Husqvarna 2100 Instruction manual

Technical Specification
Service Data
Special Tools
Fuel system, Carburettor
Electric system
Lubricating system, Oil pump
Cylinder, Piston
Crankcase, Crankshaft
Starter
Centrifugal Clutch
Safety Equipment

Displacement
Bore
Stroke
Ignition system
Ignition advance
Spark plug
Electrode gap
Carburettor
Fuel tank volume
Oil tank volume
Chain lubrication
Clutch drum/sprocket
Weights
99 cm3 (6 cu in)
56.0 mm (2 20")
40.0 mm (1.57")
Electronic Make SEM type GA 1.
24° before t.d.c. at 133 r/s (8,000 r/mm)
Bosch WSR OF
0.5 mm (0.020")
Diaphragm carburettor. Make Tillotson type HS
136C with speed governor 0.070".
Basic setting:
H= 1.0
L= 1.2
1.0 litre (0.26US gallon, 0.22 imp gallon)
Fuel mixture 4%(1:25)
With Husqvarna Twostroke Oil 2% (1:50).
0.65 litres (0.17 US gallon, 0.14 Imp gallon).
Two separate lubrication systems
Automatic
No supply during idling. Adjustable for two different
delivery rates:
Bar 15" - 21" : Position I
Bar 21" and more. Position II
Manual
Hand-operated pump on the left side of the rear
handle.
Standard
7 teeth, 0.404" Pitch
Optional .
8 teeth, 3/8" Pitch.
1. Weight sawbody (empty) 8.0 kg (17.6 lb)
2. Weight sawbody (empty) incl. 24"
bar and chain (Oregon 52L - 76E 0.404"L10 2 kg (22.5 lb)
3. Same as 2 however with full tanks. 11.4 kg (25.1 lb)
1
:
1

Classification table
Cylinder class Piston class
AA
BB
CC
PLEASE NOTE!
As ''A " denotes smallest cylinder diameter and ''C"
the largest, piston grades should be matched or
one grade smaller E g / t is no t permissable to use
a grade B piston m a grade A cylinder.
1:2

Crankcase Assy
Vacuum: 0.04 MPa (0.4 kp/cm2, 5.7 psi)
Max. leakage: 0.01 MPa/1 mm (0.1 kp/cm2,
1.4 psi, per min)
Tools: 502 50 37-01 Vacum gauge
502 50 81-01 Cover plate, exhaust port
502 50 47-01 Cover plate, inlet port
Pressure: 0.08 MPa (0.8 kp/cm2, 11.4 psi)
Max. leakage: 0.02 MPa/30 see (0.2 kp/c2,
2.8 phi, per 30 sec)
Tools: 502 50 38-01ressure gauge
502 50 81-01 Cover plate, exhaust port
502 50 47-01 Cover plate, inlet port
Fuel tank
Pressure: 0.05 MPa (0.5 kp/em2, 7.1 psi)
Leakage: No leakage permitted.
Tool: 502 50 38-01 Pressure gauge
Carburettor
Pressure: 0.03 MPa (0.3 kp/em2, 4.3 psi)
Leakage: No leakage permitted
Tool: 502 50 38-01 Pressure gauge
2:1

Oil pump
Pressure: 0.3 MPa (3 kp/cm2,42.7 psi)
Pump capacity at 6,000 r/min:
Pos 1: approx 16-18 ml/min (0 98-1.10 cu in/min)
Pos 2: approx 22-24 ml/min (1.34-1.46 cu 1n/min)
Tools: 502 50 85-01il pump tester
Grad measuring glass.
Starter
Make sure that it IS possible to turn the pulley at
least 1/2 turn further when the cord is pulled
out completely.
Fuel and oil
The twostroke engine 1S lubricated by oil mixed
with petrol m various proportions depending on
the type of oil used.
"Pre-mixed" oil 1 :20 (5% oil)
Ordinary twostroke oil 1 :25 (4% oil)
Husqvarna Twostroke Oil 1:50 (2% oil)
See also the mixing table below:

502 50 06-01
Assembling pilers
(spark plug protector)
502 50 07-01
Assembling pliers
(cable grommet)
502 50 18-014 NV 4 mm
502 50 19-01V3 NV 3 mm
502 50 57-01 NV 3/16’’
Allen key
502 50 20-01 (M5)
Stud fitting tool
502 50 22-01 NV 8 mm
502 50 23 01 NV 10 mm
Socket spanner
502 50 24-01
Spanner,clutch centre
502 50 25-01
Holding bar compl.
502 50 26-01
Puller compl. with screw
502 50 30-01
Fitting tool compl for
crankshaft
502 50 33-01
Piston stop
502 50 36-01
Revolution counter
50 25 037-01 Vacuum
gauge, compl.
502 50 38-01Pressure
gauge, compl.
502 50 42-01
Lithium grease 250 9
(0.55 lb)
502 50 45-01
Distance sleeve (35 mm)
502 50 47-01
Cover plate, inlet port
206 23 72-11
5027002-01
2820008-01
6027009-01
3:1
202 42 94-45
202 43 32-55
202 42 97-55
202 43 33-55
502 50 25-01 (compl.)

