Subaru EX13 User manual

SERVICE
MANUAL
EX13,17,21,27
SP170,SP210
EX21 Electronic Fuel Injection
ENGINES
Models
PUB-ES1934
Rev. 08/09

© Copyright 2009 Robin America, Inc.
Robin America, Inc.
905 Telser Road • Lake Zurich, IL 60047 • Phone: [phone] • Fax: [phone]
e-mail: [email protected] • www.subarupower.com

CONTENTS
Section Title Page
1. SPECIFICATIONS ...................................................................................................... 1
2. PERFORMANCE ...................................................................................................... 2
3. FEATURES ............................................................................................................... 7
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS........................................ 8
5. DISASSEMBLY AND REASSEMBLY .................................................................... 14
5-1 PREPARATIONS AND PRECAUTIONS............................................................ 14
5-2 SPECIAL TOOLS .............................................................................................. 14
5-3 DISASSEMBLY PROCEDURE.......................................................................... 15
5-4 REASSEMBLY PROCEDURE........................................................................... 29
6. ENGINE OIL ........................................................................................................... 47
7. MAGNETO .............................................................................................................. 48
8. WIRING DIAGRAM................................................................................................. 51
9. ELECTRIC STARTER............................................................................................. 53
10. OIL SENSOR .......................................................................................................... 55
11. AUTOMATIC DECOMPRESSION SYSTEM........................................................... 56
12. CARBURETOR....................................................................................................... 57
13. RECOIL STARTER ................................................................................................. 61
14. INSTALLATION ...................................................................................................... 66
15. TROUBLESHOOTING............................................................................................ 68
16. STANDARD REPAIRTABLES ............................................................................... 74
15-1 STANDARD DIMENSIONS AND LIMITS OF USE ........................................... 74
15-2 TIGHTENING TORQUE .................................................................................... 80
17. MAINTENANCE AND STORAGE .......................................................................... 81

- 1 -
1. SPECIFICATIONS
＊Specifications are subject to change without notice.
Model EX13D EX17D EX21D EX27D
Type Air-Cooled, 4-Cycle, Slant Single-Cylinder,
Horizontal P.T.O.Shaft, OHC Gasoline Engine
Bore & Stroke mm
(in.) 58 x 48 (2.28 x 1.89) 67 x 48 (2.64 x 1.89) 67 x 60 (2.64 x 2.36) 75 x 60 (2.95 x 2.36)
Piston Displacement ml
(cu.in.) 126 (7.69) 169 (10.31) 211 (12.87) 265 (16.17)
Compression Ratio 8.5 8.3
Continuous Output kW(HP)/r.p.m. 1.9(2.6)/3000
2.2(3.0)/3600 2.6(3.5)/3000 2.9(4.0)/3600 3.2(4.4)/3000 3.7(5.0)/3600 4.4(6.0)/3000 5.1(7.0)/3600
Maximum Output kW(HP)/r.p.m. 3.2(4.3)/4000 4.2(5.7)/4000 5.1(7.0)/4000 6.6(9.0)/4000
Maximum Torque N・m/r.p.m. (kgf・m/r.p.m.)
(ft・lb./ r.p.m.)
8.1/2500
(0.83/2500)
(6.01/2500)
11.3/2500
(1.15/2500)
(8.34/2500
13.9/2500
(1.41/2500)
(10.26/2500
18.6/2500
(1.9/2500)
(13.74/2500
Direction of Rotation Counterclockwise as viewed from the P.T.O.shaft side
Valve Arrangement Overhead cam system
Cooling System Forced air cooling system
Lubrication System Splash lubrication system
Lubricant
Automobile engine oil ; Grade SE or higher (SG,SH or SJ in recomended)
SAE 10W-30-----Under ordinary atmospheric temperatures
SAE 5W-30-------In cold areas
Capacity of Lubricant L 0.6 1.0
Carburetor Horizontal draft, Float type
Fuel Automobile unleaded gasoline
Fuel Consumption Rate g/kW・h
(g/HP・h) 367 (270) at continuous rated output
Fuel Supply System Gravity type
Fuel Tank Capacity L 2.7 3.6 6.1
Ignition System Transistorized magneto
Spark Plug NGK BR-6HS (CHAMPION RL86C)
Charging Capacity
(Option) V-A ------------- 12-1A, 3A, 16.7A (Opti on)
Starting System Recoil starter Recoil starter / Electric starter (Option)
Governor System Centrifugal flyweight system
Dry Weight kg
(lb.) 14 (30.87) 15 (33.08) 16 (35.28) 21 (46.31)
Dimensions (L x W x H) mm
(in.) 297 x 341 x 318 (11.7x13.4x12.5) 304 x 354 x 335 (12.0x13.9x13.2) 311 x 366 x 335 (12.2x14.4x13.2) 351 x 420 x 410 (13.8x16.5x16.1
)

