250 of 1974 used an air-cooled 250cc two-stroke engine of 70 mm bore and a 64 mm stroke, which was improved semi-annually. The air-cooled motor was replaced in 1982 with a 249 cc liquid-cooled two-stroke reed-valved engine with a mechanical, rather than servo-driven, YPVS exhaust valve for a wider spread of power. Although other ...

  3. Two-stroke power valve system - Wikipedia

    en.wikipedia.org/wiki/Two-stroke_power_valve_system

    A stroke is the action of a piston travelling the full length of its cylinder.In a two-stroke engine, one of the two strokes combines primarily the intake stroke and the combustion stroke, while the other stroke primarily combines the compression stroke and the exhaust stroke, though technically since both ports are exposed during both the combustion and compression strokes, some reversion ...

  4. Two-stroke engine - Wikipedia

    en.wikipedia.org/wiki/Two-stroke_engine

    Animation of a two-stroke engine. A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston (one up and one down movement) in one revolution of the crankshaft in contrast to a four-stroke engine which requires four strokes of the piston in two crankshaft revolutions to complete a power cycle.

  5. Yamaha YZ125 - Wikipedia

    en.wikipedia.org/wiki/Yamaha_YZ125

    The YZ125 has a 124 cc (7.6 cu in) reed valve-inducted two-stroke engine. It was air cooled from 1974 to 1980, and liquid cooled since 1981. It has a Mikuni 38 mm TMX series carburetor. [6] The engine produces 35 hp (26 kW). [1] The YZ125 has been built with five- or six-speed manual sequential gearbox depending on model year.

  6. Straight-twin engine - Wikipedia

    en.wikipedia.org/wiki/Straight-twin_engine

    A straight-twin engine, also known as an inline-twin, vertical-twin, inline-2, or parallel-twin, is a two-cylinder piston engine whose cylinders are arranged in a line along a common crankshaft. Straight-twin engines are primarily used in motorcycles; other uses include automobiles, marine vessels, snowmobiles, jet skis , all-terrain vehicles ...

  7. List of Yamaha motorcycles - Wikipedia

    en.wikipedia.org/wiki/List_of_Yamaha_motorcycles

    The first bike manufactured by Yamaha was actually a copy of the German DKW RT 125; it had an air-cooled, two-stroke, single cylinder 125 cc engine [1] YC-1 (1956) was the second bike manufactured by Yamaha; it was a 175 cc single cylinder two-stroke.

  8. Honda CR250R - Wikipedia

    en.wikipedia.org/wiki/Honda_CR250R

    The Honda CR250R was a Honda racing dirt bike. The prototype was built in 1971, but it was not until late 1972 that production of the 1973 model "out of the box racers" began sale to the general public. The CR250 was produced for nearly 37 years, 2007 being the final year of production. [2]

  9. Expansion chamber - Wikipedia

    en.wikipedia.org/wiki/Expansion_chamber

    When the transfer is complete, the piston is on the compression stroke but the exhaust port is still open, an unavoidable problem with the two stroke piston port design. To help prevent the piston pushing fresh mixture out the open exhaust port the strong acoustic wave (produced by the combustion) from the expansion chamber is timed to arrive ...