Suzuki GS400: A Comprehensive Look

The Suzuki GS400, a significant model in Suzuki's transition to four-stroke engines, presents an interesting case study for motorcycle enthusiasts and mechanics alike. Launched in October 1976, it marked Suzuki's serious foray into the four-stroke segment since the Colleda COX in the 1950s. Alongside the GS750, the GS400 was among the very first four-stroke Suzukis to hit the market, soon to be followed by the GS550. This new GS series shared technical similarities with the Kawasaki Z1, a departure from Suzuki's previous offerings in smaller displacement classes. The GS400, in particular, was lauded for its modern construction, setting it apart from its contemporaries.

The GS400's Unique Twin-Cylinder Configuration

While the larger GS550 and GS750 models featured inline-four engines, the GS400 adopted a parallel twin configuration. This design incorporated a 180-degree crank and a gear-driven balancer, a thoughtful addition aimed at mitigating vibrations that could reach the chassis and the rider. This focus on rider comfort, combined with double overhead cams, two valves per cylinder, a roller bearing crank, and a 6-speed transmission, positioned the GS400 as a highly advanced motorcycle for its class upon its release. The inclusion of a gear indicator and compliant suspension, supported by a tubular double cradle frame, further cemented its status as a technically sophisticated machine.

Braking System: A Closer Look

A crucial aspect of any motorcycle's performance and safety is its braking system. For the Suzuki GS400, the specifications reveal a clear answer to the question of its rear braking capability. The standard GS400 model was equipped with a 160 mm Drum brake at the rear. This is in contrast to the front, which featured a more contemporary single 270 mm disc with a 1-piston caliper. This combination of a disc front brake and a drum rear brake was common for many motorcycles of this era, balancing stopping power with cost-effectiveness.

Evolution and Variants

Suzuki was keen to capture a significant portion of the market, and to achieve this, they introduced several variants of the GS400. Alongside the standard wire-wheel model, an exclusive cast-wheel edition was also available. Furthermore, the GS400L "Low Slinger" cruiser offered a different style, catering to riders who preferred a more laid-back riding position. A low-cost version was also introduced, featuring less equipment and, notably, a drum front brake in addition to the drum rear brake, further highlighting the variations in specification across the range.

The GS400 wasn't static for long. For the 1979 model year, Suzuki introduced a 425cc version for certain markets, an adaptation to increasing competition and a desire for enhanced performance. This increased displacement provided a modest boost in power and torque. However, the original GS design was nearing the end of its lifecycle. By 1980, Suzuki unveiled a thoroughly reworked GS, now enlarged to 450cc. This new iteration featured a plain bearing crank and modifications to the bore and stroke, designed to reduce stress at high RPMs and increase overall power output. While the GS450 retained the two-valve-per-cylinder design, albeit improved, some markets also saw a 400cc version that shared the new GS450's bottom end but was fitted with new TSCC 4-valve cylinder heads.

Suzuki's Four-Stroke Strategy

Suzuki's history was heavily associated with two-stroke engines, and for a considerable period, they allowed other manufacturers to lead the way in the development of complex and sometimes unreliable four-stroke technology. Honda's successful CB750, launched in the late sixties, set a benchmark. Suzuki's initial response, with their powerful two-stroke T and GT series, were excellent bikes in the early seventies. However, with the advent of stricter emission regulations, particularly in the USA, the future of high-performance two-strokes looked increasingly uncertain. The RE5 rotary engine, despite its innovation, also proved to be commercially unsuccessful. It became evident that the future lay in four-stroke engines.

With the introduction of the GS series, Suzuki demonstrated its capability in four-stroke engine technology. The new engines were conventional in design, drawing on established engineering practices but refined to compete with, and often surpass, their rivals. The Suzuki GS engines, including the GS400, quickly gained a reputation for being strong, reliable, and paired with excellent gearboxes. This robust engineering is a key reason why these bikes remain popular among classic motorcycle enthusiasts today.

Performance and Handling: A Balanced Approach

When comparing the GS400 to its contemporaries, it's important to note its overall balance. While it may not have been the absolute best in terms of handling, outright speed, braking performance, or suspension compliance, it offered a compelling package that excelled in combining these elements. The Honda CB400 Four, for instance, offered a smoother engine. However, the GS400's physically larger frame provided more space and comfort, particularly for taller riders or those frequently carrying a passenger. The suspension system struck an admirable balance between responsive handling and comfortable ride quality, and the chassis provided commendable stability, even when ridden enthusiastically.

Key Specifications at a Glance

To summarise the technical prowess of the Suzuki GS400 (1976-77), here's a quick look at some key specifications:

Frequently Asked Questions

Does the Suzuki GS400 have a rear brake?

Yes, the Suzuki GS400 is equipped with a rear brake. Specifically, the standard models feature a 160 mm drum brake at the rear.

What type of engine does the Suzuki GS400 have?

The Suzuki GS400 is powered by a 398cc, four-stroke, parallel twin-cylinder engine with Double Overhead Cams (DOHC) and two valves per cylinder.

What were the main differences between the GS400 and GS400E?

The "E" designation typically signified an optional high-end version. For the GS400, this often meant the inclusion of cast wheels instead of wire wheels. It's worth noting that even with cast wheels, the 400 model retained its drum rear brake, unlike some other GS variants.

Was the GS400 the first four-stroke motorcycle from Suzuki?

No, the GS400 was not the very first four-stroke Suzuki. Suzuki had produced four-stroke motorcycles in the past, such as the Colleda COX in the 1950s. However, the GS400, launched in 1976, was one of Suzuki's first significant and modern four-stroke offerings, marking a major strategic shift for the company.

What made the GS400 advanced for its time?

The GS400 was considered advanced due to its comprehensive package of features for its class, including double overhead cams, a 6-speed transmission, a gear indicator, a gear-driven balancer, and a sophisticated frame and suspension system. These features, combined in a 400cc motorcycle, were not commonly found together in the market at that time.

In conclusion, the Suzuki GS400 was a pivotal model that showcased Suzuki's growing expertise in four-stroke engine technology. Its balanced performance, reliable engineering, and thoughtful design made it a strong contender in the mid-capacity motorcycle market of the late 1970s, and it remains a respected classic today. The presence of a rear drum brake was a standard and functional component of its braking system.