502 50 70-01
Piston mounting set,
compl,
502 50 81-01
Cover plate, exhaust port
502 50 82-01
Fitting drift (sealing ring)
502 50 83-01
Hook for oil filter
502 50 84-01
Electrotester
502 50 85-01Oil
pump tester,
compl.
502 50 86-01 NV 3 mm
502 50 87-01 NV 4 mm
Allen screwdriver with ball
3:2
502 50 49-01
Assembling pliers
(centrifugal clutch)
502 50 50-01
Repair kit for elec-
tric cables
502 50 51-01
Cable clip pliers
502 50 52-01
Fitting sleeve for
sealing ring
502 50 62-01
Fitting tool (manual
pump)
502 50 66-01
U-spanner for vibration
damper
502 50 69-01
Fitting drift
(piston pin)
502 50 70-01

502 50 90-01
Jet-Pac spray gun compl.
incl.. retouch paint
502 50 91-01
Retouch paint, orange,
1/8 l
502 50 92-01
502 51 01-01
Extractor (sealing ring)
502 51 02-01
Clamping device
502 5106-01
Glue, adhesive
502 51 07-01
Glue, epoxy
502 51 24-01
SEM electric system tester
3:3
502 51 08-01
Loctite AA (normal locking power)
502 51 09-01
Loctite AAV (strong locking power)
502 50 92-01
502 50 91-01

Removal of carburettor
Remove carburettor cover, pre-filter, air filter,
cylinder cover and fuel hose
Remove the throttle push rod from the plastic le-
ver with a pair of flat hose pliers.
Fig 4:1
Loosen the socket head screws that retain the carbu-
rettor (use the Allen key No. 502 50 18-01).
Remove screws, air filter elbow and carburettor.
Clean the carburettor on the outside.
Fig 4:2
Remove the metering diaphragm cover and the me-
tering diaphragm.
Note that the centre pin of the diaphragm enters
the forked end of the lever of the needle valve.
Connect the pressure gauge 502 50 38-01 to the
fuel inlet of the carburettor and pump until a
pressure of 0.03 MPa (0.3 kp/cm2 ) is reached.
Check for any leakage at the needle valve or at the
gasket on the pump side.
The easiest way of locating leakages IS to pour
some petrol where you suspect the leakages to be.
Loosen the screw that retains the bearing shaft of
the lever and remove lever, shaft, spring and needle
valve (see fig. 4:3).
Fl
g
4
:
3
Dell a small hole in the Welch plugs (approx. ∅2
mm) and pose away the plugs by means of a
pointed tool.
Fig 4:4
NOTE!
Drill with care m order not to damage the carburettor
housing
Fig 4:5
Unscrew the two adjusting needles. Remove the
cover above the pump diaphragm and remove
diaphragm and gasket. Lift off the fuel screen care-
fully by means of a pointed tool.
4:1

Speed governor
The purpose of the governor is to limit the engine
speed in order to protect vital parts like the crank-
shaft and ignition system from excessive stresses.
We therefore advise most strongly against any inter-
ference designed to render it inoperative. When the
saw IS run under no-load conditions, the engine
speed IS limited to 10,500 r/min as the governor
comes into operation.
Fig 4:6
1. Steel ball. 2. Spring 3 Fuel inlet. 4. Fuel outlet
The steel ball and spring in the governor are so de-
vised that vibrations in the carburettor at a certain
engine speed cause the steel he I l to open the fuel
outlet. An excessively rich mixture IS then obtained
and the engine begins to four-stroke, the speed
drops and the vibrations decrease. The steel ball
then closes the outlet, the engine speed increase
and the process IS repeated.
Removal of speed governor
Remove the screw for the choke flap. Pull out the
flap approx. 7 mm and push out the choke shaft
approx 5 mm. Remove the speed governor with a
suitable screw driver.
4:2
Carburettor check
A. Pumping section
Clean the fuel screen and -lines with compressed
air.
Check the gasket and the pump diaphragm for
damage or wear.
B. Metering section
Check that the adjuting needles are straight and
that their tapered ends are not damaged. Check the
Fig 4:8
gasket and the metering diaphragm for damage or
wear. Check with particular care the wear on the
centre pin of the diaphragm.
Fig 4:9
Check that the needle valve is not worn, neither on
its seat, nor in the groove for the lever

