Poulan 425 - Manual (Page 17)

E CARBURETOR ADJUSTMENTS
• Poor engine performance can be a result of
other causes such as dirty air filter, carbon
build-up on muffier outlets, etc. See the
“Trouble Shooting Chart” before proceed­
ing with carburetor adjustments.
• For best results, the manufacturer recom­
mends that you have a qualified service
dealer make all carburetor adjustments.
Your dealer has the training, experience, and tools
necessary to properly adjust your saw to meet fac­
tory performance specifications.
This service is
not covered by warranty. If it becomes necessary
for you to make carburetor adjustments yourself,
follow the described procedures very carefully.
• The carburetor has been adjusted at the fac­
tory for sea level conditions. Adjustments
may become necessary if the saw is used at signifi­
cantly higher altitudes or if you notice any of the
following conditions:
NOTE: Be sure to properly prepare the sa.w as de­
scribed in “1. Preparation*’ (below) before mak­
ing any adjustments.
- Chain moves when the engine runs at idle
speed. See “2. Idle Speed Adjustment.”
- Saw will not idle. See “2. Idle Speed Adjust­
ment” and “3, Low Speed Mixture Adjust­
ment.”
- Engine dies or hesitates when it should accel­
erate. See “4, Acceleration Adjustment.”
- Loss of cutting power whfch is not corrected by
air filter cleaning. See “5. High Speed Mixture
Adjustment.”
ICAUnONiJ
Permanent damage will occur to
anji^ 2—cycle engine if incorrect carburetor
adjustments are made.
• If the unit will not operate properly after
making these adjustments, take the saw to a
qualified service dealer.
A WABNING
The chain will be moving during most of this
procedure. Wear your protective gear and ob­
serve all safety precautions._______________ __
1. PREPMIATION
a. Stop the engine.
b. Use a fresh fuel mixture with proper gasoline/
oil ratio.
c. Place the saw on a solid, flat smface and make
sure the chain will not contact any object.
d. Locate the three (3) carburetor adjusting
screw openings Figure 36 .
e. Start the engine and allow engine to idle three
(3) minutes to warm up. The engine must he at
operating temperedure for proper adjustments
to be made.
2. IDLE SPEED ADJUSTMENT
a. Allow the engine to idle.
b. Adjust the idle sp^d screw until the engine
continues to run without stalling and without
the chain moving.
— Turn screw clockwise to increase engine
speed if engine stalls or dies.
— Turn screw counterclockwise to slow engine
down andfor to keep the chain from turning.
c. No further adjustments are necessary if
the chain does not move at idle speed and
if performance
is satisfactory.
A WARNING
In“3. Low Speed Mixture Adjustment,” recheck
idle speed £dter each adjustment. The chain
must not move at idle speed if performance is I
satisfactory.________________________________
3. LOW SPEED MIXTURE ADJUSTMENT
a. Allow engine to idle.
b.
Turn the low speed mixture screw slowly
clockwise until the RPM starts to drop. Note
the position.
c- Turn the low speed mixture screw slowly coun­
terclockwise until the RPM speeds up and
starts to drop again. Note the position,
d- Set the low speed mixture screw at the mid­
point between the two positions.
4. ACCELERATION ADJUSTMENT
If the engine dies or hesitates instead of accelerat­
ing, turn the low speed mixture screw 1/16 of a
turn at a time counterclockwise until you have
smooth acceleration,
5. HIGHSPEED MIXTURE ADJUSTMENT
CAVXIQS] Adjustments as small as 1/16 of a
turn can affect engine performance. It is
important to turn the screw only 1/16 of a
turn per adjustment and test the perform­
ance of the saw before making further ad­
justments.
NOTE; Never set RPM over 13,500,
a. Make a test cut.
b. Adjust the high speed mixture screw 1/16 of a
turn as follows:
- Clockwise if the saw smokes or loses power.
- Counterclockwise if the saw has speed out
of the cut but lacks power in the cut.
c. Repeat test cut.
d. Continue 1/16 of a turn adjustm^ts until the
saw^T^ smoothly in cut. ^ ^ '
A too lean hi^ si>eed settmg
(clockwise adjustment) will came enrine
damage from overheating and-BStik: of lubri­
cation. Never set hi^ speed nilxtiire screw
so far clockwise that you have hi^ speed
but lack power while cutting. An effective
approach follows.
— Turn the screw counterclockwise until the en­
gine loses power while cutting.
— Then, turn the screw clockwise m 1/16 of a
turn increments only until the engine has pow­
er while cutting.
NOTE; It is best to allow a qualified service dealer
make these adjustments.
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