The 1973 Kawasaki Z1-900 RS from Japan was powered by a 903cc DOHC inline-4 producing 82hp at 8500rpm. Weighing 230.0kg (507 lbs) and with a seat height of 820mm, it was aimed at standard riders.
The 1980 Yamaha XJ650 by contrast offered 653cc of DOHC inline-4 power, delivering 71hp at 9000rpm. Tipping the scales at 215.0kg (474 lbs) with a top speed of 190km/h (118 mph), it offered a distinct riding experience. 1970s bikes from the Japanese superbike revolution are increasingly sought after. Clean, original examples have seen significant value appreciation.
Specifications Comparison
| 1973 Kawasaki Z1-900 RS | 1980 Yamaha XJ650 | |
|---|---|---|
| Displacement | 903 cc | 653 cc |
| Power | 82 hp | 71 hp |
| Torque | 73.0 Nm | 56.0 Nm |
| Cylinders | 4 | 4 |
| Top Speed | 210 km/h | 190 km/h |
| Quarter Mile | — | — |
| Dry Weight | 230.0 kg | 215.0 kg |
| Wet Weight | 250.0 kg | 232.0 kg |
| Seat Height | 820 mm | 800 mm |
| Wheelbase | 1490 mm | 1440 mm |
| Fuel Capacity | 18.0 L | 16.0 L |
| Gears | 5 -speed | 5 -speed |
The Verdict
For pure standard performance, the 1973 Kawasaki Z1-900 RS has the edge thanks to more power (82hp vs 71hp) and a higher top speed. The 1980 Yamaha XJ650, however, excels when all-round versatility and everyday riding is the priority and offers a lighter package. For collectors, the 1973 Kawasaki Z1-900 RS commands more attention with a 8/10 collectibility rating. Parts availability is moderate for the 1973 Kawasaki Z1-900 RS and good for the 1980 Yamaha XJ650 — an important factor for any restoration project.
About the 1973 Kawasaki Z1-900 RS
Kawasaki released the 1973 Kawasaki Z1-900 RS in 1973 with a 903cc DOHC inline-4 powerplant making 82hp — a definitive standard motorcycle.
Full 1973 Kawasaki Z1-900 RS Profile →About the 1980 Yamaha XJ650
Born in 1980, the 1980 Yamaha XJ650 is a 653cc four-cylinder standard motorcycle producing 71hp from Yamaha.
Full 1980 Yamaha XJ650 Profile →