| Attribute | Specification |
|---|---|
| Production Years | 1982–1984 |
| Engine Type | Air-cooled, 4-cylinder, DOHC |
| Oil Requirement | 2.7 L (SAE 10W-40, 10W-50, 20W-40, 20W-50) |
| Tire Sizes | F: 90/90-18 51H | R: 110/90-18 61H |
| Battery Type | YB12A-A |
| Spark Plug | NGK DR8ES (0.6–0.7 mm gap) |
Engineering Highlight: The Kawasaki GPZ 550 UT (Unitrak) holds a significant place in motorcycling history as the first middleweight sportbike to successfully implement a rising-rate single-shock rear suspension system. This “Unitrak” design, coupled with an air-adjustable front fork, allowed the KZ550B/H to dominate the 550cc class by offering superior high-speed stability and cornering precision that its twin-shock predecessors could not match.
Technical Overview
The GPZ 550 UT is powered by a refined 553cc inline-four engine. While the core architecture remained air-cooled, the ‘UT’ (Unitrak) variant introduced significant improvements in frame rigidity and aerodynamic fairing design. For the 1982–1984 production run, Kawasaki focused on maximizing the power-to-weight ratio, making it a favorite for both club racers and street enthusiasts.
Maintenance Specifications
Lubrication System
To maintain the longevity of the DOHC valvetrain, regular oil changes are critical. The system requires 2.7 liters of oil. Depending on your climate, Kawasaki recommends SAE 10W-40 for general use, though 20W-50 is preferred in hotter environments. Ensure the oil meets API SE, SF, or SG standards to protect the wet clutch system.
Chassis and Tires
The GPZ 550 UT utilizes an 18-inch wheel configuration both front and rear. For optimal handling, the Front (90/90-18 51H) should be maintained at 2.0 bar (28 psi). The Rear (110/90-18 61H) requires 2.25 bar (32 psi) for standard riding, increasing to 2.5 bar (36 psi) when carrying a passenger or traveling at sustained high speeds.
Electrical and Ignition
The electrical system relies on a YB12A-A lead-acid battery. Ignition performance is highly sensitive to the spark plug condition. Use NGK DR8ES plugs and verify the gap is precisely set between 0.6 and 0.7 mm. Fouled plugs or an incorrect gap can lead to poor cold-start performance and mid-range hesitation.
MotoSpecsLab Verdict
The KZ550B/H remains a high-water mark for 1980s engineering. Its combination of the Unitrak rear end and the punchy 553cc engine makes it a rewarding machine for collectors. Strict adherence to the 2.7L oil capacity and precise tire pressures is essential to preserve the vintage handling characteristics that made this bike a legend.