Subaru EX35 User manual

1. SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. FEATURES (EX35, 40 series) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS . . . . . . . . . . . . . . . . 6
5. DISASSEMBLY AND REASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5-1 PREPARATIONS AND PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5-2 SPECIAL TOOLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5-3 DISASSEMBLY PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5-4 REASSEMBLY PROCEDURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6. ENGINE OIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7. MAGNETO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8. IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9. WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
10. ELECTRIC STARTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
11. OIL SENSOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
12. AUTOMATIC DECOMPRESSION SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . 53
13. CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
14. RECOIL STARTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
15. INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
16.TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
17. STANDARD REPAIR TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
17-1 STANDARD DIMENSIONS AND LIMITS OF USE . . . . . . . . . . . . . . . . . . 72
17-2 SERVICE DATA (The following are only for your reference.). . . . . . . . . . . 77
17-3 TIGHTENING TORQUE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
17-4 AIR GAP AND CLEARANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
18.MAINTENANCE AND STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
CONTENTS
Section Title Page

- 1 -
1. SPECIFICATIONS
*Specifications are subject to change without notice.
Model EX35D EX40D
Type Air-Cooled, 4-Cycle, Slant Single-Cylinder,
Horizontal P.T.O. Shaft, OHC Gasoline Engine
Bore & Stroke mm (in.) 89 × 65 (3.50 × 2.56)
Piston Displacement ml (cu.in.) 404 (24.65)
Compression Ratio 8.3
Continuous Output kW(HP)/r.p.m. 5.5(7.5)/3000
6.3(8.5)/3600
6.3(8.5)/3000
7.0(9.5)/3600
Maximum Output kW(HP)/r.p.m. 7.4(10.0)/3600 8.8(12.0)/3600
Maximum Torque
N
・
m / r.p.m.
(kgf
・
m / r.p.m.)
(ft
・
lb. / r.p.m.)
26/2400
(2.6/2400)
(19.18/2400)
27/2400
(2.7/2400)
(19.91/2400)
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 1.2
Carburetor Horizontal draft, Float type
Fuel Automobile unleaded gasoline
Fuel Consumption Rate g/kW
・
h (g/HP
・
h) 381 (280)
Fuel Supply System Gravity type
Fuel Tank Capacity L 7.0
Ignition System Transistorized magneto
Spark Plug NGK BR-6HS
Charging Capacity (Option) V-A 12-1A, 3A, 16.7A (Option)
Starting System Recoil starter / Electric starter (Option)
Governor System Centrifugal flyweight system
Dry Weight kg (lb.) 33 (72.75)
Dimensions (L x W x H) mm (in.) 389 x 450 x 443 (15.31 x 17.72 x 17.44)

- 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 MAXIMUM TORQUE
The maximum torque is the torque at the output shaft when the engine is producing maximum output at a
specific r.p.m..

- 3 -
EX35D
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0࡮O
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








M9












=*2?
=MIH࡮O?









MAXIMUM
TORQUE
MAXIMUM
HORSEPOWER
r.p.m.REVOLUTION
TORQUE
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE
2-4 PERFORMANCE CURVES

- 4 -
EX40D












=25?




    









M9
=MIH࡮O?






0࡮O
MAXIMUM
TORQUE
MAXIMUM
HORSEPOWER
r.p.m.REVOLUTION
TORQUE
OUTPUT
CONTINUOUS
RATED HP
RECOMMENDED
HORSEPOWER
RANGE

- 5 -
3. FEATURES (EX35, 40 series)
3-1 HIGH OUTPUT
Thanks to the adoption of a cam profile exclusively for intake and exhaust and the optimization of the shape
of the intake/exhaust port and the shape of the combustion chamber, the top-of-the-class-level maximum
output is achieved.
3-2 EXTREMELY SILENT - SOFT TONE 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:
- Resin blower housing reduce noise leakage of mechanical noise.
- Employment of an optimized capacity Rigid Muffler.
3-3 EXTREMELY EASY START
Reliable Starting and Less Pulling Force are achieved by:
Sophisticated Mechanical Compression Release System as well as newly designed Combustion Chamber.
3-4 EXTREMELY EASY MAINTENANCE
Extreme ease of maintenance is realized by:
- High Parts Commonality
simplifies maintenance & lowers repair cost due to fewer parts for service.
- Only with ordinary tools, routine maintenance, assembly and disassembly can be performed.
3-5 EXTREMELY ADVANCED TECHNOLOGY
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
3-6 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 Exhaust Valves located at optimum angle.
- Straight Intake Port with minimal air flow resistance.
Environmentally friendly
EX engines comply with EPA Phase 2 and CARB Tier III Emission Regulations in the USA.
Extreme application compatibility
With four versatile models, existing slant-cylinder engines can be easily replaced.