Fig 4:10
Check that the needle valve lever is not worn,
neither at the connection to the valve, nor to the
metering diaphragm.
Check that the filter screen near the main jet is
not dirty or damaged.
C. Mixing section
Clean all fuel Ones and jets with compressed air.
D. Speed governor
The speed governor is easily checked by means of
the pressure gauge No. 502 50 38-01.
Fig4:11
Connect the pressure gauge as shown in fig. 4.11
Check that the hose does not cover the two holes
near the thread.
The valve should be tight, which means no ''hiss
sound" at a pressure below 0.10 MPa (1 kp/cm2 ).
In case of leakage, the valve should be replaced.
The carburettor spare part kit has got No.
501 54 67-01.
Assembly
A. Pumping section
Locate the fuel screen carefully m its seating (see
fig. 4:5). Locate the pump diaphragm next to the
carburettor housing and then add gasket and cover.
Tighten the screws of the cover diagonally and evenly.
B. Metering section
Fit new Welch plugs. Install them with a suitable
drift:
for the big plug drift
∅
8 mm
for the small plug daft ∅
4 mm
NOTE!
Do not press m the plugs so that they bulge imwards!
Fig 4:13
Mount the needle valve, lever, spring and shaft.
Locate the spring properly!
4:3

When properly adjusted the lever of the needle
valve shall be on a level with the carburettor
housing surrounding it. Adjust if necessary (see
Fig 4:14
If the lever is located too high, the carburettor will
be very sensitive as regards the adjustment of the
adjusting needles.
A too low lever induces bad acceleration qualities.
Check that the lever can move freely.
Make a pressure test of the carburettor. Proceed as
mentioned above.
Then mount gasket, metering diaphragm and cover
.
NOTE!
Care should be taken to ensure that the centre pin of the
diaphragm enters the fork in the level!
Install the adjusting needles and screw them out
to the following basic position:
H = 1.0 turn open
L = 1.2 turn open
C. Speed governor
Locate the sealing washer in the carburettor hous-
ing and fasten the speed governor. Push the choke
shaft into its position and fit the choke flap and
its locking screw.
4:4
Adjustment of carburettor
A. Basic setting
Before adjusting the carburettor, proceed as
follows:
Clean the air filter or, if necessary, replace it
Check the spark plug and its electrodes
check that the fuel filter is not clogged
.
. , . . ~,.,
Fig 4:15
Examine the fuel filter as follows:
Loosen the fuel hose from the carburettor and lay
the chain saw on the clutch side. Open the tank
cap If there is enough fuel in the tank, some of it
ought to run out of the hose (see fig. 4:15)
Fig 4:16
After the abovementioned checks, make a basic
adjustment of the carburettor needles, i.e. H = 1.0
turn open and L = 1.2 turn open.
Start the chain saw and warm it up by applying
full throttle and letting it cut into a log.
A constant speed, without fourstroking, for 10-20
sec. when cutting into a log indicates not only a
good high speed function of the carburettor but
also a good condition overall.
Fig. 4:14)

The following problems may occur when warming the chain saw up:
PROBLEM DAMAGE
Engine fourstroking Speed governor faulty
Bad idling Crack in the insulating piece
Badly tightened carburettor screws
Incorrectly assembled or leaking gaskets
Tank breather valve inoperative
Fuel filter clogged
Low engine power Leakage m the pumping section of the carburettor
NOTEI
Too lean adjustment of the carburettor would cause a
considerable loss of power. Adjust the carburettor in
order to obtain maximum power and not maximum steed.
B. Adjustment of L-needle
Adjust the idling speed by means of the throttle
adjusting screw "T" (fig. 4:16). Try to reach a
position where the chain IS lust beginning to
rotate, that is at a comparatively high idling speed.
Fig 4:17
Put your right hand on the front handle and make a
fine adjustment of the L-needle with your left hand.
Use screwdriver No. 50160 02-01.
Fine adjustment IS made as follows:
1. Screw in the L-needle slowly and the speed will
increase. Screw m the needle a little further and the
speed will slow down again as the fuel
supply becomes too "lean".
Notice the position of the needle at the highest
speed.
2. Open the L-needle again and notice the highest
speed position. Note that the speed slows down
at "richer" supply.
3. Adjust the L-needle to the highest speed position.
Then open it equivalent to 10 min on a clock-face
to obtain a somewhat "richer" supply to aid
acceleration.
4. By means of the T-needle adjust the idling speed
to 2,300 - 2,500 r/min ensuring that the chain
does not rotate when engine is idling.
5. Give full throttle a couple of times to check that
the engine "responds". if not, open the L-needle
by abt. 3 min. Check again.
C Adjustment of H-needle
Adjust the high speed needle (H) as follows.
Apply full throttle by keeping a constant grasp of
the throttle trigger. At correct adjustment of the
H-needle the engine should be fourstroking.
The high idle speed should be aprox. 10.500 r/min.
4:5

