Honda CB400F: A Cafe Racer's Dream in Disguise

KustomGaras

April 14, 2024

KustomGaras.com - Many of us may not know that Honda once had a legendary in-line 4-cylinder motorcycle in the 1970s, as there are very few articles/references about this motorcycle. The Honda CB400F, introduced in 1975 to complete Honda's 4-cylinder motorcycle lineup after the release of the CB740F.

The Birth of the Honda CB400F

In fact, the Honda CB400F was an upgrade from the previous year's CB350F model. To improve the performance and persona of the 350F, Honda's R&D team began working in late 1973 with the CB350F's engine and chassis. But its air-cooled, four-cylinder engine with a total displacement of 347cc and a redline of 10,000 rpm seemed like an engineering marvel at the time.

Photo via shannons.com.au

The CB350F produced less than 30hp, so for the CB400F, the power was upgraded by increasing the bore from 47mm to 51mm, increasing the displacement to 408cc and 37hp, which is why the motorcycle was nicknamed '408' after its release. The larger bore required a redesigned cylinder head and new pistons, and they also added slightly larger valves to increase intake capacity while keeping the 350 camshaft from being too heavy to move. The compression of the new piston and combustion chamber increased fractionally, from 9.3 to 9.4:1. The Honda CB400F still used four carburetors supplied by Keihin 20mm.

Photo via 4into1.com

Aesthetics and Design of the Honda CB400F

Physically, the most noticeable change to the naked eye from the engine can be seen in the exhaust system using 4-1 where the four exhaust pipes are made into a single pipe at the end. The use of an angled fuel tank and classic cafe racer-style short handlebars all give it the look and feel of a classic racing motorcycle.

Kaz Yoshima Honda CB400F

Kaz Yoshima Honda CB400F Kaz Yoshima is a racer who used to achieve success with this motorcycle, which was dominated by 2-stroke racing motorcycles at the time. The CB400F's four-stroke engine was smoother, more refined, and far more economical than the two-stroke engines. To keep the engine at its best performance, Honda crammed in a 6-speed transmission, which was very rare at the time.

Honda CB400F Updates

1975 - Frame number CB400F-1007709

First launched in red or blue with matte black side panels.

1976 - Frame number CB400F-1010771

No major changes to the engine with the exception of the passenger footrests no longer attached to the swing arm and bolted to a loop attached to the chassis.

1977 - Frame number CB400F-1048301

Again, no major mechanical improvements, a locking filler cap was added. The cylinder studs were made longer to address the common problem of cylinder head leaks.

1978 - Frame number CB400F-1074740

The F2 model was launched (often mistakenly referred to as the F1 model previously) a few cosmetic changes marked the arrival of this new engine, the most noticeable being the repositioning of the center tank cap to a hidden hole, balancing the position.

Honda CB400F Specifications

Engine - Air-cooled SOHC 4-cylinder
Displacement - 408cc
Bore x stroke - 51x 50mm
Claimed power - 37bhp @ 8500rpm
Torque - 24ft-lb @ 7500rpm
Carburetor - Keihin 4 x 20mm
Transmission - 6-speed
Frame - Steel cradle
Suspension - 33mm telescopic forks. Dual rear shocks
Brakes - Front 267mm disc, rear drum
Tires - 3.00 x 18", 3.50 x 18"
Weight - 170kgs
Top speed - 102mph (160kmh)
Wheelbase - 1359mm
Fuel capacity - 14 liters

Honda CB400F Custom Inspirations

The Honda CB400F's timeless design and impressive performance have made it a favorite among custom motorcycle builders. From cafe racers with sleek bodywork and clip-on handlebars to scramblers with knobby tires and raised suspension, the CB400F offers a versatile platform for customization.

Here are some of the popular custom styles for the Honda CB400F:

Cafe Racer: This is perhaps the most common custom style for the CB400F. Builders often replace the stock handlebars with clip-ons, install a cafe racer seat, and modify the fuel tank for a more aggressive look.
Brat Style: This style emphasizes a minimalist aesthetic. Builders typically remove unnecessary bodywork, shorten the front fender, and install a single seat.
Scrambler: For those who crave off-road adventure, the CB400F can be transformed into a capable scrambler with knobby tires, raised suspension, and high handlebars.
Tracker: Similar to the scrambler, trackers prioritize off-road performance but often have a sleeker aesthetic. Builders might replace the headlight with a smaller unit and swap the front fender for a minimalist option.
Board Tracker: Taking inspiration from the early days of motorcycle racing, some enthusiasts transform the CB400F into a board track-style machine with wooden running boards and a stripped-down design.

The possibilities for customizing the Honda CB400F are endless. With its robust engine and classic good looks, the CB400F remains a popular choice for those who want to create a unique and personalized motorcycle.

Conclusion

The Honda CB400F may not be as widely known as some of its bigger siblings, but it holds a special place in the hearts of enthusiasts who appreciate its blend of performance, style, and reliability. From its impressive factory specs to its potential for customization, the CB400F is a true testament to Honda's engineering prowess and timeless design philosophy.