Robin America EX13 Service Manual Download Page 27

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Fig. 5-14a

Step

Parts to remove

Remarks and procedures

Fasteners

Rocker cover

(1) Remove the rocker cover from the

cylinder head.

(2) Remove the gasket (rocker cover).

10 mm box spanner

M6 × 12mm : 4 pcs.

Rocker arm

Remove the pin (rocker arm) and the rocker

arm from the cylinder head at the compression
top dead center. (See Fig. 5-14b)

Fig. 5-13

ROCKER ARM
(EXHAUST VALVE SIDE)

ROCKER ARM (INTAKE VALVE SIDE)

PIN
(ROCKER ARM)

ROCKER ARM
(EXHAUST
VALVE SIDE)

PIN
(ROCKER ARM)

CLOSE-UP A

ROCKER ARM
(INTAKE VALVE SIDE)

ROCKER COVER

GASKET (ROCKER COVER)

M6 x 12 BOLT : 4 pcs.

STEP 20

STEP 19

Punch marks

The position of compression top dead center

Fig. 5-14b

Summary of Contents for EX13

Page 1: ...SERVICE MANUAL EX13 17 21 27 SP170 SP210 ENGINES Models PUB ES1934 Rev 06 09 ...

Page 3: ......

Page 4: ... 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 REPAIR TABLES 74 15 1 STANDARD DIMENSIONS AND LIMITS OF USE 74 15 2 TIGHTENING TORQUE 80 17 MAINTENANCE AND STORAGE 8...

Page 5: ...ise 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 Automobi...

Page 6: ...th 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 cont...

Page 7: ...00 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 MAXIMUM TORQUE TORQUE MAXIMUM HORSEPOWER OUTPUT CONTINUOUS RATED HP RECOMMENDED HORSEPOWER RANGE 0 7 0 8 0 9 2 4 PERFORMANCE CURVES EX13D ...

Page 8: ...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 MAXIMUM TORQUE MAXIMUM HORSEPOWER r p m REVOLUTION TORQUE OUTPUT CONTINUOUS RATED HP RECOMMENDED HORSEPOWER RANGE 1 2 1 1 1 0 0 9 EX17D ...

Page 9: ... 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 MAXIMUM TORQUE MAXIMUM HORSEPOWER r p m REVOLUTION TORQUE OUTPUT CONTINUOUS RATED HP RECOMMENDED HORSEPOWER RANGE 1 2 1 3 1 4 1 5 EX21D ...

Page 10: ...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 MAXIMUM TORQUE 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 ...

Page 11: ...be performed 3 4 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 reli...

Page 12: ...hined 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 The crankshaft is made of spheroidal graphite cast iron and the crank pin is high frequency induction hardened The crank sprocket used to drive the chain and the gear used to drive the governor gear ar...

Page 13: ... 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 ...

Page 14: ...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 This engine is equipped with a centrifugal flyweight type governor that ...

Page 15: ...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 all...

Page 16: ...USING 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 SECTIONAL VIEW OF THE ENGINE ...

Page 17: ...D STARTING MOTOR OPTION MAGNETIC SWITCH MUFFLER PISTON CHAIN GUIDE GOVERNOR LEVER MUFFLER COVER GOVERNOR GEAR FUEL STRAINER TENSIONER OIL SENSOR OPTION CRANKSHAFT CRANKCASE ROCKER ARM INTAKE VALVE CAMSHAFT EXHAUST VALVE SPARK ARRESTER OPTION TAIL SCREEN or DEFLECTOR OPTION Cross sectional view along the shaft ...

Page 18: ...oups 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...

Page 19: ...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 ...

Page 20: ...e 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 1 pc 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 TYPE STD TYPE URETHAN FOAM PAPER ELEMENT ...

Page 21: ...procedures Fasteners 4 Stop switch Disconnect the wire and remove the stop switch from the blower housing 5 Recoil 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 ...

Page 22: ...3 Disconnect the fuel pipe from the carburetor See Fig 5 6 4 Remove the fuel tank from the crankcase 10 12 mm spanner or box wrench M6 nut 2 pcs Models EX13 17 and 21 M8 nut 2 pcs Model EX 27 M6 25mm 1 pc Models EX 13 17 and 21 M8 25mm 2 pcs Model EX27 8 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 gaske...

