| Specification | Data |
|---|---|
| Model / Year | Kawasaki H2 750 MACH IV – H2-B (1974) |
| Engine Type | 748cc, 2-Stroke, 3-Cylinder |
| Oil System | 2-stroke injection (2.0 L Capacity) |
| Spark Plug | NGK B9HS |
| Tires (F/R) | 3.25-19 4PR / 4.00-18 4PR |
| Tire Pressure (F/R) | 1.7 bar (25 psi) / 2.0 bar (28 psi) |
| Battery | 12N12A-4A-1 |
While its predecessor, the 1972 H2, earned the terrifying moniker “The Widowmaker,” the 1974 Kawasaki H2-B represents a significant engineering milestone: it was the first iteration where Kawasaki prioritized stability over raw, unbridled chaos. By lengthening the swingarm and revising the frame geometry, Kawasaki engineers successfully shifted the center of gravity forward, mitigating the notorious front-end lightness that plagued earlier Mach IV models.
Engineering Deep Dive: The H2-B Refinements
The H2-B is powered by the legendary 748cc air-cooled, three-cylinder two-stroke engine. By 1974, Kawasaki had refined the CDI (Capacitor Discharge Ignition) system to provide more consistent spark across the powerband, which was critical for a machine producing roughly 74 horsepower. Unlike the earlier models, the H2-B featured a more sophisticated oil injection routing system to ensure the outer cylinders received adequate lubrication during high-thermal stress cycles.
Maintenance and Service Guidelines
For the collector or the vintage racer, maintaining the H2-B requires strict adherence to factory tolerances. At MotoSpecsLab, we emphasize the importance of the lubrication system. The 2.0-liter oil tank must be filled with high-quality 2-stroke injection oil; failure of the pump or starvation of the lines is the leading cause of crankshaft bearing failure in these triples.
- Ignition: Ensure the NGK B9HS spark plugs are gapped correctly to maintain the integrity of the CDI system.
- Chassis: The H2-B utilizes a 12N12A-4A-1 battery. Given the high-vibration nature of the triple-cylinder engine, ensure the battery mount is secure and terminals are treated for corrosion.
- Tires: To maintain the improved handling characteristics of the H2-B, stick to the 3.25-19 front and 4.00-18 rear sizing. Operating at 1.7 bar (front) and 2.0 bar (rear) is essential for vintage carcass stability.
Technical FAQ
What oil is best for the H2-B?
The H2-B requires a dedicated 2-stroke injection oil. Do not use premix-only oils in the injection tank, as their viscosity may not be compatible with the mechanical oil pump.
How does the H2-B differ from the original H2?
The H2-B features a longer swingarm, a different fuel tank shape, and revised instrumentation. It also saw a slight reduction in peak power in exchange for a more linear torque curve and better fuel economy compared to the 1972-73 models.
What is the correct tire pressure for street use?
For standard street riding, Kawasaki specifies 25 psi (1.7 bar) for the front tire and 28 psi (2.0 bar) for the rear tire to balance grip and tire longevity.