- 2 -
2. PERFORMANCE
2-1 MAXIMUM OUTPUT
The Maximum output is the output of an engine with its throttle valve fully opened and considering that all the
moving parts are properly broken in.
A new engine may not produce full maximum output while its moving parts are still not broken-in.
NOTE :
Power curves shown in the following charts are made in conformity with SAE internal combustion engine standard
test code J1349.
2-2 CONTINUOUS RATED OUTPUT
The continuous rated output is the output of an engine at optimum governed speed which is most favorable from
the view point of engin’s life and fuel consumption.
When the engine is installed on a certain equipment, it is recommended that the continuous output required
from the equipment to be kept below this continuous rated output.
2-3 MAXIMUMTORQUE
The maximum torque is the torque at the output shaft when the engine is producing maximum output at a
specific r.p.m..

- 3 -
2000 2400 2800 3200 3600 4000
0
0
0.5
1.0
1.0
1.5
2.0
2.0
2.5
3.0
3.0
3.5
4.0
7.0
8.0
9.0
4.0
5.0
kW
[HP]
r.p.m.REVOLUTION
MAXIMUMTORQUE
TORQUE
MAXIMUM HORSEPOWER
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE
0.7
0.8
0.9
2-4 PERFORMANCE CURVES
EX13D

- 4 -
2000 2400 2800 3200 3600 4000
0
0
0.5
1.0
1.0
1.5
2.0
2.0
2.5
3.0
3.0
3.5
4.0
4.5
12.0
11.0
10.0
9.0
4.0
5.0
6.0
kW
[HP]
MAXIMUMTORQUE
MAXIMUM HORSEPOWER
r.p.m.REVOLUTION
TORQUE
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE
1.2
1.1
1.0
0.9
EX17D

- 5 -
2000 2400 2800 3200 3600 4000
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
5.0
0
1.0
2.0
3.0
4.0
7.0
6.0
5.0
5.5
4.5
12.0
13.0
14.0
15.0
kW
[PS]
MAXIMUMTORQUE
MAXIMUM HORSEPOWER
r.p.m.REVOLUTION
TORQUE
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE
1.2
1.3
1.4
1.5
EX21D

- 6 -
2000 2400 2800 3200 3600 4000
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
5.0
0
1.0
2.0
3.0
4.0
9.0
8.0
7.0
6.0
5.0
6.5
6.0
5.5
4.5
15.0
16.0
17.0
18.0
19.0
7.0
kW
[HP]
MAXIMUMTORQUE
MAXIMUM HORSEPOWER
r.p.m.REVOLUTION
TORQUE
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE
1.5
1.6
1.7
1.8
1.9
EX27D

