Suzuki GT380
1972—1978

I have tried to tell the model history of the Suzuki GT 380 as I know it. I would be grateful of any contributions — sales brochures, magazine ads, magazine articles, pictures, specs, facts, corrections etc. Please scan the material in JPEG format (large enough that all the details are visible) and send them to me. Please tell me the source and the publication date if possible. If you send me pictures of your own bike, please follow these instructions.

Suzuki launched its air-cooled two-stroke triples GT380 and GT550 in 1972. An water-cooled three-cylinder GT750 had already been presented a year earlier and the 380 and 550 followed the design of the flagship model. The GT380 and GT550 were predicatable and sporty motorcycles, but up to a point. At touring speeds they were comfortable and smooth, but twisting the grip farther brought a wobble and cornering at higher speeds showed the limitations of the suspension, swinging arm and the tube frame. The GT engines were less highly tuned than for example the Kawasaki triples. It was tuned for the long run. Porting, timing, compression, carburetor size etc. were all chosen to deliver smooth power at the expence of maximum power. It made the Suzuki GTs more reliable than fast. The odd 3 to 4 exhaust system and rigid foot pegs also limited the leaning angle and the sporting nature of the bike. The GT triples were simply made for touring and not for sport-styled riding. The Ram Air System (introduced in all of the air-cooled GT models) that forced the cool air to pass through the cylinders and behind the block was a new developement, tested earlier on Suzuki's TR500 racers. It is an simply an air scoop that ducts cold air directly onto the cylinder head the help the cooling on the engine. It was a known problem that two-stroke engines lost power when the cylinder head temperature rose too much. Cooling problem plagued other two-stroke triples but the Ram Air System made the Suzuki GT triples less suspective to the charasteric two-stroke power loss caused by too high a cylinder head temperature after a long, hard run. Nevertheless the GT triples still had a reputation for the middle piston seizing. Suzuki's automatic system mixing fuel and oil had been refined for the GT models, providing less exhaust smoke, now called CCI. A clever new item in the early seventies was the vacuum-operated petcock was first used on the GTs and later used on all Suzuki mototrcycle models. Both triples saw some minor improvements every year of their production but after only few of years production the two-stroke engined street bikes were terribly out of fashion. Although the GT380 was as strong and reliable as a four-stroke of equal displacement the rather high fuel comsuption of the two-strokers was suddenly an issue, when the gasoline prizes rose in the seventies. Even Suzuki itself dug a grave to its two-stroke models by launching its highly popular GS series with four-stroke angines. Suzuki was actually forced to change their minds and start making four-stroke engines. The tighter emission regulations in America sounded the death knell for most two-strokes. The GT550 was discontinued in 1977 and the GT380 a couple of years later, in 1979.

1972 Suzuki year code: J

The 1972 Suzuki GT380 had a 371 cc 2-stroke triple engine with square-bore and stroke of 54 x 54 mm and 6.7 :1 compression ratio. Fuel was fed via three Mikuni VS24SC carburettors and maximum power was claimed 38 bhp at 7 500 rpm. It had a six speed gearbox and starting was kickstart. The GT380 was a middle class bike and successor to the GT350. Its engine was designed with reference to the air-cooled 3-cylinder 360 cc engine of Suzuki Fronte (LC10), a fast-paced mini car Suzuki launched in 1969. A huge box-shaped air duct was installed in the cylinder head for cooling, to solve the heat problem of the central cylinder. As with the GT750, it had four mufflers with the exhausts from the middle cylinder distributed to both left and right. It was exhibited at the 1971 Tokyo Motor Show and released in January 1972, and a front disc brake model was added in April. It was othen used as a training bike because it had a smooth running 3-cylinder engine and it was stable and easy to maneuver. The Suzuki GT380 was a massive bike with a rigid chassis with standard telescopic forks up front and twin oil-damped shockers mounted on tubular steel swinging arm. The brakes were a 180 mm double-leading drum brake at the front and 200 mm rear. It had 19-inch spoke wheels front and 18-inch rear and somewhat anorectic 3.00 front tire and 3.50 rear tire. The front brake proved to be at its best only adequate and was replaced with a disc brake the following year. In Japan, a revised model (B1) with disc brake at the front was released already in April 1972 and sold alongside with the drum brake model. GT380 was equipped with a large fuel tank and saddle with plenty of room for riding with a passenger. Unfortunately the engine vibrations were transmitted to the passenger footpegs making the ride less comfortable for the passenger as it was for the fellow in front of him. The fuel tank cap had a lock in it, an unusual feature at the time, as was the rubber lip seals for the spark plugs, keeping moisture from shorting out the system. The cylinders of the GT380 were cast as three separate units and ech piston was fitted with a not-removable cast-in iron liner. The cylinder head was cast in one piece. 1972 Suzuki GT380 colors: Hawaii Green (215), Jamaica Red (157), Bright Blue Metallic (279). Matching side covers. A painted white line on both sides of the fuel tank. Intitial frame number: GT380-10001

1972 Suzuki GT 380, Hawaii Green (215), first version with drum brakes.

1972 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 800 mm (31.5 in) Overall Height: 1 100 mm (43.3 in) Wheelbase: 1 380 mm (54.3 in) Ground Clearance: 145 mm (5.7 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp (28 kW) @ 7 500 rpm, 37.3 Nm (3.8 kg-m) @ 6 500 rpm Click on the image for larger format.

