SERVICE MANUAL Models EH63, 64, 65 and EH72 ENGINES PUB-ES2158 Rev.
Robin America, Inc. 905 Telser Road • Lake Zurich, IL 60047 • Phone: 847-540-7300 • Fax: 847-438-5012 e-mail: sales@robinamerica.com • www.subarupower.com © Copyright 2009 Robin America, Inc.
CONTENTS Section Title Page 1. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. GENERAL DESCRIPTION OF ENGINE COMPONENTS . . . . . . . . . . . . . . . . . . . 8 5.
1. SPECIFICATIONS MODEL EH63D Type EH64D EH65D EH72D Air-Cooled, 4-Stroke, V-Twin Cylinder, Horizontal P.T.O. shaft, OHV Gasoline Engine Bore x stroke mm (in.) Displacement cm3 (cu. in.) 2 - 80 x 65 (3.15 x 2.56) 2 - 84 x 65 (3.31 x 2.56) 653 (39.9) 720 (43.9) 8.3 Compression Ratio Continuous Output kW (HP) / r.p.m. 10.8 (14.5) / 3600 11.9 (16.0) / 3600 12.7 (17.0) / 3600 13.4 (18.0) / 3600 Maximum Output kW (HP) / r.p.m. 13.4 (18.0) / 3600 15.3 (20.5) / 3600 16.4 (22.0) / 3600 18.
2. PERFORMANCE 2-1 MAXIMUM OUTPUT The maximum output is the output of an engine with its throttle valve fully opened under the condition that all the moving parts are properly worn in after the initial break-in period. A new engine may not produce full maximum output while its moving parts are still not broken-in.
2-4 PERFORMANCE CURVES EH63D 35 (3.57) MAXIMUM TORQUE 15 (20.1) TORQUE 45 (4.59) N-m (kgf-m) MAXIMUM HORSEPOWER HORSEPOWER kW (HP) 10 (13.4) CONTINUOUS RATED HP RECOMMENDED HORSEPOWER RANGE 5 (6.7) 2000 2400 2800 3200 REVOLUTION 3600 r.p.
EH64D 35 (3.57) MAXIMUM TORQUE TORQUE 45 (4.59) N-m (kgf-m) MAXIMUM HORSEPOWER 15 (20.1) HORSEPOWER kW (HP) CONTINUOUS RATED HP 10 (13.4) RECOMMENDED HORSEPOWER RANGE 5 (6.7) 2000 2400 2800 3200 REVOLUTION 3600 r.p.
EH65D 35 (3.57) MAXIMUM TORQUE TORQUE 45 (4.59) N-m (kgf-m) MAXIMUM HORSEPOWER 15 (20.1) HORSEPOWER kW (HP) CONTINUOUS RATED HP 10 (13.4) RECOMMENDED HORSEPOWER RANGE 5 (6.7) 2000 2400 2800 3200 REVOLUTION 3600 r.p.
EH72D 45 (4.59) MAXIMUM TORQUE 20 (26.8) TORQUE 55 (5.61) N-m (kgf-m) MAXIMUM HORSEPOWER HORSEPOWER kW (HP) 15 (20.1) CONTINUOUS RATED HP 10 (13.4) RECOMMENDED HORSEPOWER RANGE 5 (6.7) 2000 2400 2800 3200 REVOLUTION –6– 3600 r.p.
3.
4. GENERAL DESCRIPTION OF ENGINE COMPONENTS ROBIN EH63D/64D/65D/72D engine is air-cooled, 4-stroke, twin-cylinder, OHV arrangement gasoline engine. The twin-cylinder is located in the angle of 90 degree; #1 cylinder is in the RH side and #2 cylinder in LH side as viewed from flywheel (cooling fan) side. 4-1 CYLINDER AND CRANKCASE The twin-cylinder and crankcase is single piece aluminum die-casting. The cylinder liner, made of special cast iron, is molded into the aluminum casting.
4-4 CONNECTING ROD AND PISTON The connecting rod is forged aluminum alloy, and its large and small ends function as bearings. The piston is an aluminum alloy casting, and carries two compression rings and one oil ring. 4-5 PISTON RINGS The piston rings are made of special cast iron. The profile of the top ring is barrel face and the second ring has a tapered face. The oil ring is designed for better sealing and less oil consumption, in combination with 3 pieces.
4-7 CYLINDER HEAD The cylinder head is an aluminum die-casting which utilizes semi-spherical type combustion chamber for the high combustion efficiency. 4-8 VALVE ARRANGEMENT The intake valve is located on flywheel side of the cylinder head. The cooling fins and passages design lead cooling air to the exhaust valve area for the optimum cooling. Hard alloy valve seats are molded in the cylinder head.
