Built around Suzuki's sport motorcycle platform, the 1985 Suzuki RG 400 Gamma pairs a 397.4 cc (24.3 cu in) liquid-cooled v4, two-stroke architecture with road-focused gearing. In factory specification, peak output is rated at 59 HP (43.1 kW) at 9,000 rpm, transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 148.5 HP per liter, the engine character is placing it firmly in high-revving supersport territory where top-end breathing dominates.
On the scales, the RG 400 Gamma measures 181 kg (399 lbs) wet (curb), translating to a power-to-weight ratio of 0.33 HP/kg (3.07 kg per horsepower). Rider ergonomics and chassis geometry center around a 770 mm (30.3 in) seat height — offering a neutral standover height that accommodates most average-inseam riders without sacrificing cornering clearance, combined with a 1,425 mm (56.1 in) wheelbase engineered for balanced agility and highway composure. The 22-liter (5.8 US gal) fuel tank paired with a rated consumption of 9 L/100 km provides an estimated theoretical range of roughly 244 km (152 miles) between fill-ups, while factory top speed is listed at 205 km/h (127 mph).
Within MotoLibrary's Suzuki archive, this model family spans 2 indexed model years from 1985 to 1987, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
148.5 HP/L
Power-to-Weight
0.33 HP/kg (3.07 kg/HP)
Theoretical Range
~244 km (152 mi)
Engine
Displacement397.4 ccm (24.25 cubic inches)
Engine TypeV4, two-stroke
Engine DetailsV4, two-stroke
Power59.0 HP (43.1 kW)) @ 9000 RPM
Compression7.0:1
Bore x Stroke50.0 x 50.6 mm (2.0 x 2.0 inches)
Valves/Cylinder1
Fuel SystemCarburettor. Mikuni VM28SH (VM28SS), four (Flat Slide)
Fuel Consumption9.00 litres/100 km (11.1 km/l or 26.14 mpg)
Greenhouse Gases208.8 CO2 g/km. (CO2 - Carbon dioxide emission)
Exhaust4 into 4 steel pipes with expansion chambers
Chassis
Frame TypeDouble downtube, full cradle, box section aluminium perimetre frame
Rake25.5°
Trail110 mm (4.3 inches)
Front Suspension38mm Telescopic pneumatic/coil spring oil damped with posi-damp unit, adjustable anti dive valving. Spring pre-load fully adjustable
Front Travel130 mm (5.1 inches)
Rear SuspensionFull-floating suspension sytem, gas/oil damped, spring pre-load fully adjustable
Rear Travel127 mm (5.0 inches)
Wheelbase1425 mm (56.1 inches)
Ground Clearance120 mm (4.7 inches)
Wheels & Brakes
Front Tyre2.50-16
Rear Tyre2.75-17
Front BrakesDouble disc. 4-piston calipers
Front Brake Ø260 mm (10.2 inches)
Rear BrakesSingle disc. 2-piston caliper
Rear Brake Ø210 mm (8.3 inches)
Dimensions & Weight
Dry Weight154.0 kg (339.5 pounds)
Weight incl.181.0 kg (399.0 pounds)
Power/Weight0.3831 HP/kg
Seat Height770 mm (30.3 inches) If adjustable, lowest setting.
Overall Height1185 mm (46.7 inches)
Overall Length2100 mm (82.7 inches)
Overall Width695 mm (27.4 inches)
Fuel Capacity22.00 litres (5.81 US gallons)
Reserve Fuel5.00 litres (1.32 US gallons)
Other
StarterKick
Color OptionsBlue/white, Black/white, Black/red
Notes
Differences to the 500 model: cylinders; gaskets; cylinder heads; upper engine case is different, would be needed to drill out for a 500 barrel fittment; big end crankshaft needle bearing has one less pin than the 500; 2 different RVs and both different to the 500, different inner-outer covers and rotary valves themselves, only in the center match, same durations; shorter clutch basket; shorter clutch hub; 8 instead of 9 clutch plates; shape of the carb needle, #135 main jet instead of #120 (500); exhaust pipes have thinner stingers and only there, the lower silencers themselves; 400+500 exhaust pipes are interchangeable; final ratio 15/41 instead of 16/40 (500); 525 chain instead of 530 (500); decals, but only on the side panels next to the front seat; 400 has the fuel integrated gauges; tank with fuel gauge output adaption; electrical harness has only a few wires more for fuel gauge; front break rotors are ´no´ floating type.
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.
