At the heart of the 2023 Janus Halcyon 450 allround motorcycle, Janus utilizes a 445 cc (27.2 cu in) oil & air-cooled single cylinder, four-stroke layout. In factory specification, peak output is rated at 30 HP (21.9 kW) at 7,500 rpm, transferring power to the rear wheel through a 5-speed gearbox and chain final drive. With a specific output of 67.4 HP per liter, the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.
On the scales, the Halcyon 450 measures 156.5 kg (345 lbs) dry, translating to a power-to-weight ratio of 0.19 HP/kg (5.22 kg per horsepower). Rider ergonomics and chassis geometry center around a 762 mm (30 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,422 mm (56 in) wheelbase engineered for balanced agility and highway composure. The 7.57-liter (2 US gal) fuel tank supports practical everyday commuting and weekend road stints, while factory top speed is listed at 145 km/h (90 mph).
Within MotoLibrary's Janus archive, this model family spans 2 indexed model years from 2021 to 2023, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
67.4 HP/L
Power-to-Weight
0.19 HP/kg (5.22 kg/HP)
Standover Height
762 mm (30 in)
Engine
Displacement445.0 ccm (27.15 cubic inches)
Engine TypeSingle cylinder, four-stroke
Engine DetailsSWM engine
Power30.0 HP (21.9 kW)) @ 7500 RPM
Compression10.1:1
Valves/Cylinder4
Fuel SystemInjection
Fuel ControlSingle Overhead Cams (SOHC)
IgnitionCDI
LubricationDry sump with gerotor pump, cartridge filter, and oil cooler
CoolingOil & air
Transmission
Gearbox5-speed
Final DriveChain (final drive)
ClutchWet multiplate
Performance
Top Speed144.8 km/h (90.0 mph)
Chassis
Frame TypeDOM tubular steel cradle
Front SuspensionProprietary dual progressive shock leading-link
Rear SuspensionProprietary cantilever transom with dual progressive coil-over Ikon shocks
Wheelbase1422 mm (56.0 inches)
Wheels & Brakes
Front Tyre4.00-18
Rear Tyre4.50-18
Front BrakesDouble disc. Two-piston caliper Brembo
Front Brake Ø280 mm (11.0 inches)
Rear BrakesSingle disc. Single Piston caliper brembo
Rear Brake Ø220 mm (8.7 inches)
WheelsAluminum alloy rims and stainless steel straight-pull spokes
Dimensions & Weight
Dry Weight156.5 kg (345.0 pounds)
Power/Weight0.1917 HP/kg
Seat Height762 mm (30.0 inches) If adjustable, lowest setting.
Overall Height1041 mm (41.0 inches)
Overall Length2184 mm (86.0 inches)
Overall Width787 mm (31.0 inches)
Fuel Capacity7.57 litres (2.00 US gallons)
Other
StarterElectric
Color OptionsBritish Racing Green, Vintage Red, Aga Cream, Black, American Blue, Charcoal, Olive, Cardinal Red
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
