YAMAHA YZR500 TIMELINE

1973 OW20

Liquid-cooled, inline four-cylinder, two-stroke engine, chrome-moly frame. This won at the first round of the 1973 season, ridden by Jarno Saarinen.

1974-1975 OW23

Yamaha won their first 500cc constructor’s championship with the 23 in 1974 and in 1975 Giacomo Agostini rode it to their first rider’s world championship, as well as giving Yamaha their second constructor’s title.

1977 OW35

Changes made to stroke-ratio, carbs and valve intake system.

1978 OW35K

In comes Yamaha’s Power Valve System (YPVS). Kenny Roberts bags the first of his three championships on the bounce.

1979 OW45

Second title for Roberts.

1983 OW70

Full Deltabox frame and 17-inch front wheels. Roberts narrowly beaten to 500cc title in his final year by a young Freddie Spencer.

1984 OW76

Eddie Lawson wins the 500cc title with this machine, which uses a crankcase reed-valve system.

1985-1986 OW81

The two-stroke V4 motor is re-designed. Title lost to Spencer in 1985, but regained in 1986 by Lawson.

1987 OW86

Cooling and exhaust improvements.

1988 OW98

Lawson takes his final title for Yamaha. New exhaust layout and asymmetrical swingarm.

1989 OWA8

Lawson takes title on a Honda NSR with Wayne Rainey second on a Yamaha. Data recording now introduced.

1990 OWC1

Rainey takes first of three back-to-back titles.

1991 OWD3

Min weight now 131 kilos; updated suspension.

1992 OWE0

Final title for Rainey after Honda/mick Doohan crash/ injury. Big-bang YZR motor comes in second half of the season.

1993 OWF2

Stiffer frame developed, but Rainey complains of lack of feeling. Team Roberts switches to a ROC chassis from round eight. Rainey paralysed at Misano. Kevin Schwantz/suzuki are champions.

1994-1995 OWF9

Ram-air intakes introduced; re-designed fairing. Doohan takes first of five world titles with the NSR.

1996 OWJ1

Re-designed frame and engine.

1997 OWH0

Space between the V4 cylinders widened for a bigger air-box. J1 and H0 were developed back-toback.

1998-1999 OWK1

Unleaded fuel used.

2000 OWK6

Small improvements to motor, frame and aerodynamics.

2001 OWL6

Max Biaggi takes second in the championship behind Honda’s Valentino Rossi. Development slowed due to imminent entry of factory four-strokes.

2002 OWL9

Final (28th) generation of YZR500 competes against new four-strokes, including Yamaha’s own M1 inline-four.