Classic and Classy Motorcycles Ltd

Historical Context

Introduced in 1969 and continuing through the early 1970s, the Kawasaki H1 500cc Mach III was a groundbreaking motorcycle that earned a reputation as one of the most exciting performance bikes of its time. By 1973, the H1 had matured into a more refined version of its early aggressive self, with improved handling and braking. It was powered by a fierce two-stroke, three-cylinder engine that produced explosive acceleration, making it a favorite among thrill-seeking riders. Kawasaki’s goal was to create the fastest-accelerating production motorcycle in the world, and the H1 delivered—earning it the nickname “The Widowmaker” due to its raw power and light frame.

Technical Specifications and Features

• Year: 1973
• Make: Kawasaki
• Model: H1 500 Mach III
• Engine Displacement: 498cc
• Engine Type: Air-cooled, two-stroke, inline 3-cylinder
• Compression Ratio: 7.0:1
• Power Output: Approximately 60 horsepower
• Torque: Approximately 42 lb-ft
• Transmission: 5-speed manual
• Brakes: Single disc front, drum rear
• Fuel System: Triple Mikuni carburetors
• Fuel Capacity: 4.0 gallons
• Wheelbase: 54.3 inches
• Dry Weight: Approximately 384 pounds
• Top Speed: Over 115 mph
• Key Features: CDI ignition, Ram Air cylinder head cooling system, aggressive powerband, and iconic 3-pipe exhaust.

Project Potential

A 1973 Kawasaki H1 project is a dream build for vintage two-stroke enthusiasts. Restoring one to its original specification preserves a key piece of performance motorcycle history. The distinctive triple exhaust, classic tank lines, and bold color schemes make the H1 stand out visually. Mechanically, the two-stroke triple is simple but demanding—requiring attention to carburetor tuning and timing for peak performance. Thanks to its cult following, parts are available, and communities exist worldwide to help guide restorations or light customizations. Whether as a show bike or weekend screamer, the H1 is an icon worth reviving.

Riding Experience

Once restored, the H1 offers a thrilling and visceral ride unlike anything produced today. The power comes on abruptly in the mid-range, launching the bike forward with a signature two-stroke bark. Lightweight and compact, it’s agile but requires a steady hand—braking and suspension performance are modest by modern standards. The narrow chassis and upright seating give the rider good control, but its high-revving, unpredictable nature makes it better suited for experienced riders. Still, there’s nothing quite like the acceleration and sound of a properly tuned Kawasaki H1.

Legacy and Collectibility

The 1973 H1 500cc Mach III remains one of the most collectible and respected Japanese motorcycles of the era. It was bold, fast, and unapologetically aggressive—traits that helped redefine what a middleweight motorcycle could be. The 1973 model year reflects improved build quality and rideability over the earlier versions, making it a practical choice for riders who want authenticity with just a bit more refinement. Restoring a 1973 H1 preserves one of the most important two-stroke triples ever built, ensuring its legend lives on for future generations of motorcycle fans.