RCCK
Fuel
System
GENERAL
Satisfactory engine performance is largely aepen-
dent upon correct fuel system adjustments. However,
adjustments cannot fully compensate for low engine
power due to wear, etc.
If
trouble develops, follow an
orderly procedure to determine the cause before
making any adjustment.
Adjusting the carburetor is a means of obtaining the
correct fuel-to-air mixture for smooth, efficient
operation. Always adjust in two steps, first the load
adjustment and then the idle adjustment.
GASOLINE CARBURETORS
Before adjusting the carburetor, be sure the ignition
system is working properly and the governor is
adjusted. Allow the engineto warm-up before starting
carburetor adjustments.
If
carburetor is completely out
of
adjustment
so
the engine will not
run, open both valves
1
to
1-112
turns off their seats to permit
starting.
Do
not force the needlevalves against theirseats.This can
bend the needle.
.-
.-
Adjustments
1.
With
no
load, turn idle fuel adiustrnent out until
enginespeed dropsslightly below normal, Figure
5.
Then
turn
needle in until speed returns
to
normal.
2.-Apply a full load to engine.
3.
Loosen packing nut and carefully turn main
adjustment in until speed drops slightly below
normal. Then turn needle out until speed returns
to normal.
4.
Tighten packing nut.
Alternate Method
(No
load adjustment possible)
1.
Start engine and allow it to warm up.
,
2.
Push in on governor mechanism to slow engine
.
_.
down to about
400
to
500
rpm.
3.
4.
Set idle fuel adjustment screw for even operation
so
engine is firing on both cylinders and running
smoothly.
Release governor mechanism to allow engine
to
accelerate. If engine accelerates evenly and
without a lag, the main adjustment is correct. If
not, adjust the needle outward about
1/2
turn and
again slow down the engine and release the
mechanism. Continue until the engine
accelerates evenly and without a time lag after
releasing the governor.
Loosen the packing
nut
before mak-
D
ing main fuel adjustment and then
tighten the
nut
to
a snug fit affer the adjustment has
been made. This procedure makes if easier
to
use the
carburetor adjusting fool and prevents fuel leaks
around the packing
nut.
Fuel leaks cause hard start-
ing because the float level becomes lower than
normal.
Cleaning and RepaicTo clean thecarburetor, soak all
components thoroughly in a good carburetorcleaner
following the cleaner manufacturer's instructions. Be
sure all carbon is cleaned from the carburetor bore,
especially in the area of the throttle valve. Blow out
the passages with compressed air. If possible, avoid
using wire to clean out the passages.
WARNING
Cleaning solutions fypically contain
I
strong chemicals fhaf may cause
injury if used improperly. Read all warning labels
before using.
Check the adjusting needles and nozzle for damage.
If the float is loaded with fuel or damaged, replace
it.
The float should
fit
freely on its pin without binding.
Invert the carburetor body and measure the float
level, Figure6. If necessary, bend thesmall lipthatthe
inlet valve rides on to adjust float level.
DIMENSION
SHOULD
BE
I
I
/%"
-
3/
16"
A9,3
(3.2-4.8
mm)
FIGURE
5.
GASOLINE CARBURETOR
FIGURE
6.
CHECKING FLOAT LEVEL
Redistribution or publication of this document
by any means, is strictly prohibited.
Redistribution or publication of this document
by any means, is strictly prohibited.
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