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G120F/G160F/G200F Part IV Disassembly and maintenance

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-7. Crankcase body, piston, connecting rod and crankshaft

1. Diassembly/reassembly

Reassembly:
Install

with

the

triangle

mark

toward the push rod
hole.

Piston

Oil alert unit

Inspection:

With

the

engine

running,

when

connecting

the

yellow

lead and ground wire for a
moment

the

engine

should

stop.

not,

replace oil alert unit.

Camshaft assy

Reassembly:
Check  that  the  decompressor  weight
moves  smoothly  and  the  spring  is  not
weak  or  worn,  then  align  the  triangle
marks and install.

Decompressor
weight

Valve lifter

Reassembly:

Install

the

lifters

immediately

before

installing the camshaft;
take care not to let lifters
drop.

Crankshaft

Reassembly:

Push in until the bearing
touches the crankcase. Be
careful not to damage the oil
seal.

Connecting rod cap

Reassembly:

Install with the oil dipper
toward the camshaft and the
ribs

the

cap

and

connecting rod aligned.

Crankcase cover

Oil dipstick

Oil seal

41.25

6205 ball bearing

Crankcase cover seal gasket

Oil seal 25

41.25

Reassembly:

Take care not to damage
the lip of the oil seal when
inserting the crankshaft

Summary of Contents for G120F

Page 1: ...G120F G160F G200F Contents 1 G120F G160F G200F Shop manual Loncin Motor Co LTD ...

Page 2: ...tenance 12 2 1 Safety precautions 12 2 2 Maintenance standards 14 2 3 Torque values 16 2 4 Troubleshooting 17 Part III Maintenance 22 3 1 Maintenance schedule 22 3 2 Engine oil 23 3 3 Oil alert system inspection 24 3 4 Air cleaner 25 3 5 Muffler 26 3 6 Fuel filtering system 27 3 7 Spark plug 28 3 8 Carburetor idle speed 29 3 9 Valve clearance 29 3 10 Governor 30 Part IV Disassembly and maintenance...

Page 3: ...4 4 Fuel tank and speed governing system 39 4 5 Flywheel ignition coil starter motor and lighting coil 40 4 6 Cylinder head and valves 44 4 7 Crankcase body piston connecting rod and crankshaft 50 4 8 Governing gear and fuel level switch 58 4 9 Reduction system 60 4 10 Battery 63 ...

Page 4: ...ble When the engine has warmed up the choke lever shall be fully opened Engine switch before starting the engine the switch shall be put in the ON position if you put the switch in the OFF position the engine will be shut down Throttle lever serves to adjust the engine speed so as to obtain the power and speed you want Fuel tank cap when loosened fuel can be added into the fuel tank when tightened...

Page 5: ... 6 Fuel consumption rate g KW h 395 Engine oil consumption rate g KW h 6 8 Idle speed r min 1400 150 Noise 7m 70dBA Starting mode Recoil Recoil Electric Noise 7m 70dBA Lubrication mode Splash Cooling system Forced air cooling Stopping mode Grounding Fuel Unleaded gasoline for vehicles PTO shaft rotation Counterclockwise seen from the end of output shaft Ignition system T C I Ignition timing 25 BTD...

Page 6: ...pacity L 0 6 0 6 0 6 0 6 Fuel consumption rate g KW h 395 395 395 395 Engine oil consumption rate g KW h 6 8 Idle speed r min 1400 150 Noise 7m 70dBA Starting mode Recoil Electric Lubrication mode Forced splash Cooling system Forced air cooling Stopping mode Grounding Fuel Unleaded gasoline for vehicles PTO shaft rotation Counterclockwise seen from the end of output shaft Ignition system T C I Ign...

Page 7: ...G120F G160F G200F Part I specifications 6 1 3 Dimensions boundary and mounting dimensions G120F ...

Page 8: ...G120F G160F G200F Part I specifications 7 G160F G200F ...

Page 9: ...t I specifications 8 1 4 PTO assembly drawing G120F G160F G200F A Type C Type R Type D Type To crankcase cover mount surface To crankcase cover mount surface To crankcase cover mount surface To crankcase cover mount surface ...

