CONTENTS Section 1 2 . . 3. 4 . 4-1 4-2 4-3 4-4 4-5 4-6 4-7 4-8 4-9 4-10 4-11 4-12 4-13 4-1 4 4-15 4-1 6 4-1 7 5. 6 7 8 . . .
m Feed I.SPECIFICATIONS ~~ ~ ~~~ ~ ~ ~~ ~~ ~~~ EH12-2B ~~~ ~ ~ EHl2-2D EH12-2DS EH12-2BS Air-Cooled, 4-Cycle, Single-Cylinder, HorizontalP.T.O. Shaft, Gasoline Engine TYPe 60 x 43 rnm (2.36 x 1.57 in.) Bore X Stroke 121 cm3 (7.38 cu.in.) Piston Displacement Max. Torque Nem (kaf*m)/rDm 7.5 (0.76) /2600 15 (152)/1300 CounterclockwiseAs Viewd From P.T.O.
EH17-2 Model Air-Cooled, 4-Cycle, Single-Cylinder, HorizontalP.T.O. Shaft, Gasoline Engine TYPe ~~ ~~ ~~ ~~~~ ~ ~ 67 x 49 mrn (2.64X 1.93 in.) Bore X Stroke 172 cm3(10.50cu.in.) Compression Ratio Output Kw (HP)/rpm EH17-2DS EH17-2D EH17-2BS EH17-2B . 8.5 Continuous 2.6 (3.5)/ 1500 2.9 (4.0) / 1800 /3000 2.9 (4.0) /3600 2.6 (3.5) 4.4 (6.0) /2000 4.4 (6.0) /4000 Max. Max.Torque 10.7 (1 -09)/ 2600 21.4 (2.
~~~~~~ ~~ ~ EH25-2 Model EH25-2 6 EH25-2DS EH25-2D EH25-26s Air-Cooled, 4-Cycle, Single-Cylinder, HorizontalP.T.O. Shaft, Gasoline Engine TYPe Bore x Stroke 75 X 57 mm (2.95X 2.24 in.) Piston Displacement 251 cm3(15.31 cu.in;) 8.5 Compression Ratio Continuous output Kw (HP)hm 4.0 (5.5) I 1500 4.7 (6.4) / 1800 4.0 (5.5)/3000 4.7 (6.4) /3600 6.3 (8.5)/2000 6.3 (8.5)/4000 33.1 (3.38) / 1300 16.6 (1.69)/ 2600 Max. Max.
2-1 MAXIMUMOUTPUT The maximum output is the output of an engine with its throttle valve fully opened under the condition that all the moving parts are properlyworn 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. 2-2 CONTINUOUS RATED OUTPUT Thecontinuousratedoutputistheoutput of anengineatoptimumgovernedspeedwhichismost favorable from the view pointof engine’s life and fuel consumption.
2-4 PERFORMANCECURVES 0 EHlPD, B for B type HP kW 4 3 l2 2 3 + n + 3 1 0 1 0 2000 (1000) - 3000 (1 500) REVOLUTION r.p.m.
0 EH17D, 6 for B tvDe N . m kgfam - 3000 (1000) (1500) REVOLUTION -6- r.p.m.
EH25D, B N . m kgf-m r I I I I I " I I " -I I MAXIMUM TORQUE AL\ " I HP kW I I I 1.7 (3.4) 16.5 (33) 1 I I I I 1.6 (3.2) 15.5 (31) 1.5 (3.0) 14.5 (29) 1.4 (2.8) I I MAXIMUM HORSEPOWER'(NET) I 8 - 6 7 t: 5 c 4 I RECOMMENDED $4 I- & 2 I 1 i 0 2000 (1 000) - 3000 ' (1500) REVOLUTION -7- r.p.m.
3. FEATURES ,, 1. The overhead valve design offers a compactness, light weight and ideal combustion characteristics resulting in more power from Iess fuel and prolonged engine life. 2. An optimum lubrication and better tilted operation thanks to upright cylinder design. 3. A crossflow arrangement of intake and exhaust ports ensures stable performance under high ambient temperature. 4. Theautomaticdecompressiomsystemlightens the recoilpull force by 40% comparingtothe conventional SV engines. 5.
W 4-3 CRANKSHAFT The crankshaft is forged carbon steel, and the crank induction-hardened. pin is The output end of the shaft has a crankshaft gear, and EH25-2 whicharepressedinto balancergearfor position. B TYPE D TYPE Fig. 4-3 4 4 CONNECTING ROD AND PISTON The connecting rod is an aluminum alloy diecasting, and its largeandsmalIendsfunctionasbearings. The piston is an aluminum alloy casting, and carries two compression rings and oneoil ring. I f i g .