Page 23: ...from the carburetor 10 mm box spanner or spanner M6 30mm 1 pc 10 Carburetor Insulator Remove the carburetor from the cylinder head Remove the insulator 11 Speed control lever and Bracket Remove the speed control lever and bracket from the cylinder head 10 mm box spanner M6 12mm 2 pcs STEP 9 STEP 10 STEP 11 GOVERNOR LEVER GOVERNOR ROD and ROD SPRING GOVERNOR SPRING SPEED CONTROL LEVER and BRACKET I...

Page 24: ...nsert a screwdriver or other object between the flywheel blades otherwise the risk of damaging the blades might be occured 2 Knock the wrench with a hammer in a counter clockwise direction 3 The fan of the Model EX21 engine is made of synthetic resin Take the utmost care when handling it 19 24 mm box spanner or socket wrench M14 nut Models EX13 17 and 21 M18 nut Model EX27 14 Flywheel Remove the f...

Page 25: ...edures Fasteners 15 Electric starter option Control box Diode rectifier Magnetic switch 1 Disconnect the grounding cable from battery 2 Disconnect the wire leading from the key switch ST terminal to the magnetic switch 3 Disconnect the wire that connects the positive terminal of the battery to the magnetic switch 4 Remove the electric starter 12 mm box spanner M8 nuts 10 mm box spanner 12 mm box s...

Page 26: ...driver 18 Spark plug Remove the spark plug from the cylinder head 21 mm plug wrench SPARK PLUG CLAMP VIEW A EX27 only A BAFFLE 1 CASE BOLT M6 x 40L CHARGE COIL CHARGE COIL M6 x 12 FLANGE BOLT 1 pc EX13 17 21 M8 x 12 FLANGE BOLT 1 pc EX27 For the model without electric starter STEP 16 STEP 17 STEP 18 SPACER M6 x 35L 15W 40W 15W 40W 200W 15W 40W 200W 15W 40W 200W M6 x 35L M6 x 40L M6 x 25L M6 x 35L ...

Page 27: ...ove the pin rocker arm and the rocker arm from the cylinder head at the compression top dead center See Fig 5 14b Fig 5 13 ROCKER ARM EXHAUST VALVE SIDE ROCKER ARM INTAKE VALVE SIDE PIN ROCKER ARM ROCKER ARM EXHAUST VALVE SIDE PIN ROCKER ARM CLOSE UP A A ROCKER ARM INTAKE VALVE SIDE ROCKER COVER GASKET ROCKER COVER M6 x 12 BOLT 4 pcs STEP 20 STEP 19 Punch marks The position of compression top dead...

Page 28: ...earing cover while tapping gently around the cover using a plastic hammer or similar tool See Fig 5 16 Be careful not to damage the oil gauge or oil seal or not to lose the pipe knocks 12 mm box spanner M8 35mm 6 pcs Models EX13 17 and 21 M8 35mm 7 pcs Model EX27 Fig 5 15 MAIN BEARING COVER M8 x 35mm 6 pcs MODELS EX13 17 AND 21 M8 x 35mm 7 pcs MODEL EX27 PIPE KNOCK STEP 21 ...

Page 29: ...ft from coming out PIN CAMSHAFT Step Parts to remove Remarks and procedures Fasteners 22 Tensioner Camshaft 1 Remove the tensioner See Fig 5 18a Do not lose the pin tensioner 2 Remove the retaining bolt of pin camshaft from the cylinder head See Fig 5 18b 3 Remove the pin camshaft taking care not to scratch the O ring 4 Remove the chain from the camshaft sprocket and then take out the camshaft See...

Page 30: ... is removed from the inner side of the crankcase it might be damaged 12 mm box spanner M8 68mm 4 pcs M8 35mm 1 pc 24 Intake and exhaust valves 1 Remove the collet valve from the spring retainer See Fig 5 21 2 Remove the intake valve and the exhaust valve M8 x 35 BOLT 1 pc This bolt is same as the main bearing cover bolt STEP 23 STEP 24 PIPE KNOCK GASKET CYLINDER HEAD M8 x 68 BOLT 4 pcs EXHAUST VAL...