4-10 COOLING SYSTEM The large fins on the flywheel provide sufficient cooling air capacity for cylinder and cylinder head. The cylinder baffle helps the cooling air flow efficiently. 4-11 LUBRICATION SYSTEM The engine is furnished with full pressure lubrication system. The trochoid type oil pump is driven by crankshaft and delivers pressurized engine oil through the fullflow type oil filter to the journal and pin portions of crankshaft and camshaft.
4-14 CARBURETOR The engine is equipped with a down draft carburetor that has a float controlled fuel system and a fixed main jet. The carburetors are calibrated carefully for the sure FUEL CUT SOLENOID VALVE starting, low fuel consumption and sufficient output. Fuel cut solenoid valve is provided to prevent engine running on when the key switch is turned to off. Accelerator-pump is provided for obtaining quick and ACCELERATOR-PUMP good throttle response.
4-17 SECTIONAL VIEW OF ENGINE CARBURETOR INTAKE MANIFOLD IGNITION COIL P.T.O.
CAMSHAFT AIR CLEANER GOVERNOR LEVER PUSH ROD ROCKER ARM INTAKE AND EXHAUST VALVES SPARK PLUG PISTON RING PISTON PISTON PIN TAPPET OIL COOLER (EH72D) OIL FILTER ELECTRIC STARTER CRANKCASE CRANKSHAFT – 14 – CONNECTING ROD
5. DISASSEMBLY AND REASSEMBLY 5-1 PREPARATIONS AND SUGGESTIONS When disassembling the engine, memorize the locations of individual parts so that they can be reassembled correctly. If you are uncertain of identifying some parts, it is suggested that tags be attached to them. Have boxes ready to keep disassembled parts by group. To prevent losing and misplacing, temporarily assemble each group of disassembled parts. Carefully handle disassembled parts, and clean them with washing oil if necessary.
5-3 DISASSEMBLY PROCEDURES Step Parts to remove Remarks and procedures Fasteners Drain engine oil by removing plugs located on both side of crankcase. 1 Engine oil drain 2 Muffler cover M6 x 14 Flange bolt : 4 pcs. M6 x 8 Flange bolt : 2 pcs. 3 Muffler M8 SUS Flange nut : 4pcs. 4 Muffler bracket M8 x 20 bolt and washer : 2pcs. M6 FLANGE BOLT M14 x 12 Drain plug : 2 pcs.
Step Parts to remove Remarks and procedures Fasteners 5 Air cleaner cover and elements Remove cleaner cover and cleaner element. 6 Air cleaner base Remove breather pipe from #1 cylinder head. M6 x 12 Flange bolt : 3 pcs.
Step Parts to remove Remarks and procedures Fasteners 7 Blower housing Control box Disconnect fuel pipe and remove blower M6 x 18 Flange bolt : 2 pcs. housing along with control box. M6 x 14 Flange bolt : 6 pcs. 8 Chock control lever and link (1) Remove the choke knob. (2) Remove the choke contol link. M6 bolt : 1 pc.
Step Parts to remove Carburetor Remarks and procedures Fasteners M8 x 80 Flange bolt : 2 pcs. At first remove fuel pipe. Take out carburetor along with governor rod and rod spring.
Step Parts to remove Remarks and procedures Governor lever 1. Remove bolt and take out lever. (Make sure the fitting location of governor springs.) 2. Disassemble in the following order. (1) Governor spring (2) Self lock nut (3) Stop plate (4) Spring washer (5) Friction washer (6) Speed control lever Speed control lever 10 11 Speed control bracket unit 12 Starting motor Fasteners M6 x 12 bolt and washer : 3 pcs. M6 self-lock nut : 1 pc. M6 x 12 Flange bolt : 2 pcs. At first remove wiring.
Step 13 Parts to remove Fuel pump Ignition coil 14 Remarks and procedures Remove pluse pipe at first. Remove fuel pump ASSY and detach bracket. (1) Take out plug cap. (2) Remove ignition coil. (3) Cut out stop wire fixing bands. (4) Disconnect stop wires from ignition coil. Fasteners M6 x 12 Flange bolt : 2 pcs. M6 x 12 Flange bolt : 2 pcs. M6 x 25 bolt & washer : 4 pcs.
Step Parts to remove 15 Intake manifold 16 Regulator and Wire CP Remarks and procedures Fasteners M8 flange nut : 4 pcs. Disconnect wire connector from regulator, and then remove regulator from #1 cylinder baffle. M8 FLANGE NUT M6 x 12 Flange bolt : 2 pcs.
Step 17 Parts to remove Remarks and procedures Cylinder baffles (#1, #2, #3 & #4) Fasteners M6 x 12 flange bolt : 8 pcs.