- 7 -
3. FEATURES
3-1 EXTREMELY SILENT - SOFTTONE QUALITY
EX engines are 2dBA quieter and softer in tone than other engines in the same class.
This quiet and soft tone is achieved by:
- A reduction in mechanical noise realized by employing sophisticated OHC system.
- Employment of an optimized capacity Rigid Muffler.
3-2 EXTREMELY EASY START - NO KICK-BACK
Reliable Starting and Less Pulling Force are achieved by:
- Sophisticated Mechanical Compression Release System as well as newly designed Combustion Chamber.
- EX engines start instantly even at minus (-) 10°C, without any perceptible kick-back.
3-3 EXTREMELY EASY MAINTENANCE
Extreme ease of maintenance is realized by:
- High Parts Commonality
simplifies maintenance & lowers repair cost due to fewer parts for service.
More than 90% of component parts are in common between more than two models, in such as Muffler,
Intake and Exhaust Valves,Valve Springs, etc.
Furthermore, more than 50% of component parts are in common among EX13, EX17 and EX21, in
such as Chain Guide, Air Cleaner, Ignition Coil, etc.
- Only with ordinary tools, routine maintenance, assembly and disassembly can be performed.
3-4 EXTREMELY ADVANCEDTECHNOLOGY
Extreme reliability and durability are achieved by:
- Heavy Duty Chain Driven OHC System
Oval type case-hardened steel links enhance performance and resist stretching, which result in extended
maintenance free operation.
- Completely New Main Bearing Cover’s Design
Flush-mounted main bearing cover with lower moment of deformation significantly increases reliability and
engine life.
- Superior Cooling and Lubrication System
Heat reduction is achieved by more efficient, larger and more numerous cooling fins on crankcase, cylinder
and mounting base, as well as by outstanding oil delivery system.
- Large Ball Bearings on both ends of crankshaft for maximum stability under demanding loads.
- Cast Iron Cylinder Liner resists wear
3-5 EXTREME POWER AND PERFORMANCE
Extremely Higher Power and Lower Fuel Consumption are realized by:
- High speed and homogeneous combustion achieved by sophisticated Pentroof Combustion Chamber which
includes Intake and ExhaustValves located at optimum angle.
- Straight Intake Port with minimal air flow resistance.
Environmentally friendly
EX engines comply with EPA Phase 2 and CARB Tier II Emission Regulations in the USA.
Extreme application compatibility
With four versatile models, existing slant-cylinder engines can be easily replaced.

- 8 -
4-1 CYLINDER AND CRANKCASE
The cylinder and crankcase are aluminum die-casting
as a single piece.A special cast iron cylinder liner is
molded into the aluminum die-casting.
The crankcase has a mounting surface on the output
shaft side to which the main bearing cover is attached.
The cylinder is inclined to the right at an angle of 25
degrees from the horizontal as viewed from the output
shaft side.
4-2 MAIN BEARING COVER
The main bearing cover is an aluminum die-casting,
which is mounted on the output shaft side of the
crankcase. By removing the main bearing cover, the
inside of the engine can be inspected with ease.Pilots
and bosses are machined into the cover to facilitate the
direct coupling of the engine with machines such as
generators and pumps.There is an oil filling port, with
oil gauge, on either side of the cover.
4-3 CRANKSHAFT
Thecrankshaft is made ofspheroidal graphitecastiron,
andthecrankpinishigh-frequencyinduction-hardened.
The crank sprocket used to drive the chain and the
gear used to drive the governor gear are pressed into
the output end of the shaft.
4-4 CONNECTING ROD AND PISTON
Theconnectingrodisaspeciallyheat-treatedaluminum
alloy die-casting. Its large and small ends function as
bearings. A splasher built into the connecting rod
lubricates by splashing engine oil.The piston is an
aluminum alloy casting with grooves for mounting two
compression rings and one oil ring.
Fig. 4-1
Fig. 4-2
Fig. 4-3
Fig. 4-4
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS

- 9 -
4-5 PISTON RINGS
The piston rings are made of special cast iron.The profile of the top ring is a barrel face or tapered face, and
that of the second ring is a tapered face.There are 2 types of oil ring depending on the engine specification.
As those are interchangeable, the cutter ring with coil expander type can be selected as the spare part.
Fig. 4-6
Fig. 4-5
4-7 VALVE ARRANGEMENT
This engine has a chain-driven overhead cam and
overhead valve construction, with a single cam
performing both intake and exhaust operations.
Fig. 4-7
Fig. 4-8
4-8 CYLINDER HEAD
The cylinder head is an aluminum die-casting with a
pent roof combustion chamber construction.The intake
and exhaust ports are arranged in a cross direction to
improve combustion efficiency.
EXHAUST VALVE INTAKE VALVE
4-6 CAMSHAFT
The camshaft and the sprocket are made of special
sintered alloy.They are constructed as a single piece.
The camshaft is provided with intake and exhaust cam,
and the decompression release lever is mounted on
the sprocket shaft end side.
TOP
RING
SECOND
RING
OIL
RING
1
2
3
BARREL
(EX13/27)
TAPER
TAPER
(EX17/21)
1
2
3
CUTTER RING
WITH COIL
EXPANDER
THREE-PIECE
CONSTRUCTION