Page 31: ...r 10 mm box spanner M6 33mm 2 pcs Models EX13 17 and 21 M7 40mm 2 pcs Model EX27 26 Piston and piston rings 1 Remove the piston clips 2 pcs Take out the piston pin and then remove the piston from the connecting rod small end taking care not to damage the connecting rod small end 2 Remove the piston rings from the piston by spreading them at the gap Take special care not to damage the rings when do...

Page 32: ... plastic hammer taking care not to damage the oil seal See Fig 5 24 Plastic hammer 28 Oil sensor option 1 Remove the clamp See Fig 5 25 2 Remove the oil sensor from the crankcase M6 12mm 1 pc M6 16mm 2 pcs Fig 5 23 Fig 5 24 CRANKCASE WOODRUFF KEY CRANKSHAFT M6 x 16 BOLT 2 pcs OIL SENSOR STEP 27 STEP 28 SHIELD PLATE For charge coil only M6 x 10 TAPPING BOLT 1 pc EX27 only CLAMP Fig 5 25 OIL SENSOR ...

Page 33: ...ace them if damaged Apply oil to the lip before reassembly 4 Replace all the gaskets with new ones 5 Replace the keys pins bolts and nuts with new ones if necessary 6 Tighten nuts and bolts to the specified torque settings 7 When reassembling the engine apply oil to all moving parts 8 Check clearances and end plays and adjust if necessary 9 When mounting any major part during reassembly of the eng...

Page 34: ...ey may be damaged Install the oil ring first followed by the second ring and then the top ring When installing the second ring make sure that the N mark is face up See Fig 5 33 Fig 5 31 OPEN ENDS OF PISTON RING Fig 5 33 Fig 5 32 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 MARK N EX17 EX21 EX27 MARK R EX13 ...

Page 35: ...h the MAG mark on the connecting rod 5 CONNECTING ROD a Install the piston and connecting rod assembly into the cylinder by holding the piston rings with the ring guide with the MAG mark on the connecting rod on the flywheel side If you do not have a ring guide hold the piston rings with the fingers and tap the upper part of the piston with a piece of wood NOTE 1 Apply oil to the piston rings the ...

Page 36: ...ace the valve with a new one if it shows signs of wear Refer to the STANDARD REPAIR TABLES on page 78 and 79 NOTE 2 Carefully scrape off any carbon deposits on the combustion chamber Apply oil to the valve stems before mounting the intake and exhaust valves Insert the valves in the cylinder head and place it on a level workbench Next mount the valve springs the spring retainers and collet valves M...

Page 37: ...M8 68mm flange bolt 4pcs by 26 1 N m 2 When replace to new cylinder head and flange bolts Oil the screw thread Tighten all bolts 5pcs by 18 1 N m primary and then tighten longer ones M8 68mm flange bolt 4pcs by 29 1 N m Fig 5 40 PIPE KNOCK PIPE KNOCK GASKET CYLINDER HEAD M8 x 35 BOLT 1 pc M8 x 68 BOLT 4 pcs 1 2 3 4 5 1 2 3 4 Cylinder head bolts Tightening Torque Remarks 1st step 2nd step M8 68mm f...

Page 38: ...s not have a camshaft side or crankshaft sprocket side The mark plate does not have a camshaft side or crankshaft sprocket side CAMSHAFT SPROCKET CAMSHAFT SPROCKET CAMSHAFT SPROCKET CRANKSHAFT SPROCKET CRANKSHAFT SPROCKET CRANKSHAFT SPROCKET 9 SETTING THE TIMING CHAIN a Align the timing mark on the crankshaft sprocket with the mark plate of the timing chain b Align the timing mark on the crankshaf...

Page 39: ...E CAMSHAFT ON THE CYLINDER HEAD Mount the camshaft on the cylinder head by inserting the pin camshaft through the head Fix the bolt to prevent the pin camshaft from coming out TENSIONER PIN TENSIONER SPRING TENSIONER PIN TENSIONER Fig 5 41b Fig 5 42a 11 MOUNTING THE TENSIONER M6 x 12 BOLT 1 pc Bolt used to prevent the pin camshaft from coming out PIN CAMSHAFT CAMSHAFT CHAIN ...