4-6 CAMSHAFT Thecamshaft for theD-typeengine ismade of special cast iron and camshaft gears are casted together in one piece. Both sides of the shaft fit into the plane bearings on the crankcase and main bearing cover. ThecamshaftfortheB-typeengineismade of forged carbon steel and also functions as PTO shaft. The cam gear is press fitted on the shaft and the ball bearings are employed on both sides for supporting the shaft. B TYPE D lYPE Fig.
4-9 GOVERNORSYSTEM The governor is a centrifugal flyweight type which ensuresconstantoperationattheselectedspeed against load variations. The governor gear with governor weights is installed on the main bearing cover. 4-10 COOLING SYSTEM Thelargefinsontheflywheelprovidesufficient coolingaircapacity for theinletandexhaustarea and cylinder. The cylinder baffle helps the cooling air flow efficiently. / GOVERNOR GEAR Fig.
4-13 CARBURETOR Theenginesareequippedwithahorizontaldraft carburetor that has a float controlled fuel system and a fixed main jet. Thecarburetors are calibratedcarefullyforeasy starting,goodacceleration,lowfuelconsumption and sufficient output. 4-14 AIR CLEANER The air cleaner is a single urethane foam element system. As an option, heavy duty type with element type is available. a double CLEANER COVER CLEANER CASE Double element type Single element type Fig. 4- 13-2 Fig.
4-16 DECOMPRESSION SYSTEM An automatic decompression mechanism which opens exhaust valve before the piston reaches compression top is assembled on the camshaft for easy starting. AUTOMATIC DECOMPRESSOR SYSTEM Fig.
4-1 7 SECTIONAL VIEW OF ENGINE FUEL TANK MAIN BEARING COVER FLYWHEEL - 14-
a ROCKER ARM - 15 - PUSH ROD
5. DISASSEMBLY AND REASSEMBLY 5-1 PREPARATIONS AND SUGGESTIONS 1) Whendisassemblingtheengine,memorizethelocations of individualparts so thatthey canbe reassembedcorrectly. If yor areuncertain of identifyingsomeparts,it is suggestedthattagsbe attached to them. 2) Have boxes ready to keep disassembed partsby group. 3) To prevent losing and misplacing, temporarily assemble each group of disassembed parts. 4) Carefully handle disassembed parts, and clean them with washing oil if necessary.
5-3 DISASSEMBLYPROCEDURES Step Part to remove 1 Oil drain Tool Procedures Remarks (1) Remove oil drain plug and drain oil. (2) To discharge oil quickly, remove oil gauge. Be careful not to lose the gasket. GASKET Fig.
Step Part to remove Procedures 2 Fuel tank Tool Remarks ~ 1 ~ ~~ ~~ Wipe off spilt fuel (2) Disconnect fuel hose between fuel strainer thoroughly. and carburetor. (3) Remove fuel tank from cylinder head. M6X14mm bolt * . - - 4pcs. (EH12-2,17-2) M8X20mm bolt 4pcs. (EH25-2) (1) Close fuel valve. 1Omm (12mm) socket wrench 0 - (EH12-2, 17-2) (EH25-2) FUEL HOSE -* Fig.
Step I Part to remove I Recoil starter I 5 I housing Oil sensor (Option) I Procedures Remarks I Tool (1) Remove recoil from blower housing. M6 X 8mm flange bolt 4pcs. 1Omm box wrench (1) Remove blower housing from crankcase. M6X i2mm flange bolt 4pcs. lOmm box wrench - - (1) Remove oil sensor probe. Be careful not to damage stick and sensor since these are sensitive and an erratic operation may result. BLOWER HOUSING Fig.
)art to remove I Procedures Muffler cover, (1) Remove muffler coverand exhaust pipe Becareful not to lose Muffler and cover. muffler gasket. M6X lOmm flange bolt Spcs. Exhaust pipe ( 2 ) Remove muffler from crankcase and cover cylinder head. M8 nut 2pcs. 1PC. M6 X 12mm flange bolt (EHl2-2,17-2) M8X 16mm flange bolt 1pc. (EH25-2) 0.. - - Tool Remarks 8mm, lOmm and 12mm socket wrench c M8 NUT : 2 pcs. MUFFLER COVER Fig. 5-5 - 20.
