Cobra Y173V Page 41 Service Manual Download

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4. DISASSEMBLING AND SERVICING

PILOT SCREW

FLOAT LEVEL GAUGE

re.

After washing the carburetor, reset the pilot screw

back. Only repairing the carburetor can disassemble

it.If the pilot screw is broken, replace with new one.



Disassemble the broken pilot screw from the

carburetor.



Put the spring onto the replaced pilot screw and then

install it onto the carburetor.



Turn the pilot screw in until it is lightly seated the

bottom of hole, then turn the screw out the specified

numbers of the turns.

PILOT SCREW BROKEN

Inspection

Float level height

Place the carburetor in the position as shown and measure the distance between the float top

and carburetor body when the float just contacts

the seat without compressing the valve spring.

If the height is out of specification, replace the float valve and recheck the float height

Tool: Float level gauge.

Carburetor idle speed adjusting



Start the engine to preheat it to normal running temperatu



Adjust the pilot screw to specified idle speed.

Specified idle speed

：

2100±100rpm

Specified Float Height

13.7mm

Pilot Screw Standard Opening State

2-5/8 turns out

Summary of Contents for Y173V

Page 1: ...MODEL Y173V COBRA ENGINE SERVICE MANUAL Cobra Garden Machinery Henton and Chattell Ltd London Road Nottingham NG2 3HW UK www cobragarden co uk ...

Page 2: ...ue 7 3 MAINTENANCE 8 3 1 Maintenance Schedule 8 3 2 Engine Oil 8 3 3 Air Cleaner 10 3 4 Wash The Strainer 11 3 5 Spark Plug 11 3 6 Valve Clearance Adjustment 12 3 7 Governor 14 4 DISASSEMBLING AND SERVICING 15 4 1 Troubleshooting 15 4 1 1 Starting Difficult 15 4 1 2 Power Lack 17 4 1 3 Speed Unstable 18 4 1 4 Unable Igniting 18 4 1 5 Gasoline Engine Is Overheat 19 4 1 6 Abnormal Sound 19 4 2 Prepa...

Page 3: ...line Engine 23 4 4 1Recoil starter fan cover 23 4 4 2 Muffler 26 4 4 3 Fuel Tank 27 4 4 4 Air Cleaner 28 4 4 5 Governor 30 4 4 6 Carburetor 32 4 4 7 Flywheel 37 4 4 8 Cylinder Head Valve 41 4 4 9 Crankshaft Piston 49 4 5 Electric Diagrams 58 TRANSFORMATION POINTS 59 ...

Page 4: ......

Page 5: ...1 INTRODUCTION 1 1 INTRODUCTION 1 1 Parts Description START HANDLE OIL DIPSTICK SPARK PLUG MUFFLE AIR CLEANER FUEL TANK COVER ...

Page 6: ...ance Discharge Type PTO Shaft Rotation Vertical Shaft Output 1 3 Service Limit UNIT mm PARTS ITEM STANDARD SERVICE LIMIT Engine Maximum Speed No Load 2850 100rpm Idle Speed 2100 100rpm Cylinder Compression 1 40Mpa 1200rpm Cylinder Head Sleeve I D 70 70 165 Cylinder Head Warpage 0 10 Piston Skirt O D 69 980 69 865 Piston to Cylinder Clearance 0 020 0 050 0 10 Piston Pin Bore I D 18 002 18 010 18 04...

Page 7: ...Free Length 0 10 0 02 0 15 0 02 5 465 5 480 5 465 5 480 5 500 5 512 0 020 0 044 0 050 0 077 0 8 64 0 5 315 5 315 5 562 0 10 0 12 2 0 63 Camshaft Cam Height IN EX Journal O D 27 70 27 75 13 965 13 990 27 45 27 50 13 915 Crankcase Cover Camshaft Bracket I D 14 0 14 018 14 048 Carburetor Main Jet 68 DL or 70 KAMA Float Height 13 7 Pilot Screw Opening 2 5 8turns Spark Plug Gap 0 7 0 8 Spark Plug Cap R...