Page 40: ...does not face the main bearing cover 12 BALANCER SHAFT OPTION for EX27 only Mount the balancer shaft on the crankcase align the timing marks on the balancer gear and the crankshaft gear NOTE Incorrect alignment of the timing marks can result in malfunction of the engine leading to damage due to interference of the parts Fig 5 44 Fig 5 43 M8 x 35 BOLT 6 pcs EX13 17 21 M8 x 35 BOLT 7 pcs EX27 MAIN B...

Page 41: ...center The position of two punch marks on cam sprocket is in parallel with the cylinder head surface at a time NOTE After adjusting the valve clearances rotate the crankshaft and check again that the intake and exhaust valve clearance are correct Valve clearance when the engine is cold Intake valve side Exhaust valve side Tightening torque 5 0 7 0 N m 50 70 kgf cm 3 6 5 1 ft lb EX13 17 21 EX27 The...

Page 42: ... IGNITION COIL TO OIL SENSOR HOOK BAFFLE 1 CASE OIL SENSOR UNIT Tightening torque New spark plug Re tightening torque 12 0 15 0 N m 120 150 kgf cm 8 7 10 8 ft lb 23 0 27 0 N m 230 270 kgf cm 16 6 19 5 ft lb 17 SPARK PLUG Remove any carbon deposits from the spark plug and inspect the electrode for damage before mounting Replace with a new one if necessary Spark plug NGK BR 6HS or CHAMPION RL86C Tig...

Page 43: ...crankshaft Tighten the flywheel together with the starting pulley 20 IGNITION COIL When mounting the ignition coil insert a thickness gauge between the ignition coil and the flywheel to check the air gap Tightening torque 7 0 9 0 N m 70 90 kgf cm 5 1 6 5 ft lb Align the 2 bosses of starting pulley with the depression of flywheel Tightening torque 59 0 64 0 N m 590 640 kgf cm 42 7 46 3 ft lb M14 nu...

Page 44: ...INSULATOR A Detail A GASKET GASKET 21 SPEED CONTROL LEVER BRACKET AND BAFFLE Mount the speed control lever and bracket baffle 2 head and baffle 3 on the crankcase NOTE The baffle 3 is used for Model EX21 only 22 CARBURETOR a Replace the gasket of insulator with a new one and mount the insulator on the cylinder head intake side b Mount the carburetor ...

Page 45: ...n the adjustment method after mounting air cleaner base Variation of the governor spring The dimensions of the governor spring are different each other according to the Hz The governor spring for the standard engine is same as that for the engine to be connected to the 60Hz generator Discrimination according to the dimensions Fig 5 55 GOVERNOR ROD and ROD SPRING GOVERNOR SPRING Long length side Sh...

Page 46: ...ttle valve is fully open 2 Hold the top of the governor shaft with the plier and turning it clockwise as far as it will go Tighten the bolt on the governor lever Fig 5 58 GOVERNOR LEVER GOVERNOR SPRING GOVERNOR ROD and ROD SPRING GOVERNOR SHAFT Fig 5 57 24 AIR CLEANER BASE Insert the breather pipe into the rocker cover and then mount the air cleaner base M6 flange nut 2 pcs M6 x 20 mm flange bolt ...

Page 47: ... 0 22 0 N m 180 220 kgf cm 13 0 15 9 ft lb Model EX13 EX17 EX21 EX27 Fuel pipe length mm in 145 5 7 150 5 9 155 6 1 195 7 7 Fig 5 59a FUEL STRAINER FUEL PIPE HOSE CLAMP M6 x 25 BOLT 1pc EX13 17 25 M8 x 25 BOLT 2pcs EX27 M6 NUT 2pcs Fig 5 59b Tightening torque for fuel strainer 3 0 4 0 N m 30 40 kgf cm 2 2 2 9 ft lb 2 Connect the fuel pipe and fix it with a clamp NOTE Make sure the fuel pipe is loc...

Page 48: ...nt the blower housing on the crankcase M6 12 mm bolt 4 pcs 3 Mount the recoil starter on the blower housing M6 8 mm bolt 4 pcs M6 x 8 BOLT 4 pcs M6 x 12 BOLT 4 pcs RECOIL STARTER BLOWER HOUSING FUEL PIPE BOSS Fig 5 59c 3 Mount the fuel tank on the crankcase M6 nut 2 pcs M6 25 mm bolt 1 pc Models EX13 17 and 21 M8 25 mm bolt 2 pcs Model EX27 ...