Procedures Control box and Electric (Option) Remarks (1) Disconnect wires. blue 1 (diode rectifier ) light blue 1 (diode rectifier ) black * * * 1 (magnetic switch) (2) Remove black wires from electric starter. (3) Remove controlbox. (4)Loosen two bolts and removeelectric starter. M8 bolt 2pcs. to - 21 - Tool Fastened together with fuel tank.
Remarks Procedures Head cover 1Omm socket wrench (1) Remove head cover from crankcase. M6 X 12mm flange bolt 1pc. L Air cleaner Fastened together with carburetor. (1) Remove cleaner coverand cleaner 1 Tool element. (2) Remove cleaner case. M6 flange nut 2pcs. c lOmm socket wrench .GASKET \ CLEANER CASE c c Fig.
Step Part to remove I - ~ Procedures Governor lever, Governor rod and Governor spring (1) Unhook governor spring from speed control lever. (2) Removegovernor lever from governor shaft. M6X30mm boltand washer lpc. (3) Detach governor lever, governor rod and rod spring from carburetor. 11 Carburetor (1) Remove carburetor from intake pipe. 12 Speed control lever (1)Remove stop plate,frictionplateand speed control lever. M6 X 14mm flange bolt 1PC.
l - I Procedures “ 14 Ignition coil Remarks (1) Disconnect ignition plug cap and remove ignition coil from crankcase. M6X25mm bolt and washer ...-2pcs. ” (1) Remove starterpulley from flywheel. Do not place bar or screw driver in flywheel fin to loosen flywheel nut. Place socket wrench on flywheel fastening nut and strike tip of thelever with hammer. Refer to the illustration below. (See Fig. 5-9.) 14mm nut lpc. (EHl2-2, 17-2) 18mmnut * * * * 1pC.
Step Part to remove ~ I 16 Flywheel (1) Remove flywheelfrom crankshaft. 17 Charge coil (Option) (1) Remove charge coil. M6 X 25mm Screw Spark plug (1) 18 TooI Remarks Procedures Useflywheelpuller (2) Remove key from crankshaft. illustrated below. (See Fig.5-11.) (See Fig. 5-12.) as Flywheel puller 2pcs. 21 mrn Remove spark plug from cylinder head. socket wrench Fig.
~~~ ~ step Part to remove Remarks Procedures Tool 19 Rocker cover (I) Remove rocker coverfrom cyIinder head. M6X 12mm flange bolt 4pcs. (2) Remove gasket. (rocker cover) 1Omm socket wrench 20 Cylinder head (1) Remove cylinder head from crankcase. 4pcs. M8x65mm flange bolt (EH12-2, 17-2) MIOX75mmflangebolt 4pcs. (EH25-2) (2) Detach cylinder head gasket from cylinder head. (3) Remove push rods. 12mm, 14mm socket wrench ..-. .... --.- M6 FLANGE BOLT : 4 pcs. Fig.
I I !Step -- Partto remove Procedures Remarks 21 Main bearing cover (1) Remove mainbearing cover fastening bolts. M6X30mm boltand washer 8pcs. (EH 12-2, 17-2) M8X30mm bolt and washer 8pcs. (EH25-2) (2) Remove main bearing cover using plastic hammer. (See Fig. 5-15) Be careful not to damage oil seal. - -.-. 1Omm, 12mm socket wrench L L Fig. 5-15 MAIN M6 BOLT and WASHER : 8 pcs. (EH12-2, 17-2) M8 BOLT and WASHER : 8 pcs. (EH25-2) Fig.
I I Step Part to remove 22 23 , Remarks Procedures Tool t 1 Cam shaft and (1) Remove cam shaft from crankcase. Balancer shaft (2) Remove balancer shaft. (Option for (Option for EH25-2) EH25-2) To prevent tappets from getting damaged, put the crankcase upside down. (See Fig. 5-17.) Tappet Puta tag on tappets to identify intakeand ,. exhaust. (1) Remove tappets from crankcase.
I Step Partto remove I Procedures Remarks Tool ~~~ 24 Connecting rod and Piston (1) Remove connecting rodbolt after scraping off carbon from cylinder and piston. M6 X 34mm flange bolt 2pcs. (EHI 2-2) M7X37mmflange bolt2pcs.(EH17-2) M8x46mm flange bolt 2pcs. (EH25-2) (2) Remove connecting rod cap. (3) Remove connecting rod from upper side of crankcase after rotating crankshaft so that piston comes up to top dead center. Piston and Piston rings (1) Remove clips and piston pin.
Step Part to remove 26 Crankshaft Remarks Procedures (1) Remove crankshaft tapping the at flywheel end. Be careful not to damage oil seal. Too! c Fig. 5-20 c CRANKSHAIT (D type) c fig.