Step 18 Parts to remove Fasteners Cooling fan Remove cooling fan from flywheel. M6 x 16 bolt & washer : 4 pcs. Flywheel Untighten flywheel nut and leave it to avoid the flywheel fell out. Take out flywheel by means of flywheel puller. M18 Flange nut: 1 pc. 19 20 Remarks and procedures M5 x 20 bolt & washer : 4 pcs.(15A coil) M5 x 25 bolt & washer : 4 pcs.
Step Parts to remove Remarks and procedures Fasteners 21 Spark plug Take care the spark plug is hot just after stopping engine. 22 Oil cooler (EH72) 1. Disconnect oil hoses with clamps detached. M6 x 12 Flange bolt : 4 pcs. 2. Remove oil cooler. 3. Remove bracket unit.
Step 23 24 Parts to remove Remarks and procedures Fasteners Rocker cover Remove rocker cover along with hook. Cylinder head and Push rod 1. Bolt, pivot 2. Rocker arm When removing “rocker arm” and “Bolt,pivot”, M10 x 65 Flange bolt : 8 pcs. turn and adjust flywheel at TDC with the marking “T” faced to “1” or “2” on each cylinder head. Put the marking of original position onto each push rod, rocker arm and valve for reassembly. M6 x 28 Flange bolt : 8 pcs.
Step Parts to remove Intake & exhaust valves 25 Remarks and procedures Fasteners Take out collet-valves with spring retainer depressed by hand. Take out valve springs. Breather cover Breather plate M6 x 14 Flange bolt : 2 pcs.
Step Parts to remove Remarks and procedures Take out key from PTO shaft. M8 x 45 Flange bolt : 10 pcs. Wrap PTO shaft with polyvinyl tape not to damage oil seal by key groove edge. Tapping with plastic hummer, take out main bearing cover.
Step 27 Parts to remove Remarks and procedures Camshaft Mate the markings both on crankshaft gear and camshaft gear and then take out camshaft. tappet Put the marking of original position onto each tappet for reassembly.
Step Parts to remove Connecting rod Piston *Piston pin clip *Piston pin *Piston rings 28 Crankshaft 29 Remarks and procedures Fasteners (1) Remove connecting rod bolts. M8 Connecting rod bolt : 4 pcs. Take out connecting rod cap. (2) Push the connecting rod upwards and take out along with piston. (3) Take out clip and pull out piston pin, and then take out piston from connecting rod. (4) Remove piston rings from piston.
Step Parts to remove Crankcase *Oil pump *Oil filter *Oil pressure switch *Oil pump filetr *Oil relief spring & ball *Governor lever shaft 30 Remarks and procedures Fasteners (1) Disconnect wire connector from oil pressure switch, and remove switch. (2) Remove oil filter and adapter. M6 x 28 Flange bolt : 3 pcs. (3) Remove oil pump filter. 10-32 x 11: 1 pc. (4) Remove oil relief plug and take out spring and ball. (Make sure spring is jumped out.
5-4 REASSEMBLY PROCEDURES 5-4-1 PRECAUTIONS FOR REASSEMBLY 1) Clean parts thoroughly before reassembly. Pay most attention to cleanliness of piston, cylinder, crankshaft, connecting rod and bearings. 2) Scrape off all carbon deposits from cylinder head, piston top and piston ring grooves. 3) Check lip of oil seals. Replace oil seal if the lip is damaged. Apply oil to the lip before reassembly. 4) Replace all the gaskets with new ones. 5) Replace keys, pins, bolts, nuts, etc., if necessary.
B. CYLINDER HEAD, VALVES and ROCKER ARM NOTE ; * Clean valves and wash cylinder head thoroughly. * Remove carbon and gum deposits from the valves, seats, ports and guides. * Inspect valves, valve seats and valve guides. * Replace valves that are badly burned, pitted or warped. * Valve guides should be replaced when valve stem clearance exceeds specifications. (Refer to SERVICE DATA for clearance specifications. ) If exceeds, draw valve guides out and press new guides in.
C. PISTON RING and CONNECTING ROD (1) PISTON and PISTON RING Install oil ring first, then second ring and top ring. Spread ring only far enough to slip over piston and into correct groove. Use care not to distort ring. NOTE ; * Top ring can be fit either way. * Install second ring with punched mark beside the gap on the top side. * As for oil ring, rails should be placed on and below the expander.
