1973 Yamaha GTMX80
Specifications and workshop reference information for the 1973 Yamaha GTMX80, including engine, chassis, service data and setup details.
Note: Specs are compiled from factory data, manuals and owner feedback. Bikes vary — if yours is different, jump into the forum and share it.
General Specifications
| Engine Type | Air-cooled, 2-stroke, single-cylinder, piston port |
| Displacement | 72 cc |
| Bore × Stroke | 47.0 × 41.0 mm |
| Compression Ratio | Approx. 6.6:1 |
| Maximum Power | Approx. 6.5 hp @ 7500 rpm |
| Maximum Torque | Approx. 6.5 Nm @ 7000 rpm |
| Carburetor | Mikuni VM18 |
| Lubrication | Premix |
| Fuel Mix Ratio | 20:1 – 25:1 |
| Ignition | Magneto (points) |
| Spark Plug | NGK B7HS |
| Spark Plug Gap | 0.6 – 0.7 mm |
Transmission
| Transmission Type | 4-speed manual |
| Clutch | Wet multi-plate |
| Primary Reduction | Approx. 3.722 |
| Final Reduction | Approx. 3.923 |
| Overall Reduction | Varies by gear |
Dimensions
| Overall Length | Approx. 1650 mm |
| Overall Width | Approx. 700 mm |
| Overall Height | Approx. 950 mm |
| Wheelbase | Approx. 1100 mm |
| Ground Clearance | Approx. 180 mm |
| Fuel Tank Capacity | Approx. 5.5 L |
Chassis
| Frame Type | Steel tubular, single cradle |
| Caster Angle | Approx. 28° |
| Trail | Approx. 90 mm |
| Front Suspension | Telescopic fork |
| Rear Suspension | Twin shock swingarm |
| Front Suspension Travel | Approx. 120 mm |
| Rear Suspension Travel | Approx. 90 mm |
Brakes & Wheels
| Front Tire | 2.50-17 |
| Rear Tire | 2.75-14 |
| Front Brake | Drum |
| Rear Brake | Drum |
Community
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