Historical Engineering Highlight: The Yamaha SZR 660 is a unique specimen of mid-90s engineering, representing a rare collaboration between Yamaha Japan and Belgarda (Yamaha Italy). While its heart—the 659cc single—was sourced from the rugged XTZ 660 Ténéré, its skeleton was a direct evolution of the TZR 250 (3MA) aluminum Deltabox frame. This created a ‘Supermono’ that offered GP-level handling paired with the torque-heavy reliability of an adventure engine.
| Quick Specs: Yamaha SZR 660 (4SU) | |
|---|---|
| Production Years | 1995-1997 |
| Engine | 659cc, Liquid-cooled, 5-valve SOHC Single |
| Oil Requirement | 2.1 L – 10W-40 JASO MA2 |
| Spark Plug | NGK DPR8EA-9 |
| Battery Type | YTX9-BS |
| Tire Sizes | F: 110/70-17 | R: 150/60-17 |
Technical Review: The Belgarda Masterpiece
The SZR 660 (4SU) remains one of the most underrated lightweight sportbikes of the 20th century. At its core is the Genesis 5-valve cylinder head design, which was intended to optimize intake gas flow and combustion efficiency—a technology shared with the legendary YZF-R1 and TDM series of the era.
From a chassis perspective, the SZR 660 utilized premium components often reserved for higher-displacement machines. It featured 41mm inverted Paoli forks and a Brembo braking system (320mm front disc), providing feedback and stopping power that significantly outclassed its contemporary rivals like the BMW F650 or the Suzuki Freewind.
Maintenance Guide & Fluid Specifications
To maintain the SZR 660’s performance, adherence to the following technical specifications is critical:
1. Lubrication System
The SZR 660 uses a dry-sump lubrication system. When performing an oil change, ensure you use 2.1 Liters of 10W-40 JASO MA2 compliant oil. Because the engine shares oil with the gearbox, the MA2 rating is essential to prevent clutch slippage.
2. Wheel and Tire Setup
The 4SU model is sensitive to tire profile. For optimal turn-in characteristics, maintain the following pressures:
- Front: 110/70-17 54H at 2.0 bar (29 psi)
- Rear: 150/60-17 66H at 2.25 bar (33 psi)
3. Electrical and Ignition
The ignition system relies on a single NGK DPR8EA-9 spark plug. Gapping should be checked every 6,000 km. The electrical system is powered by a YTX9-BS battery; given the high-compression nature of the 660cc single, a healthy CCA (Cold Cranking Amps) rating is vital for reliable starting.
Common FAQs
What makes the 4SU model different from other SZR variants?
The 4SU is the primary European designation for the SZR 660 produced by Belgarda. It features specific carburetor jetting and exhaust configurations designed to meet European noise and emission standards of the mid-90s.
Is the SZR 660 suitable for modern highway speeds?
While the single-cylinder engine produces significant vibration at high RPMs, the SZR 660 is geared to comfortably cruise at 110-120 km/h, with a top speed approaching 170 km/h.