FORM NO. 50-275
INSTRUCTION SHEET FOR
EVINRUDE-JOHNSON CARBURETOR
NOTE: Numbers in parenthesis used in these instructions
are the index numbers on the exploded view drawing on
opposite side of sheet.
I. DISASSEMBLY
Disassemble the carburetor to the extent indicated by the
drawing on opposite side of sheet, and in the order of
index numbers on the drawing. Removal of these parts will
permit proper inspection and cleaning of the various
carburetor parts. Give special attention to the following:
a. Inspect needle valves (2 and 6) for damage caused by
overtightening against their seats in the float chamber and
body assemblies. Replace the parts if grooves have been
made on tapered ends or if parts have been mutilated from
abusive handling.
b. Check the float assembly (17) for damage due to
careless servicing, and looseness of the float lever on the
cork float ring. Replace the float if damaged.
c. Check the nozzle (21) for distortion and mutilated
screwdriver slot. Replace for either condition.
d. Replace all damaged or defective parts.
e. Make sure the nozzle gasket (20) is removed. It will
probably stick to either the carburetor body assembly (14)
or float chamber assembly (22). Scrape off fragments.
II. CLEANING.
A regular commercial carburetor cleaning solvent is
ideal for cleaning the carburetor body and parts. If this
solvent is not available, procure some low-grade lacquer
thinner and clean parts as follows:
a. Use enough solvent to cover the body (14) and float
chamber (22) and drop all parts except float into the
solvent.
b. Allow the parts to “soak” for approximately 10
minutes to loosen foreign material in internal passages.
c. Using a small bristle brush, brush the parts until all
foreign accumulations have been removed.
d. Use clean solvent to rinse, then blow out all passages
and orifices with compressed air.
CAUTION: Do not use rags or waste for cleaning or
drying parts. Also do not permit the float
assembly
(17) to come in contact with the cleaning
solvent .
Rinse float in clean gasoline if dirty.
III. REASSEMBLY.
Replace old parts with corresponding new parts in
kit and assemble carburetor in reverse order of index
numbers on the exploded drawing on opposite side of
sheet. Be sure to observe the following conditions.
a. After installing the float assembly (17), hold the
carburetor body (14) upside down and measure the
float height as shown in figure 1. Distance “A” should
be the same at both sides. If an adjustment is required,
carefully bend the float lever until the two
measurements are equal.
b. Rotate needle valves (2 and 6) carefully into their
respective castings until they seat (never force them).
Back needles out for a trial setting as follows: One
turn for (2) and two turns for (6). These adjustments
must be rechecked after starting engine.
c. Make sure the nozzle gasket (20) is in place
during assembly.
IV. ADJUSTMENTS
Install the carburetor on engine and connect
throttle and other controls. This carburetor has a fixed
idle air control through holes in throttle valves. No
attempt should be made to change this arrangement.
a. Start and warm up engine.
b. Accelerate the engine rapidly and note response.
Adjust high-speed needle (6) clockwise (toward lean)
as far as possible to keep engine from hesitating when
throttle is opened quickly.
c. Adjust slow-speed needle (2) intermittently with
the high-speed needle (6) until a smooth idle is
obtained.
NOTE: Be sure to allow a few seconds
between each trial adjustment for the
engine to “settle down”.
d. Sharpen both adjustments by setting the idle
mixture with slow-speed needle valve (2) and power
response (high-speed) with high-speed needle valve
(6).
e. Test carburetor by operating the equipment and
finalize both idle, and high-speed adjustments by
rotating each screw slightly and noting response.
N-7793
