Poulan PRO 305 - Manual (Page 19)

I^IIARBURETOR ADJUSTS
• Poor eni^é performance can be a result of
other causes such as dirty air filter, carbon
bldld-up on muffler outlets, etc. See the
**lVouble Shooting Chart** before proceed­
ing with carburetor adjustments.
• For best results, it is recommended that you
have a qualified service dealer make all car­
buretor su^ustments. Your dealer has the train­
ing, experience, and tools necessary to properly ad­
just you saw to meet our factory performance speci­
fications. Ì^isseruicc is reoi cowered èyicammJiy. If
it becomes necessary for you to make carburetor
a^* *ustments yourself, follow the described proce­
dures very carefully.
• The cwburetor has been adijusted at the fac­
tory for sea level conditions. Adjustments may
become nwessaiy if the saw is used at significantly
higher altitudes or if you notice any of the following
conditions:
NOTE; Be sure to properly prepare the saw as de­
scribed in “1. Preparation” (below) before making
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 acceler­
ate. See “4. Acceleration Adjustment.”
— Loss of cutting power which is not corrected by
air filter cleaning. See “5. High Speed Mixture
Adjustment.”
I CAVTfQNlJ perm^ent damagé will occur to
any 2-cycle engine if incorrect carburetor
aijgustments are made.
• If the unit will not operate properly after
makmg these acljustments, take the saw to a
qualified service dealer.
A WARNING
The chain will be moving during most of this pro­
cedure. Wear your protective gear and observe
all safety precautions.
1. PREPARATION
a. Stop the engine.
b. Use a fresh fuel mixture with proper gasoline/oil
ratio,
c. Place the saw on a solid, flat surface and make
sure the chain will not contact any object.
d. Locate the three (3) carburetor adjusting screw
openings to the right of the air filter cover. Fig­
ure 41.
e. Start the engine and allow engine to idle three
(3) minutes to wann up. The en^Tie must be at
operating temperature for proper adjustrnents to
oeniade.
Idle Speed
Screw'
Low Speed
Mixture
Screw
2. IDLE SPEED ADJUSTMENT
a. Allow the engine to idle.
b. Adjust the Idle Speed Screw imtil the engine
continues to run without stalling and without
the chain moving.
— Turn screw cUxkwise to increase engine
speed if engine ataUs or dies,
— Turn screw coimterclockwise to slow en^ns
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 Low Speed Mixture Adjustment,** recheck
idle speed ^ter each adjustment. The chain
must not move at idle speed.
Figure 41
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
counterclockwise 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. AGCELERATION 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
I
CAUTION; j Adjustments as small as 1/16 of a
turn can afiect engine performance. It is im­
portant to turn the screw only 1/16 of a turn
per adjustment and test the performance of
the saw before making further adjustments.
a. Make a test cut.
b. Adjust the High Speed Mixture Screw 1/16 of a
tipn as folloyi^:
-— Clockwise if saw smokes or loses power.
— Counterclockwiseifthesawhas speed out of
the cut but lacks power in the cut.
c. Repeat test cut.
d. Continue 1/16 of a turn adjustments imtil the
saw runs smoothly in cut.
I CAUTION; I
A too lean high speed setting
(clockwise adjustment) will cause engine
damage to any 2-cycIe engine from over­
heating and lack of lubrication. Never set
idle h^h speed mixture screw so ^r clock­
wise that you have high speed but lack pow­
er while cutting. An effective approach fol­
lows,
T— Turn screw counterclockwise until engine loses
powerwhile cutting.
turn screw clockwise in 1/16 of a turn in­
crements ouZy imtil the engine has power while
cutting
NOTO; If the unit will not operate properly after
^ngthese a^ustments, take the sawto a quaU-
fied service dealer.
-
19
-