Page 8: ...2 DIMENSION AND TORQUE 4 2 DIMENSION AND TORQUE 2 1 Dimension ...

Page 9: ...5 2 DIMENSION AND TORQUE 2 2 The Position Of Installing Hole 2 3 PTO Installing Drawing Q161 Shaft ...

Page 10: ...entilation Chamber Cover Bolt M6 12 7 1 Side Shield Bolt M6 10 10 2 End Shield Bolt M6 10 10 2 Brake Bolt M6 35 11 1 Flywheel Nut Cast Iron M14 1 5 80 6 Ignition Wire Bolt M6 25 11 1 Fuel Tank Support Bolt M6 12 10 2 Fuel Tank Bolt M6 22 8 1 Recoil Starter Reel Nut M6 10 2 Throttle Control Sub Assemble Bolt M6 10 10 2 Air Cleaner Nut M6 1 0 10 2 Muffler Cover Nut M6 1 0 10 2 Engine Cover Nut M6 1 ...

Page 11: ... N m Bolt Nut 5mm Bolt Nut 4 5 6 6mm Bolt Nut 8 12 8mm Bolt Nut 18 25 10mm Bolt Nut 29 34 12mm Bolt Nut 49 59 4mm Screw 1 5 2 6 5mm Screw 3 5 5 6mm Screw 7 11 5mm Flange Bolt 3 6 6 9 6mm Screw 7 11 5mm Flange Bolt 3 6 6 9 6mm Flange Bolt 10 14 8mm Flange Bolt 20 26 10mm Flange Bolt 35 45 ...

Page 12: ...ck Adjust Cylinder Head Clean Fuel Tank Replace Every three years These items should be serviced by company authorized dealer unless you have the proper tools and mechanically proficient 3 2 Engine Oil Engine oil is a key factor in deciding the engine s performance Do not apply engine oil with additives or 2 stroke gasoline engine oil because they haven t enough lubrication and may shorten the eng...

Page 13: ...hat have been identified as carcinogenic If repeatedly left in contact with the skin for prolonged periods it may cause skin cancer Wash your hands thoroughly with soap and water as soon as possible after contact with used engine oil Please dispose of used oil in manner that will pollute the environment We suggest you take it in a sealed container to your local service station or recycling center ...

Page 14: ...ment before reusing Clean the element Foam Element Wash the element with detergent and dry it Immerse the element into the oil and squeeze the excessive oil The element should be wet but not drop the oil Paper Element Blow the compressed air from the inner side or lightly tap to move the dust If dirty badly replace in time Be careful to prevent dirt from entering the air duct that leads to the car...

Page 15: ...er on the fuel tank and connect the fuel tube e Check for leaking 3 5 Spark Plug a Remove the spark plug cap Clear away dirt around the spark plug base b Dismantle the spark plug with a spark plug wrench SPARK PLUG SOCKET WRENCH SPARK PLUG CAP c Visually check the spark plug Clean with a Steel brush If the insulator is damaged replace the spark plug instead d Measure the spark plug clearance with ...

Page 16: ...Spark plug torque value 18 2N m Spark Plug Type F7TC The spark plug must be tightened securely or it may become very hot to damage the engine Only use recommended spark plug or the equivalent Incorrect heat range of the spark plug may damage the engine 3 6 Valve Clearance Adjustment Measure the valve clearance in the cold of the engine state SPARK PLUG SPARK PLUG CAP a Remove the bolt M6 14 cylind...

Page 17: ...earance with feeler d Valve clearance adjustment method Loose the locking nut turn the adjusting nut to get the correct valve clearance Screw down the locking nut Torque value 10N m e Recheck the valve clearance f Set the new gasket with the projection of the cylinder head g Install the cylinder head cover and tighten the four bolts to the specified torque Torque value 6N m Standard Valve Clearanc...

Page 18: ...ering serious carbon deposit or burn on the valve surface even valve impacting the piston 3 7 Governor Governor adjustment a Remove the air cleaner b Loosen the nut M6 Be sure that the carburetor throttle valve is fully open c Rotate the governor support shaft fully to the right governor fully closed position and tighten the nut TORQUE VALUE 10 12N m d Check to see that the governor support and th...