Page 10: ...120F G160F G200F Part I specifications 9 E Type S Type U Type A22 Type To crankcase cover mount surface To crankcase cover mount surface To crankcase cover mount surface To crankcase cover mount surface ...

Page 11: ...BI Black Br Brown Y Yellow R Red W White G Green IG E BAT ST OFF ON START 1 With oil alert and electric starter Control box Rectifier Ignitor Charging coil Spark plug Oil level switch Oil alert unit Circuit breaker Engine switch Starter motor Battery Starter solenoid Fuse W Bl W Bl Bl R Bl Y W W W Br W W ...

Page 12: ...G120F G160F G200F Part I specifications 11 2 With oil alert and without electric starter Ignitor Spark plug Oil alert unit Oil level switch Engine switch ...

Page 13: ...ern to the specified torque diagonally 5 Clean parts in cleaning solvent upon disassembly Lubricate any sliding surfaces before reassembly 6 After reassembly check all parts for proper installation and operation 7 Don t maintain unless the engine is stopped and has cooled otherwise bun can happen in the hot state of engine 8 If you want to perform a test run of the engine in the work area after ma...

Page 14: ...k are joined with adhesive if you use local welding the hot temperature may cause adhesive to fall off If it is necessary to use welding it must be performed for the whole circumference of joint seam No treatment beyond specification may be performed on muffler flywheel and other parts Serial number location The engine s serial number type and variant number are all stamped on the crankcase You wi...

Page 15: ... 0mm 1 0mm 1 37mm 2 37mm Connecting rod Small end ID Big end ID Big end oil clearance Small end side clearance 13 005mm 26 02mm 0 040 0 063mm 0 1 0 7mm 13 07mm 26 066mm 0 12mm 1 1mm Crankshaft Crankshaft OD 25 98mm 25 92mm Valves Valve clearance IN EX Stem OD IN EX Guide ID EX IN Valve lifter clearance IN EX Seat width Spring free length 0 15 0 02mm 0 20 0 02mm 5 48mm 5 44mm 5 50mm 0 02 0 044mm 0 ...

Page 16: ...Small end ID Big end ID Big end oil clearance Small end side clearance 18 002mm 30 02mm 0 040 0 063mm 0 1 0 7mm 18 07mm 30 066mm 0 12mm 1 1mm Crankshaft Crankpin OD 29 98mm 29 92mm Valves Valve clearance IN EX Stem OD IN EX Guide ID EX IN Valve lifter clearance IN EX Seat width Spring free length 0 15 0 02mm 0 20 0 02mm 5 48mm 5 44mm 5 50mm 0 02 0 044mm 0 06 0 087mm 0 8mm 30 5mm 5 318mm 5 275mm 5 ...

Page 17: ...Valve lock nut M6 0 75 12 16 Valve adjusting bolt M8 1 25 26 32 Crankcase cover bolt M6 1 G120F M8 1 25 G160F G200F 8 12 27 30 Crankcase oil drain bolt M10 1 25 25 30 Spark plug 27 30 Oil level switch nut M10 1 25 6 8 Muffler mounting nut M8 1 25 27 30 Air cleaner wing nut M6 1 7 10 Air cleaner mounting nut M6 1 8 12 M5 bolt nut 4 7 M6 bolt nut 8 12 M8 bolt nut 20 28 M10 bolt nut 35 40 Standard to...

Page 18: ...seat improperly Cylinder piston or piston ring worn Spark plug faulty Governor out of adjustment Carburetor faulty Governor out of adjustment Valve clearance incorrect Poor performance at low speed Engine lacks power Hard starting Clean P27 3 6 Readjust P29 3 8 Disassemble and inspect P37 4 3 Readjust P40 4 5 Inspect P40 4 5 Readjust P30 3 10 Inspect P28 3 7 Inspect P28 3 7 Readjust P30 3 10 Readj...

Page 19: ... procedure Add fuel and restart the engine Check for blockage of the fuel tube or fuel filter Check for blockage in the carburetor port and nozzle Dry electrodes and restart taking care that the choke is not closed too much If flooding is severe check if fuel leaks form carburetor Perform the spark test again using a new spark plug Check for volt leakage caused by damaged high tension wire insulat...

