Operation; Fuel Mixture And Gasoline/Oil Recommendations; Cavitation; Ventilation - Mercury 50 User Manual

OPERATION

WEIGHT DISTRIBUTION
of weight (passengers and
A Shifting weight to real (stern).
At extremes, can cause boat to porpoise.
Causes bow to bounce in choppy water.
Increases danger of the following-wave
splashing into boat when coming off plane.
Improves ease of planing off.
At extremes, can cause boat to veer back
and forth (bow steer).
Reduces engine RPM.
BOTTOM OF BOAT
To maintain maximum speed the following
conditions of the boat bottom should be
observed:
A. Clean, free of barnacles and marine
growth.
B. Free of dtstort~on, nearly flat where it
contacts the water.
C. Straight and smooth, fore and aft
GEAR HOUSING
If outboard is not tilted up when boat is
docked, marine vegetation may accumu-
late. This growth MUST BE REMOVED
before operation; it may clog water inlets
and cause engine to overheat.

CAVITATION

Cavitation occurs when water flow cannot
follow the contour of afast moving under-
water object, such as a gear housing or
propeller. Cavitation permits the propeller
to speed up, but the boat speed t o reduce.
Cavitation can seriously erode the surface
of the gear housing or propeller. Common
causes of cavitation are:
A. Bent propeller blade or damaged gear
housing skeg.
B. Raised burrs of sharp edges o n pro-
peller or gear housing.
C. Weeds or other debris snagged on pro-
peller or gear housing.

VENTILATION

exhaust gases which are introduced
around the propeller resulting in propeller
speed-up and a reduction in boat speed.
Excessive ventilation is annoying and
usually caused by:
A. Outboard installed too high o n tran-
som.
B. Outboard tilted out too far.
C. A missing propeller diffuser ring
D. Damaged propeller or gear housing
which allows exhaust gases to escape
between propeller and gear housing
FUEL MIXTURE and GASOLINE/
OIL RECOMMENDATIONS
USE CARE when transporting fuel con-
tainer, whether i n a boat or car. D O N O T f i l l
fuel container to maximum capacity. Gaso-
line will expand considerably as i t warms
u p and can build u p pressure i n the fuel
container. This c a n cause fuel leakage and
a potential fire hazard.
GASOLINE RECOMMENDATIONS
Use of improper gasolines and/or oils can
cause serious damage t o your outboard
motor.
Any leaded or unleaded (lead-free) gaso-
line, with a minimum posted octane rating
of 87 (research octane number 90) is satis-
factory for use in these model outboard
motors.
However, gasolines containing alcohol,
either methyl alcohol (methanol) or ethyl
(ethanol) may cause increased:
Corrosion of metal parts
Deterioration of elastomer and plastic
parts.
Fuel permeation through flexible fuel
lines.
Wear and damage of internal englne
parts.
Starting and operating difficulties
Some of these adverse effects are due to
the tendency of gasolines containing alco-
hol to absorb moisture from the air, result-
ing in a phase of water and alcohol separat-
ing from the gasoline in the fuel tank.
The adverse effects of alcohol are more
severe with methyl alcohol (methanol) and
are worse with increasing alcohol content.
leakage from any part of the fuel system
can be a fire a n d explosion hazard which
c a n cause serious bodily injury or death.
Careful p e r r ~ d i c inspection of the entire
fuel system mandatory, particularly after
storage. All t el components including fuel
tanks, whether plastic, metal or fiberglass,
fuel lines, pr*mer bulbs, fittings, fuel filters
a n d carburetors should b e inspected for
leakage, softening, hardening, swelling or
corrosion. Aoy sign of leakage o r deterio-
ration nece.isitates replacement before
further e n g i r e operation.
Because of the possible adverse effects of
alcohol i n gasoline, i t is recommended that
only alcohol-free gasoline be used where
possible. If only alcohol-containing fuel is
available, or if the presence of alcohol is
unknown, then increased inspection fre-
quency for leaks a n d abnormalities is
required.
OIL RECOMMENDATIONS
The use of other than recommended gaso-
line and Quicksilver 2-Cycle Outboard Oil
o r a n acceptable N M M A TC-W 11'" o i l may
cause piston scoring, bearing failure or
both. D O NOT, under any circumstances,
use multi-grade o r other highly detergent
automobile oils o r oils which contain
metallic additives.
I n an emergency, if Quicksilver 2-Cycle
a
Outboard O i l is not available, substitute
high quality 2-cycle oil that is intended for
outboard use and meets N M M A rating
TC-W II'", shown o n o i l container. Use the
oil manufacturer's recommended gasoline-
oil mixture as shown o n the label, not to
exceed 50:l