Fig 4:19
Screw in the H-needle slowly until acceleration
becomes slower (position A).
Then screw the needle out equivalent to 10 min
on a clock-face.
Fig 4:20
Check by means of e.g. revolution counter No.
502 50 36-01, that the high idle speed is approx.
10,500 r/min. Should the high idle speed of the
engine be below 10,000 r/min, check the speed
governor of the carburettor and replace it, if neces-
sary.
4:6

4:7

A. ignition system,
trouble shooting
In all ignition testing the plug must be firmly
earthed against the cylinder in order to prevent da-
mage to the system
1. Remove the spark plug.
Connect the ignition cable and "earth" the plug
e.g. aga!nst the cylinder.
Check for a spark between the electrodes when
Fig 5:1
you rotate the engine by means of the starting
handle.
The stop switch should be in position ‘’1’’.
Fig 5:2
If no spark occurs, try a new plug.
If still no spark, check the connection between
Ignition cable and spark plug protector.
2. Disconnect the short circuiting cable from the
switch. Check for a spark. If a spark occurs,
the stop switch IS faulty and should be
exchanged.
3. Remove the starter and air conductor.
Cables that are squeezed or otherwise
damaged ho''ló he exchanged.
Fig 5:3
4. In case the trouble has not been detected, check
the armature plate by means of testing device No.
502 51 24-01.
Remove the armature plate (see below, "Removal,
assembly") and test it under load.
For test values, see the instruction supplied with
the testing device.
Fig 5:4
Remove starter and air conductor. Remove cylinder
cover and spark plug and fit piston stop No.
502 50 33-01 in the spark plug hole. Then loosen the
flywheel nut by means of a box spanner (17 mm).
5:1

Fig
5.5
Fit holding bar No. 502 50 60-01 on the flywheel
and puller No; 502 50 26-01 on the holding bar
Fig 5.6
Remove the three screws retaining the armature
plate. Remove the bracket for the ignition cable
and disconnect the short circuiting cable from the
stop switch. Then remove the armature plate.
Assembly is made in reverse order.
When fitting the armature plate notice the marking
(fig. 5:7), ensuring a correct advance ignition. The
flywheel nut should be thightened by torque 40-43
Nm.
NOTEI
Before fitting a new flywheel remove every trace of rust
preventive be especially on the hub.
5:2
Flg 5:7
Changing the starter pawls and springs
Place the flywheel on the working bench with the
starter pawls downwards.
Fig 5.8
Push the bearing pins of the starter pawls out of the
flywheel with a drift (0 3 mm). Change
starter pawls and springs, and press back the
bearing pins from the fan side. Use Loctite AA in the
pin holes before putting the pins back Check that
the pins reach the bottom and that springs and
pawls work properly.
To ensure proper connection between contact
spring and ignition cable, use assembling pliers
No. 502 50 06-01 for fitting the spark plug protec-
tor on the ignition cable.
We recommend the use of Lithium grease No.
502 50 42-01 when connecting the ignition cable
to the spark plug protector.

Removal of oil pump
Remove the follow mg parts in order to get at the
oil pump:
Clutch cover, chain and bar, centrifugal clutch
(NOTE! Left-hand threads), clutch drum.
NOTE!
The washer between the of purr, p drive gear and the mom
bearing seal!
Fig 6:1
Loosen the three screws that retain the pump with
a screwdriver and remove the oil pump.
Fig 6:2
Check if there 1S dirt in the suction channel by ro-
tating the pump shaft m both directions. When the
pump works properly and is filled with oil, the Oil
goes alternately through the suction channel (A)
and the pressure channel (B)
For cleaning, dismantle the pump as follows.
1. Remove the adjusting screw (A, fig. 6:3).
2. Knock the edge of the pump housing against a
piece of wood to make the pump piston (B.
Fi
g
. 6:3
)
and its bearin
g
slide out of the casin
g
.
Fly 6.4
3. Check the wear of the adjusting screw against
which the cam curve of the pump piston runs.
Replace if necessary.
4 Check the oil hoses and their connections to
tank and crankcase (fig. 6:5)
6:1