Page 20: ...e Disconnect the engine switch s black lead and the ignition coil s black lead ground the ignition coil primary side the disconnected black lead and check igniting state of spark plug Engine switch oil alert unit faulty Replace engine switch Ignition coil s primary side broken Engine doesn t stop when oil is insufficient oil alert unit s performance is poor Check continuity between oil level switc...

Page 21: ...the cylinder Install the spark plug cap Set gasoline engine switch to ON position Ground spark plug s negative electrode threaded section via cylinder head pull starter grip and observe spark producing state Check spark plug igniting state Spark plug gap 0 7 0 8mm Refer to the part about spark check Starting poor Check with a new spark plug Replace spark plug Disconnect engine switch s black lead ...

Page 22: ...ination switch is open or faulty Fuse melted Starter solenoid faulty Starter motor faulty Battery faulty Battery faulty Charging coil faulty Starter motor doesn t rotate Battery is unable to be charged Inspect P33 4 2 Replace Inspect P40 4 5 Inspect P40 4 5 Inspect P63 4 10 Inspect P63 4 10 Inspect P40 4 5 ...

Page 23: ...ner Clean Every 2 years 2 Fuel tube Replace Every 2 years 2 Maintenance items Replace foam and paper elements only 1 Service more frequently when used in the dusty areas 2 These items are to be maintained by Loncin s designated dealers unless the user has special tools and skills for maintenance When the engine is used frequently only maintenance as per the above schedule can ensure long and norma...

Page 24: ...er viscosities shown in the chart may be used when the average temperature in your area is within the recommended range Oil level check 1 Remove the oil cap dipstick and wipe it clean 2 Insert the oil dipstick into oil filler neck but do not screw it in and check oil level 3 Oil level is too low if there is no oil on the dipstick Add recommended oil to bring the oil level to the upper limit of the...

Page 25: ...ase can fall below a safe limit the oil alert system will automatically shut down the engine the engine switch will remain in the ON position The oil alert system shuts down the engine and the engine will not start If this occurs first check engine oil level then check for other faults 1 With the engine running disconnect the engine switch s yellow lead and ground it to the engine the engine shoul...

Page 26: ...r element and foam element 3 Remove the foam filter from the paper filter 4 Check both filter elements and replace them if they are damaged Normally paper element may be replaced at the scheduled maintenance interval Clean paper element Tapping paper element several times and then blow compressed air at no more than 207KPa through the filter from the inside Never try to brush off dirt Brushing wil...

Page 27: ...etergent and allow them to dry thoroughly 4 Empty the used oil from the air cleaner case and wash out any accumulated dirt with nonflammable solvent and dry the case 5 Fill the air cleaner case to the OIL LEVEL mark with the same oil that is recommended for the engine Oil capacity 60 cc 6 Reinstall the air cleaner parts and tighten the wing nut securely 3 5 Muffler Carbon will deposit on muffler a...

Page 28: ... 3 6 Fuel filtering system No smoking or flame is allowed during cleaning of the fuel check to ensure no fuel leaks after tightening Clean sediment cup and O ring in nonflammable solvent and allow them to dry thoroughly Open the fuel cock if there is any leak replace the O ring Clean the fuel filter element and strainer remove the deposits on the strainer and check if its meshes are damaged if so ...

Page 29: ...gap by carefully tapping tapping for a too big gap the electrode or gently forcing up for a too small gap the electrode using a slotted screwdriver 5 Make sure the spark plug s sealing washer is in a good condition 6 Install the spark plug and use a spark plug wrench to tighten it into the cylinder head 7 When installing the spark plug in order to prevent cross threading first use hand to screw it...

Page 30: ...fully closed The position of the flywheel s magnet corresponding to the front face of the ignitor is the timing point 3 Insert a feeler gauge between the rocker arm and valve to measure valve clearance 4 If adjustment is necessary proceed as follows a Hold the rocker arm pivot with a wrench and loosen the pivot lock nut b Loosen the rocker arm pivot and turn the rocker arm pivot to obtain the spec...

