This 1956 KHK was an orphan model when released by H-D. It was an intermediate step in production that ultimately led to one of the company's most enduring models... the Sportster.

The bike grew out of the post-war era when even in America, British bikes had become the rage thanks to their light weight, agile handling, superior acceleration and modern controls. Companies like Royal Enfield, BSA, Triumph and Norton were all making huge inroads into the traditional motorcycle market and Harley dealers clamored for a Milwaukee made machine to counter the onslaught.

Harley wanted to offer plenty of modern touches in this new machine; a hand clutch, foot shift and a swingarm with shock absorbers but when it came to the powerplant, the company faced a tough choice. It could rush development on a new engine with overhead valves (and risk bringing an unreliable machine to market) or wring more power out of aging old side-valve motor.

Moving cautiously, Harley debuted the Model K in 1952. It was a sporting motorcycle using a 45-cubic-inch (750cc) side-valve V-twin that had more in common with a WLA than anything in the 50s. A race version of the bike won Daytona in 1953 but the streetbike was down on power compared to the 500cc OHV Britbikes of the day and suffered for it in the showrooms.

Only two years after its introduction, lackluster sales of the K forced Harley to upgrade the engine. Still choosing not to launch their OHV motor, Harley engineers did what they always had done in the past when chasing more power... they made the motor bigger and pumped the size of the K's motor out to 54 cubic inches and thus the KH was born. That displacement, equal to 883cc would become legendary for Harley and is still available to this day.

For those who wanted an even sportier bike, the company added the KHK in 1955. This was a KH with a speed kit that included a roller-bearing bottom end, hot cams and polished ports. Produced only for two years, this motorcycle was an instant cult classic with demand far outstripping supply in an age when drag racing V8's and motorcycles was booming across the States.

In 1957 Harley finally released its OHV engine to critical acclaim. It had the same 883cc displacement of the KH motors but it marked the start of a brand new product line that has endured to this day and is the worlds longest produced motorcycle model. It is the Sportster.