| Parameter | Specification |
|---|---|
| Production Years | 1982 – 2000 |
| Engine Type | Single-cylinder, 4-stroke, SOHC |
| Oil Grade | SAE 10W-40 API SF or SG |
| Front Tire | 2.75-18 42P |
| Rear Tire | 3.50-16 58P |
| Battery | YB7-A / 12N7-4B |
| Spark Plug | NGK D8EA / DR8EA |
The Suzuki GN 125 (NF41A) holds a unique place in motorcycling history as one of the first machines to successfully blend the ‘cruiser’ aesthetic with a high-revving, over-square OHC engine architecture borrowed from the rugged DR off-road series. This engineering choice provided the GN 125 with a level of mechanical resilience and top-end performance that far exceeded its budget-commuter competitors of the 1980s.
Engineering Overview
The heart of the NF41A is its air-cooled, 124cc single-cylinder engine. Unlike many utility bikes of the era that used pushrod configurations, Suzuki opted for a Chain-driven Single Overhead Camshaft (SOHC). This allowed for better valve timing precision at higher RPMs. The chassis, characterized by its teardrop tank and stepped seat, offers a low center of gravity, making it an ideal platform for both novice riders and urban delivery fleets.
Maintenance Specifications
Lubrication System
To maintain the longevity of the SOHC valvetrain, regular oil changes are critical. The NF41A uses a wet-sump system. Use a high-quality SAE 10W-40 oil meeting API SF or SG standards. The capacity is 0.85 Liters for a standard drain, or 0.95 Liters when the internal oil filter is replaced.
Tires and Pressure
The GN 125 utilizes a staggered wheel setup (18-inch front, 16-inch rear) to achieve its cruiser stance. For optimal handling and fuel economy, maintain the following pressures:
- Front (2.75-18): 1.75 bar (25 psi)
- Rear (3.50-16): 2.00 bar (28 psi) solo / 2.25 bar (33 psi) with passenger
Ignition and Electrical
The ignition system relies on a specific spark plug gap to ensure complete combustion. Whether using the NGK D8EA or the resistor-type DR8EA, the gap must be set between 0.6 – 0.7 mm. The electrical system is powered by a 12V YB7-A or 12N7-4B battery; ensuring clean terminals is essential for the reliable operation of the electric starter.
MotoSpecsLab Verdict
The Suzuki GN 125 NF41A remains a masterclass in ‘simple-but-effective’ engineering. Its over-engineered engine and accessible ergonomics have allowed it to remain in production in various forms globally for decades. For the modern owner, adhering to the 10W-40 oil requirements and precise valve clearances is the key to another 40,000 miles of service.