- 10 -
4-13 IGNITION SYSTEM
The ignition system is a transistor controlled magneto
systemwith the ignitiontiming set at23 degrees(EX13/
17/21)[27 degrees (EX27)] before the top dead center.
The magneto consists of a flywheel and ignition coil.
The flywheel (which also works as a fan) is directly
mounted on the crankshaft and the ignition coil is
directly mounted on the crankcase.
※Model EX13,17,21 and 27D has a smooth advanced
ignitiontiming system toimprovestarting performance.
(For further details, refer to page 48, section
“7. MAGNETO”.)
Fig. 4-10
Fig. 4-11
4-11 LUBRICATION SYSTEM
The rotating parts, sliding parts and valves of the engine
are lubricated with oil in the crankcase.The oil is splashed
onto the parts by the oil splasher on the connecting rod.
4-10 COOLING SYSTEM
The engine uses a forced air-cooling system in which a cooling fan (which also works as a flywheel) forces
cooling air into the cylinder and the cylinder head. Baffles are provided to guide the flow of the cooling air.
(Model EX21 is provided with a synthetic resin cooling fan that is separate from the flywheel.)
4-9 GOVERNOR SYSTEM
Thisengine isequippedwith acentrifugalflyweighttype
governor that makes it possible to operate the engine
at a constant speed, even with load variations. (The
governor flyweights are mounted on a governor gear.)
Fig. 4-9
GOVERNOR GEAR
OIL SPLASHE
R
TIMING CHAIN
FLYWHEEL
IGNITION COIL
4-12 TIMING CHAIN
Timing chain system is adopted and designed for
lubricating for the upper portion of cylinder head.
The timing chain is engaged between the sprocket
portion of integrated camshaft in the cylinder head and
the crankshaft gear sprocket.
The sprocket teeth in particular shape are adopted to
enhance the durability and to realize low noise level.

- 11 -
4-14 CARBURETOR
The engine is equipped with a horizontal draft
carburetor. The carburetor setting is calibrated after
careful testing for optimum all-round performance
(including starting, acceleration, fuel consumption,
output power characteristics).Special attention is also
paid to the general-purpose use of the engine. (For
further information, refer to page 57, section “11.
CARBURETOR”.)
4-15 AIR CLEANER
The engine uses an air cleaner that is quieter than
conventional ones.A semi-wet urethane foam element
is used in the STD air cleaner.Dual element air cleaner
(with a primary element of dry type sponge and
secondary element of dry type paper) and other types
are also provided as special options.
4-16 BALANCER
(PROVIDED ONLY IN MODEL EX27D)
Unbalanced inertia force is cancelled by the balancer
which rotates at the same speed as the crankshaft to
effectively reduce vibration.
4-17 DECOMPRESSION SYSTEM
The automatic decompression system is mounted on
the camshaft. It opens the exhaust valve before the
compression top, thereby alleviating the compression
pressure and reducing the force required to pull the
recoil starter.
During engine operation, the decompression system is
overpowered by centrifugal force and compression is
fully utilized to produce power.
CLEANER
COVER
CLEANER
COVER
URETHANE
FOAM
URETHANE
FOAM
STD Type Dual Element Type
PAPER
ELEMENT
Fig.4-12
Fig.4-13
Fig.4-14
Fig.4-15
EXHAUST
VALVE
ROCKER ARM
(EXHAUST VALVE SIDE)
RETURN SPRING
CAMSHAFT

- 12 -
Fig. 4-16
TANK CAP
FUEL TANK
BLOWER HOUSING
STARTING PULLEY
RECOIL STARTER
FLYWHEEL CHARGE COIL
(OPTION)
OIL SENSOR
(OPTION)
MAIN BEARING COVER
CONNECTING ROD
CRANKSHAFT
GOVERNOR GEAR
GOVERNOR LEVER
GOVERNOR SHAFT
Cross sectional view – across the shaft
4-18 SECTIONALVIEW OFTHE ENGINE

