Both models of the Suzuki GS 550 produced in 1978 were fitted with the same engine: a 549 cc (cubic-centimeter), in-line, air-cooled four-cylinder. Each cylinder had two valves. The engine on these motorcycles produced 49 horsepower at 9,000 rpm.
Both 1978 models of the Suzuki GS 550 had the same dimensions. They both had a 56.5-inch wheelbase, a length of 85.6 inches, a width of 33.5 inches and a height of 45.3 inches.
The GS 550 weighed 429 pounds. The GS 550 featured a single front disc brake, like the 1977 model. The GS 550 E was available with either a single front disc or twin front disc brakes. According to Suzuki Cycles, the newer braking system offered better braking performance. The GS 550 E was released as the GS 550's replacement in August of 1978. This GS 550 E also had a rear disc brake. Other than the new braking system, the GS 550 E was manufactured to the same specifications as the GS 550.