Robin America EK13 User manual

EK13
EK17
EK20
EK28
EK30

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CONTENTS
Section Title Page
1. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 04
2. PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 06
3. FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 08
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS . . . . . . . . . . . . . . . . 10
5. DISASSEMBLY AND REASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5-1 PREPARATIONS AND PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5-2 SPECIAL TOOLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5-3 DISASSEMBLY PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5-4 REASSEMBLY PROCEDURE .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6. ENGINE OIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7. MAGNETO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8. IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
9. WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
10. ELECTRIC STARTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
11. OIL SENSOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
12. AUTOMATIC DECOMPRESSION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . 55
13. CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
14. RECOIL STARTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
15. TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
16. STANDARD REPAIR TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
16-1 STANDARD DIMENSIONS AND LIMITS OF USE . . . . . . . . . . . . . . . . . . 66
16-2 SERVICE DATA (The following are only for your reference.) . . . . . . . . . . 75
16-3 AIR GAP AND CLEARANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
16-4 TIGHTENING TORQUE .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
17. MAINTENANCE AND STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

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1. SPECIFICATIONS
Model EK13 EK17
B D B D
Type
Air-Cooled, 4-Cycle, Single-Cylinder,
Horizontal P.T.O. Shaft, OHV Gasoline Engine
Bore & Stroke mm 61 × 43 67 × 48
Piston Displacement ml 125 169
Compression Ratio 8.5
Continuous Output kW/r.p.m.
(HP/r.p.m.)
2.1/1800
(2.9/1800)
2.1/3600
(2.9/3600)
3.2/1800
(4.3/1800)
3.2/3600
(4.3/3600)
Maximum Output kW/r.p.m.
(HP/r.p.m.)
3.2/2000
(4.3/2000)
3.2/4000
(4.3/4000)
4.5/2000
(6.1/2000)
4.5/4000
6.1/4000
Maximum Torque N・m/ r.p.m.
(kgf・m/r.p.m.)
15.6/1400
(1.59/1400)
7.8/2800
(0.8/2800)
23.2/1300
(2.37/1300)
11.6/2600
(1.18/2600)
Direction of Rotation Counterclockwise as viewed from the P.T.O. shaft side
Valve Arrangement Overhead Valve
Cooling System Forced air cooling system
Lubrication System Splash lubrication system
Lubricant Automobile engine oil ; Grade SE or higher (SG,SH or SJ in recommended)
SAE 10W-30-----Under ordinary atmospheric temperatures
SAE 5W-30-------In cold areas
Capacity of Lubricant L 0.55 0.6
Carburetor Horizontal draft, Float type
Fuel Automobile unleaded gasoline
Fuel Consumption
Rate g/kW・h
(g/HP・h) 313
(230)
Fuel Supply System Gravity type
Fuel Tank Capacity L 3.0 3.6
Ignition System Transistorized magneto
Spark Plug NGK BP-6HS
Charging Capacity V-A 12-1A (Option) 12-1A (Option)
Starting System Recoil starter / Electric starter (Option)
Governor System Centrifugal flyweight system
Dry Weight kg 13 15.5
Dimensions (LxWxH)
mm 306 x 354 x 335 326 x 360 x 358
*Specifications are subject to change without notice.

