In the early Fifties, British bikes started gaining popularity in the American marketplace. Needing to offer a motorcycle that was lighter and faster than their 1200cc Big-Twins, Harley-Davidson introduced the sporty K Model. Although a four-year run may seem insignificant in the Motor Company's 100 year-plus history, a change from flathead to overhead valve design in 1957 turned the K-model into Harley's most successful selling motorcycle of all time, the Sportster.
K-Model 1952-1953
The 'middleweight' K-series engine was based on the bottom end of Harley's 750cc side-valve W-series. Using the same 2-3/4" bore with a 3-13/16" stroke, displacement measured 45 cubic-inches. Compression ratio was 6.5 to 1. Cylinder heads were aluminum and finned to aid cooling. To save weight and space, the K series transmission was housed inside the rear of the engine cases, with a primary chain used to connect the crankshaft to a dry clutch. Unitized cases were new for the Motor Company, but English bikes such as the Vincent Black Shadow had used this design previously.
Clearly the best handling Harley V-twin yet, the K-model's front forks were hydraulic, with a swingarm and twin shock absorbers used in the rear. This was the first time a civilian motorcycle produced by Harley-Davidson used hydraulic suspension on both wheels.
With a motor producing 30-horsepower on a bike weighing 400 pounds, first-year models were not much faster than Harley's 600-pound Big-Twin bikes. For 1953, H-D introduced the KK-model, which featured hotter cams and factory cylinder porting. Production total for 1952-1953 the K and KK-models was 3,693. Also this year, t he race-only KR-model started it's long and successful 16 years of production.
1954 KH and KHK Model
1954 Golden Anniversary KH-Model
In the Fall of 1953, Harley-Davidson celebrated its 50th Anniversary in business. To commemorate this occasion, 1954 models displayed special medallions on the front fenders. Golden Anniversary KH's and KHK's were available in Pepper Red, Glacier Blue, Forest Green, Daytona Ivory, or Anniversary Yellow. If a customer so chose, gas tanks could be ordered in one color and fenders in another.
In 1955, a frame redesign included a lower seating position and shorter front fork tubes, both improving handling and giving the bike a sharper profile. To resolve problems caused by the increased engine torque, the rear wheel hub and spoke diameter were increased in size. A running change from 1954 saw revised engine cases having a trap-door, allowing access to the transmission without having to split the cases.
1956 KH-Model
Elvis Presley's Harley-Davidson KH Model
The 'middleweight' K-series engine was based on the bottom end of Harley's 750cc side-valve W-series. Using the same 2-3/4" bore with a 3-13/16" stroke, displacement measured 45 cubic-inches. Compression ratio was 6.5 to 1. Cylinder heads were aluminum and finned to aid cooling. To save weight and space, the K series transmission was housed inside the rear of the engine cases, with a primary chain used to connect the crankshaft to a dry clutch. Unitized cases were new for the Motor Company, but English bikes such as the Vincent Black Shadow had used this design previously.
Clearly the best handling Harley V-twin yet, the K-model's front forks were hydraulic, with a swingarm and twin shock absorbers used in the rear. This was the first time a civilian motorcycle produced by Harley-Davidson used hydraulic suspension on both wheels.
With a motor producing 30-horsepower on a bike weighing 400 pounds, first-year models were not much faster than Harley's 600-pound Big-Twin bikes. For 1953, H-D introduced the KK-model, which featured hotter cams and factory cylinder porting. Production total for 1952-1953 the K and KK-models was 3,693. Also this year, t he race-only KR-model started it's long and successful 16 years of production.
1954 KH and KHK Model
1954 Golden Anniversary KH-Model
In the Fall of 1953, Harley-Davidson celebrated its 50th Anniversary in business. To commemorate this occasion, 1954 models displayed special medallions on the front fenders. Golden Anniversary KH's and KHK's were available in Pepper Red, Glacier Blue, Forest Green, Daytona Ivory, or Anniversary Yellow. If a customer so chose, gas tanks could be ordered in one color and fenders in another.
In 1955, a frame redesign included a lower seating position and shorter front fork tubes, both improving handling and giving the bike a sharper profile. To resolve problems caused by the increased engine torque, the rear wheel hub and spoke diameter were increased in size. A running change from 1954 saw revised engine cases having a trap-door, allowing access to the transmission without having to split the cases.