Page 31: ...e nut 4 Check whether governor support and throttle valve move freely 5 Check and adjust the gasoline engine s maximum no load speed a Start the gasoline engine and allow it to warm up for about 10 minutes b If the gasoline engine s maximum no load speed is not as specified adjust the cross recessed pan head screw M5 35 Gasoline engine s maximum no load speed 3 850 150 rpm Speed too high Adjust th...

Page 32: ...body piston connecting rod and crankshaft 4 8 Governing gear and fuel level switch 4 9 Reduction system Oil bath type Dual element type Air cleaner base Disassembly Reassembly Remove and install with the choke lever in ON position and fuel valve in OFF position Clean the inside with compressed air before installation Wing nut M6 Cap Element Air cleaner cover Air cleaner case Oil capacity 60cc Reas...

Page 33: ...2 Disassembly reassembly of muffler Muffler protector M5 8mm cross recessed pan head screw 4 8mm hexagon nut 2 2 4kg m Exhaust pipe gasket Muffler Reassembly Install after removing the carbon deposits from the muffler by gently knocking with a plastic hammer ...

Page 34: ...allation The installation direction can be changed by changing the relative positions of the holes in recoil starter case Hexagon flange bolt 6 8 3 Starter reel Reassembly Install reel on the starter case after installing the return spring Starter rope Reassembly Check the rope for fraying or wearing before installation Guide plate Reassembly Allow end of ratchet to be out of the notch of the reel...

Page 35: ...e tab on the starter case Install the starter reel and turn the starter reel leftward to hook the inner hook to the tab on the starter case 4 Make a figure eight knot at the rope end feed the other end through starter reel s rope hole and pull the rope out of the hole by a certain length Then turn starter reel counterclockwise five turns Return spring Spring cover Starter case Spring cover Put spr...

Page 36: ...6 Assemble the ratchets and then tighten them with special bolts Pay special attention to the installation direction of the ratchets 7 Check the operation of the ratchet by pulling the starter rope out several times Starter case hole Grip M5 10 special bolt Apply thread locking agent Ratchet Reel cover Friction spring Grease the inner side Ratchet Ratchet Ratchet spring ...

Page 37: ...table with the switch in different positions OFF ON START Position S N Color State W Bl W Br W Bl ground W Bl W Br W Bl ground W Bl W Br W Bl ground 1 ON 2 OFF Black white wire Connected to relay s excitation winding Black wire Unidirectional conductional device White wire Connected to relay Black wire Connected to ignition coil s stop switch wire Brown wire Connected to charging coil Overload pro...

Page 38: ... order contrary to the order of disassembly Reassembly Blow out the passage using compressed air and install noting the inatllation directions on inner and outer sides After installing securely install high tension cord and fuel tube Fuel tube High tension cord Reassembly Plug the fuel tube with the choke lever s lug after removing the fuel tube to prevent fuel leakage Fuel tube Choke lever Govern...

Page 39: ... Reassembly Blow out the passage using compressed air and install Main jet Reassembly Blow out the passage using compressed air and install Float pin Float Reassembly Check for smooth movement by finger after installing Choke lever Carburetor body Reassembly Blow out the passage using compressed air and install Float valve Reassembly Check for worn end of float valve and spring operation before in...

Page 40: ...t be performed for the whole circumference of seam Never perform local welding on fuel tank Fuel tube Replace it every 2 years Inspect for cracks or deterioration before installation Fuel filter 2 0N m Reassembly Check to be sure the meshes are clean and undamaged before installing Governor arm Reassembly Adjust the governor before installation P31 3 10 M8 Flange nut 2 2 4N m M6 Lock nut Reassembl...

Page 41: ...the boss of the cooling fan High tension cord Reassembly Check for cracked or damaged insulation to prevent electric shock Woodruff key Reassembly After installing the flywheel check to be sure the woodruff key is still in its slot Ignition coil Check and readjust P42 Cooling fan Reassembly Install by aligning the three lugs on the rear side of the fan with the small hole in the flywheel When disa...