Step 27 'art to remove Procedures (1) Loosen nut and remove bolt (pivot). Intake valve and Exhaust valve Tool Remarks (2) Remove rocker arms. (3) Press down spring retainer, take out collet valve, and then remove spring retainer and valve spring Inspect valves, valve seats and guide. Do not remove valve guides unless they are worn beyond the limit shown in page 58. (4) Remove intake and exhaust valve. .(See Fig. 5-23.) .M6 NUT / INTAKE VALVE EXHAUST VALVE Fig.
5-4 REASSEMBLY PROCEDURES 0 PRECAUTIONS FOR REASSEMBLY 1)Clean parts throughly before reassembly. Pay most attentionto cleanliness of piston, cylinde:r, crankshaft, connecting rod and bearings. Scrape off all carbon deposits from cylinder head, piston top and piston ring grooves. Check lip of oil seals. Replace oilseal 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. SPECIFICATIONS”.
"R" MARK (EH12-2,EH17-2) "N" MARK (EH25-2) Fig. 5-28 Fig. 5-29 5-4-3 PISTON AND CONNECTING, ROD (1) When installing the piston on the connecting rod, placethevalvercess of thepistoncrown as shown in the illustration to the "MAG" side of the connecting rod. Apply oil to the small end of the connecting rod, piston and piston pin before installation. Be sure to use clips on the both end of the piston pin to secure the pin in position. I "MAG"SIDE VALVE RECESS Fig.
( 2 ) Install the piston and connecting rod assembly into the cylinder. Use a piston ring compressor to hold the piston rings. Place “MAG” side of the connecting rod on the magneto side of the crankcase. PISTON RING COMPRESSOR CONNECTING ROD [NOTES] (1) Apply enough oil to piston rings, connecting rod bearings assembly. and cylinder bore before CRANKCASE (FLYWHEEL SIDE) (2) Set gaps of the piston rings 90 degrees apart Fig. 5-31 from each other before assembly. SECOND RING < = / . 0 Fig.
BALANCER SHAFT (Option for EH25) Install balancer shaft aligning the timing markon the balancershaftgearandthebalancergear on the crank shaft as shownin the illustration. 5-4-5 TIMING MARKS Incorrect timing of the gears will cause engine and may result in matfunction of the damage due to interferenceof the parts. 5-4-6 TAPPET AND CAMSHAFT Fig. 5-34 (1) Oil the tappets and install them in their original position. Push in fully to avoid damage during the installation of the camshaft.
5-4-7-1 CRANKSHAFT END PLAY (For D type and B type) (1) Measure the depth “ A l ” (From the mating surface to the inner race of the ball bearing.) (2) Measure the height “ B l ” (From the mating surface to the crank gear.) ( A l + 0.3) - Bl=SIDE CLEARANCE (mm) (SIDE CLEARANCE) - 0.2=THICKNESS OF CRANKSHAFT SHIM (mm) (A+ 0.012”) - Bl=SIDE CLEARANCE (in) SIDE CLEARANCE - 0.
MAIN Fig. 5-36 ( 2 ) Lubricate the oil seal and bearing surfaces. Add a light film of oil on the main bearing cover face to hold the gasket in place. Place spacers chosen at procedure(1) on crankshaft and camshaft. Use an oil seal guide when installing the main bearing cover to avoid damaging the seal. Tap the cover into place with a soft hammer. Main bearing cover EH12-2, 17-2 M6 X 30 mm bolt and washer 8 pcs. EH25-2 M8 X 30 mmboltandwasher 8 pcs. .... .
5-4-8 CYLINDERHEAD (1) Clean carbon and gum deposits from the valves, seats, ports and guides. Inspect the valves, valve seats and valve guides. (2) Replace valves that are badly burned, pitted or warped. (3) When installing the valves in the cylinder head, oil the valve stems and insert them into the valve guide. and collet Then place the cylinder head on a flat table, install the valve springs, spring retainers valves.
( 2 ) Loosen the nut under the rocker arm and turn the bolt rocker arm and the valve stem end. Tighten the nut under the rocker arm. I I (pivot) to adjust the clearance between the I Valve clearance I 0.08-0.12 mm 0.0031-0.0047in. Check operationof valves by turning crankshaft. Recheck valve clearance. (3) Install rocker cover and gasket. Rocker cover M6 X 12 mm bolt Fig. 5-38 .-..4 pcs. 5-4-1 1 SPARK PLUG Install spark plug to the cylinder head.