Page 49: ...pe Fig 5 62 29 AIR CLEANER Mount the air cleaner element and cleaner cover 28 STOP SWITCH 1 Mount the stop switch on the blower housing 2 Refer to the wiring diagram See page 51 and 52 for wiring details Fig 5 61 STOP SWITCH ...

Page 50: ...ne operating speed Step Model EX13 Model EX17 Model EX21 Model EX27 Engine Speed Time Step 1 No Load 2500 r p m 10 min Step 2 No Load 3000 r p m 10 min Step 3 No Load 3600 r p m 10 min Step 4 1 5 HP 2 HP 2 5 HP 3 5 HP 3600 r p m 30 min Step 5 3 HP 4 HP 5 HP 7 HP 3600 r p m 30 min 30 EXTERNAL INSPECTION Reassembly is completed Check that the wiring is correct and that there are no loose nuts and bo...

Page 51: ...falls below 20 C or rises above 40 C be sure to choose engine oil of appropriate viscosity and grade according to the prevailing conditions Care must be taken when using multi grade engine oil because the oil consumption rate tends to increase when the air temperature is high 6 3 ADDING AND CHANGING ENGINE OIL Engine oil inspection and filling up Every time you use the engine add engine oil up to ...

Page 52: ...for defects according to the following procedure 1 Carefully check the high tension cable for any damage or short circuiting 2 Check the sparking Take the spark plug out of the cylinder head connect the spark plug with the plug cap and ground it on the cylinder head or any other metallic part of the engine The gap between the electrodes of the spark plug should be between 0 6 mm and 0 7 mm Rotate ...

Page 53: ... because the power transistor is turned off This sudden current change generates a big voltage on the secondary side of the ignition coil and which sparks the spark plug 2 At the higher engine speed Rotation of the flywheel generates the current I1 as this current flows through the base terminal of the power transistor it is activated and the current I2 starts of flow As the engine reaches the ign...

Page 54: ...vancing control circuit operates to run the gate current I4 to turn the control thyristor ON thus the current I1 bypass the thyristor as current I5 At this moment the power transistor turns OFF and the current I2 is shut off abruptly resulting in the high voltage generated in the secondary coil which produces sparks at the spark plug At over 2 000rpm ignition timing on each engine revolution is co...

Page 55: ...UT ELECTRIC STARTER Models EX13 17 21 and 27 8 2 MODEL WITH ELECTRIC STARTER Models EX17 and 21 Fig 8 1 Fig 8 2 M M ST B LA106 LA406 LA306 Black Red Charge coil Diode rectifier Ignition coil Spark plug Key switch Battery 12V24AH Electric starter Magnetic switch Magneto Key switch 066 00003 30 M M B S OFF ON START ...

Page 56: ...ition coil Spark plug Key switch Battery 12V24AH Electric starter Magneto Key switch 066 00003 30 M M B S OFF ON START 8 4 MODEL WITH OIL SENSOR To LED Lamp Yellow Yellow Red Black Oil sensor control unit Orange Orange Body earth Black White LA106 Black To stop switch Spark plug Oil sensor Fig 8 4 Oil sensor as option ...

Page 57: ...f the arrows the coil of the magnetic switch is magnetically excited and the contactor is pulled As a result a low current flows through the M circuit and a high starter current flows through the S circuit This energizes the starter motor and cranks the engine Engagement of the pinion gear EX17 21 When the starter motor is started the weight built into the spiral splines located on the shaft moves...

Page 58: ...T 2 pcs BRUSH HOLDER BRUSH SPRING BRUSH REAR COVER MAGNETIC SWITCH PINION AY FRONT COVER BATTERY CABLE ARMATURE AY YOKE AY O RING O RING THROUGH BOLT 2 pcs WASHER SPRING BRUSH REAR COVER BRUSH HOLDER BRUSH MAGNETIC SWITCH PINION STOPPER SET Fig 9 3 9 3 COMPONENT PARTS Models EX17 and EX21 Model EX27 ...