Page 19: ...w to get through Float is damaged or sticking Repair float Fuel supply is normal Fuel is too filthy or deteriorated Replace There is water in fuel Replace Too much fuel in engine Drain extra fuel dry up spark plug electrodes Wrong fuel brand Select proper fuel brand corresponding with the requirements Normal fuel supply system Normal high tension line spark Spark plug is in bad conditions Too much...

Page 20: ...atness of the surface by which cylinder block contacting with cylinder head Tighten cylinder head bolts in stipulated order to stipulated torque Air leakage in the valves Check valve Clearance and tightness repair if necessary If still can t starting have the engine to our authorized dealer for repairing Spark plug testing Make sure there is no spilled fuel outside the engine and that the spark pl...

Page 21: ...t In carburetor needle valve hole and main oil flow hole clogged Clean and blow to get through Fuel cock is clogged up Clean replace damaged part Too much carbon deposit in combusting chamber Clear away Too much car bon fouling in muffler and exhaust pipe Clear away Air cleaner is clogged up Clean air cleaner filter element Intake pipe is leaking Repair or replace Poor Compression Piston or cylind...

Page 22: ...oper spark plug electrodes clearance Adjust Something wrong with induced coil and so on Check and replace damaged parts 4 1 4 Unable Igniting TROUBLE CAUSE REMEDY Unable Igniting Fuel Supply System Fuel is finished Refill fuel Carburetor is clogged Check fuel line and dredge Float is leaking Repair Needle valve is locked Dismantle float chamber and eliminate it Ignition System Spark plug is punctu...

Page 23: ...ne governor to produce speed high Readjust engine governor Crankshaft main bearing burnt out Replace main bearing 4 1 6 Abnormal Sound TROUBLE CAUSE REMEDY Beating sound Piston piston ring or cylinder is worn Replace the worn part Connection rod or piston pin and piston pin hole are worn Replace the worn part Crankshaft main neck is worn Replace bearing Piston ring is broken Replace piston ring Me...

Page 24: ...he operator should be familiar with the working principle and structure of the gasoline engine knowing how to make an emergent stop and the operation of all controlling parts Any one without training is forbidden to operate the engine Keep periodical maintenance Solve problems in time Do not run the engine in spite of malfunction 7 Running the engine in a well ventilated place keep it at least one...

Page 25: ...r 5 Diamond lap 450 6 Diamond lap 320 7 Flywheel driver 8 Bearing extractor 9 Valve guide reamer Carburetor float level inspection Valve guide removal installation Assembling ball bearing Installing handle and bearing Assembling ball bearing and time Rectifying valve seat surface Rectifying valve seat surface Dismounting flywheel Dismounting flywheel Fine reaming the guide inner hole ...

Page 26: ...24 4 DISASSEMBLING AND SERVICING 4 3 Dismounting Chart RECOIL STARTER ENGINE HOUSING MUFFLER FLYWHEEL SHROUD ENGINE CARBURETOR AIR CLEANER ...

Page 27: ...25 4 DISASSEMBLING AND SERVICING 4 4 Gasoline Engine 4 4 1Recoil starter fan cover Removal NUT M6 WASHER ENGINE COVER RECOIL STARTER FUEL COVER SHROUD STUD II STUD III STUD I ...

Page 28: ...g the side hook of the recoil starter spring in the groove of the recoil starter case set the recoil starter spring into the case with counterclockwise rotating starter spring CUTOUT REEL COVER GROOVE Set the recoil starter spring outside hook into the groove of the recoil starter pulley Set the starter drive cam on the recoil starter pulley and install the return spring on the recoil starter pull...

Page 29: ...G AND SERVICING Pass the recoil starter rope through the recoil starter case and recoil starter grip and make a figure eight knot at the rope end Pull the recoil starter rope lightly to check the drive cam for function ...