1 I Tightening torque I I 59-63N-m I 600-650kgocm 43-47ft*lb I 54-13 IGNITION COIL Install the ignition coil to the crankcase. Adjust the air gap between the ignition coil and the flywheel using a thickness gauge (filler gauge) and tighten the bolts. Tightening torque 8.8-10.8 Nom I 90-110 kgecrn 6.5-8.0ft4b A Fig. 5-40 5-4-14 INTAKE PIPE, lNSULATOR (1) Install the intake pipe to the cylinder head with gasket. EH12-2, 17-2 M6 flange nut ..---.....-.......-. 2 pcs. M6 X 25mm flange bolt .
’ (3) Connect the speed control lever and the governor lever with the governor spring. The governor spring should be hooked to the number 2 hole on the speed control lever for the regular specifications. Refer to the illustrations below. (See Fig. 5-42.) (4) Turn the speed control lever all the way toward the high speed position and make sure that the throttle valve in the carburetor is at the wide open position.
54-17 AIR CLEANER Install the air cleaner gasket and the cleaner case and tighten them with 2-M6 flange nuts. Then install the element and the cleaner cover. 5-4-1 8 HEAD COVER Install the head cover to the cylinder head. M6 X 12mm flange bolt 1PC. ..a- 5 4 - 1 9 MUFFLER, MUFFLER COVER and EXHAUST PIPE COVER Install the muffler to the cylinder head. M 8 flange nut .... 2 pcs. 230-270 k g c m 16.6-19.5 ft-lb Then tighten the muffler bracket portion. M6 X 12mm flange bolt 1PC.
B 5-5 BREAK-IN OPERATION An enginethathasbeencompletelyoverhauled by beingfittedwithanewpiston,rings,valvesand connecting rod should be throughly RUN- IN before being put back into service. Goodbearingsurfacesandrunningclearancesbetweenthevariouspartscanonlybeestablishedby a short period of time. operating the engine under reduced speed and loads for While the engine is being tested, checkfor oil leaks. Make final carburetor adjustment and regulate the engine operating speed.
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 currentIZ starts of flow. As the engine reaches the ignition timing, the ignition timing control circuit for the higher engine Is to the power transistor.
6-3 WIRING DIAGRAM STANDARD Stop switch Ignition Coil Black Connector > Black Spark Plug Flywheel ElNGlNE WITH ELECTRIC STARTER L 12VOLT BATTERY MtNIMUM 24 AMP.HR. I """"_"""" DIODE RECTIFIER Fig.
7. AUTOMATIC DECOMPRESSION SYSTEM EH12-2, 17-2, 25-2 engines are employing the automatic decompression systemas a standard feature. This enables easy and light startof the engine. The automatic decompression system releases the compression of the engine by lifting up the exhaust valve at the cranking. Following are the explanation using type “D”engine as a sample how the system works.
B 8. CARBURETOR 8-1 OPERATION AND CONSTRUCTION 8-1-1 FLOAT SYSTEM The float chamber is located below the carburetor body and,withafloatandaneedlevalve,maintainsa constant fuel level during the engine operation. The fuel flows from the fuel tank into the float chamber throughtheneedlevalve.Whenthefuelrises to a specificlevel,thefloatrises, and when its buoyancy and fuel pressure are balanced, the needle valve shuts off the fuel, thereby keeping the fuel at the predetermined level. FI Fig.
8-1-2 PILOTSYSTEM The pilot system feeds engine the fuel the to during idling and low-speed operation. The .fuel is fed through the main jet to the pilot jet, where it is metered, and mixed with the air metered by the pilot air jet. The fuel-air mixture is fed to the engine through the pilot outlet and the by-pass. At the idling speed, the fuelis mainly fed from the pilot outlet. 8-1-3 MAIN SYSTEM The main system feeds the fuel to the engine at medium-and high-speed operation.
B 8-2-4 MAIN SYSTEM (1) Remove the bolt(l2)and take out float chamber body(l3). (2) From the body (14) remove the main nozzle (15), andthen remove the main jet (16) and guide holder (17) from the main nozzle(15). (3) Reassembly a)Fasten the main jet securely to the body. Otherwise, the fuel may become too rich and cause engine malfunction. b)The bolt tightening torque is 70kg-cm. Be sure to set the gasket (19) and washer (18) for chamber (13).
9. STARTING SYSTEM 9-1 RECOIL STARTER Equipments to be prepared : Driver, Pinchers (Pliers) and Protective Glasses WARNING starting the disassembly; make sure to wear the protective glasses. 9-1-1 Disassembly Steps I (1) Setting off the spring power -1 : Hold the starterknob and extractthestarter rope. -2 : Extract the rope fully and hold the rope so that the knob of the rope in the reel makes a dicrect line with the rope guide.