Page 59: ...at moves up Fig 10 1 OIL SENSOR Type Float type with lead switch incorporated Resistance at FULL oil level 100 M ohms or over Operating Temperature 30 to 180 degree Celsius Fig 10 2 FLOAT LEAD SWITCH PERMANENT MAGNET Fig 10 3 When the oil level is lower level the float moves down The permanent magnet is close to the lead switch and the lead switch is activated by the magnetic force MAGNETIC FORCE ...

Page 60: ...end of the compression process the release lever lifts up the rocker arm exhaust which in turn opens up the exhaust valve slightly to release the compression The release lever has a flyweight on its end and another end of the lever is a crescent cam When the engine is cranked the crescent cam projects above the cam profile and lifts up the rocker arm exhaust because the force of the return spring ...

Page 61: ...gine through the pilot outlet and the bypass During idling fuel is fed to the engine mainly through the pilot outlet 12 2 3 MAIN SYSTEM The main system feeds fuel to the engine at medium and high speed operation Fuel is metered by the main jet and flows into the main nozzle Air metered by the main air jet is mixed with fuel through the bleed holes of the main nozzle The fuel air mist is injected i...

Page 62: ... 58 PILOT OUTLET BYPASS PILOT AIR JET CHOKE VALVE AIR INTAKE PORT MAIN AIR JET MAIN NOZZLE FLOAT CHAMBER PILOT JET FLOAT MAIN JET FUEL NEEDLE VALVE FLOAT Fig 12 2 Fig 12 1 FUEL SYSTEM OUTLINE ...

Page 63: ...AND REASSEMBLY Mechanical failures aside most carburetor malfunctions occur when the fuel air ratio of the mixture is not correct This is usually caused by clogged jets air passages and fuel passages or by variations in the fuel level To get the best possible performance from the carburetor ensure that the each passages are kept clean so that air and fuel can flow freely through them ...

Page 64: ...and remove the float chamber body 2 Remove the main jet from the body 3 Remove the main nozzle from the body 4 When reassembling the main system be sure to fasten the main jet and main nozzle firmly to the body otherwise the fuel concentration in the fuel air mixture may become too rich leading to engine malfunction 5 The tightening torque of the bolt is 9 N m 90 kgf cm 6 5 ft lb Be sure not to fo...

Page 65: ...he reel untie the knot and pull the rope out toward the starter knob Note This procedure requires 2 people 5 While controlling the reel with the thumbs slowly wind it back as far as it will go Fig 13 1 13 RECOIL STARTER 13 1 RECOIL STARTER Tools required Screwdriver pliers and protective glasses NOTE Put on the protective glasses prior to start disassembly NOTE When the rope is pulled out to its f...

Page 66: ...ents Fig 13 2 1 Grip the case and loosen the set screw 2 Take out the set screw the ratchet guide the friction spring and the ratchet in that order 3 Remove the reel Fig 13 2 1 Hold down the reel gently to keep it from escaping from its case and rotate it slowly back and forth by quarter turns until it moves smoothly 2 Lift the reel up little by little and take it out of the case 3 If the spring i...

Page 67: ...ng force reaches its maximum value when the reel is wound up Be careful not to drop it or release your grip on it suddenly THE RATCHET SHOULD BE IN THE CLOSED POSITION Ratchet guide sub assembly Set screw Ratchet guide Friction spring APPROX 200 M M FRO M THE REEL ROPE HOLE IN REEL ROPE GUIDE 4 Tension the reel spring 1 Grip the case and turn the reel 6 times counterclockwise 2 Fix the reel so tha...

Page 68: ...p Fig 13 9 4 Grasp the rope firmly with one hand at approximately 50 cm from the rope guide and keep the rope tense taking care that the rope is not pulled into the reel 5 Release the reel carefully and allow the rope to be wound back slowly by the force of the spring until the knob reaches the rope guide Assembly is completed Fig 13 8 Fig 13 9 The disassembly and the reassembly are completed howe...

Page 69: ... taking care not to over stress the spring c If there is a sound indicating that the spring is off the hook and the starter rope does not be wound back reassemble the recoil starter from the beginning 13 1 4 OTHER GUIDES 1 If the spring escapes from the reel during disassembly a Hook the outer end of the spring onto the gap in the reel and rewind the spring holding the spring with your fingers so ...

