| Quick Specs: GS 650 G Katana | |
|---|---|
| Production Years | 1981 – 1983 |
| Engine Type | 4-Stroke, DOHC, Inline-4, 8-Valve |
| Displacement | 673cc |
| Final Drive | Shaft Drive |
| Engine Oil | SAE 10W-40 API SE/SF (2.5 L) |
| Spark Plugs | NGK D8EA (0.6–0.7 mm gap) |
| Battery | YB14L-A2 |
| Tire Sizes | F: 100/90-19 / R: 110/90-17 |
The Suzuki GS 650 G Katana holds a unique position in motorcycle history as the first shaft-driven motorcycle to wear the legendary ‘Katana’ badge. While the 1100 and 750 variants focused on pure sport performance, the 650G was engineered by Hans Muth’s Target Design to harmonize aggressive aesthetics with the reliability and low maintenance required for long-distance sport touring.
Engineering & Performance
At the heart of the GS650G is a 673cc DOHC inline-four engine featuring Suzuki’s Twin Swirl Combustion Chamber (TSCC) technology. This design enhances flame speed and efficiency, providing the bike with a surprisingly punchy mid-range. Unlike its chain-driven siblings, the GS650G utilizes a spiral-bevel gear shaft drive system, which significantly reduces the maintenance burden for high-mileage riders while maintaining a sleek, uncluttered rear profile.
Maintenance & Fluid Specifications
To maintain the longevity of the TSCC engine and the intricate shaft-drive assembly, adhering to precise fluid specifications is mandatory:
- Engine Lubrication: Use 2.5 liters of high-quality SAE 10W-40 oil. For vintage seals and clutch performance, an API SE or SF rating is recommended.
- Ignition System: The GS650G utilizes NGK D8EA spark plugs. Ensure the electrode gap is set precisely between 0.6mm and 0.7mm to prevent fouling and ensure crisp throttle response.
- Electrical: The system relies on a standard YB14L-A2 lead-acid battery. Given the age of these charging systems, regular voltage regulator checks are advised.
Handling and Chassis Setup
The GS650G features a robust steel cradle frame paired with air-assisted front forks. Handling is heavily dependent on maintaining correct tire pressures, especially given the weight of the shaft drive unit. The factory recommends 1.75 bar (25 psi) for the front 100/90-19 tire and 2.0 bar (28 psi) for the rear 110/90-17 tire. Modern radial tires are often swapped in, but riders should ensure they match the load ratings of the original bias-ply specifications.
MotoSpecsLab Verdict
The GS 650 G Katana is a masterclass in early 80s functional design. It offers the iconic ‘Silver Saber’ styling with a mechanical package that is far more practical for the modern enthusiast than the peakier, chain-driven sportbikes of the same era. Proper maintenance of the final drive and the DOHC valvetrain ensures this machine remains a reliable classic for years to come.