WARNING Before startingthe assembly, make sure to wear the protective glasses. 9-1-2 Assembly Steps PASTING (1) Setting the reel into the case. -1:Paste grease on the case. (Fig. 9-3) -2 : Adjust the position of the inner end of the spring, which is set in the reel. (Fig. 9-4) -3 :Hold the reel so that the shafthook part and theinnerend of thespringarehookedtogether. Drop the reel gently from above into the -4 : Move the reel slightly counter-clockwise and make sure the spring is hooked. GREASE case.
(3) Tightening the set-screw. -1 i Push the latchet-guide lightly by hand so that the latchet guide won’t move and tighten the set-screw. (4)Storing the spring-power. -1 :Holdthecasetightandusingbothhands, wind up the reel counter-clockwise 6 times. -2: Set the ree to keep the position, whereby the rope hole of the reel and the rope guide make a direct line. (Fig. 9-7) Fig. 9-7 WARNING The spring power is at its most when the reel is being wound.
(6) Test the operation of the recoil starter to see if the rope recoils satisfactorily and the ratchets project and retract properly. Mount the recoil starterto the engine. (7) If the spring escapes from the reel when disassembling the recoil, hook the outer end onto the notch of the reel and rewind the spring into the housing. (8) Lubricate the rotating parts, sliding parts and spring with heat resistant grease reassembling the recoil and priorto long term storage.
IO. TROUBLESHOOTING The following three conditionts 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 aboutto start at low speed, and a high back pressure due toa long exhaust pipe.
B 0 10-1-3 IGNITIONSYSTEM Check the followings for lackof sparks. (1) Wires of the ignition coil, spark plug or contact breaker disconnected. (2) Ignitioncoildamagedandshorted. (3) Spark plug cable wet or soaked with oil. (4)Spark plug dirty or wet. (5) Spark plug electrode gap incorrect. (6) Spark plug electrodes are connectedor bridged. (7) Incorrect spark timing. 10-2 ENGINGEMISFIRES Incorrect spark plug electrodge gap. Adjust it to anywhere between 0.6 and 0.7mm. Ignition cable worn and leaking.
10-5 ENGINE KNOCKS (1) Poor quality gasoline. (2) Engine operating under heavy load at low speed. (3) Carbon or lead deposits in the cylinder head. (4)Spark timing incorrect. ( 5 ) Loose connecting rod bearing due to wear. (6) Loose piston pin due to wear. (7) Cuases of engine overheat. 10-6 ENGINE BACKFIRES THROUGH CARBURETOR (1) Water or dirt in gasoline, or low-grade gasoline. (2) Intake valve stuck. (3) Valves overheated, or hot carbon particles in the combustion chamber (4) Engine cold.
11. INSTALLATION I) Engine life, ease of maintenance and inspection, frequency of checks and repairs, and operating cost all dependontheway in whichtheengine is installed.Reviewthefollowinginstructionscarefullyfor installing the engine. 11-1 INSTALLING When mounting the engine, carefully examine its position, the method of connecting it to a machine, the foundation, and the mehtodof supporting the engine.
12. 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 partsto be used on the engine. If the measurement exceedsbeyond the “Limit”, the part needsto be replaced and/orrepaired. 12- 1 CLEARANCE DATA AND LIMITS r r Unit : mrn (in) EH12-2 / 17-2 / 25-2 Limit STD Flatness LESS THAN 0.05 (0.002) 1 Valve seat contact width - EX. 0.7 1.O (0.028 0.039) EH1 2-2 EH17-2 EH25-2 6.035 6.053 (0.
Unit: mm (in) I EH17-2 EH12-2 ITEM Lmit STD CYLINDER STD 60.000 (2.3622 - 60.019 - 2.3630) To be rebored when the lifference letween m a . snd min. of jiameter .cached to 0.1 :0.004). 1st reboring 60.250 (2.3720 - 60.269 - 2.3728) Ditto 2nd reboring 60.500 (2.3819 - 60.519 - 2.3826) Inside dia. STD Lmit -0be rebored 57.000 2.6378 - 67.01 9 - 2.6385) 67.250 2.6476 - 67.269 - 2.6484) 67.500 2.6575 - 67.51 9 - 2.6582) vhen the lifference letween m a . n d rnin.
