Suzuki S10/K125
1964—2020

I have tried to tell the model history of the Suzuki K 125 on this page as I know it. The page is still under construction. 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.

The K125 was one of Suzuki's longest-lived motorcycle models.

The Suzuki S10, released in 1964, was basically the same bike as the K125 that came three years later. The basic specifications were the same. They had a 2-stroke 125cc engine, electric starter, 4-speed gearbox, pressed steel underbone frame, drum brakes, and looked like just about every Japanese bike at the time. What was unusual was the the single-cylinder engine had two exhaust pipes, one at each side of the vehicle. It was also the first Suzuki with a rotary valve engine, technology enherited from a GP racing machine. ”Despite having only a single cylinder, the 125 S10 generates the same level of performance as a 2-cylinder model” said Suzuki. The dual-exhaust/dual-muffler system was said to give the engine ideal exhaust performance, excellent acceleration, combining the high-speed performance of a sporty machine with the gutsy performance at low revolutions of a commercial bike. The S10 engine delivered 9.6 PS at 6,500 rpm and, according to Suzuki, could be ridden 65 km with 1 liter gasoline (when driving at 40 km/h). The model was replaced by the K125 in 1967. While the S10 used pre-mixed oil/gasoline fuel, the K125 was equipped with the new CCI oil supply mechanism. Starting frame number: S10-00001 Color: Black with Chrome plated fuel tank sides

The Suzuki 125 S10 (1964–1966) developed to the long-lived K125.

1964 Suzuki 125 S10 Overall Length: 1 900 mm (74.8 in) Overall Width: 675 mm (26.6 in) Overall Height: 965 mm (40.0 in) Wheelbase: 1 260 mm (49.6 in) Ground Clearance: 130 mm (5.1 in) Dry Weight: 117 kg (258 lbs) Top Speed: 115 km/h (49.7 mph) Engine: Air-cooled 123 cc 1-cylinder 2-stroke, 2-stroke. 9.6 PS (7.1 kW) @ 6 500 rpm, 10.8 Nm (1.1 kg-m) @ 5 000 rpm. 4 speeds. Here's even larger picture.

The S10 model name was changed to K125 in 1967. The basic components are carried over from the S10. In fact, the engine code remained the same, S10, through the entire history of the K125 model. All together, oly minor changes were made to the model during the years. The rotary valve air-cooled 2-stroke single cylinder 123cc S10 engine was mounted on a pressed steel backbone frame, and the transmission was a 4-speed rotary. That never changed. However, the carburetor was changed from M21 to VM21 in 1967, increasing the peak power output from 9.6 horsepower to 10.5 horsepower. Even the maximum torque was slightly increased. Also, Suzuki introduced its original separate oil supply mechanism (CCI), which directly supplies 2-stroke oil to each part of the engine via an oil pump, to the K125, eliminating the need to pre-mix lubricating oil with gasoline. Furthermore, the clutch plate is now made of steel, to improve durability. The K125 also received larger headlight, tail light and turn signal lights compared to the S10 model. The capacity of the fuel tank was increased by 25% from the previous 8 to 10 liter. The rear suspesion was now 3-stage adjustable, enabling setting changes according to loading conditions and road surface conditions. The retail price for the K125 in Japan was 135,000 yen – a 5,000 yen increase from the price of the 1964–1966 S10. The first model version was manufactured until late 1969. Frame numbers: K125-10001 to K125-75370 Color: Black with Chrome plated fuel tank sides

1967 K125, basically a S10 with CCI oil injection, different carburetor and adjustable rear suspension

1967 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

The 1970 model "K125-2" is a carryover from the previous year's model without any changes to the mechanical parts. It's still equipped with a rotary valve type air-cooled 2-stroke single cylinder S10 engine that produces 10.5 horsepower at 7,000 rpm. Although it is a single-cylinder engine, the unique styling of 2 exhausts and 2 mufflers has been inherited. Some minor changes were made. The K125-2 got new seat, new position lights with built-in headlights and the new reflectors on both the front and rear sides are details that take safety into account. The switch is in the bag, front light, rear light, turn signal, miles change. The new car price of the K125-2 was 138,000 yen, which was 3,000 yen higher than the previous year's model. The production of the K125-2 ended at the end of 1971. Frame numbers: K125-75371 to K125-106299 Color: Black with Chrome plated fuel tank sides

The Suzuki 125 S10 (1964–1966) eveloped to the long-lived K125.

1970 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

1972 Suzuki year code: J

The model version produced from the beginning of 1972, the K125-3, was unchanged from the previous model, except for the K12-3 was also available in color Red – at leat in Taiwan and China (special production with different fenders/mud guards). Frame numbers· K125-106300— K125-133928. It was produced until late 1974. Color: Black with Chrome plated fuel tank sides

The Suzuki 125 S10 (1964–1966) eveloped to the long-lived K125.

