Oregon Chainsaw 73701540 PCS3840 2006 06 20 Operators Manual

							
PCS 3840
Operating Instructions Read operating instructions before use! 
Manuel d’utilisation Lire attentivement le mode d‘emploi avant chaquemise en service !
EN
73701540
FR 
						

							1EN1. For Safe Operation
Dear Customer,
Firstly, we wish to thank you for having chosen our products and hope that the use of this machine will
be extremely satisfying for you and fully meet your expectations. This manual has been drawn up to
allow your to get to know your machine well and use it in safe and efficient conditions; please do not
forget that it is an integral part of the machine and keep it to hand to be consulted at all times and con-
sign it with the machine if you should sell or lend it to others.
Your new machine has been designed and manufactured to current standards and is safe and reliable
if used in full respect of the instructions contained in this manual (forecast use); any other use or fail-
ure to comply with the instructions for safe use, maintenance and repair shall be considered as
“improper use”, cause the warranty to become null and void and relieve the Manufacturer from all
responsibility, with the user becoming responsible for charges for damages or personal or third party
injury.
If any slight differences are found between the description herein and the machine you own, please
bear in mind that due to continual product improvement, the information contained in this manual is
subject to modification without prior notice or obligatory updating,  although the essential features for
the purposes of safety and operation remain unchanged. In the event of doubt, please contact your
dealer. Enjoy your work!
EXPLANATION OF SYMBOLS AND SAFETY
WARNINGS
Read operators instruction
book before operating this
machine.
Use the chain saw with two
hands.
Read, understand and follow all
warnings.
Wear head, eye and ear protec-
tion.
Warning! Danger of kickback.
WARNING!!!
RISK OF DAMAGING HEARING
IN NORMAL CONDITIONS OF USE,
THIS MACHINE MAY INVOLVE A DAILY
LEVEL OF PERSONAL EXPOSURE TO
NOISE FOR THE OPERATOR EQUAL
TO OR GREATER THAN 
85 dB(A)
1.For Safe Operation ...................................................................... 12.Explanation of Symbols on the Machine  ................................... 43.Installing Guide Bar and Saw Chain  .......................................... 54.Fuel and Chain Oil  ...................................................................... 65.Operating the Engine .................................................................. 86.Sawing ....................................................................................... 117.Maintenance .............................................................................. 138.Maintenance of Saw Chain and Guide Bar  .............................. 159.Troubleshooting Guide  ............................................................. 16
Contents
1. For Safe Operation    
						

							2MM2EN1. For Safe Operation
1.Never operate a chain saw
when you are fatigued, ill, or
upset, or under the influence of
medication that may make you
drowsy, or if you are under the
influence of alcohol or drugs.
2.Use safety footwear, snug fit-
ting clothing and eye, hearing and
head protection devices.
Use the vibration-proof glove.
3.Keep the saw chain sharp and
the saw, including the AV system,
well maintained. A dull chain will
increase cutting time, and press-
ing a dull chain through wood will
increase the vibrations transmit-
ted to your hands. A saw with
loose components or with dam-
aged or worn AV buffers will also
tend to have higher vibration lev-
els.
4.All the above mentioned pre-
cautions do not guarantee that
you will not sustain whitefinger
diseaseor carpal tunnel syn-
drome.
Therefore, continual and regular
users should monitor closely the
condition of their hands and fin-
gers. If any of the above symp-
toms appear, seek medical advice
immediately.
5.Always use caution when han-
dling fuel. Wipe up all spills and
then move the chain saw at least 3
m from the fueling point before
starting the engine.
6.Eliminate all sources of sparks
or flame (i.e. smoking, open
flames, or work that can cause
sparks) in the areas where fuel is
mixed, poured, or stored.
7.Do not smoke while handling
fuel or while operating the chain
saw.
8.Do not allow other persons to
be near the chain saw when start-
ing or cutting. Keep bystanders
and animals out of the work area.
Children, pets and bystanders
should be a minimum of 10 m
away when you start or operate
the chain saw.
9.Never start cutting until you
have a clear work area, secure
footing, and a planned retreat
path from the falling tree.
10.Always hold the chain saw
firmly with both hands when the
engine is running. Use a firm grip
with thumb and fingers encircling
the chain saw handles.
11.Keep all parts of your body
away from the saw chain when the
engine is running.
12.Before you start the engine,
make sure the saw chain is not
contacting anything.
13.Always carry the chain saw
with the engine stopped, the
guide bar and saw chain to the
rear, and the muffler away from
your body.
14.Always carry the chain saw
with the engine stopped, the
guide bar and saw chain to the
rear, and the muffler away from
your body.
15.All chain saw service, other
than the items listed in the
Owner’s Manual, should be per-
formed by competent chain saw
service personnel. (E.g., if improp-
er tools are used to remove the
flywheel, or if an improper tool is
used to hold the flywheel in order
to remove the clutch, structural
1. For Safe Operation  
						

