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| In 1911 Ignaz Schwinn,
heir to
the Schwinn Bicycle Empire, bought a small motorcycle company, on
Randolph
Street in Chicago. Indian and Harley-Davidson were the top two
motorcycle
manufacturers in the United States. Mr. Schwinn would soon be
number
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
external Vee band brake is operated by back pressure on the pedals,
like
a coaster brake. The drum has a vee groove around it like an automotive
vee pulley. Rivets are used to attach the wheel pulley to the rear
wheel.
Inside the wheel pulley is a leather friction band held in place by
rivets.
You can see them on the inside of the pulley. The four rivets together
are where the free ends of the band come together.
 |
  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. |
  The
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
on
motorcycle engines. An advantage of this design is the exhaust valve is
cooled by the intake air. A major disadvantage is extra combustion
chamber
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
picture
on the right you get a better view of the tank recesses for the upper
valve
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. |