| Attribute | Specification |
|---|---|
| Production Years | 1994 – 1999 |
| Engine Type | 659cc, Single Cylinder, 5-Valve SOHC |
| Oil Type / Capacity | SAE 20W-40 or 10W-30 (JASO MA) / 2.1 L |
| Tire Sizes (F/R) | 90/90-21 54S / 120/90-17 64S |
| Tire Pressure (F/R) | 2.0 bar / 2.0 bar (Solo) / 2.25 bar (Loaded) |
| Battery | YTX9-BS |
| Spark Plug | NGK DPR8EA-9 |
While most single-cylinder enduros of the 1990s relied on traditional four-valve heads, the Yamaha XTZ 660 Ténéré (4MY) distinguished itself through the application of Yamaha’s proprietary Genesis engineering philosophy. It utilized a sophisticated 5-valve cylinder head (three intake and two exhaust), a design intended to maximize volumetric efficiency and broaden the powerband—a rarity for mid-displacement thumping singles of that era.
Engineering Overview: The 4MY Evolution
The 4MY generation represents the final refinement of the liquid-cooled 660 Ténéré line before the model went on hiatus. Unlike its predecessor (3YF), the 4MY featured updated bodywork, including more aerodynamic fairings and improved cooling airflow to the radiator. The heart of the machine remained the 659cc liquid-cooled single, which was praised for its reliability and smooth power delivery at highway speeds, thanks to its integrated counter-balancer.
Technical Maintenance Guide
To maintain the longevity of the 4MY, adherence to specific technical tolerances is mandatory for the Editor-in-Chief’s seal of approval.
Lubrication System
The XTZ 660 utilizes a dry-sump lubrication system. When performing an oil change, ensure the engine is warm. The total capacity is 2.1 liters. We recommend SAE 20W-40 for warmer climates or 10W-30 for temperate regions, provided it meets JASO MA standards to ensure wet-clutch compatibility.
Chassis and Contact Patch
The dual-sport capability of the 4MY is heavily dependent on tire selection and pressure. The standard 21-inch front and 17-inch rear setup requires 2.0 bar (29 psi) for both ends during solo riding. If the bike is loaded with panniers or a pillion, the rear pressure must be increased to 2.25 bar (33 psi) to prevent carcass overheating and maintain stability.
Ignition and Electrical
The electrical system is supported by a YTX9-BS battery. For optimal combustion and fuel efficiency, the NGK DPR8EA-9 spark plug should be inspected every 6,000 km. Ensure the gap is set to factory specifications to prevent misfires under high-load, low-RPM scenarios typical of off-road trekking.
MotoSpecsLab Verdict
The Yamaha XTZ 660 Ténéré 4MY remains a pinnacle of ’90s over-engineering. Its 5-valve head provides a unique mechanical character that modern singles often lack. For the collector or the adventure rider, it offers a perfect balance of mechanical simplicity and sophisticated engine design, provided the cooling and lubrication systems are maintained with precision.