1938 HARLEY-DAVIDSON PROTOTYPE KNUCKLEHEAD Engine 51 cu in # SP7074 #4, X-Ray # underneath EX 38 #4 One of One William Harley's...
1938 HARLEY-DAVIDSON PROTOTYPE KNUCKLEHEAD
Engine 51 cu in # SP7074 #4, X-Ray # underneath EX 38 #4
One of One
William Harley's personally designed prototype Knucklehead
Harley believed there was a market for a 45 CI OHV motorcycle
Four others were made this being the only one with Alloy heads and barrels
There is nothing on this bike that would ever fit a later production bike
Engineering model fully documented
Possibly one of the most valued Harley's ever to come available
Offered here is Bill Harley’s experimental “second generation” 52-cubic-inch overhead valve 1938-39 Knucklehead prototype. There were five prototypes produced, but this example is the only one equipped with aluminum heads and barrels. The lower end is overhead-valve only and utilizes an oil pump from a 1937 motorcycle. The motor is proprietary to this machine using narrow cams and oversized cam cover. Notice where the lower pump area fits; this is for the pressure-fed crank on the Harley-designed overhead valve. With an A-frame style head, motor no. 4 is marked EX, and the oil return angle is straight, unique to this example. The lifter blocks are drilled to the channel to vacuum the oil from the OHV heads. The wheels sport one-off narrow stepped hubs with small-spoke rims.
This prototype uses the “dome piston” mentioned in the Harley-Davidson board meetings between 1938 and 1939. Bill Harley took pride that this piston would end his overheating problem. The motorcycle was purchased from Roy Egeberg in 1974 by restorer Daniel Pugens, a known Harley-Davidson CAC, DAH and OHV specialist. The prototype is mentioned extensively in Herb Wagner’s “Harley-Davidson 1930-1941” and Jerry Hatfield’s “Inside Harley-Davidson.”
Engine 51 cu in # SP7074 #4, X-Ray # underneath EX 38 #4
One of One
William Harley's personally designed prototype Knucklehead
Harley believed there was a market for a 45 CI OHV motorcycle
Four others were made this being the only one with Alloy heads and barrels
There is nothing on this bike that would ever fit a later production bike
Engineering model fully documented
Possibly one of the most valued Harley's ever to come available
Offered here is Bill Harley’s experimental “second generation” 52-cubic-inch overhead valve 1938-39 Knucklehead prototype. There were five prototypes produced, but this example is the only one equipped with aluminum heads and barrels. The lower end is overhead-valve only and utilizes an oil pump from a 1937 motorcycle. The motor is proprietary to this machine using narrow cams and oversized cam cover. Notice where the lower pump area fits; this is for the pressure-fed crank on the Harley-designed overhead valve. With an A-frame style head, motor no. 4 is marked EX, and the oil return angle is straight, unique to this example. The lifter blocks are drilled to the channel to vacuum the oil from the OHV heads. The wheels sport one-off narrow stepped hubs with small-spoke rims.
This prototype uses the “dome piston” mentioned in the Harley-Davidson board meetings between 1938 and 1939. Bill Harley took pride that this piston would end his overheating problem. The motorcycle was purchased from Roy Egeberg in 1974 by restorer Daniel Pugens, a known Harley-Davidson CAC, DAH and OHV specialist. The prototype is mentioned extensively in Herb Wagner’s “Harley-Davidson 1930-1941” and Jerry Hatfield’s “Inside Harley-Davidson.”
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