1972 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 800 mm (31.5 in) Overall Height: 1 100 mm (43.3 in) Wheelbase: 1 380 mm (54.3 in) Ground Clearance: 145 mm (5.7 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp (28 kW) @ 7 500 rpm, 37.3 Nm (3.8 kg-m) @ 6 500 rpm Click on the image for larger format.

1972 Suzuki GT 380 B1, upgraded version with a disc brake at the front.

1972 Suzuki GT 380 B1 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 380 mm (54.3 in) Ground Clearance: 145 mm (5.7 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp (28 kW) @ 7 500 rpm, 37.3 Nm (3.8 kg-m) @ 6 500 rpm Click on the image for larger format.

1972 Suzuki GT380 specifications (Japan) Overall Length: 2 090 mm (82.3 in) Overall Width: 800 mm (31.5 in) Overall Width (B1): 815 mm (32.1 in) Overall Height: 1 100 mm (43.3 in) Overall Height (B1): 1 125 mm (44.3 in) Wheelbase: 1 380 mm (54.3 in) Ground Clearance: 145 mm (5.7 in) Dry Weight: 183 kg (402 lbs) Engine type: Air-cooled 3-cylinder 2-stroke, rotary disc valve Cylinder displacement: 49 cc Bore x Stroke: 54 x 54 mm (1.614 x 1.614 in) Compression ratio: 7.2 :1 Maximum power: 38.0 hp (27.95 kW) @ 7 500 rpm Maximum torque 37.3 Nm (3.8 kg-m) @ 6 700 rpm Fuel economy: 35 km/l at 60 km/h Carburetor: 3 x VM24 Starter method: Kick Ignition method: Battery Lubrication method CCI (separate Lubrication) Lubricating oil amount: 1.3 liter Fuel tank capacity: 15.0 liter Clutch type: Wet multi-plate, coil spring Transmission type: 6-speed content mesh Gear ratios: 2.333 / 1.500 / 1.157 / 0.904 /0.782 / 0.708 Primary reduction ratio: 2.576 (B1: 2.833) Secondary reduction ratio: 3.285 (B1: 3.000) Frame type: Double craddle Front brake type: Double-leading drum brake (B1: Disc brake) Rear brake type: Double-leading drum brake Front tire size: 3.00-19-4PR Rear tire size: 3.50-18-4PR Caster: 28°00' Trail: 109 mm (4.29 in) Steering angle: 42° Minimum turning radius: 2.3 m (7.54 feet) Recommended GT380 price in Japan, January 1972: 245,000 Yen Recommended GT380 B1 price in Japan, April 1972: 260,000 Yen

1973 Suzuki year code: K

After the revision in April 1972 no major changes were to the GT380 during the years it was manufactured. Only minor changes such as coloring changes and headlight rims were made to the 1973 model. The drum brake model was dropped from the catalog in Japan, only disc brake version was available. Some changes were made to the frame and exhaust system to provide more ground clearance and reduce vibration. The 1973 Suzuki GT380K (B2 in Japan) had a 275 mm brake disc at the front, mounted on the right side of the wheel with the caliper in front of the fork leg. It was and improvement compared to the drum brake — if the weather was dry. The early Japanese disc brakes were hopeless in the wet. A warning sticker was attached to the fork leg saying ”Caution — braking performance at beginning of the apllication may change with wet brake disc”. Modern brake pads and Goodridge hoses can improve the original braking power and cure sponginess. Launched in April 1973 (Japan). Intitial frame number: GT380-30919

1973 Suzuki GT 380 Overall Length: 2 105 mm (82.9 in) Overall Width: 850 mm (33.5 in) Overall Height: 1 100mm (43.3 in) Wheelbase: 1 355 mm (53.3 in) Dry Weight: 171 kg (376 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3,9 kg-m @ 6 000 rpm. 6 speeds. Click on the image for larger format.

1974 Suzuki year code: L

The 1974-year's GT380L (B3 in Japan) had different carbs than all the other models. The VM carburettors were replaced by carburettors of constant velocity type. That, along with the change of air filter box meant that the 380 lost one horsepower. A cooling fan was available as an option. Final drive sprockets were changed to raise the gearing and a gear indicator was fitted to the instruments. The Ram Air cover took an smoother shape and lost its fins. Headlight case was redesigned, its brackets and shell were now chromed, as was the chaingueard and airbox. The earlier gunmetal alloy finish of the engine became natural lacquered alloy. The dummy airscoops were removed from the side panels. The front fork rubber boots were now gone. A grab rail was installed for the passender to hold on to. Launched in January 1974 (Japan, B3). Intitial frame number: GT380-43732

1974 Suzuki GT 380 Overall Length: 2 105 mm (82.9 in) Overall Width: 850 mm (33.5 in) Overall Height: 1 100mm (43.3 in) Wheelbase: 1 355 mm (53.3 in) Dry Weight: 171 kg (376 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 37 hp @ 7 500 rpm, 3,9 kg-m @ 6 000 rpm. 6 speeds. Click on the image for larger format.

