Engine

The Honda CB450 has an air-cooled, 4-stroke DOHC V-twin mill. Compression ratio plays between 9.0:1 and 9.3:1, while dual 32-mm constant-velocity carburetors handle air-fuel mixture across all production models (some sources indicate 36-mm carbs).

Bore-stroke ratio was initially 70 x 57.8 mm (2.76 x 2.28 inches). It later changed to an over-square 75 x 50.6 mm (2.95 x 2.00 inches) to improve fuel delivery and airflow and allow the engine to rev higher.

Similarly, piston displacement started at 444 cm³ (27.1 in³) but eventually increased to 447 cm³ (27.3 in³) due to bore and stroke adjustments.

Overall, these configurations lend to an advertised top speed of 112 mph (180 km/h), a horsepower of 43 – 45 hp/32 – 33.5 kW @ 8,500 – 9,000 RPM, and a maximum torque of 37.4 Nm (3.8 kgf-m, 27.6 ft-lb) @ 8,500 RPM. Although the motorcycle has a high-revving nature, no one in CB450-dedicated forums has so far declared going beyond the 110-mph top-speed mark.

Fuel & Lubrication

Fuel tank capacity across all Super Sport trims is 12.5 L (3.3 USgal) of unleaded gasoline and a PON 87/RON 91 minimum rating. Only the K2 model had a 13.5-L/3.57-USgal fuel tank (though with the same reserve capacity of 1.8 L/0.5 USgal). ’80s versions, on the other hand, had their tank capacity upgraded to 17 L (4.5 USgal), with a 3.5-L/0.92-USgal reserve.

Lube-wise, the CB450 has a Forced lubrication (wet sump) system and requires 2.8 – 3.0 L (2.9 – 3.2 US quarts) of Honda GN4 SAE 10W-40 motor oil or its equivalent. Other multigrade oils are permissible (as specified in the manual), provided they have a minimum API grade of SJ and meet JASO T903 MA/MB standards. Alternatively, the following single-grade oils are also allowed – SAE 30 (above 15°C/59°F); SAE 20 (0°C/32°F to 15°C/59°F); SAE 10 (below 0°C/32°F).

Drivetrain

During its launch, the CB450 had a manual 4-speed gearbox. It changed in 1968 with the introduction of the K-series (until 1974), which had a 5-speed, forward constant-mesh. It changed again in 1982, with the launch of the Nighthawk trims with their 6-speed constant-mesh transmission. These return-shift systems were left foot-operated and mated to a wet, multi-plate clutch assembly. A standard (non O-ring, clip-type) 530 drive chain handles power delivered to the wheels.

(Source: https://bigbikereviews.com/honda-cb450/ )