Harley J, JD, & JDH
Motor Lubrication, Mechanical Oil
Pump, Motor Care and Repair
What Perfect, Motor Lubrication Means
The Harley-Davidson oil pump is designed to feed
just the right, amount of oil to the motor. With oil in the tank, a
scarcity of oil in the motor is impossible. Neither can the pump feed an
oversupply when properly adjusted. This makes for great economy.
More advantageous than this economy of oil is the fact
that perfect lubrication eliminates excessive, carbonizing of the motor
and all the attendant evils. Strange as it may seem at first thought,
too much oil, w while not so serious as an undersupply, will eventually
wear out any motor. Harley-Davidson engineers found .that that the only
way to prevent an oversupply was to lubricate the motor by an 'automatic
mechanical driven pump, with a large, positively operated, rotary valve
working independently of temperature conditions.
On the subject of over oiling we want to call
attention to the fact that it is not necessary to have blue smoke at the
exhaust to indicate that the motor is receiving sufficient oil. There
may be an oversupply of oil in the crank case and; the motor not smoke.
Too much oil in the crank case will cause loss of power and speed due to
the overheating of the oil. Read carefully the instructions on the
adjustment of the mechanical oiler and the use of the hand pump.
Serious Results of Excessive Lubrication
When a motor becomes carbonized, tiny particles of
carbon gradually work into the cylinder walls, piston face and piston
rings, acting as an abrasive, eventually causing wear to these parts.
Some of this carbon works past the pistons into the crank case, where
the circulation of oil carries this destructive mixture to other moving
parts. If the rider neglects to flush out the crank case occasionally,
this mixture of fine carbon and oil causes the cylinders, pistons,
rings, bearings, crank pin, crank shafts, gears and valve action to wear
Much so-called "motor trouble" is caused by improper
carburetor adjustment. To offset the poor running of the motor, due to
heavy oil vapor in the combustion chamber as a result of an over-supply
of oil, the rider will adjust the carburetor so that it feeds an
excessively rich mixture to the motor. This mixture not only rapidly
deposits carbon, but makes a
slow burning or poorly combustible gas, tending to overheat the motor
and causing a material loss of power. The rider in attempting to remedy
this overheated condition will give the motor more oil, making matters
worse than ever.
Summed up briefly, proper lubrication means sustained
speed and power, and prolonged motor life. It means a uniform gas
mixture and the end ai most so-called "motor troubles," due to fouled
spark plugs, burnt, pitted or warped valves which are often the results
of an improperly adjusted carburetor, furnishing too rich a mixture to
offset the effects of too much oil.
From the foregoing it is clear that too much oil is
almost as serious in its effects as not enough oil. It has usually been
taken for granted that as long as a motor received enough oil it made
little difference whether an oversupply was used. This is positively
wrong. Not only is excessive lubrication expensive from the viewpoint of
the cost of the oil itself, but from the standpoint of motor service and
The Harley-Davidson mechanical oil pump makes it
possible to adjust your oil supply to a nicety; to use just enough oil,
not too much, nor too little.
Use of Hand Pump
Occasionally it is advisable to give the motor a little extra oil by
means of the hand pump when speeding, negotiating a long steep hill, or
when going through long stretches of heavy mud or sand, especially if
the machine is carrying a sidecar and an extra passenger.
THE HAND PUMP SHOULD ONLY
BE USED WHEN EXTRA LUBRICATION IS NEEDED—NEVER FOR ORDINARY SERVICE.
|Illustration No. 12
Sectional view- of Automatic Oil Pump.
Operation of Harley-Davidson Automatic
Mechanical Oil Pump
(1915-1929 Model J, JD, JDH)
The Harley-Davidson oil pump has no check valves to
stick, no ball valves to "float," no valve springs to break and no small
parts to go wrong.
In illustration No. 12 the rotary valve member R
rotates in a left hand direction, looking at it from the top.
After the cam H has raised the plunger P to its highest
point, the spring Y returns the plunger, drawing a charge of oil from
the tank through the supply pipe S, and through the intake system as
Through the channel L, oil reaches the intake port I, in the
valve chamber. The port I is connected with the hollow center C of
distributor R. From C the oil passes through the opening A into the
distributor channel X, then through channel B to pump chamber T.
Just after the completion of the intake
stroke of the plunger P the intake port I closes and the discharge port
D opens, lining up with channel E. As soon as the plunger is raised by
the cam I-I, the oil in chamber T is discharged through the channels B,
X, A, C, D, (D is now opposite E), E and F to the sight feed. From
the sight feed the oil is forced to the motor through opening G.
Although the highest crank case pressure registered to
date in any Harley-Davidson motor tested was 4 pounds to the square
inch, the Harley Davidson oil pump will operate against a pressure of 70
pounds if necessary. It is absolutely infallible in its operation. There
are no small parts to break. The pump has but two moving parts, the
plunger "P" and the distributor valve member "R," rotated by a worm gear
made integral with one of the gears.
To Adjust the Automatic Oil Pump
When each motor is tested at the factory the mechanical
oiler is adjusted so as to give the proper oil supply at speeds up to 45
miles per hour. With this adjustment a hial.f pint of oil will average
approximately 45 miles (720 miles to the gallon), if Harley-Davidson
cylinder oil is used. This adjustment. as it leaves the factory, is such
that plenty of oil will be fed to the motor and should not be changed
excepting for good reason.
When the machine leaves the factory the mechanical oil
pump is not fitted with any definite number of washers at 'K.' The
number of washers varies, depending on the amount required to give the
plunger %2 inch stroke.
If, for good reason it is desired to decrease the oil supply, remove one
thin washer. The adjusting screw "J" regulates the stroke of the oil
pump plunger and should be securely tightened after adjusting.
When all the washers have been removed the plunger has
no stroke, and nothing can be gained by counterboring the cover or
adding to the length of the screw.
In the tool box will be found two thin washers, each .013 inch thick and
two washers each .065 inch • thick. To increase the oil supply, add one
of the thin washers at a time to the standard washers with which the
machine comes from the factory, until the proper oil supply is obtained.
Be very careful not to reduce the oil supply below the safety margin. It
is better to feed a trifle too much oil than to run the chance of
underoiling, but an absolutely correct adjustment can be made, and