1974 Suzuki GT 380 Overall Length: 2 105 mm (82.9 in) Overall Width: 850 mm (33.5 in) Overall Height: 1 100mm (43.3 in) Wheelbase: 1 355 mm (53.3 in) Dry Weight: 171 kg (376 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 37 hp @ 7 500 rpm, 3,9 kg-m @ 6 000 rpm. 6 speeds. Click on the image for larger format.

1975 Suzuki year code: M

The GT380M model saw the carburettors revert back to the previous slide type. Otherwise the model remained virtually unchanged, except for a new color scheme. The Canadian model (see the picture below) didn't seem to have a grab rail behind the seat. Launched in October 1974 (Japan, B4). Intitial frame number: GT380-65984

1975 Suzuki GT 380 Overall Length: 2 105 mm (82.9 in) Overall Width: 850 mm (33.5 in) Overall Height: 1 100mm (43.3 in) Wheelbase: 1 355 mm (53.3 in) Dry Weight: 171 kg (376 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

1976 Suzuki year code: A

No major changes were made for the 1976 Suzuki GT380A. The coloring was changed to Black and Green Metallic, and the design of the front fender was slightly changed. Until the middle of this model, the meter lens was made of resin, which sometimes became cloudy due to aging, but it was changed to glass. In 1976 the GT380 was concidered as an old-fashioned bike from the early seventies while its rivals were not. Still, there was nothing wrong with the bike. The engine was nice and its power band was nearly as wide as the rev range, the clutch was easily controlled and the shifts were quick and precise. The sixth gear was a cruising gear, good for long flat streches and when the rider needed more power in hands the fifth worked well with not much extra fuel consumption. The handling was considered excellent within the bike's limitations. It was stable and steered well. The original suspension didn't react properly on small irregularities but that was a minor problem. The problem was that the GT380 looked like an old bike and performed like an old bike. Its rivals, like Honda CB400F, Yamaha RD400C and Kawasaki KH400 looked new, had electric starters and cast wheels. They were lighter, faster and better handlers. You could read in the Cycle World magazine in 1976: ”The GT380 is like going to the movies with your sister: Nothing wrong with it, but more exciting alternatives spring readily to mind.” Launched in February 1976 (Japan, B5). Intitial frame number: GT380-86754

1976 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 385 mm (54.7 in) Ground Clearance: 140 mm (5.5 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

1976 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 385 mm (54.7 in) Ground Clearance: 140 mm (5.5 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

1976 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 385 mm (54.7 in) Ground Clearance: 140 mm (5.5 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

1977 Suzuki year code: B

The models between 1975 and 1978 looked a lot like each other but the 1977 model can quite easily be identified for its black (not color matching) side covers. The shape of the tail lamp was square, the turn signal was the same type as the RG250, and the headlight case was also black. The GT380 was still selling quite well in various parts of the world but the number of units built had dropped to less than 10,000 units a year, compared to the 30,000 units in 1972. Only cosmetic changes were made to the 1977 Suzuki GT380B. In Japan, the color options were Candy Calypso Red and Olive Green Metallic. Presented in February 1977 (Japan, B6). Intitial frame number: GT380-95063

1977 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 385 mm (54.7 in) Ground Clearance: 140 mm (5.5 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

1978 Suzuki year code: C

1978 was the last year the GT380 was manufactured. The color matching side covers were back. The final model of the ”Sanpachi” as it was called in Japan, was released in April 1978. The tank cap is a flat push-in type, and the front fender has also been changed. Three colors are available: Candy Gypsy Red, Deep Burgundy Metallic, and Olive Green Metallic. Presented in April 1978 (Japan, B7).

1978 Suzuki GT 380 Overall Length: 2 090 mm (82.3 in) Overall Width: 815 mm (32.1 in) Overall Height: 1 125 mm (44.3 in) Wheelbase: 1 385 mm (54.7 in) Ground Clearance: 140 mm (5.5 in) Dry Weight: 183 kg (402 lbs) Engine: Air-cooled 371 cc inline-3, 2-stroke. 38 hp @ 7 500 rpm, 3.8 kg-m @ 6 500 rpm Click on the image for larger format.

More: Suzuki GT380 brochures

More: Suzuki GT models

More: All Suzuki models

Sources: Cycle World (USA), Classic & Motorcycle Mechanics (UK) etc.

This free site is managed by Jarmo Haapamäki.
If you find this site helpful, please leave a donation for Jarmo
so you can enjoy the spirit of giving too.

Came here from a search engine?
Click at the home button below to get to the main page with frames.