5-4-3 Re-assembly CRANKSHAFT 1) CRANKSHAFT Install crankshaft onto crankcase. NOTE ; * Apply enough oil to bearing portion of crankcase. * For smooth fitting of crankshaft, assemble oil pump related parts later. * For easy installation, put crankcase on box or wood blocks. 2) PISTON and CONNECTING ROD NOTE ; * The "1" mark of the connecting rod for #1 cylinder and "2" mark for #2 cylinder should be faced to the PTO side when assembled.
3) TAPPET and CAMSHAFT CAMSHAFT GEAR (1) Apply oil to tappets and install in their original position. Push in fully to avoid damage during camshaft installation. (2) Lubricate bearing surfaces of camshaft. Install camshaft into the crankcase with the timing mark on both crankshaft gear and camshaft alined. TIMING MARK CRANKSHAFT GEAR CAUTION: Incorrect alinement will cause malfunction of the engine. 4) Adjust side clearance HEIGHT GAUGE Measure end play of crankshaft and camshaft.
5) MAIN BEARING COVER (1) Put a oil seal guide onto PTO shaft portion to avoid damaging the main bearing cover oil seal. (2) Place gasket onto the mating surface of crankcase. (3) Lubricate oil seal lip portion and bearing surfaces, and install main bearing cover. Tighten bolts evenly to the specified torque. M8 x 45 Flange bolt : 10 pcs. Tightening torque 22.5 - 27.5 N・m (230 - 280 kgf・cm) (16.5 - 20.2 ft・lb.
8) PUSH RODS Rotate crankshaft to the position in the no lifted condition of tappet. Be sure to loose the rocker arm adjust screw. (1) Insert push rods into the concave portion of tappet and set the other end to the concave portion of rocker arm adjust screw with valve spring depressed. (2) Temporally tighten adjust screw. 9) VALVE CLEARANCE ADJUSTMENT NOTE ; Temporally fit the flywheel in position for easy operation.
11) BREATHER PIPE and COVER GASKET , breather plate Attach breather plate (breather valve) and breather cover to crankcase using proper gaskets. Put breather plate in such position as its reed valve opens outside. BREATHER PLATE M6 x 14 Flange bolt : 2 pcs. Tightening torque 2.9 - 4.9 N・m (30 - 50 kgf・cm) (2.2 - 3.6 ft・lb.) GASKET , breather plate BREATHER COVER M6 FLANGE BOLT NOTE ; * Never tighten the bolts over the specified torque, or gasket is damaged and cut.
16) INTAKE MANIFOLD GASKET, muffler (1) Set gasket (stainless steel) onto both #1 and #2 cylinder head. M8 FLANGE NUT (2) Install intake manifold. INTAKE MANIFOLD M8 flange nut : 4 pcs. Tightening torque 16.6 - 18.6 N・m (170 - 190 kgf・cm) (12.3 - 13.7 ft・lb.) M8 FLANGE NUT GASKET, muffler 17) OIL COOLER (EH72 only) BRACKET UNIT (1) Attach bracket. M6 FLANGE BOLT OIL COOLER (2) Assemble oil cooler onto bracket. M6 x 12 Flange bolt : 4 pcs. Tightening torque 6.8 - 8.8 N・m (70 - 90 kgf・cm) (5.
20) IGNITION COIL and WIRE CP Temporally fit ignition coil to crankcase. THICKNESS GAUGE IGNITION COIL Adjust air gap between ignition coil and flywheel using a thickness gauge and tighten bolts. Ignition coil air gap WIRE 0.3 - 0.5 mm (0.012 - 0.020 in.) M6 x 30 bolt & washer : 4 pcs. Tightening torque 6.8 - 8.8 N・m (70 - 90 kgf・cm) (5.1 - 6.5 ft・lb.) Connect wiring from key switch to the primary terminal of ignition coil.
22) CARBURETOR M8 FLANGEBOLT Set gasket onto intake manifold and install carburetor. CARBURETOR M8 x 80 Flange bolt : 2 pcs. Tightening Torque 16.6 - 18.6 N・m (170 - 190 kgf・cm) (12.3 - 13.7 ft・lb.) GASKET, carburetor 23) CHOKE CONTROL Attach chock control link between carburetor chock lever and chock control lever. Attach governor spring between governor lever and speed control lever.
25) SPEED CONTROL LEVER (1) Install speed control bracket onto intake manifold. M6 SELF LOCK NUT (2) Attach return spring, spacer, friction washer, wing nut, etc. to speed control lever as shown in the ilustration. STOP PLATE SPRING WASHER FRICTION WASHER (3) Connect governor spring to governor lever and speed control lever. SPEED CONTROL LEVER FRICTION WASHER (4) Fit chock control link between carburetor chock lever and chock control lever.