Page 30: ...moved the carbon deposits Lightly tap the muffler and blow it with compressed air in cleaning carbon deposits Replace it if the muffler exist in water and is seriously rusted to make noise increasing Don t clean with iron wire or the muffler material out to lower the muffler performance Don t reuse the muffler gasket The muffler can glow heat Please place the gasoline engine out touch of the passe...

Page 31: ...29 4 DISASSEMBLING AND SERVICING Don t place the flammable materials near the exhaust vent during operation ...

Page 32: ...uble the fuel system so that periodically washing it with lubrication oil and gasoline is required b Clean Installation Check the fuel tube for damage or leak Fill the fuel into the proper container Remove nut M6 recoil starter grip fuel tank cover and engine housing FUEL TANK COVER ENGINE COVER FUEL TANK 1L NUT M6 BOLT M6x22 FUEL STRAINER CLIP I FUEL TUBE CLIP II ...

Page 33: ... fuel tube Check the fuel tank for leak Install the engine housing fuel tank cover recoil starter grip and nut M6 ｃ Notice Check fuel tank cover vent foe blocked Check the fuel strainer for clogged or broken Check the fuel hose for aging or cracks If finding trouble replace it in time before installation 4 4 4 Air Cleaner Removal Installation BREATHE TUBE GASKET CASE NUT M6 PAPER FILTER ELEMENT FO...

Page 34: ...r tube check for deterioration or damage Replace if necessary Pay attention to connect the beveled end smaller to the air cleaner case and other end to the engine AIR CLEANER GASKET Don t wash the foam element with the gasoline acidity alkalic or organic solvent Don t pull and wrest the sponge or it will be damaged Don t start the engine without air cleaner or the engine will be quickly worn ...

Page 35: ...E PIN φ 9 14 PIN φ8 14 CRANKCASE COVER WASHER φ6 5 φ12 1 GOVERNOR DRIVEN GEAR Before Installing Check For Wear WASHER φ6 5 φ15 0 5 GOVERNOR SLIDER Insert the governor slider into the governor shaft and check for slider moving smoothly GOVERNOR HOLDER SHAFT Alight the shaft groove with the projection in case ...

Page 36: ...T BOLT M6 14 GOVERNOR RASSY GOVERNOR LEVER Insert the left end into vertical hole of the throttle valve CHOKE LEVER THROTTLE CONTROL THROTTLE VALVE RETURN SPRING Hook the left end hook into the hole of the Throttle valve shaft projection SPRING SPRING ...

Page 37: ...f no carburetor modification is made If a carburetor suitable to high altitude is equipped with engine suitable to a lower altitude the lean air fuel mixture will make engine output power lowering over heat and seriously damage The gasoline enters into the carburetor from the fuel tank and fuel filter The fuel filter can filter the foreign matters in the gasoline and oxide out of the fuel tank If ...

Page 38: ... surface Blow the washed parts clean with compression air and don t use cloth and paper against recontaminating Don t use the steel wire and other hard material to open the blocked hole to prevent carburetor performance from changing holes diameter Use the gasoline and compression air to clean it THROTTLE VALVE THROTTLE SHAFT CHOKE SHAFT INSULATOR GASKET Don t Reuse CHOKE CARBURETOR INSULATOR AIR ...

Page 39: ... PILOT JET O RING PILOT SCREW CARBURETOR Clean With Compressed Air Before Installation FLOAT PIN MAIN NOZZLE FLOAT VALVE MAIN JET FLOAT After installation check for operation by lightly pushing with a finger FLOAT CHAMBER GASKET DRAIN BOLT FLOAT CHAMBER Install So That The Drain Bolt Facing To Choke Valve SET BOLT Tighten The Bolt Securely And Check For Gasoline Leakage ...

Page 40: ...ear FLOAT VALVE FLOAT VALVE WORN NORMAL Clean with compressed air before installation Clean with compressed air before installation MAIN NOZZLE Clean with compressed air before installation Apply light coat of oil to the O ring to facilitate installation O RING O RING IDLE SPEED JET CARBURETOR BODY ...