Page 42: ...n coil are equal 3 Inspection of ignition coil lighting coil and charging coil 1 Ignition coil Primary side Measure the resistance of primary coil by attaching one ohm meter lead to the ignition coil s primary lead while touching the other test lead to the iron core Primary side resistance value 0 8 1 0Ω Secondary side Measure the resistance of the secondary side of the coil by removing the spark ...

Page 43: ...g coil Measure resistance between the two leads Resistance value 3 15 3 85Ω 4 Starter relay Disconnect negative of battery and disconnect electromagnetic relay s S terminal plug and connect a 12 V battery between starter terminal and starter body then check continuity using a tester as shown There should be continuity when the battery is connected and no continuity when the battery is not connecte...

Page 44: ...mit 11 0 mm 6 0 mm 2 Continuity between commutator segments Check for continuity between segments if an open circuit on continuity exists between any two segments replace the armature 3 Continuity check commutator to shaft Check for continuity between the commutator and armature shaft Replace the armature if continuity exists between any of the comrnutator segments and the armature shaft ...

Page 45: ...park plug before installation Cylinder head Reassembly Before installing remove any carbon deposits from the combustion chamber and inspect valve seats M8 60 4 hexagon flange bolt Removal installation Apply oil on thread Loosen and tighten the bolts in a crisscross pattern when tightening all bots should be tightened in such way and finally be tightened to the specified torque values Torque 32 35N...

Page 46: ...t installed the valve may drop into the cylinder when starting the engine Valve spring retainer Valve spring Valve spring seat Lifter push rod Reassembly First make sure no end of them is worn and both lifters and rods are straight then insert them through the guide plate holes then through crankcase s lifter holes and install them to the specified places Exhaust valve Reassembly Before installati...

Page 47: ...Valve spring free length Measure the free length of valve spring Replace the springs if they are short than standard length or beyond service limit 3 Cylinder head Remove carbon deposits from the combustion chamber clean off any gasket material from the cylinder head surface Check the spark plug hole valve areas and valve guides for cracks Check the cylinder head for warpage with a straight edge a...

Page 48: ... the combustion chamber side using a valve guide driver When driving the valve guide out be careful not to damage the head c Install the new valve guide from the valve spring side of the cylinder head Exhaust valve drive the valve guide until the clip is fully seated as shown Intake valve drive the intake valve guide until it reaches the specified height measured from top of valve guide to cylinde...

Page 49: ...ce e Stem to guide clearance Subtract each valve stem OD from the corresponding guide ID to obtain the stem to guide clearance f If the stem to guide clearance exceeds the service limit determine if the new guide with standard dimensions would bring the clearance within tolerance If so replace the guide as necessary and ream to fit Recondition the valve seat whenever the valve guide is replaced 5 ...

Page 50: ...Service limit 0 8mm 2 0mm e Make a light pass with the 45 cutter to remove any possible burrs at the edges of the seat f After resurfacing the seats inspect for even valve seating Apply a light coat of Prussian Blue or erasable marker ink on the valve faces Insert the valves and then lift them and snap them close against their seats several times Be sure the valve does not rotate on the seat The s...

Page 51: ... the spring is not weak or worn then align the triangle marks and install Decompressor weight Valve lifter Reassembly Install the lifters immediately before installing the camshaft take care not to let lifters drop Crankshaft Reassembly Push in until the bearing touches the crankcase Be careful not to damage the oil seal Connecting rod cap Reassembly Install with the oil dipper toward the camshaft...

Page 52: ...ve holding the other end with long nosed pliers and rotating the clip in Do not align the end gap of the clip with the cutout in the piston pin bore Piston pin clip Reassembly 1 Install all rings with the markings facing upward 2 Be sure that the top and second rings are not interchanged 3 Check that the rings rotate smoothly after installation 4 Space the piston ring end gaps 120 degrees apart an...

Page 53: ...ve carbon deposits completely before inspection Saturate the carbon deposits with kerosene and then use a blunt scraper or a wire brush to remove carbon deposits 1 Piston skirt O D measure and record the piston O D using an outside micrometer at a point 10mm 0 4in from the bottom of the skirt 90 to the piston pin bore Replace it if its size exceeds service limit Standard Service limit G120 59 985m...