26) ADJUST GOVERNOR SYSTEM ● Governor system is centrifugal flyweight type. Governor weight is installed into governor gear driven by crankshaft. Governor weight movement is transferred to carburetor throttle lever via governor shaft and lever. ● Engine speed is maintained at the constant speed by carburetor throttle valve opening and closing operation in accordance with load condition of engine.
28) FUEL PUMP and FUEL PIPE (1) Install fuel pump bracket onto #2 cylinder baffle. FUEL PUMP BRACKET M6 x 12 Flange bolt : 2 pcs. Tightening torque 6.8 - 8.8 N・m (70 - 90 kgf・cm) (5.0 - 6.5 ft・lb.) (2) Install fuel pump onto fuel pump bracket. FUEL PUMP FUEL PUMP M6 x 12 Flange bolt : 2 pcs. Tightening torque 4.5 - 5.5 N・m (45 - 56 kgf・cm) (3.3 - 4.1 ft・lb.) (3) Connect fuel pipe between carburetor and fuel pump. 29) AIR CLEANER and BREATHER PIPE (1) Connect breather pipe to air cleaner base.
30) OIL PRESSURE SWITCH ● Install oil pressure switch onto crankcase. [EH63, 64, 65] ● Install oil pressure switch onto adapter(Oil cooler). [EH72] [EH63, 64, 65] OIL PRESSURE SWITCH Tightening torque 5.9 - 9.8 N・m (60 - 100 kgf・cm) (4.3 - 7.2 ft・lb.) [EH72] NOTE ; Not to tighten excessively. OIL PRESSURE SWITCH 31) OIL FILTER [EH63, 64, 65] Apply oil to O-ring and install oil filter by tighte3/4 TURNS ning about 3/4 turns after attaching crankcase surface. OIL FILTER Tightening torque 9.
32) FUEL PUMP PLUSE PIPE Connect fuel pipe between fuel pump and crankcase nipple. 33) MUFFLER (1) Install Muffler bracket onto Cylinder head. M6 FLANGE BOLT M8 x 20 bolt & washer : 2 pcs. Tightening torque MUFFLER COVER 16.6 - 18.6 N・m (170 - 190 kgf・cm) (12.3 - 13.7 ft・lb.) (2) Install Muffler onto Muffler bracket and Cylinder head. M6 FLANGE M6 FLANGE BOLT BOLT M8 SUS flange nut : 4 pcs. Tightening torque A 16.6 - 18.6 N・m (170 - 190 kgf・cm) (12.3 - 13.7 ft・lb.
35) ENGINE OIL Refill engine oil and start the engine. Standard Option Engine oil will be lubricated oil passages and OIL GAUGE oil filter. Check the engine oil level and refill again to the upper level of oil level gauge. Oil Capacity 1.55 liter (0.41 U.S. gal.) NOTE ; * Check the oil level with the oil gauge inserted. * Use “SE” (API classification) or higher grade engine oil.
6. LUBRICATION SYSTEM OPERATION AND FUNCTION * Full lubrication system is adopted, in combination with large-size torchoid oil pump and cartridge type oil filter. * The large-size trochoid type oil pump is driven directly by crankshaft, and delivers pressurized engine oil to the journal and pin portions of crankshaft, camshaft etc. * The engine oil in the oil pan is fed through the oil pump filter into oil pump and the engine oil pressure is adjusted by the relief valve after discharging from oil pump.
[EH72] OIL PRESSURE SWITCH OIL COOLER CAMSHAFT OIL FILTER CRANKSHAFT RELIEF VALVE OIL PUMP OIL PUMP FILTER Oil 1 relief valve Oil pan Oil pump filter Oil pump 2 Oil puressure switch 1 Oil relief Valve opening pressure : 3.8 kg/cm2 (373KPa) Camshaft journal Oil cooler Element Crankshaft journal (Flywheel side) Crankpin & Connecting rod large end Splash Cylinder Crankpin & Connecting rod small end Cam & Tappet 2 Oil pressure switch Normally close type Contact pressure : 1.
ENGINE OIL Using engine oil of the correct grade and viscosity greatly lengthens engine life and improves performance. Too much or too little oil can also result in serious problems, including engine seizure.
7. FUEL SYSTEM 7-1 FUEL PUMP ● Fuel suction process The inside of crankcase becomes vacuum condition in accordance with the piston moving upwards to the top dead center. The vacuum pressure, which is introduced via hose into the pulse chamber of fuel pump, pulls the diaphragm, and then the inside of pump chamber becomes vacuum condition. As the results, the suction valve is opened and fuel goes into pump chamber frown suction chamber.
7-2.
FLOAT SYSTEM The float system is consists of a float and a needle valve, and maintains a constant fuel level during engine operation. The fuel flows from the fuel tank into the float chamber through needle valve. When the fuel rises to a specific level, the float rises, and when its buoyancy and fuel pressure are balanced, the needle valve closes to shut off the fuel, thereby keeping the fuel at the predetermined level.
