29th RMC Choppershow

Above a photo of Spike Judd’s beautiful bobbed knucklehead from England. In any case, we would like to mention that we are very proud to have a dozen participants from England on the show this year. There is now quite a revival of the sixties and seventies going on there. The motorbike in the photo is even built in a fifties style.

Knuckleheads were in production from 1936 till 1947 and had two engine sizes; 61ci and 74ci.
However, the first OVH dry-sump oil lubricated Knucklehead was showcased in the winter of 1935 at the Schroeder Hotel in downtown Milwaukee and dealers reacted positive.

Left a Flathead 1919-1973 and right a Knucklehead 1936-1947. Image courtesy; Riding Vintage

It’s predecessor, the Flathead, had a side-valve layout, meaning that the valves were located in the engine block. The cylinder head contained only a spark plug and combustion chamber under its cooling fins, hence the name Flat Head.

The Knucklehead however used a overhead-valve layout, where the inlet- and exhaust valves are in the cylinder head. Therefor they are much less affected by heat and easier to tune to produce more horsepower with less overheating problems then its predecessor. Also the introduced re-circulating oil system added up to better performance. Flatheads run on total-loss lubrication!
It may be hard to imagine, but as it sounds, the Flathead’s lubricating oil was only required to make a one-way trip. Oil drip-fed from its reservoir in the left gas tank into the crankcases, splashed around the engine before it got burned up, blown out, or dripped onto the drive chain.

Make no mistake; the 1936 Knucklehead was a beautiful motorcycle. Everything from the Knuckle’s deep balanced fenders and the beefed-up twin cradle frame to its extruded steel Springer forks and high-mounted headlamp all came together to create a timeless classic symmetry. But as with many first models, the first production year Knuckleheads [E and EL units] weren’t without their problems and needed to be resolved and therefor subject of almost constant upgrades.

In 1937 Joe Petrali set a new land speed record for its class of 136.183mph with a 61ci EL Knucklehead which lasted a decade. This achievement boosted the name and fame of this model from Harley Davidson.

Joe Petrali in 1937. Image courtesy; Harley Davidson Museum

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