Page 41: ...crew out the specified numbers of the turns PILOT SCREW BROKEN c Inspection Float level height Place the carburetor in the position as shown and measure the distance between the float top and carburetor body when the float just contacts the seat without compressing the valve spring If the height is out of specification replace the float valve and recheck the float height Tool Float level gauge d C...

Page 42: ...ttaching the puller Installation a Clean the tapered part of dirt oil grease and other foreign material before installation Be sure that there is no washer and other foreign material on the magnetic part b Set the key in the key groove c Install the flywheel over the crankshaft FLYWHEEL BRAKE The flywheel may push the key out of its slot check after installation Flywheel cast iron Attach by aligni...

Page 43: ...41 4 DISASSEMBLING AND SERVICING FLYWHEEL CAST IRON IMPELLER d Apply light coat of the oil to the threads and surface of the nut and install the nut loosely Torque 52N m START LUG HOLE HOLE LUG ...

Page 44: ...t IGNITION COIL FLY WHEEL CLEARANCE 0 35 0 45mm Ignition coil a Remove the fuel tank air cleaner carburetor and recoil starter assy b Measure the clearance between the ignition coil and flywheel with the feeler c Adjust the clearance of the ignition and flywheel d Adjusting method Loosen the bolt and move the ignition coil up and down for adjusting the clearance then screw down the bolt ...

Page 45: ... 1 1 3Ω Secondary side Measure the resistance of the secondary side of the coil with the spark plug cap removed touching one test lead to the high tension cord while touching the other tester lead to the coil s iron core Secondary side resistance value 10 6 11kΩ Spark plug cap Measure the resistance of the spark plug cap by attaching one ohmmeter lead to the wire end of the plug cap while touching...

Page 46: ...44 4 DISASSEMBLING AND SERVICING 4 4 8 Cylinder Head Valve 1 Removal Installation Remove the muffler Remove the air cleaner Remove the recoil starter and shroud Remove the carburetor and insulator ...

Page 47: ...ve seats Measure the cylinder compression after reassembly GASKET SPARK PLUG BOLT Ｍ８５０ Loosen and tighten the bolts in a crisscross pattern in 2 or 3 steps CYLINDER GASKET HEAD COVER BOLT Ｍ６１4 Apply oil to thread Loosen and tighten the bolts in a crisscross pattern especially tightening uniformly and gradually tighten finally to the specified torque Torque 8N m ...

Page 48: ...46 4 DISASSEMBLING AND SERVICING INTAKE VALVE Reassembly ...

Page 49: ...ps through the side hole Do not remove the valve spring retainers while the cylinder head is attached to the cylinder or the valves will drop into the cylinder 2 Inspect service repair Valve stem outside diameter Inspect the valve stem outside diameter with the micrometer if finding out of the standard or service limit or if visually inspecting the burn and damaged on the valve face please replace...

Page 50: ...ce and matching between the valve guide and cylinder cover for fastness b Using the valve guide reamer ream the valve guides to remove any carbon deposits before measuring If the valve guide inside diameter is lower than standard or out of the service limit replace the guide Standard Service Limit 5 500 5 512mm 5 562mm Replacement a Chill the replacement valve guides in the freezer section of a re...

Page 51: ...e cylinder cover as shown as fig d After installation inspect the valve guide for damage if damaged please replace VALVE GUIDE DRIVER Reamer For best results be sure the cylinder head is at room temperature before reaming valve guides a Coat the reamer and valve guide with cutting oil b Rotate the reamer clockwise through the valve guide for the full length of the reamer c Continue to rotate the r...

Page 52: ...50 4 DISASSEMBLING AND SERVICING check operation If the valve does not operate smoothly CORRECT INCORRECT ...

Page 53: ... if conforming to replace the guide and ream the guide refinish the valve when replacing the valve guide Valve seat a Thoroughly clean the combustion chambers and valve seats to remove carbon deposits Apply a light coat of red lead powder or erasable color painting to the valve faces b Insert the valves and then press the valve Several times forcefully Be sure the valve does not rotate on the seat...