COMPORNENT PARTS [EH63, 64, 65] 19 3 4 7 5 6 2 12 18 11 13 9 17 8 14 10 16 1 15 1. BODY, lower 11. MAIN JET 2. GASKET, body upper 12. SOLENOID VALVE ASS’Y 3. BODY, upper 13. JET, slow 4. LEVER ASSY, choke 14. NEEDLE, idle adjust 5. SPRING, choke 15. THROTTLE SHAFT ASS’Y 6. SHAFT ASSY, choke 16. THROTTLE VALVE 7. CHOKE VALVE 17. EXPANSION PLUG 8. VALVE, float 18. PLUG 9. FLOAT ASSY 19. O-RING 10. FLOAT PIN 20.
[EH72] 29 12 4 3 5 6 7 8 10 9 11 2 40 38 32 34 31 45 33 41 43 37 42 44 20 39 36 30 19 14 18 13 23 35 17 28 16 22 27 21 15 1 25 26 24 1. BODY, lower 16. SCREW, float pin set 31. SCREW and WASHER ASS'Y 2. GASKET, air horn 17. MAIN JET 32. SPRING 3. BODY, upper 18. GASKET 33. DIAPHRAGM ASS'Y 4. LEVER ASS'Y, choke 19. SOLENOID VALVE ASS'Y 34. COVER ASS'Y 5. RING, choke lever 20. JET, slow 35. BODY ASS'Y 6. SPRING, choke 21. SPRING, adjust screw 36. U RING 7.
8. ELECTRIC SYSTEM OPERATION AND FUNCTION The ignition system is pointless flywheel magneto with automatic advancing characteristic. Being different from the breaker point type ignition system, this system is completely free from such troubles as starting-up failure owing to dirty, burnt or corroded point surface.
(3) At higher engine revolution, the advancing control circuit operates at the ignition timing to run the base current I5 to turn the signal transistor B "ON" allowing the current I1 to bypass as current I6. At this moment the power transistor turns "OFF" and the current I2 is abruptly shut resulting in the high voltage generated in the secondary coil which produces sparks at the spark plug.
ELECTRIC STARTER When key switch is turned ON, lower electric current (M →) flows through coil of magnetic switch and the coil is excited. The plunger is pulled and higher current (S→) flows through electric starter. When electric starter is operated, pinion gear is pushed out by means of centrifugal force of weight located in the spline of armature shaft. The pinion gear is engaged with ring gear and flywheel and crankshaft are rotated.
SPARK PLUG CAP Spark plug cap • Check continuity with a circuit tester. • Spark plug cap has no resistor. • If there is no continuity, replace the spark plug cap. SPARK PLUG Sparking performance a: Over 6.0 mm (0.236 in.) Engine body Associated cable Electrode gap b: 0.7 to 0.8 mm (0.028 - 0.031 in.) a • Check the sparking performance with an ignition checker.
IGNITION COIL • Adjust the air gap between the ignition coil and flywheel using a thickness gauge and tighten bolts. Ignition coil air gap 0.3 - 0.5 mm (0.012 - 0.020 in.) Measure the resistance between the wires and core. Resistance High-tension cable (Secondary) 1 Core Stop wire (Primary) 2 8 - 16 kΩ 0-5Ω • Replace the ignition coil if the actual resistance value greatly THICKNESS GAUGE IGNITION COIL differs from the rated value. (Ω ± 20% when 20˚C) WIRE 1 2 CHARGE COIL 1 and 2).
REGULATOR • Measure the resistance between the wires. Rated resistance value: (Ω ± 20% when 20˚C) Apply black (-) needle of the circuit tester D Apply red (+) needle of the circuit tester A C B • Replace the regulator if the actual resistance value differs from the rated value. OIL PRESSURE SWITCH Structure of Oil Pressure Switch (Sensor) Switching Pressure : 1.0 kg/cm2 ± 0.3 Contact • Inspect the switch action. • The structure of the oil pressure switch is shown in a right figure.
9. TROUBLESHOOTING The following three conditions must be fulfilled for satisfactory engine start. (1) The cylinder filled with a proper fuel-air mixture. (2) Good compression in the cylinder. (3) Good spark, properly timed, to ignite the mixture. The engine cannot be started unless these three conditions are met. There are also other factors which make engine start difficult, e.g., a heavy load on the engine when it is about to start at low speed, and a high back pressure due to a long exhaust pipe.
9-2 STARTING DIFFICULTIES Phenomenon 1. Low engine speed at starting 2. Ignition system malfunction 3. Fuel system malfunction 4.