- 6 -
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS
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.
Oil gauges (fillers) are on both sides of the cover for
easy maintenance.
4-3 CRANKSHAFT
The crankshaft is forged carbon steel, and the crank
pin is high-frequency inductionhardened.
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
The connecting rod is a specially heat-treated
aluminum 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 one compression ring and one oil ring.
Fig.4-1
Fig.4-2
Fig.4-3
25°
Fig.4-4

- 7 -
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 which
has individual profile for intake and exhaust to
perform high output.
Fig.4-7
EXHAUST VALVE INTAKE VALVE
Fig.4-8
4-8 CYLINDER HEAD
The cylinder head is on aluminum die-casting with a
dome-shaped combustion chamber. The intake and
exhaust ports are arranged in a cross direction to
improve combustion efficiency.
TOP
RING
OIL
RING
1
2
TAPER
THREE-PIECE
CONSTRUCTION
1
2
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.
4-5 PISTON RINGS
The piston rings are made of special cast iron. The profile of the top ring is a tapered face.
The oil ring is designed for better sealing and less oil consumption, in combination with 3 pieces.

- 8 -
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.
4-13 IGNITION SYSTEM
The ignition system is a transistor controlled magneto
system with the ignition timing set at 24 degrees
before the top dead center. The magneto consists of
a flywheel and ignition coil. The flywheel (cooling fan
is separete from the flywheel) is directly mounted on
the crankshaft and the ignition coil is directly
mounted on the crankcase.
*Model EX35 and 40 has a smooth advanced
ignition timing system to improve starting
performance. (For further details, refer to page
46, 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 synthetic resin cooling fan (which is separate from the
flywheel), reduce noise and forces cooling air into the cylinder and cylinder head.
Baffles are provided to guide the flow of cooling air. (As for with starting motor, baffle 1 is not mounted.)
4-9 GOVERNOR SYSTEM
This engine is equipped with a centrifugal flyweight
type 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
TIMING CHAIN
OIL SPLASHER
IGNITION COIL
FAN
FLYWHEEL

- 9 -
4-16 BALANCER
Unbalanced inertia force is cancelled by the balancer
which rotates at the same speed as the crankshaft to
effectively reduce vibration.
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 54, section “13.
CARBURETOR”.)
Fig.4-12
Fig.4-13
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.
Urethane Element Type
Dual Element Type
AIR
CLEANER
COVER
AIR
CLEANER
BASE
AIR
CLEANER
BASE
URETHANE
FOAM
URETHANE
FOAM
AIR
CLEANER
COVER
PEPER ELEMENT
Fig.4-14
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.
Fig.4-15
RETURN SPRING
ROCKER ARM
(EXHAUST VALVE SIDE)
EXHAUST VALVE
CAMSHAFT

- 10 -
4-18 SECTIONAL VIEW OF THE ENGINE
Fig.4-16
Cross sectional view – across the shaft
FUEL TANK TANK CAP
CHARGE COIL
(OPTION)
BLOWER HOUSING
STARTING PULLEY
RECOIL STARTER
RECOIL STARTER
HANDLE
FLYWHEEL
OIL SENSOR
(OPTION)
MAIN BEARING COVER
CONNECTING ROD
CRANKSHAFT
GOVERNOR GEAR
GOVERNOR LEVER
BOLT
(RECOIL BRACKET)
RECOIL BRACKET
COOLING BLOWER