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Model EK20 EK28 EK30
B D B D B D
Type
Air-Cooled, 4-Cycle, Single-Cylinder,
Horizontal P.T.O. Shaft, OHV Gasoline Engine
Bore & Stroke mm 72 × 48 79 × 56 80 × 59
Piston Displacement ml 195 274 296
Compression Ratio 8.5
Continuous Output kW/r.p.m.
(HP/r.p.m.)
3.5/1800
(4.8/1800)
3.5/3600
(4.8/3600)
4.9/1800
(6.6/1800)
4.9/3600
(6.6/3600)
5.5/1800
(7.5/1800)
5.5/3600
(7.5/3600)
Maximum Output kW/r.p.m.
(HP/r.p.m.)
5.1/2000
(7.0/2000)
5.1/4000
(7.0/4000)
7.1/2000
(9.7/2000)
7.1/4000
(9.7/4000)
7.4/1800
(10/1800)
7.4/3600
(10/3600)
Maximum Torque N・m / r.p.m.
(kgf・m/r.p.m.)
26.4/1300
2.70/1300
13.2/2600
1.35/2600
38.2/1250
3.90/1250
19.1/2500
1.95/2500
42.0/1250
4.29/1250
21.0/2500
2.15/2500
Direction of Rotation Counterclockwise as viewed from the P.T.O. shaft side
Valve Arrangement Overhead Valve
Cooling System Forced air cooling system
Lubrication System Splash lubrication system
Lubricant
Automobile engine oil ; Grade SE or higher (SG,SH or SJ in recommended)
SAE 10W-30-----Under ordinary atmospheric temperatures
SAE 5W-30-------In cold areas
Capacity of Lubricant L 0.6 1.1
Carburetor Horizontal draft, Float type
Fuel Automobile unleaded gasoline
Fuel Consumption
Rate g/kW・h
(g/HP・h)
313
(230)
Fuel Supply System Gravity type
Fuel Tank Capacity L 3.6 6.0
Ignition System Transistorized magneto
Spark Plug NGK BP-6HS TORCH E6TC
Charging Capacity V-A 12-1A (Option) 12-1A (Option) 12-1A (Option)
Starting System Recoil starter / Electric starter (Option)
Governor System Centrifugal flyweight system
Dry Weight kg 16 26 27
Dimensions
(L x W x H) mm 326 x 360 x 358 353 x 418 x 420 353 x 418 x 437
*Specifications are subject to change without notice.

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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 accordance 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 engine’s life and fuel consumption.
When the engine is installed on 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..


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MAXIMUM
TORQUE MAXIMUM TORQUE
MAXIMUM
TORQUE MAXIMUM
TORQUE
Continuous
Rated HP
Continuous
Rated HP
Continuous
Rated HP Continuous
Rated HP
TORQUE
TORQUE
TORQUE
TORQUE
OUTPUT
OUTPUT
OUTPUT
OUTPUT
REVOLUT
REVOLUTION REVOLUTION
REVOLUTION REVOLUTION
r.p.m. r.p.m. r.p.m.
r.p.m. r.p.m.
MAXIMUM
TORQUE
Continuous
Rated HP
OUTPUT
TORQUE

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3. FEATURES
1. EK Series has newly developed combustion system and resulting in high performance.And its inclined
cylinder offers compactness.
2. In addition to high output and fuel efficient, clean emission, less vibration and low noise promises
environmental friendly, easiness in use and reliability.
3-1 ENVIRONMENTAL FRIENDLY
High performance with fuel efficient and less oil consumption.
Cross flow ports design enables engine’s high output and
Pent-roof combustion chamber makes lean burning possible and realized fuel efficient,
(EK13/17/20/28)
Lens shape combustion chamber, napier ring for second ring and optimum setting of the carburetor
resulted in fuel efficient and less oil consumption. （EK30）
3-2 USER FRIENDLY
Remarkably silent among same range of engines.
Suitable clearance in between rocker arm and rocker shaft, in addition cylinder head cover with double
metal sheets enables less valve noise. (EK13, 17, 20, 28)
Unlike above noted models, pivot type rocker arm is adopted as simple construction and achieving low
noise. （EK30）
3-3 EXTREMELY EASY START
Mechanical automatic de-comp system and suitable combustion timing needs less starting power,
ladies and seniors can start engine easily without any problem.

