The De Luxe motor is a wondrously complicated device, incorporating many “features” which can be best be described as bizarre. It is fascinating to compare it to the simple – but entirely adequate – engineering of the JAP twin of the period, which must have used around half the number of parts required for the De Luxe, and have been correspondingly cheaper to produce.
1915 Spacke Twin “Behemoth”
The Spacke Twin was a collaboration between Ted Doering, Don Scheck and Tom Owejan. It took three years to build and was finished early in 2011. The motors are 1915 Spacke 1200 cc L heads (one flat head valve and one overhead valve) connected together wit a serpentine double roller chain. It was designed to start one engine and then the other thru use of compression releases. One engine has battery ignition and the other has a magneto. The frame is constructed using the lower half of a 30″s Harley VL,the upper half of a 20’s Harley JD stretched to accommodate the large engines. Every thing from the seat post rearward is fabricated and the front end is a stretched out JD. The wheels are 36 inch dropped center John Deere hay rake wheels with smoothed tires and fabricated hubs. Drive is achieved by connecting the engines to a jack shaft which in turn connects to a Harley VL three speed transmission then to the rear wheel by one inch industrial chain and fabricated sprockets. The 6 volt electrical system is maintained by a chain drive generator. This machine was built to run and drive but has never been started because Ted wanted at his museum for the grand opening. Up to that point the engines had not been taken apart for cleaning and inspection.
Beginning with the top end, we find a rather typical (for the period) American overhead-inlet valve, side exhaust layout. The cast-iron pistons have floating gudgeons, onto which the conrods are clamped. Not unheard-of in car engines, this is rather uncommon in motorcycles. The rods themselves are in the “master and slave” configuration, where the bearing for the front rod is carried on a boss on the rear.
Things start getting very weird at the bottom. The crank is built up from many pieces, with the crankpin fixed to a pair of small diameter, light-weight “flywheels”, with the “real” flywheels sliding over the mainshafts to rest against them. The pulley (my machine is direct belt drive) slides over a parallel mainshaft on the drive-side, while the skew gear to drive the cam does the same on the timing side. Tightening nuts at either end clamps everything together, holding the flywheels in place and taking up endfloat.
The camshaft runs fore-and-aft, with face cams on which bell cranks bear to drive tappets. End thrust on the cam is taken up by an elaborate system of adjustable ball races. The mechanism to lift the exhaust valves is just a tad more complicated than most!