							3EN1. For Safe Operation
damage to the flywheel could
occur which could subsequently
cause the flywheel to disinte-
grate.)
16.Always shut off the engine
before setting it down.
17.Use extreme caution when
cutting small size brush and
saplings because slender material
may catch the saw chain and be
whipped toward you or pull you
off balance.
18.When cutting a limb that is
under tension, be alert for spring-
back so that you will not be struck
when the tension in the wood
fibers is released.
19.Never cut in high wind, bad
weather, when visibility is poor or
in very high or low temperatures.
Always check the tree for dead
branches which could fall during
the felling operation.
20.Keep the handles dry, clean
and free of oil or fuel mixture.
21.Operate the chain saw only in
well ventilated areas. Never start
or run the engine inside a closed
room or building. Exhaust fumes
contain dangerous carbon
monoxide.
22.Do not operate the chain saw
in a tree unless specially trained to
do so.
23.Guard against kickback.
Kickback is the upward motion of
the guide bar which occurs when
the saw chain at the nose of the
guide bar contacts an object.
Kickback can lead to dangerous
loss of control of the chain saw.
24.When transporting your chain
saw, make sure the appropriate
guide bar scabbard is in place.
KICKBACK SAFETY PRECAUTIONS FOR
CHAIN SAW USERS 
Kickback may occur when
the nose or tip of the guide bar touches an
object, or when the wood closes in and
pinches the saw chain in the cut. Tip contact
in some cases may cause a lightning fast
reverse reaction, kick-
ing the guide bar up
and back towards the
operator.
Pinching the saw
chain along the top of
the guide bar may
push the guide bar
rapidly back towards the operator. Either of
these reactions may cause you to lose control
of the saw, which could result in serious per-
sonal injury.
• Do not rely exclusively on the safety devices
built into your saw. As a chain saw user you
should take several steps to keep cutting
jobs free from accident or injury.
1. With a basic understanding of kickback you
can reduce or eliminate the element of surprise.
Sudden surprise contributes to accidents.
2. Keep a good grip on the saw
with both hands, the right hand on
the rear handle, and the left hand
on the front handle, when the
engine is running. Use a firm grip
with thumbs and fingers encircling
the chain saw handles. A firm grip
will help you reduce kickback and
maintain control of the saw.
3. Make certain that the area in
which you are cutting is free from
obstructions. Do not let the nose
of the guide bar contact a log,
branch, or any other obstruction
which could be hit while you are
operating the saw.
4. Cut at high engine speeds.
5. Do not overreach or cut above
shoulder height.
6. Follow the manufacturer’s
sharpening and maintenance
instructions for the saw chain.
7. Only use replacement bars and
chains specified by the manufac-
turer or the equivalent.

!WARNING! 
						

							4MM4EN2. Explanation of Symbols on the Machine
For safe operation and
maintenance, symbols are carved in relief on
the machine.
According to these indications, please be
careful not to make any mistake.
The port to refuel “MIX GASO-
LINE”
Position:Fuel cap
The port to top up chain oil
Position:Oil cap
Setting the switch to the “I”
position, the engine starts.
Setting the switch to the “O”
position, the engine stops
immediately.
Position: Front at the top of
the rear handle
Starting the engine. If you pull
out the choke knob (at the
back-right of the rear handle)
to the point of the arrow, you
can set the starting mode as
follows:
•First-stage position – start-
ing mode when the engine is
warm.
•Second-stage position –
starting mode when the
engine is cold.
Position:Upper-right of the
aircleaner cover

!WARNING!The screw under the “H”
stamp is The High-speed
adjustment screw.
The screw under the “L” stamp
is The Slow-speed adjustment
screw.
The screw at the left of the “T”
stamp is the Idle adjustment
screw.
Position:Left side of the rear
handle
Shows the directions that the
chain brake is released (white
arrow) and activated (black
arrow).
Position:Front of the chain
cover
If you turn the rod by screw-
driver follow the arrow to the
MAX position, the chain oil
flow more, and if you turn to
the MIN position, less.
Position:Bottom of the
power unit
2. Explanation of Symbols on the Machine   
						

							5EN3. Installing Guide Bar and Saw Chain
A standard saw unit package contains the items
as illustrated.
Open the box and install the guide bar and the
saw chain on the power unit as follows:
The saw chain has very
sharp edges. Use thick protective gloves for
safety.
1. Pull the guard towards the front handle to
check that the chain brake is not engaged.
2. Loosen the nuts and remove the chain cover.
3. Gear the chain to the sprocket and, while fit-
ting the saw chain around the guide bar,
mount the guide bar to the power unit. Adjust
the position of chain tensioner nut.