- 11 -
Fig.4-17
CRANKSHAFT
OIL SENSOR
(OPTION)
CONNECTING ROD
AIR CLEANER
BAFFLE 2
PISTON
TIMING CHAIN
OIL DRAIN PLUG CRANKCASE
For without starting motor㧦Buffle 1 is mounted, instead of starting motor.
INTAKE
VALVE
PISTON RING
OIL GAUGE
TENSIONER
STOP
SWITCH
BALANCER GEAR
CAMSHAFT
ROCKER
ARM
FUEL TANK GOVERNOR LEVER
GOVERNOR SHAFT CHAIN GUIDE
GOVERNOR
GEAR
MAGNETIC
SWITCH
STARTING
MOTOR
(OPTION)
PISTON PIN
MUFFLER COVER
EXHAUST
VALVE MUFFLER
TAIL SCREEN
or DEFLECTOR
(OPTION)
SPARK
ARRESTER
(OPTION)
Cross sectional view – along the shaft

- 12 -
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 SPECIAL TOOLS
Tool name Use
Commercially available product Flywheel puller For pulling off the flywheel
Commercially available product Chain wrench For locking the flywheel
FLYWHEEL PULLER
CHAIN WRENCH

- 13 -
5-3 DISASSEMBLY PROCEDURE
Step Parts to remove Remarks and procedures Fasteners
1
Drain the engine oill Remove a drain plug (M14 x 12mm) located on both
sides of the case.
Take care not to lose the gaskets.
*
To discharge oil quickly, remove the oil guage(M22).
14 mm spanner
2
Drain the fuel Shut (OFF) the fuel strainer.
Drain fuel from the carburetor drain.
+ or - screwdriver
Fig.5-3
GASKET
GASKET
OIL GAUGE
DRAIN PLUG
FUEL STRAINER
OFF
STEP 1
STEP 2
Fig.5-2

- 14 -
Fig.5-4
Step Parts to remove Remarks and procedures Fasteners
3
Air cleaner cover Remove the air cleaner cover and element. - screwdriver
4
Air cleaner Remove the air cleaner while pulling the breather pipe
away from the rocker cover.
10 mm box spanner
M6 nut : 2 pcs.
M6 x 16 : 1 pc.
PAPER ELEMENT
URETHAN FOAM
URETHANE ELEMENT
TYPE
DUAL ELEMENT TYPE
AIR CLEANER
COVER
URETHAN FOAM
AIR CLEANER
COVER
AIR CLEANER BASE
M6 FLANGE NUT : 2 pcs.
M6 x 16 FLANGE BOLT : 1 pc.
GASKET
BREATHER PIPE
STEP 3
STEP 4
STEP 3

- 15 -
Step Parts to remove Remarks and procedures Fasteners
5
Muffler and Muffler cover (1) Remove the muffler cover from the muffler.
(2) Remove the muffler from the cylinder head. Take
care not to lose the gasket.
*Take care not to cut your hand with the muffler
gasket.
*Seal the exhaust port with adhesive tape or plug
it with cloth to prevent nuts and other objects from
falling inside.
12 mm box spanner
10 mm box spanner or
spanner
M6 x 8 mm : 4 pcs.
M8 nut : 2 pcs.
M8 x 12 mm : 1 pc.
6
Fuel tank (1) Remove the fuel tank mounting nuts and bolts from
the crankcase.
(2) Disconnect fuel hose from the strainer to carburetor
side. Remove the bolt for fuel strainer.
(3)Remove the fuel tank from the crankcase.
12 mm box spanner
12 mm spanner
M8 nut : 2 pcs.
M8 x 25 mm : 2 pcs.
- screwdriver
10 mm box spanner
M6 x 12 mm : 1 pc.
MUFFLER COVER
MUFFLER
M8 x 12
BOLT : 1 pc.
M8 NUT
: 2 pcs.
M6 x 8 FLANGE BOLT : 4 pcs.
GASKET(It has two faces)
M8 NUT : 2 pcs.
FUEL TANK A
A
M8 x 25
BOLT : 2 pcs.
Seal the exhaust port with adhesive
tape or plug it with cloth.
STEP 5
STEP 6
FUEL STRAINER
M6 x 12 BOLT : 1 pc.
Fig.5-6
Fig.5-5