1970 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

1974 Suzuki year code: L

The 1974 model "K125" is a carryover from the previous year's model without any changes to the mechanical parts. It's still equipped with a rotary valve type air-cooled 2-stroke single cylinder S10 engine that produces 10.5 horsepower at 7,000 rpm. Although it is a single-cylinder engine, the unique styling of 2 exhausts and 2 mufflers has been inherited. Some minor changes were made. The K125-2 got new seat, new turn signal lights, new reflectors on both the front and tail lights. New speedometer. The new car price of the 1970 model "K125" was 138,000 yen, which was 3,000 yen higher than the previous year's model. Frame numbers: K125-133929 — K125-160395 Color: Black with Chrome plated fuel tank sides

The Suzuki 125 S10 (1964–1966) eveloped to the long-lived K125.

1974 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Click on the image for larger format.

1974 K125 specifications (International) Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 1-cylinder 2-stroke, rotary-disc valve. Cylinder volume: 123 cc Maximum Power Output: 10,3 hp/ 7.000 rpm SAE Maximum Torque: 1,15 kg-m (8.29 lb-ft)/ 5.500 rpm Top Speed: 110 km/h (69 mph) Starting system: kick start Lubricating system: Suzuki CCI Transmission: 4 speed rotary, constant mesh Front Brakes: drum Rear brakes: drum Front Tyre: 3.00-16, 4PR Rear Tyre: 3.00-16, 4PR

1975 Suzuki year code: M

1975 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 114 kg (250 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Click on the image for larger format.

1976 Suzuki year code: A

1976 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 114 kg (250 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Click on the image for larger format.

1984 Suzuki year code: E

The speedometer of the 1984 Suzuki K125 (K125-8) is no longer built in to the headliught casing but is ”floating” above it. Red area indicating high revs was added to the speedometer. New graphics of the fuel tank. The rear mirror covers were now made of plastic. The K125-8 was manufactured until the end of 1987. Frame numbers: K125-359441 — K125-382084 Total number of production: 22644 units Color: Pearl Black (08E) with Gold striping

1984 K125-8, Pearl Black (08E) with Gold striping

1984 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

1988 Suzuki year code: J

The 1988 K125J looked the same as the previous model but received a new exhaust system. In 1988, due to the global noise pollution policy the Suzuki K125-J received a more sound-absorbing exhaust system. The new integrated silencers were easy to attach and detach. Frame numbers: K125-382085 — K125-391104 Color: Pearl Black (08E) with Gold striping

1988 K125-J

1984 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 780 mm (30.7 in) Overall Height: 1 010 mm (39.8 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 113 kg (248 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 10.3 hp (7.6 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

1990 Suzuki year code: L

Suzuki K125L was released in February 1990. The ignition method was updated from the battery ignition system that had been used since its debut in the mid-sixties to transistorized CDI ignition. It also received a larger fuel tank, the capacity was expanded from 10 to 13 liter. The price was raised by 8,000 yen from the previous year's model to 222,000 yen (excluding tax). Land new, somewhat larger exhaust system. At least the Japanese domestic version had leg shields. Color: Solid Black (019) with Chrome plated fuel tank sides Frame numbers: K125-391105 to K125- 402573 Recommended retail price in Japan: 222,000 yen (excluding tax)

1990 Suzuki K125, Pearl Black (08E). Solo seat, luggage rack and leg shields

1990 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 800 mm (31.4 in) Overall Height: 1 040 mm (40.9 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 118 kg (260 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 12 hp (8.95 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Click on the image for larger format.

1990 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 800 mm (31.4 in) Overall Height: 1 040 mm (40.9 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 118 kg (260 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 12 hp (8.95 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

1995 Suzuki year code: S

Carrying over the basic vehicle components from the previous model, the good old S10 rotary valve air-cooled 2-stroke single-cylinder engine was still mounted on a pressed steel backbone frame. The maximum output is 12 horsepower at 7,000 rpm, unchanged from the 1987 model. It still had 4-speed rotary trans,ossion and 16-inch wheels, like it always had. Color: Solid Black (019) with Chrome plated fuel tank sides Since the introduction of the 1990 model, the "K125" was sold until 2000 without undergoing minor changes, ending the history of Suzuki's long-selling model for about 35 years. The price of the final specification was 239,000 yen (excluding tax).

1995 Suzuki K 125 Overall Length: 1 905 mm (75.0 in) Overall Width: 800 mm (31.4 in) Overall Height: 1 040 mm (40.9 in) Seat Height: 755 mm (29.7 in) Wheelbase: 1 260 mm (49.6 in) Dry Weight: 118 kg (260 lbs) Engine: Air-cooled 123 cc single cylinder 2-stroke, rotary-disc valve. 12 hp (8.95 kW) @ 7 000 rpm, 1.15 kg-m (8.29 lb-ft) @ 5 500 rpm Here's even larger picture.

More: Suzuki S models

More: Suzuki K series

More: All Suzuki models

Sources: Suzuki Motor Company

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