!WARNING!
Pay attention to the correct
direction of the saw chain.
4. Fit the chain cover to the power unit and fas-
ten the nuts to finger tightness.
5. While holding up the tip of the bar, adjust the
chain tension by turning the tensioner screw
until the tie straps just touch the bottom side
of the bar rail.
6. Tighten the nuts securely with the bar tip held
up (12 ~ 15 Nm). Then check the chain for
smooth rotation and proper tension while
moving it by hand. If necessary, readjust with
the chain cover loose.
7. Tighten the tensioner screw.
A new chain will expand its
length in the beginning of use. Check and read-
just the tension frequently as a loose chain can
easily derail or cause rapid wear of itself and the
guide bar.
NOTE
NOTE
3. Installing Guide Bar and Saw Chain
(1) Chain cover
(2) Chain Tensioner
nut
(1) Moving
direction
(1) Loosen
(2) Tighten
(3) Lift up
(4) Tensioner
screw
(1) Power unit
(2) Bar protector
(3) Guide bar
(4) Saw chain
(5) Plug wrench
(6) Screwdriver for carburetor adjustment     
						

							6MM6EN4. Fuel and Chain Oil
• FUEL
Gasoline is very flamma-
ble. Avoid smoking or bringing any flame or
sparks near fuel. 
Make sure to stop the engine and allow it cool
before refueling the unit. 
Select outdoor bare ground for fueling and
move at least 3 m (10 ft) away from the fuel-
ing point before starting the engine.
•The engines are lubricated by oil specially for-
mulated for air-cooled 2-cycle gasoline engine
use. Use an anti-oxidant added quality oil
expressly labeled for air-cooled 2-cycle engine
use (JASO FC GRADE OIL or ISO EGC
GRADE).
•Do not use BIA or TCW (2-stroke water-cool-
ing type) mixed oil.
•RECOMMENDED MIXING RATIO GASO-
LINE 50: OIL 1
•Exhaust emission are controlled by the funda-
mental engine parameters and components
(eq., carburation, ignition timing and port tim-
ing) without addition of any major hardware or
the introduction of an inert material during
combustion.
•These engines are certified to operate on
unleaded gasoline.
•Make sure to use gasoline with a minimum
octane number of 89RON (USA/Canada:
87AL).
•If you use a gasoline of a lower octane value

!WARNING!
than prescribed, there is a danger that the
engine temperature may rise and an engine
problem such as piston seizing may conse-
quently occur.
•Unleaded gasoline is recommended to reduce
the contamination of the air for the sake of
your health and the environment.
•Poor quality gasolines or oils may damage
sealing rings, fuel lines or fuel tank of the
engine.
•HOW TO MIX FUEL
Pay attention to agitation.
1. Measure out the quantities of gasoline and oil
to be mixed.
2.Put some of the gasoline into a clean,
approved fuel container.
3. Pour in all of the oil and agitate well.
4. Pour in the rest of gasoline and agitate again
for at least one minute. As some oils may be
difficult to agitate depending on oil ingredi-
ents, sufficient agitation is necessary for the
engine to last long. Be careful that, if the agi-
tation is insufficient, there is an increased
danger of early piston seizing due to abnor-
mally lean mixture.
5. Put a clear indication on the outside of the
container to avoid mixing up with gasoline or
other containers.
6. Indicate the contents on outside of container
for easy identification.
•FUELING THE UNIT
1. Untwist and remove the fuel cap. Rest the
cap on a dustless place..
2. Put fuel into the fuel tank to 80% of the full
capacity.
3. Fasten the fuel cap securely and wipe up any
fuel spillage around the unit.

!WARNING!
4. Fuel and Chain Oil  
						

							7EN4. Fuel and Chain Oil
1. Select flat and bare ground for fueling.
2. Move at least 10 feet (3 meters) away from
the fueling point before starting the
engine.
3. Stop the engine before refueling the unit.
At that time, be sure to sufficiently agitate
the mixed gasoline in the container.
•FOR YOUR ENGINE LIFE, AVOID:
1. FUEL WITH NO OIL (RAW GASOLINE) – It will
cause severe damage to the internal engine
parts very quickly.
2. GASOHOL – It can cause deterioration of
rubber and/or plastic parts and disruption of
engine lubrication.
3. OIL FOR 4-CYCLE ENGINE USE – It can
cause spark plug fouling, exhaust port block-
ing, or piston ring sticking.
4.
Mixed fuels which have been left unused
for a period of one monthor more may clog
the carburetor and result in the engine failing
to operate properly.
5. In the case of storing the product for a long
period of time, clean the fuel tank after ren-
dering it empty. Next, activate the engine and
empty the carburetor of the composite fuel.
6. In the case of scrapping the used mixed oil
container, scrap it only at an authorized
repository site.
Moreover, normal wear and
change in product with no functional influence
are not covered by the warranty. Also, be careful
that, if the usage in the instruction manual is not
observed as to the mixed gasoline, etc.
described therein, it may not be covered by the
warranty.
•CHAIN OIL
Use motor oil SAE #10W-30 all year round or
SAE 30 ~ #40 in summer and SAE #20 in winter.
Do not use wasted or regen-
erated oil that can cause damage to the oil
pump.
NOTE
NOTE

!WARNING!  
						

