1939 Harley-Davidson OHV Experimental Prototype

1939 HARLEY DAVIDSON EXPERIMENTAL PROTOTYPE
Here is BIll Harley Experimental "Second Generation" All Aluminium OHV 52 cubic inch 1938-39 Harley. Bill Harley's dream of an over-head valve lightweight machine created experimentally by Harley- Davidson Motor Co.
He only built one of these and four of the all iron models, this one has all aluminium heads and barrels with EX clearly marked to both. The lower end is OHV only with 1937 OHV oil pump. 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 Presure Fed Crank on the OHV Bill Harley desighned for this motor. The Iron head motors are simular.
The all aluminium one has the "A frame" style head and the Iron model is the "Gap type" with many diffrences in design as pictured. All are EX marked clearly and this motor is also marked #4. Note the oil return angle is straight instead of angled on the OHV, also the bearing is removeable and not blind on the output shaft.
Also to note is the diffrence of the lifter blocks. They are drillled to the channel to vacuum the oil from the OHV heads. The wheels sport one off narrow stepped hubs with small spoke rims. There are many experimental parts on Bill Harley's machine.
This is the actual, Bill Harley’s experimental, “second generation” 52-cubic-inch overhead valve 1938-39 Knucklehead prototype designed and fought for by Bill Harley in the late 1930’s. There were five prototypes produced, but this example is the only one equipped with aluminum heads and barrels. (It may be the only complete experimental Harley Davidson motorcycle known to remain in existence). The 1938 lower end is overhead-valve only, specific to this model, and utilizes an oil pump from a 1937 motorcycle. The motor is proprietary to this machine using narrow cams and oversized cam cover. With an A-frame style head, Motor No. 4 is marked EX. 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. This experimental motorcycle was sold to Roy Egeberg just after production and remained with him until 1974 when it was purchased by restorer Daniel Pugens, a known Harley-Davidson CAC, DAH and OHV specialist.
This experimental 1938-1939 Harley Davidson motorcycle has recently been restored to its original glory utilizing all of the parts purchased from Egeberg. Egeberg acquired this exact machine from the factory and had it titled in Minnesota until he sold it in 1974. The authenticity of this particular prototype experimental motorcycle is well documented including in the Harley Davidson archives, extensively in Herb Wagner’s “Harley-Davidson 1930-1941” and in Jerry Hatfield’s “Inside Harley-Davidson.” This 1938-39 motorcycle may be the only experimental Harley Davidson to be released from the factory.