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3-4 RUST FREE DESIGN FOR LONG LIFE
Anti –rust and anti –corrosion, suitable for agriculture machine.
This model has advanced anti-rust carburetor by considering agriculture machine which works in limited
period in a year.And fuel tank has double anti –rust character, plated sheet metal and inner painting makes
its life longer.
3-5 HIGH POWER MODEL EK30（10PS）
Superior output in low to medium engine speed range
The model assures output required in low to medium engine speed for agriculture work.
It shows quick response, tough and strong in operation.
3-6 EASY INSTALLATION ON AGRICULTURE MACHINE
Low center of gravity, light weight and compact design
30 degrees inclined cylinder makes the model lower height and low center of gravity then achieving light
weight and compactness.
(The inclined cylinder makes installing engine easier for various agriculture machine.)
Wide range of suitable specification
Suitable engine specification is available for variety of agriculture machines, such as cultivator, loading truck
and sprayer etc.
PTO, reduction type
Crankshaft
Camshaft

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4. GENERAL DESCRIPTION OF ENGINE COMPONENTS
4-1 CYLINDER AND CRANKCASE
The cylinder and crankcase is aluminum die-casting
as one 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 30
degrees from the horizontal as viewed from the output
shaft side.
4-2 MAIN BEARING COVER
The main bearing cover is aluminum die-casting,
which is mounted on the output shaft side of
the crank case.
Remove the main bearing cover to inspect inside
of the engine.
Oil gauges (fillers) are on both sides of the cover
for easy maintenance.
4-3 CRANKSHAFT
The crankshaft is forged carbon steel to have tough
metal structure, and the crank pin is induction-hardened.
The output side of the shaft has a crankshaft gear
and balancer gear, those are pressed into position.
4-4 CAMSHAFT
The camshaft for reduction type engine is made of
forged carbon steel.
And it works as PTO shaft.
Cam gear is press fitted on the shaft, ball bearing is fixed in bearing cover to support the PTO shaft.
Crankshaft
Camshaft

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4-5 CONNECTING ROD AND PISTON
The connecting rod is an aluminum alloy die-casting
and its large and small ends have function as bearings.
The piston is an aluminum alloy casting, and carries
two compression rings and one oil ring.
4-6 PISTON RINGS
The piston rings are made of special cast iron.
The profile of the top ring is a barrel face and the
second ring has a tapered under cut face.
The oil ring is designed for better sealing and less
oil consumption, in combination with 3 pieces.
4-7 VALVE ARRANGEMENT
The intake valve is located on flywheel side of the
cylinder head.
Hard alloy valve seats are molded in the cylinder
head and stellite is fused to the exhaust valve face.
The cylinder baffle leads cooling air to the exhaust
valve area for the optimum cooling.
4-8 CYLINDER HEAD
The cylinder head is an aluminum die-casting with a
pent roof combustion chamber construction. (EK13, 17, 20, 28)
The intake and exhaust ports are arranged in a cross
direction to improve combustion efficiency.
Based on lens shaped combustion chamber and simplification
of the valve components make maintenance easy. （EK30）
Rocker arm
Exhaust valve Intake valve
Rocker shaft
EK13/17/20/28
EK30
Exhaust valve
Intake valve
EK
series
EK13,17
EK20,28
EK30
EK
series

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4-9 GOVERNOR SYSTEM
The governor is a centrifugal flyweight type which
ensures constant operation at the selected speed
against load variations.
The governor gear with governor weights is installed
on the main bearing cover.
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.
4-11 LUBRICATION SYSTEM
The rotating parts, sliding parts and valves of the engine
are lubricated with oil in the crankcase.
Lubrication oil is splashed onto those parts in the case by the
oil splasher on the connecting rod.
4-12 IGNITION SYSTEM
The ignition system is a transistor controlled magneto
system which consists of a flywheel and an
ignition coil with a built-in transistor mounted on
the crankcase.
This ignition system has latest automatic ignition timing
control for easy start.
4-13 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 56, section “13.
CARBURETOR”.)
「フライホイール側」or「MAG」
Ignition coil
Magneto
Cooling fan
PS

