Yamaha TZ 250

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1977 Yamaha TZ 250.jpg
Yamaha TZ 250 (1977)
Manufacturer Yamaha engine
Production period 1973 to 1990
class motorcycle
Motor data
Two-stroke engine , water-cooled two-cylinder engine, inlet through piston edge control
Displacement  (cm³) 247
Power  (kW / PS ) 51-76 hp at 10,500-11,750 rpm
Top speed (  km / h) 225
drive Chain
Wheelbase  (mm) 1300-1320
Empty weight  (kg) 101-118

The Yamaha TZ 250 was a commercially available racing motorcycle from the Japanese manufacturer Yamaha , which was used in the motorcycle world championship from 1973 to 1990 . The basis of the Production Racer was the OW17, the factory machine from Yamaha, with which Dieter Braun became motorcycle world champion in the class up to 250 cm³ in 1973 . The almost identical Yamaha TZ 350 was manufactured with a larger bore (64 instead of 54 mm) .

History and technology

The water-cooled TZ series of commercially available racing machines in the class up to 250 cm³ displacement was presented in June 1973 and replaced the air-cooled variants of the Yamaha TD series, which were derived from tuned series engines. The bore-to-stroke ratio of 54 × 54 mm was adopted from the TD 3, which appeared in 1972. With the model year 1981 (TZ 250 H) a completely new design was brought onto the market. Instead of a modified standard housing, a sand-cast housing specially developed for racing was used; the two cylinders were no longer cast in a block, but standing individually. The bore / stroke ratio changed to 56 × 50.7 mm. 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 stage, the TZ 250 A (3TC) from 1990, 76 HP.

While the diaphragm control was taken over into series production, Yamaha decided to use the piston edge control for the Production Racer up to model year 1984 (TZ 250 L). With the TZ 250 N model, the inlet diaphragm was also controlled in the TZ engine. The fresh oil system provided by Yamaha was easily converted to mixed lubrication (1:20) by some private drivers.

The power was transmitted via a chain to the rear wheel via a six-speed gearbox. The chassis consisted of a double-loop tubular frame with a telescopic fork and two spring struts on the rear swing arm . At the front, a worried Duo-duplex brake on the rear wheel a duplex brake for the delay. With the model TZ 250 C (1975) the chassis was revised, a cantilever swing arm with central spring strut and disc brakes were introduced. The petrol tank held 23 liters, the oil supply was 1.5 liters.

"During the following 15 years, private drivers around the world couldn't get past the TZ racing machines."

- Hugo Wilson

In 1991, the engine of the TZ 250 was thoroughly revised and adapted to the factory racing machine (YZR 250). The new model series, now with a V-engine, was delivered to selected drivers until 2004.

literature

  • Collin MacKellar: Yamaha. All Factory and Production Road-Racing Two-Strokes from 1955 to 1993 . The Crowood Press, 1st edition 1995, ISBN 978-18522-3920-6 .

Individual evidence

  1. ↑ a b Collin MacKellar: Yamaha ., P. 184.
  2. ↑ Collin Mackellar: Yamaha , p.127..
  3. ↑ Siegfried Rauch: Famous Racing Motorcycles - 150 old and new racing machines for Grand Prix use . 2nd Edition. Motorbuch Verlag, Stuttgart 1980, ISBN 3-87943-590-1 , p. 257.
  4. ^ Hugo Wilson: The Lexicon from the motorcycle. Motorbuch Verlag, Stuttgart 2001, ISBN 3-613-01719-9 , p. 204.
  5. ^ Axel Koenigsbeck, Hans J. Schneider, Peter Abelmann: Yamaha. Schneider Text Editions LTD., 1st edition 2004, ISBN 0-9541746-0-7 , p. 376.