- 13 -
Fig. 4-17
FUEL TANK
OIL GAUGE
OIL DRAIN PLUG
TIMING
CHAIN
FILLER PLUG
PISTON PIN
PISTON RING
CONNECTING ROD
STARTING
MOTOR
(OPTION)
M
AGNETIC
S
WITCH
MUFFLERPISTON
CHAIN GUIDEGOVERNOR LEVER MUFFLER COVER
G
OVERNOR
G
EAR
FUEL STRAINER
TENSIONER
OIL SENSOR
(OPTION)
CRANKSHAFTCRANKCASE
ROCKER
ARM
INTAKE VALVE
CAMSHAFT
EXHAUST
VALVE
SPARK
ARRESTER
(OPTION)
TAIL SCREE
N
or DEFLECTO
R
(OPTION)
Cross sectional view – along the shaft

- 14 -
Fig. 5-1
5. DISASSEMBLY AND REASSEMBLY
5-1 PREPARATIONS AND PRECAUTIONS
(1) When disassembling the engine, memorize the location of each part so that you can reassemble the engine
correctly. If necessary, attach identification tags with the required assembly information to the parts.
(2) Store groups of parts in separate boxes.This will make reassembly easier.
(3) To prevent parts from being mislaid, keep each group provisionally assembled after removing the parts from
the engine.
(4) Handle the disassembled parts with the utmost care.Clean them with cleaning oil if necessary.
(5) Use the correct tools in the correct way when disassembling and reassembling the engine.
5-2 SPECIALTOOLS
Tool name Use
Commercially available product
Flywheel puller For pulling off the flywheel
FLYWHEEL PULLER

- 15 -
Step Parts to remove Remarks and procedures Fasteners
1 Drain the engine oill (1) Remove a drain plug (M14×12mm)
located on both sides of the case.
Take care not to lose the gaskets.
(2) To discharge oil quickly, remove the oil
guage.
14 mm spanner
Fig. 5-2
OIL GAUGE
GASKET
GASKET
DRAIN PLUG
STEP 1
5-3 DISASSEMBLY PROCEDURE

- 16 -
Fig. 5-3
Step Parts to remove Remarks and procedures Fasteners
2
Air cleaner cover Remove the air cleaner cover.
3
Air cleaner Remove the element, and remove the air
cleaner while pulling the breather pipe away
from the rocker cover.
10 mm box spanner
M6 nut: 2 pcs.
M6×20:1pc.
M6 x 20
FLANGE BOLT : 1 pc.
M6 FLANGE
NUT : 2 pcs.
AIR CLEANER COVER
AIR CLEANER
COVER
AIR CLEANER COVER
BREATHER
PIPE
URETHANE FOAM
STEP 2
STEP 3 STEP 3
DUAL ELEMENT TYPESTD TYPE
URETHAN FOAM
PAPER
ELEMENT

- 17 -
Fig. 5-4
STEP 4
STEP 5
STEP 6
STEP 6
M6 x 8 BOLT : 4 pcs.
M6 x 12 BOLT : 4 pcs.
STOP SWITCH
BAFFLE 2 (HEAD)
BAFFLE 3
(EX21 ONLY)
M4 TAPPING SCREW : 2 pcs.
RECOIL STARTER
BLOWER HOUSING
M6 x 12 BOLT : 1 pc.
M5 TAPPING BOLT : 2 pcs.
Step Parts to remove Remarks and procedures Fasteners
4Stop switch Disconnect the wire and remove the stop
switch from the blower housing.
5Recoil starter Remove the recoil starter from the blower
housing. 10 mm box spanner M6 × 8mm : 4 pcs.
6
Blower housing
Baffle 2 (head)
Baffle 3
(1)Remove the blower housing from the
crankcase.
(2)Remove the baffle 2 (head) and baffle 3.
10 mm box spanner
M6 × 12mm : 4 pcs.
10 mm box spanner or
spanner
M6 × 12mm : 2 pcs.
(Baffle 2 (head))
M5 tapping bolt : 2 pcs.
(Baffle 3)