- 16 -
Fig.5-7
Step Parts to remove Remarks and procedures Fasteners
7
Stop switch Disconnect the wire and remove the stop switch from
the blower housing.
+ screwdriver
M4 x 12 mm : 2 pcs.
8
Recoil starter Remove the recoil starter from the blower housing. 10 mm box spanner
M6 x 14 mm : 4 pcs.
9
Blower housing
Recoil bracket
(1) Remove the blower housing (synthetic resin) from
the crankcase.
(2) Remove the recoil bracket from the crankcase.
10 mm box spanner
M6 x 16 mm : 5 pcs.
M6 nut : 4 pcs.
10
Baffle 2 Remove the baffle 2 ( synthetic resin ) from the
crankcase.
10 mm box spanner
M6 x 12 mm : 3 pcs.
M4 x 12 SCREW and WASHER : 2 pcs.
M6 x 14 BOLT : 4 pcs.
STOP SWITCH
RECOIL STARTER
BLOWER HOUSING
RECOIL BRACKET
M6 FLANGE NUT : 4 pcs.
M6 x 16 BOLT : 5 pcs.
BAFFLE 2
STEP 7
STEP 8
STEP 9
STEP 10
M6 x 12 BOLT : 3 pcs.

- 17 -
Fig.5-8
Step Parts to remove Remarks and procedures Fasteners
11
Speed control lever and
Bracket
Remove the speed control lever and bracket from the
cylinder head.
Release the bolt temporarily.
Slide to dismount the speed control lever and bracket
from the cylinder head and the choke lever of the
carburetor.
10 mm box spanner
M6 x 12 mm : 1 pc.
12
Governor system (1) Loosen the bolt and remove the governor lever
from the governor shaft. There is no need to
remove the bolt.
(2) Remove the governor spring.
(3) Remove the governor rod and the rod spring from
the carburetor.
10 mm box spanner or
spanner
M6 x 25 mm : 1 pc.
13
Carburetor, Insulator Remove the carburetor from the cylinder head.
Remove the insulator.
GOVERNOR SPRING
M6 x 12 BOLT : 1 pc. (temporary screw)
ROD SPRING
GOVERNOR ROD
SPEED CONTROL LEVER and BRACKET
GASKET
CHOKE LEVER
GASKET
CARBURETOR
GASKET
INSULATOR
GOVERNOR LEVER
GOVERNOR
SHAFT
STEP 11
STEP 12
STEP 13

- 18 -
FLYWHEEL
M6 x 25 BOLT and
WASHER : 2 pcs.
M6 x 8 BOLT : 1 pc.
CLAMP
COOLING BLOWER
M18 NUT : 1 pc.
WIRE : 1 pc.
IGNITION COIL
STARTING PULLEY
STEP 14
STEP 15
STEP 16
Fig.5-9
Step Parts to remove Remarks and procedures Fasteners
14
Ignition coil Remove the spark plug cap from the spark plug and
remove the ignition coil from the crankcase.
10 mm box spanner
M6 x 25 mm
：
2 pcs.
15
Starting pulley
Cooling Blower
Remove the starting pulley and cooling Blower from the
flywheel.Fit a box wrench or a socket wrench on the
flywheel nut and loosen the nut by knocking the wrench
sharply with a hammer. (See Fig. 5-10)
NOTE:
1. Do not insert a screwdriver or other object between the
flywheel blades which is a synthetic resin, otherwise the
risk of damaging the blades might be occurred.
2. Knock the wrench with a hammer in a counter clockwise
direction.
24 mm box spanner or
socket wrench
M18 nut
16
Flywheel Remove the flywheel from the crankshaft. Leave the nut
temporarily to prevent the flywheel from dropping out. Fit
the flywheel puller as shown in Figure 5-11 and remove
the flywheel from the crankshaft by rotating the bolt at the
center in a clockwise direction.
(Knock the center bolt with a hammer sometimes)
Flywheel puller
Fig.5-10 Fig.5-11
FLYWHEEL PULLER
ATTACH NUT
TEMPORARILY