|In 1911 Ignaz Schwinn,
the Schwinn Bicycle Empire, bought a small motorcycle company, on
Street in Chicago. Indian and Harley-Davidson were the top two
manufacturers in the United States. Mr. Schwinn would soon be
three with the Excelsior Autocycle.
This "Series 13" Twin has a 61 cubic inch engine producing approximately 15 horsepower. It has a belt drive which Excelsior continued on certain models (such as, the "Series 18 Light Weight.") at least until 1918. The "Series 13" is a single speed motorcycle. The belt directly connects the engine to the rear wheel. Excelsior used the Eclipse clutch, originally developed by Victor Bendix in 1909, as well as a belt tensioning idler.
Click on the photos to enlarge.
The leather belt had its advantage over the chain drive. It made for a smoother start under a heavy throttle. One disadvantage was excessive belt tension would torque the frame out of trueness. Another disadvantage was the wheel pulley, because of its size, often ended up in mud puddles causing the belt to slip. The large lever on the side of the tank operates the idler pulley located under the bottom lay of the belt. It is used to keep the belt properly tensioned as it stretches. Both the clutch and wheel pulleys are fitted with leather friction bands to prevent belt slippage.
The Eclipse clutch on the end of the crankshaft is actuated by the left handle bar grip through a series of links. The small lever on the tank is for the ignition advance control on the American Bosch magneto. Directly above the tank decal and almost invisible is the gas tank cap. This tank is a typical dual compartmented tank. The tank cap to the rear, with the tee handle, is the oil tank cap with a built in injection pump. As with most motorcycles of this period, at extended speeds above 45 mph it is necessary to give occasional shots of extra oil. Oiling of the engine otherwise is facilitated by the adjustable drip glass at the rear of the tank bottom. The seat is an original made by Troxel Elyria Manufacturing Company of Ohio.
|Excelsior made fine 61 cu.in. twin cylinder engines. They were smart looking as well as functional and sturdy. On the outside of the cam cover are two levers connected by a rod. They lift the exhaust valves to decompress the cylinders for easy starting. These are operated by a rod connected to the pivot arm on the front brace of the frame. This pivot arm is actuated by the right handlebar grip. At the same time the pivot arm also operates the linkage of the Schebler carburetor. By twisting the hand grip backwards fully, the compression release is activated. Once the engine starts, the hand grip is turned clockwise to deactivate the compression release and pickup the throttle. As were most American twin cylinder engines of this period, this is an intake valve over exhaust valve (IOE) type. The left picture shows the drip oil feed tube running parallel to the rear exhaust and into the cam housing. Notice in the right picture the recesses in the tank for the intake valve train.|
left picture is a close-up of the valve chamber. It is an integral part
of the cylinder casting. The intake valve sits over the exhaust valve.
This design was typical before the common practice of removable heads
motorcycle engines. An advantage of this design is the exhaust valve is
cooled by the intake air. A major disadvantage is extra combustion
area, causing a lower compression ratio. The spark plug is also screwed
into the valve chamber. Notice the oil line going into the block. It is
the one fed by the manual injector pump on the tank. In the
on the right you get a better view of the tank recesses for the upper
train. On the rocker arms you also see the small holes where occasional
drops of oil must be placed to lubricate the pivot points.
The last picture is the muffler. Built into the muffler is the exhaust cutout. The purpose of the cutout is to give the engine more power through improved aspiration. It is operated by a wire attached to the lever on the back of the muffler. The wire is operated by a small slide knob mounted on the toolbox under the seat. When open the exhaust gases escape through four holes as well as the slots in the short tailpipe. Running with the cutout open was usually reserved for country riding where no one would be bothered by the excessive noise. In town, the cutout would be closed, quieting the exhaust. The gases are then forced entirely through the slots in the tailpipe.
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The Owner of the machine in the photos
of Motorcycles, edited
by Erwin Tragatsch
Inside American Motorcycling
by Harry V. Sucher
Schwinn Bicycle Company
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