Evinrude 4906B 4HP 1969, Owner'S Manual

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2-16 TUNING
bottom carefully for marine growth or evi-
dence of a "hook" or a "rocker" in the
bottom. Either one of these conditions will
greatly reduce performance.
Performance
Mount the motor on the boat. Install the
remote control cables and check for proper
ad justment.
Make an effort to test the boat with
what might be considered an average gross
load. The boat should ride on an even keel,
without a list to port or starboard. Adjust
the motor tilt angle, if necessary, to permit
the boat to ride slightly higher than the
stern. If heavy supplies are stowed aft of
Boat performance will be drastically hampered,
if
the bottom is damaged.
the center, the bow will be light and the
boat will "plane" more efficiently. For this
test the boat must be operated in a body of
water.
Check the engine rpm at full throttle.
The rpm should be within the Specifications
in the
Appendix. All OMC engine model
ser ial number identification plates indicate
the horsepower rating and rpm range for the
engine. If the rpm is not within specified
range, a propeller change may be in order.
A higher pitch propeller will decrease rpm,
and a lower pitch propeller will increase
rpm.
For maximum low speed engine perform-
ance, the idle mixture and the idle rpm
should be readjusted under actual operating
conditions.
Maximum engine performance can only
be
obtained
through proper tuning using
a
tachometer.