Page 70: ...and to prevent the working equipment from heating up Be sure to keep the engine room temperature below 50 C all year round and to prevent the accumulation of hot air in the engine room 14 3 EXHAUST EQUIPMENT Exhaust gas is noxious When operating the engine indoors make sure that exhaust gases are discharged outdoors However if the exhaust pipe is long resistance increases and this lowers engine ou...

Page 71: ...y of the machine Install the engine pulley as close to the engine as possible If possible span the belt horizontally Disengage the load when starting the engine A belt tensioner or similar should be installed if no clutch is used 14 5 2 FLEXIBLE COUPLING When using a flexible coupling run out and misalignment between the driven shaft and the engine shaft should be minimized The permissible margin ...

Page 72: ... Retighten replace gasket 7 Leakage from carburetor gasket Retighten replace gasket 8 Insufficient tightening of spark plug Retighten 15 TROUBLESHOOTING If the engine shows any sign of malfunction the cause should be determined immediately and appropriate countermeasures should be taken to prevent the problem from worsening This section describes certain known problems their possible causes and ap...

Page 73: ...tighten joints 4 Poor quality gasoline or water in gasoline Replace 4 Low air intake volume 1 Air cleaner clogged Clean or replace 2 Throttle valve malfunction Repair or replace 1 Engine 1 Cooling air flow obstructed at inlet or cylinder baffle portion Clean 2 Poor quality engine oil Replace 3 Lean fuel air mixture Check and adjust carburetor 4 Excessive back pressure of exhaust system Check and c...

Page 74: ...ly Repair or replace 2 Engine core components 1 Low compression Check and repair 2 Overcooling Check and adjust load and or engine speed 1 Ignition system problems 1 Loose ignition system wiring Inspect and tighten 2 Improper or faulty spark plug Clean or replace 2 Fuel system problems 1 Lean or rich fuel air mixture Clean adjust or replace carburetor 2 Carburetor contamination Overhaul or clean 3...

Page 75: ... gap Replace motor brush holder or armature OK OK OK NG NG NG NG NG NG There is any contact failure of starter magnetic switch Please replace OK OK Normal rotation Engine does not start OK NG Too slow Check battery charged state and battery terminal connection or corrosion for any abnormality Check viscosity of engine oil for any abnormality Replace the starter with a new one and check if it runs ...

Page 76: ... or sound of magnetic switch contactor is heard If the pinion does not operate or magnetic switch sound is not heard check continuity of each coil of magnetic switch 1 If the pinion operates or contactor sound is heard step to 4 Checking of magnetic switch 1 2 In case of no continuity Replace the magnetic switch 3 When continuity is OK Step to 4 Checking of magnetic switch 2 1 Charge or change the...

Page 77: ...tarter pinion and ring gear 3 Both starter and engine run but the engine does not start Check if the rotation speed is normal or slow If slow check the battery and engine oil viscosity 1 Remove the starter and check pinion and ring gear end faces If worn replace the pinion and ring gear 2 In case of sliding fault of the pinion correct it 3 If shift lever or spring is deformed replace it 1 When the...

Page 78: ... USE ITEM STD Limit CYLINDER HEAD Flatness EX13 EX17 EX21 EX27 0 05 0 002 0 1 0 004 Intake exhaust valve seat contact width Intake Exhaust EX13 EX17 EX21 EX27 0 7 1 0 0 0276 0 0394 Intake exhaust valve guide inner diameter Intake Exhaust EX13 EX17 EX21 EX27 5 500 5 518 0 2165 0 2172 Rocker arm pin outer diameter Pin outer diameter D1 D2 EX13 EX17 EX21 EX27 5 970 5 980 0 235 0 235 5 9 0 232 Rocker ...

Page 79: ...7 EX21 67 500 67 519 2 6575 2 6582 EX27 75 500 75 519 2 9724 2 9732 EX13 EX17 EX21 EX27 Less than 0 01 0 0004 EX13 EX17 EX21 EX27 Less than 0 015 0 0006 PISTON Outer diameter at skirt in thrust direction Standard EX13 57 980 58 000 2 2827 2 2835 57 89 2 2791 EX17 EX21 66 960 67 000 2 6362 2 6378 66 88 2 6331 EX27 74 980 75 000 2 9520 2 9527 74 89 2 9484 Oversize 0 25 EX13 58 230 58 250 2 2925 2 29...

