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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.
YDS-3 (1964) 246 cc, two-stroke, parallel-twin, it used the world's first oil injection lubrication system in a 2-stroke engine. [2] DT-1 (1968) Yamaha's first true off-road motorcycle. [1] XS-1 (1970) Yamaha's first four-stroke engine motorcycle (650 cc twin). [3] YZ Monocross (1975) First production motocross bike with a single rear shock. [3]
Print/export Download as PDF; Printable version; In other projects Wikidata item; Appearance. ... 1973–2003 [2] [3] Class: 250cc Grand Prix motorcycle:
The YA-1 was followed by the YA-2 of 1957, another 125cc two stroke, but with significantly improved frame and suspension. [9] The YD-1 of 1957 was a 250cc two-stroke twin cylinder motorcycle, resembling the YA-2, but with a larger and more powerful motor.
The Yamaha YZ250F is a motocross motorcycle first released in 2001 by Yamaha.It features a DOHC, four-stroke engine and initially had a steel frame and subframe in 2001–2002.
The Yamaha YZ450F is a four-stroke racing motocross bike built by Yamaha Motor Corporation.It was the successor to the previous YZ426F which was discontinued in 2003. It is credited by Cycle World and Dirt Rider magazines as the bike that started the four-stroke dirt bike revolution.
The bore/stroke ratio changed to 56 mm × 50.7 mm (2.20 in × 2.00 in). In addition, the cylinders received a so-called Yamaha Power Valve System (YPVS). The first model series (TZ 250 A) of the water-cooled twin with contactless thyristor magneto ignition had a power output of 51 HP, the last expansion stage [ clarification needed ] , the TZ ...
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 ...