Page 54: ...ndard Service limit 0 015 0 045mm 0 15mm 4 Piston ring width Standard Service limit Top second 1 5mm 1 37 mm 5 Piston ring end gap Standard Service limit Top second 0 02 0 04mm 1 0mm Before measuring piston ring end gap correctly install the rings onto the piston Then put the piston into the cylinder As oil ring is used together with top ring and second rings so if any these rings should be they s...

Page 55: ...f service limit the piston or piston pin may be replaced according to the wearing condition Standard Service limit G120 0 002 0 014mm 0 08 mm G160 200 0 002 0 014mm 0 06 mm 9 Cylinder I D Standard Service limit G120 60 0mm 60 165 mm G160 200 68 0mm 68 165 mm Inspection of connecting rod Replace the connecting rod if it s bent warped or its big end cap or the outer race of its small end s shaft sle...

Page 56: ...m 3 Crankpin O D Standard Service limit G120 25 98mm 25 92 mm G160 200 29 98mm 29 92 mm 4 Connecting rod big end side clearance 5 Connecting rod big end oil clearance radial a Clean all oil from the crankpin b Place a piece of plastic gauge on the crankpin install the connecting rod and cap and tighten the bolts to the specified torque Torque 12 14N m Note Do not rotate the crankshaft while tighte...

Page 57: ...standard value Inspection of camshaft As the main driving part of the gasoline engine s valve actuating mechanism the camshaft controls the intake and exhaust valves opening and closing following a certain principle Visually check the cam surface and cam height for any damage and check whether bearings and camshaft are loose or worn if so replace them all 1 Cam height Standard Service limit IN 27 ...

Page 58: ...ce 57 3 Camshaft holder ID Inspection of bearings Clean the bearing in solvent and dry it Spin the bearing by hand and check for play Replace the bearing if it is noisy or has excessive play Standard Service limit 14 0mm 14 048mm Axial Radial Play Play ...

Page 59: ...heck for wear or damage of the gear Governor weight Reassembly Check that the weights move freely after installation Clip Reassembly Securely fix it in the groove Governor slider Reassembly Check to be sure it moves smoothly after installing Washer 2 Governor arm shaft Reassembly After installing rotate the shaft to the cylinder barrel side Pin clip Reassembly Immediately fix the pin clip after in...

Page 60: ...firm there no continuity between yellow lead and ground wire 2 Hold the oil level switch in its normal position confirm the continuity exists between the yellow lead and ground wire 3 Inspect the float by dipping the oil level switch into a container of oil confirm there is no continuity between the yellow lead and ground wire ON OFF ...

Page 61: ...e lip of the oil seal when installing the P T O shaft into the reduction cover 6 55 9 6206 ball bearing Clutch center M8 20 5 Clutch center key Bush Drive sprocket Reassembly Attach the drive chain to the sprocket and P T O shaft and install in the reduction case as a set Chain Clutch weight Clutch cover Reassembly When installing it to the crankshaft key slot of the retainer must be aligned with ...

Page 62: ...eassembly Check the sprocket teeth for wear or damage before installing install the drive sprocket chain and drive sprocket as a set Bolt M8 30 Washer 8 5 23 3 Drive sprocket Reassembly Check the sprocket teeth for wear or damage for wear or damage before installing Attach the chain to the drive sprocket and P T O shaft and install in the case as a single unit Washer 20 5 39 3 1 Drive chain Reasse...

Page 63: ...F G160F G200F Part IV Disassembly and maintenance 62 3 Inspection 1 Clutch friction disc Standard Service limit 3 5mm 3 0mm 2 Clutch plate Check the clutch plate warpage on a flat plate using a feeler gauge ...

Page 64: ...ials away Battery gases are explosive don t smoke near it and keep spark and flame away When charging the battery keep good ventilation Connecting to the starter motor Take care not to reverse the polarity or shortcircuiting will occur Normally connect the starter cable to the battery positive before connecting the battery negative 1 Connect one end of the battery s positive cable to the starter s...

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LONCIN G120F, Shop Manual

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