							8MM8EN5. Operating the Engine
It is very dangerous to run
a chainsaw that mounts broken parts or lacks
any parts. Before starting engine, make sure
that all the parts including bar and chain are
installed properly.
•STARTING THE ENGINE
1. Fill fuel and chain oil tanks respectively, and
tighten the caps securely.
2. Set the switch to “I” position.
3. While holding the throttle lever together with
the trigger safety, push in the side latch and
release the throttle lever to leave it at the
starting position.

!WARNING!When restarting immediately
after stopping the engine, set the Choke knob in
the first-stage position (choke open and throttle
lever in the starting position).
Once the choke knob has
been pulled out, it will not return to the operating
position even if you press down on it with your
finger. When you wish to return the choke knob
to the operating position, pull out the throttle
lever instead.
4. While holding the saw unit securely on the
ground, pull the starter rope vigorously.
Do not start the engine
while the chain saw hangs in one hand. The
saw chain may touch your body. This in very
dangerous.
5. When engine has ignited, first push in the
choke knob to the first-stage position and
then pull the starter again to start the engine.
6. Allow the engine to warm up with the throttle
lever pulled slightly.
Keep clear of the saw
chain as it will start rotating upon starting of
engine.
•CHECKING THE OIL SUPPLY 
Make sure to set up the bar
and the chain when checking the oil supply.
If not, the rotating parts may be exposed. It is
very dangerous.
After starting the engine, run the chain at medi-
um speed and see if chain oil is scattered off as
shown in the figure.

!WARNING!

!WARNING!

!WARNING!
NOTE
NOTE
5. Operating the Engine
(1) Chain oil
(2) Fuel
(1) Switch
(2) Throttle lever
(3) Throttle interlock
(1) Choke knob:
(a) When the engine
is cool
(b) When the engine
is warm up
(c) After the engine
starts     
						

							9EN5. Operating the Engine
The chain oil flow can be changed by inserting a
screwdriver in the hole on bottom of the clutch
side.  Adjust according to your work conditions.
The oil tank should become
nearly empty by the time fuel is used up. Be sure
to refill the oil tank every time when refueling the
saw.
•ADJUSTING THE CARBURETOR
The carburetor has been adjusted at the factory.
Should your unit need readjustment due to the
changes in altitude or operating conditions,
please let your skillful dealer make the adjust-
ment. 
A wrong adjustment may cause damage to your
unit. 
If you have to make the adjustment yourself,
please follow the procedure below carefully.
Before adjusting the carburetor, make sure that
the provided air/fuel filters are clean and fresh
and the fuel properly mixed.
NOTE
When adjusting, take the following steps:
Be sure to adjust the carbu-
retor with the bar chain attached.
1. “H” and “L” needles are restricted within the
number of turn as shown below.
“H” needle: -1/4
“L” needle: -1/4
2. Start the engine and allow it to warm up in
low speed for a few minutes.
3. Turn the idle adjusting screw (T) counter-
clockwise so that the saw chain does not
turn. If the idling speed is too slow, turn the
screw clockwise.
4. Make a test cut and adjust the “H” needle for
best cutting power, not for maximum speed.
Over revolution of “H” needle
causes a lack of power or a poor acceleration. In
such a case please turn the “H” needle a little
counterclockwise.
•CHAIN BRAKE
This machine is equipped with an automatic
brake tostop saw chain rotation upon occur-
rence of kickback during saw cutting.
The brake is automatically operated by inertial
force, which acts on the weight fitted inside the
front guard.
This brake can also be operated manually with
the front guard turned down to the guide bar.
To release the brake, pull up the front guard
toward the front handle till a “click” sound is
heard.
CautionBe sure to confirm brake operation during daily
inspection.
How to confirm:
1. Turn off the engine.
NOTE
NOTE
(1) Front handle
(2) Released
(3) Braking
(4) Brake lever
(1) “L” needle
(2) “H” needle
(3) Idle adjusting
screw
(1) Chain oil
(1) Chain oil flow
adjusting shaft
(2) Rich
(3) Lean