Page 80: ...13 EX27 17 991 18 009 0 7083 0 7090 18 035 0 7224 Piston pin outer diameter EX13 12 992 13 000 0 5115 0 5118 12 960 0 5102 EX17 EX21 15 992 16 000 0 6296 0 6299 15 960 0 6283 EX27 17 992 18 000 0 7083 0 7087 17 960 0 7071 Clearance between piston and cylinder at skirt EX13 0 040 0 079 0 0016 0 0031 0 25 0 010 EX17 EX21 EX27 0 050 0 089 0 0020 0 0035 Piston ring end gap Top EX13 0 15 0 35 0 0059 0 ...

Page 81: ...8 0 6331 EX27 18 010 18 021 0 7091 0 7095 18 08 0 7118 Clearance between small end and piston pin EX13 EX17 EX21 EX27 0 010 0 029 0 0004 0 0011 0 12 0 0047 Large end side clearance EX13 EX17 EX21 EX27 0 100 0 780 0 0040 0 307 1 0 0 0394 CRANKSHAFT Crank pin outer diameter EX13 EX17 EX21 29 967 29 980 1 1798 1 1803 29 85 1 1752 EX27 34 467 34 480 1 3570 1 3575 34 35 1 3524 Journal outer diameter D1...

Page 82: ...75 0 3525 0 3533 8 95 0 3524 INTAKE EXHAUST VALVES Valve stem outer diameter Intake EX13 EX17 EX21 EX27 5 440 5 455 0 2142 0 2148 5 35 0 2106 Exhaust EX13 EX17 EX21 EX27 5 426 5 444 0 2136 0 2143 5 35 0 2106 Clearance between valve stem and valve guide Intake EX13 EX17 EX21 EX27 0 045 0 078 0 0018 0 0031 0 3 0 0118 Exhaust EX13 EX17 EX21 EX27 0 056 0 092 0 0022 0 0036 0 3 0 0118 Valve clearance in...

Page 83: ...69 0 10 5906 272 1 10 7126 EX21 281 7 11 0906 284 9 11 2165 EX27 307 1 12 0906 310 6 12 2284 Unit mm in 160N 16kgf F L L Oil consumption has been measured under following condition Good break in operation has been finished Oil 10W 30 Grade SE Load Continuous load 3600 rpm EX13 EX17 EX21 EX27 Compression pressure kg cm2 500 rpm 3 5 4 0 4 0 4 0 Fuel consumption Continuous load 3600 rpm L Hr 1 2 1 6 ...

Page 84: ...00 20 3 21 7 M8 35 flange bolt 17 0 19 0 170 190 12 3 13 7 Connecting rod cap bolts EX13 17 21 13 0 15 0 130 150 9 4 10 8 EX27 17 0 20 0 170 200 12 3 14 5 Flywheel nut 59 0 64 0 590 640 42 7 46 3 Main bearing cover bolts 22 0 24 0 220 240 16 2 17 7 Spark plug New 12 0 15 0 120 150 8 7 10 8 Re tightening 23 0 27 0 230 270 16 6 19 5 Muffler nut 18 0 22 0 180 220 13 0 15 9 Ignition coil 7 0 9 0 70 90...

Page 85: ...k all parts are securely fastened Tighten if necessary 4 Check oil level and add up to full mark 5 Check that the air cleaner element is clean Clean or replace if necessary 1 Dust can impair operation of various parts Governor linkage is especially sensitive to dust 2 Uneconomical and dangerous 3 Looseness can result in vibration and accidents 4 Running the engine with insufficient oil can result ...

Page 86: ...lastic cover or similar over the engine and store the engine in a dry place MAINTENACE ITEMS REASON REMARKS 1 Overhaul the engine Clean and correct the engine parts replacing if necessary 2 Replace the piston rings 3 Replace the fuel hose 1 Dirty misaligned or worn parts can cause low power output and engine malfunction 2 Faulty piston rings can cause low output power and engine malfunction 3 To p...

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Page 88: ...PRINTED IN THE USA ...

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Robin America EX13, Service Manual

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