9-3 INSUFFICIENT OUTPUT Phenomenon 1. Low compression 2. Ignition system malfunction 3. Fuel system malfunction 4.
9-5 ROUGH IDLING Phenomenon Possible causes Remedy 1) Low idling speed Adjust 2) Carburetor slow system passage clogged Check and clean 2. Intake system 1) Air mixing from connecting portion of air intake system Check, tighten or replace gasket 3. Cylinder head 1) Cylinder head gasket faulty (blow-by) Replace 1) Improper valve clearance Adjust 2) Leakage from valve seat Adjust valve seat contact 3) Excessive clearance between valve stem and guide Replace 1. Carburetor 4. Valve system 5.
9-7 HIGH FUEL CONSUMPTION Phenomenon Possible causes 1) Over-size main jet 1. Fuel system 2. Engine core components Remedy Replace 2) Needle valve faulty and/or high fuel level in float Adjust or replace chamber 3) Chock valve does not open fully. Repair or replace 1) Low compression Check or repair 2) Over cooling Check and adjust load and/or engine speed 9-8 DETONATION Phenomenon 1. Ignition system malfunction 2.
9-9 ENGINE MISFIRE Phenomenon Possible causes Remedy 1) Improper spark plug gap or damaged electrode Cealn, adjust or replace 2) Ignition coil faulty Replace 3) Damaged ignition system wirings Replace 4) Poor connection of ignition system wirings Check and connect properly 1) Lean or rich air/fuel mixture Disassembly and repair 2) Carburetor clogged Disassembly and repair 3) Improper idling adjustment of carburetor Adjust 4) Improper gasoline or water infiltration Replace 1) Valve heat de
10. INSTALLATION Engine life, ease of maintenance and inspection, frequency of checks and repairs, and operating cost all depend on the way in which the engine is installed. Review the following instructions carefully for installing the engine. 10-1 INSTALLING When mounting the engine, carefully examine its position, the method of connecting it to a machine, the foundation, and the method of supporting the engine.
11. SERVICE DATA "STD" in the following table is the parts dimension from the brand new engine or the spare parts. Whereas, "Limit" shows the maximum allowance for the parts to be used on the engine. If the measurement exceeds beyond the "Limit", the part needs to be replaced and/or repaired. 11-1 STANDARD DIMENSIONS AND SERVICE LIMITS Unit : mm(in.) STD Limit EH63 EH64 EH65 EH72 0.05 or less (0.002 or less) 0.1 (0.004) IN. EX. EH63 EH64 EH65 EH72 0.7 - 1.0 (0.028 - 0.039) 2.0 (0.079) IN. EX.
Unit : mm(in.) ITEM CYLINDER * Inside dia. STD 1st reboring 2nd reboring * Roundiness after reboring. * Cylindricity after reboring. PISTON * Piston size (At skirt in thrust direction) 16 mm STD 1st o/s 2nd o/s – 71 – STD Limit EH63 EH64 EH65 80.000 - 80.019 (3.1496 - 3.1504) EH72 84.000 - 84.022 (3.3071 - 3.3080) To be rebored when the difference between max. and min. of diameter reached to 0.1 (0.004). EH63 EH64 EH65 80.250 - 80.269 (3.159 - 3.160) EH72 84.250 - 84.272 (3.3169 - 3.
Unit : mm(in.) ITEM PISTON * Ring groove side clearance STD Limit Top EH63 EH64 EH65 EH72 0.05 - 0.09 (0.0002 - 0.0035) 0.15 (0.006) 2nd EH63 EH64 EH65 EH72 0.03 - 0.07 (0.0012 - 0.0028) 0.15 (0.006) Oil ring EH63 EH64 EH65 EH72 0.057 - 0.175 (0.0022 - 0.0069) 0.15 (0.006) EH63 EH64 EH65 EH72 20.989 - 21.002 (0.8263 - 0.8269) 21.035 (0.8281) EH63 EH64 EH65 EH72 20.991 - 21.000 (0.8264 - 0.8268) 20.960 (0.8251) EH63 EH64 EH65 0.012 - 0.051 (0.0005 - 0.0020) 0.25 (0.0098) EH72 0 - 0.
Unit : mm(in.) ITEM CONNECTING ROD * Big end inside dia. STD Limit EH63 EH64 EH65 EH72 39.000 - 39.016 (1.5354 - 1.5361) 39.100 (1.5394) EH63 EH64 EH65 EH72 0.030 - 0.060 (0.0012 - 0.0024) 0.2 (0.079) EH63 EH64 EH65 EH72 21.010 - 21.023 (0.8272 - 0.8277) 21.080 (0.8299) EH63 EH64 EH65 EH72 0.010 - 0.032 (0.0004 - 0.0013) 0.12 (0.0047) EH63 EH64 EH65 EH72 0.1 - 0.4 (0.0039 - 0.0127) 1.0 (0.0394) EH63 EH64 EH65 EH72 38.956 - 38.970 (1.5337 - 1.5343) 38.90 (1.