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4-14 AIR CLEANER
The engine uses an air cleaner that is quieter than
conventional one. 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 options.
4-15 BALANCER
Unbalanced inertia force is cancelled by the balancer
which rotates at the same speed as the crankshaft to
effectively reduce vibration. (EK17 UP)
4-16 DECOMPRESSION SYSTEM
The automatic decompression system is mounted on
the camshaft. It opens the exhaust valve before the
compression top, thereby releasing 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.
Decompression pin Flyweight
Element
Oil pan
Dumper
Cover Element AY
Element
Cover
Oil bath type Dual element type

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4-17 DIMENSIONS
B Type
D Type

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[] D type number in parentheses
Model
Position EK13 EK17 EK20 EK28 EK30
(1) 306 326 353 [355.2] 353
(2) 178 187 196.5
(3) 128 139 156.5 [158.7] 156.5 [159]
(4) 80 [106] 101.5 [133.5]
(5) 354 360 418.5
(6) 125 116 143
(7) 229 244 275.5
(8) 335 358 420 437
(9) 26 32
(10) 48.5 56.4 63.7
(11) 56 64
(12) 38 49 46.5
(13) 40 50 50 [52.2]
(14) 50 60
(15) 80 96
(16) 14 25 14.5
(17) 5 13
(18) 182 219.5
(19) 162 195.5
(20) 10 12
(21) 66 90.5
(22) 114.5
[66] 122.4 [66] 154.2 [90.5]
(23) 18 20 25
(24) 5 7
(25) 5 7
(26) 2-9 hole 2-11 hole
(27) 2-9 hole X 14 slotted hole 2-11 hole X 24 slotted hole
The number is subject to change without notice.
(mm)

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4-18 SECTIONAL VIEW OF THE ENGINE
1) EK13, 17, 20, 28
Governor spring Rocker cover
Balancer shaft
Piston
Rocker arm
Cross flow port
Center plug placement
pent roof combustion chamber
2) EK30

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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 suitable tools with correct way when disassembling and reassembling the engine.
5-2 SPECIAL TOOLS
Tool name Purpose
Commercially available product Flywheel puller For pulling off the flywheel
Commercially available product Chain wrench For locking the flywheel

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5-3 DISASSEMBLY PROCEDURE
Step Parts to remove Remarks and procedures Fasteners
1Drain the engine oil 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 gauge (M22).
14 mm spanner
2Drain the fuel Shut (OFF) the fuel strainer.
Remove the fuel strainer cup.
Open the strainer to drain fuel from fuel tank.
Drain fuel from the carburetor drain.
+ or - screwdriver
Drain plug
Oil gauge

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Step
Parts to remove Remarks and procedures Fasteners
3 Front cover Remove the front cover from the bracket. 10 mm box spanner
M6 bolt : 2 pcs.
4
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.
12 mm box spanner
10 mm box spanner
or spanner
5
Fuel tank (1) Remove the fuel tank mounting nuts/or and bolts
from the crankcase.
(2) Disconnect fuel hose from the fuel tank to strainer
side.
(3)Remove the fuel tank from the crankcase.
10 or 12 mm
box spanner
10 or 12 mm
spanner
M8 X 18L
M8 X 18L
M8 X 16L
M8 X 16L
M6 X 8L
M8 Nut 2pcs
M6 X 12L
M8 Nut
Front cover
Bracket

20
Step Parts to remove Remarks and procedures Fasteners
6
Speed control lever and
Bracket Remove the speed control lever and bracket from the cylinder head.
Slide to dismount the speed control lever and bracket
from the cylinder head
Release the bolt.
10 mm box spanner
M6 x 14 mm : 1 pc.
7
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 or 12 mm
box spanner or
spanner
M8 X 35L
With washer M6 X 14L
M8 Nut
M8 Nut
Speed control lever
Bracket