Unit: mm (in) r ITEM EH25-2 Lmit STD 2Y LIN DER -0be rebored inside dia. STD /hen the ifference 75.000 75.019 letween m a . 2.9528 2.9535) md min. of liameter eached to 0.1 - 0.004). - 1 st reboring 75.250 75.269 2.9626 2.9633) 2nd reboring 75.500 75.519 2.9724 2.9732) Ditto - B Roundiness after reboring. LESS THAN 0.01 (0.004) Cyiindricity after reboring. LESS THAN 0.015 (0.0006) PISTON 0 Piston size (At skirt in thrust direction) STD 74.98- 75.00 (2.9520 2.9528: 1 st 01s 75.
Uni : rnm (in) T ITEM 0 Ring groovesideclearance EH17-2 STD Limit - 0.15 (0.006) :0.0014 0.030 0.075 (0.0012 0.0030) t - STD - 0.035 0.080 0.0031) Limit 0.15 - (0.006) 2nd 0.030 0.075 (0.0012 0.0030) - 0.15 (0.006) 0.025 0.070 (0.0010 0.0028) - 0.15 (0.006) Oil ring 0.020 0.075 (0.0008 0.0030) - 0.15 (0.006) 0.010 - 0.065 (0.0004 0.0026) - 0.15 (0.006) - 13.035 (0.5132) 15.991 16.002 (0.6296 0.6300) - 16.035 (0.6313) 12.992 13.000 (0.5115 0.51 18) - 12.960 (0.
Unit: mrn (in) EH25-2 1 STD Ring 0.050 1.0020 side groove clearance ~ 2nd Oil ring I - 0.090 - 0.0035) ~ ~ Limit 0.15 (0.006) ~~~~~ - 0.030 0.070 ).0012 0.0028) 0.15 (0.006) 0.010 - 0.065 0.0026) - (0.006) 17.991 - 18.002 1.7083 0.7087) 7 8.035 (0.7100) - 1.0004 0.1 5 Pistonpinhole ~rn Pistonpinoutside - dia. - 17.992 18.000 3.7084 - 0.7087) 17.960 (0.7071) Clearance between piston and cylinderatskirt area. 0.025 0.0001 I Piston ring - 0.064 - 0.0025) 0.25 (0.
Unit: mm (in) EH12-2 ITEM Limit STD ZONNECTING ROD D Big end inside dia. 26.000 26.01 3 (1 -0236 1.0241) - - 26.1 (1.0276) - 0.2 (0.008) Clearance between big end and crankpin 0.020 0.046 (0.0008 0.0018) I 0 Small end inside dia. - - 13.08 (0.5150) 0.010 0.029 (0.0004 0.0011) - - 0.12 (0.0047) 0.1 - 0.7 (0.004 0.028) 1 .o (0.040) 13.010 13.021 (0.51 22 0.51 26) 0 0 Clearance between small end and piston pin Big end side clearance - CRANKSHAR 0 Crankpin outsidedia. I - 25.
Unit: mm (in) m- ITEM - EH17-2 Limit STD CONNECTING ROD 0 Big end inside dia. - 30.000 30.016 (1.1811 -1.1817) 30.1 (1.1850) Clearance between big end and crankpin 0,020- 0.049 (0.0008 0.0019) - 0.2 (0.008) - 16.08 (06331) Small end inside dia. 16.010 16.021 (0.6303 0.6308) 0 Clearance between small end and piston pin - 0.010 0.029 (0.0004 0.001 1) 0.12 (0.0047) Big end side clearance - 0.1 0.7 (0.004 0.028) - 1.o (0.040) I CRANKSHAFT - 29.967 29.980 (1.1798 1.
Unit: mm (in) lTEM w F EH25-2 - ~ STD Limit - (1 .3425) 34.000 34.016 (1.3386 1.3392) - 34.10 0 Clearance between big end and crankpin 0.025- 0.057 (0.0010 0.0022) - 0 Small end inside dia. 0.2 (0.008) t - 18.08 (0.71 18) 0.010 0.029 (0.0004 0.0011) - 0.1 2 (0.0047) - (0.040) 18.010 18.021 (0.7091 0.7095) I 0 Clearance between small end and piston pin 0 Big end side clearance 0.1 0.7 (0.004 0.028) 1 .o I CRANKSHAFT - 33.959 33.975 (1.3370 1.3376) - 0 Journal dia.
Unit : mrn (in) EH12-2 / EH17-2 ITEM STD Limit CAMSHAFT 0 I Cam height - IN.=. CAMS 29.6 29.8 (1.165 1.173) Dl 16.973 16.984 (0.6682- 0.6687) D2 14.973 14.984 (0.5895 0.5899) IN. 5.440 5.455 (0.2142 0.2148) EX. 5.426 5.444 (0.21 - 36 0.21 43) IN. 0.045 0.078 (0.0018 0.0031) Ex. 0.056 0.092 (0.0022 0.0036) IN./EX. 0.08 0.12 (0.0031 0.0047) Journal outside dia. "D" type - Dl - VALVE Valvestemoutside 0 dia. Clearancebetweenvalve valveguide - - stem dia.