Page 54: ...it 0 8mm 2 0mm e Make alight pass with the 45 cutter to remove any possible burrs at the edges of the seat f After resurfacing seat inspect for even valve seating width Apply colorant to the valve tapered face insert the valve and press it forcefully several times be sure the valve does not rotate on the seat The seating surface as shown by the transferred marking compound should have good contact...

Page 55: ...51 4 4 9 Crankshaft Piston PISTON PIN CLIP SEAL 25 38 7 CONNECTION CRANKSHAFT Reassembly Push in firmly until contact is made with the rearing surface Be careful not to damage the oil seal BEARING 6205 P5 CRANKCASE PISTON PIN PISTON ...

Page 56: ...e second ring top ring with chrome plated After assembly check for smooth movement of the piston ring Stagger the piston ring end gaps 120 apart Reassembly a Piston pin clip Install by setting front end of the clip in the piston groove holding the other end with long nosed pliers and rotating the clip in PISTON PIN CLIP Do not align the end gap of the clip with the cutout in the piston pin bore CU...

Page 57: ...rcumference of a oil seal Drive the oil seal in the cylinder barrel using following tool BEARING INNER RETAINER ASSEMBLER Driver Handle RETAINER ASSEMBLE OIL SEAL 25 40 7 Tools Driver handle Retainer assembler Apply the lubrication oil on after reassembling e Piston Apply oil to the piston and cylinder Install the piston with the mark on the piston head toward the push rod hole side Piston check C...

Page 58: ...measure the piston pin bore I D and O D with inside micrometer and outside micrometer Then calculate clearance by measuring results Standard Service Limit 0 002 0 014mm 0 08mm c Piston cylinder clearance Difference between cylinder maximum diameter and piston skirt should be considered as piston cylinder clearance This clearance must be checked before and after repairing Check with piston converti...

Page 59: ... feeler that clearance not too big or not to small too big can result in cylinder sealing performance poor while too small can result in piston expanded from heating and blocked in the cylinder PISTON RING thus causing piston broken and sticking If opening clearance is too small file the opening with fine flat file Often check in the cylinder when filing until the proper clearance is got Standard ...

Page 60: ...ig end oil clearance Wipe oil off the crank pin and connecting rod bearing mating surface Set the plastic gauge on the crank pin connecting rod and bolt to specified torque Torque 15 N m Place the plastic gauge axially Remove connecting rod and measure with plastic gauge PLASTIC GAUGE PLASTIC GAUGE WITH SCALE Standard Service limit 0 040 0 063mm 0 12mm If the clearance exceeds the service limit re...

Page 61: ...rvice limit replace the camshaft Standard Service limit 27 70mm IN 27 75mm EX 27 45mm IN 27 50mm EX Check outside diameter of the camshaft if less than the service limit replace the camshaft Standard Service limit 13 965 13 990mm 13 915mm Camshaft wearing cause and to engine performance influence Poor lubrication will result in camshaft abnormal wearing such as oil viscosity low impurity too much ...

Page 62: ...ment clearance with aligning two side mark on the gear ALIGNMENT MARK CAMSHAFT GEAR CAMSHAFT GEAR Bolt M8 50 Oil Seal 25 40 7 Crankcase Cover GASKET DON T REUSE IT GASKET 25 4 34 1 GOVERNOR WASHER 6 5 12 1 IN INNER SIDE FIX WITH PIN AFTER SSEMBLING GOVERNOR OIL SEAL 6 11 4 ...

Page 63: ...e replace with new one Please replace the gear with a new set to ensure the engaging face completely engage in b Reassembly Oil seal Apply grease to new oil seal around Install the oil seal into the crankcase cover with special tools RETAINER ASSEMBLER LAP OIL SEAL 25 40 7 After installing apply special grease to the oil seal c Check Camshaft handle inside diameter Standard Service limit 14 0 14 0...

Page 64: ...4 DISASSEMBLING AND SERVICING 4 5 Electric Diagrams ...

Page 65: ...61 appendix TRANSFORMATION POINTS Engine Cover SHROUD Recoil Starter ...

Page 66: ......

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