Unit : mm(in.) ITEM STD Limit EH63 EH64 EH65 EH72 35.35 - 35.37 (1.392 - 1.393) 35.20 (1.385) EH63 EH64 EH65 EH72 19.967 - 19.980 (0.7861 - 0.7866) 19.950 (0.7854) IN. EH63 EH64 EH65 EH72 5.970 - 5.985 (0.2350 - 0.2356) 5.85 (0.2303) EX. EH63 EH64 EH65 EH72 5.970 - 5.985 (0.2350 - 0.2356) 5.85 (0.2303) IN. EH63 EH64 EH65 EH72 0.050 - 0.083 (0.00197 - 0.00327) 0.30 (0.0118) EX. EH63 EH64 EH65 EH72 0.050 - 0.083 (0.00197 - 0.00327) 0.30 (0.0118) CAMSHAFT * Cam height (IN. and EX.
Unit : mm(in.) ITEM TAPPET * Stem outside dia. STD Limit EH63 EH64 EH65 EH72 8.954 - 8.979 (0.3525 - 0.3535) 8.924 (0.3513) EH63 EH64 EH65 EH72 9.00 - 9.015 (0.3543 - 0.3549) 9.08 (0.3575) 0.021 - 0.061 (0.000827 - 0.002402) 0.15 (0.0059) 39.5 (1.5551) ——— * Guide inside dia. * Tappet guide clearance EH63 EH64 EH65 EH72 VALVE SPRING FREE LENGTH EH63 EH64 EH65 EH72 VALVE SEAT ANGLE (IN. EX.) * Valve cutter angle (a) * Valve contact width (b) EH63 EH64 EH65 EH72 a: 90˚ b: 0.7 - 1.0 (0.
11-2 TIGHTENING TORQUE Tightening Torque ITEMS N・m ・cm kgf・ ft・lb. 2.9 - 4.9 30 - 50 2.2 - 3.6 16.6 - 18.6 170 - 190 12.3 - 13.7 Charge coil 2.9 - 3.9 30 - 40 2.2 - 2.9 Connecting rod cap bolts 22 - 27 225 - 275 16.3 - 19.8 Cylinder head bolts 41 - 49 400 - 500 30.2 - 36.1 Flywheel nut 100 - 120 1020 - 1220 73.8 - 88.5 Ignition coil 6.8 - 8.8 70 - 90 5.0 - 6.5 Intake manifold bolts 16.6 - 18.6 170 - 190 12.3 - 13.7 Main bearing cover bolts 22.5 - 27.5 230 - 280 16.
12. MAINTENANCE AND STORAGE 12-1 DAILY MAINTENANCE Every day before operating engine, check the following items : MAINTENANCE ITEMS REMARKS 1) Clean away dust and chaff from engine. Governor linkage is especially sensetive to dust. 2) Check fuel leakage from fuel system. If any, retighten fasteners or replace necessary parts. 3) Inspect for loose hardware and retighten if necessary. Loose bolts and nuts may come off and result in breakage of other parts. 4) Check oil level and add to full level.
Periodic Maintenance Schedule table Maintenance Items Every 8 hours (Daily) Every 50 hours (Weekly) Clean engine and check bolts and nuts ● (Daily) Check and refill engine oil ● (Refill daily up to upper level) Change engine oil (*Note : 1) ● (Initial 20 hours) Replace engine oil filter (*Note 1) ● (Initial 20 hours) Every 200 hours (Monthly) Every 500 hours Every 1000 hours ● (Every 100 hours) ● Check battery electrolyte fluid level ● Clean spark plug ● Clean air cleaner ● Clean spark
12-3 SPARK ARRESTER (OPTIONAL) In a dry or wooded area, it is recommendable to use the product with a spark arrester. Some areas require the use of a spark arrester. Please check your local laws and regulations before operating your product. The spark arrester must be cleaned regularly to keep it functioning as designed.
12-4 ENGINE STORAGE (1) Change the engine oil and perform the daily maintenance items above mentioned. (2) Drain fuel from carburetor float chamber. (3) To prevent rust in the cylinder bore, apply oil through the spark plug hole and turn the crankshaft several turns by hand. Reinstall the plug. (4) Turn the crankshaft by hand and leave it where the resistance is the heaviest. (5) Clean outside of the engine with oiled cloth.
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