Unit: mm (in) EH25-2 ITEM I Limit ZAMSHAFT Camheight a - IN.=. CAMS Journaloutsidedia. 'D" type 30.6 30.8 (1.205 1.213) - 30.45 (1.199) - 24.95 (0.9823) Dl 24.967 24.980 (0.9830 0.9835) D2 14.973 14.984 (0.5895 0.5899) - 14.95 (0.5886) IN. 5.975 5.990 (0.2352 0.2358) - 5.85 (0.2303) Ex. 5.960 5.975 (0.2346 0.2352) - 5.85 (0.2303) IN. 0.045 0.078 (0.0018 0.0031) - 0.3 (0.012) - VALVE Valvestemoutside dia. 1 Clearancebetweenvalvestemdia. valveguide and " P . . ..... ..
Unit: rnrn (in) 1 ITEM STD TAPPET 0 Stem outside dia. - 7.960 7.975 (0.3134 0.3140) 0 Guide inside dia. - 8.000 8.01 5 (0.3150 0.31 56) - 0 Tappet guide clearance - 0.025 0.055 (0.001 0 0.
Unit: mrn (in) EH25-2 ITEM Limit STD TAPPET Stem outside dia. 8 - 7.960 7.975 (0.31 34 0.31 40) - Guide inside dia. - 8.000 8.015 (0.3150 0.3156) - 0 Tappet guide clearance - 0.025 0.055 (0.0010 0.0022) ~~ ~ ~~~ VALVE SPRING FREE LENGTH I 35.5 (1.4) 1 ~ Unit: rnm (in EH12-2117-2 ITEM STD 125-2 limit VALVE SEAT ANGLE(IN. EX.) 0 0 Valve cutter angle(a) Valve contact width(b) a : 90" b : 0.7 1.O - - (0.028 0.039) a - 69 - 2.0 (0.
12-2 TORQUE SPECIFICATIONS EH12-2 / 17-2 type TIGHTENING TORQUE DESCRIPTION N*m kg cm - 26.5 Cylinder head bolts 230 - 270 22.5 EH12-2 Connecting rod cap bolts EH17-2 .16.6-19.6 8.8-11.2 16.6 - 19.5 EH12-2EH17-2EH17-2 EH12-2 12.2-14.4 90-115 6.5-8.3 170-200 80 - 100 - 63.7 7.8 - 9.8 Flywheel nut ft- Ib - 47 5.7 - 7.2 43 58.8 600 650 New spark plug 11.8-14.7 120 - 150 8.7 - 10.9 Retightening 22.6 - 26.5 230 - 270 16.6 - 19.
12-3 OIL GRADE CHART T- Comparison between oil viscosity and temparature Single grade Specified Lubrican Quality Multigrade I - 20 -4 I I - 10 I 1 I I I 0 10 32 50 20 68 30 14 40 "C 104 "F Use oil classified as SE or higher. Multi-grade oil tends to increase its consumption at high ambient temperature.
13. MAINTENANCE AND STORAGE The following maintenance jobs apply when the engine is operated correctly under normal conditions. The indicated maintenance intervals are by no means guarantees for maintenance free operations during these intervals. For example, if the engine is operated in extremely dusty conditions, the air cleaner should be cleaned every day instead of every 50 hours. 13-1 DAILY MAINTENANCE MAINTENANCE REMARKS 1) Clean away dust and chaff from engine.
13-4 EVERY 100-200 HRS. (MONTHLY) MAINTENANCE I I MAINTENANCE 1) Clean REMARKS ~ I fuelfilter and fuel tank. Remove blower housing and cleanup between fins and housing. 2) Inspect cooling system and remove dirt and chaff. 13-5 EVERY 500-600 HRS. MAINTENANCE I I I I MAINTENANCE 1) Remove carbon from cylinder head. I REMARKS ~ ~~~ Carbon depositsin combustion chamber causes lackof power. I I 2) Disassemble and clean carburetor. 13-6 EVERY 1000 HRS.
SU6ARU ~bin America, 940 LivelyBlvd. l Wood Dale, IL 60191 e-mail: sale.s@robinamerica.com l l Inc. Phone:630-350~8200 l Fax:630-350-8212 www.robinamerica.
