LONCIN YF300 Manual
  1. Manuals
  2. Brands
  3. LONCIN Manuals
  4. Engine
  5. YF300
  6. Manual
LONCIN YF300 Manual

LONCIN YF300 Manual

Hide thumbs

Advertisement

Table of Contents

Foreword
The types of motorcycles increased day by day due to new structures
and new technologies are adopted. For users and maintainers knowing
well about the maintenance, adjustment and repair technologies of
LX178MN engine, we made this maintenance manual for more
convenience and better guidance for users and maintainers of Loncin.
All the data, diagrams, informations, performance targets are the latest
when the manual is printing. Loncin motor co. ltd. reserves the right of
revising the manual at any time without notification in advance. All
rights reserved by Loncin motor co. ltd. for any parts of this manual,
and no reprint is allowed before agreed by Loncin.
1

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the YF300 and is the answer not in the manual?

Questions and answers

Related Manuals for LONCIN YF300

Summary of Contents for LONCIN YF300

  • Page 1 Loncin. All the data, diagrams, informations, performance targets are the latest when the manual is printing. Loncin motor co. ltd. reserves the right of revising the manual at any time without notification in advance. All rights reserved by Loncin motor co.

  • Page 2: Table Of Contents

    Directory 1 .Summary....................3 2 .Lubrication system................7 3 .Checking and adjustment..............10 4 .Fuel system..................13 5 .Cooling system..................16 6 .Cylinder and air valves..............18 7 .Cylinder body and piston..............28 8 .Clutch component................33 9 .Gearshift system................38 10 Magneto and electrical starting component........40 11.Crankshaft and transmission system..........44 12.Fault diagnosis..................50...

  • Page 3: Summary

    Precaution in maintenance 1. Spare parts, lubricant and other auxiliary material adopted should be agreed or recommended by Loncin. In case selected material failed to meet demands of Loncin specification and requirement, the motorcycle may damage. 2. Washer, seal parts and split pin need to be replaced when re-intallation after disassembly is needed.
  • Page 4 Technological parameters for main performance Type Items YF300 Type LX178MN Single cylinder, 4 stokes, standing type engine, Style water cooled, 4 air valves, double OHV Max. power and its (19.3±5%)kW/(8500±1.5%)rpm rotation speed Main Max. torque and its （24.5±5%）N·m/（7000±1.5%）rpm parameters rotation speed ≤340 g/km·h...
  • Page 5 Data of standard torque Specification Torque N·m Ref.No. Parts name Spark plug 15～20 Bolt on cylinder head cover 8～12 Bolt for bracket of camshaft 10～15 Fastening bolt of cylinder 10～15 body 40～50 （Pre-fastening） Fastening bolt for cylinder head 50～60 （Final-fastening） Locking bolt timing...
  • Page 6 Bolt, nut, washer-checking √ √ √ √ √ Lubricant system-checking Maintenance of motorcycle should be conducted according to chart above Items in chart above should be done by Loncin service maintainer, in case of self-maintenance, reference to chart above is also necessary.

  • Page 7: Lubrication System

    Lubrication system Notice of maintenance Replacement of lubricant filter Troubleshooting Replacement of decompression valve Lubrication system of engine Assembly and disassembly of oil pump … Inspection of oil pump Checking of lubricant Replacement of lubricant Wash oil screen net Notice of maintenance This section introduce washing, inspection and replacement of lubrication system and its parts.
  • Page 8 different region and temperature in right picture Before oil replacement, drain off old oil in Crankcase first, and then wash by washing kerosene. Lubricant checking In case engine just stopped running, waiting for minutes is needed which makes oil reach the bottom of crankcase. Lay engine vertically to ground and check through view window 3,, and the level should be within upper and lower scale line.
  • Page 9 Disassembly of oil pump Remove right crankcase cover first, Remove screw A and oil pump B Assembly of oil pump Clean up metal and dirt on screen A Spray lubricant on oil pump needs installation. Confirm positioning pin B and seal ring C and filtering screen already installed.

  • Page 10: Checking And Adjustment

    Carburetor idling Timing ignition Test for cylinder pressure Notice in maintenance This section introduce checking and adjustment of YF300 engine and its each part, and also introduce technological requirement when it is in checking and adjusting. Technological requirement 1. Engine...
  • Page 11 buildup and dirt by steel wire or spark plug washer. Screw up spark plug by hand first and then by sleeve when it is assembling, and then screw up cap of spark plug. Valve clearance Caution：Engine should be under cold condition when valve clearance is in adjustment.
  • Page 12 Install bracket of cam and cylinder head cover. Idling adjustment of carburetor Note： Check and adjust idling speed of Carburetor after all other performance of engine reached stipulation range. Engine should be under hot condition when it is in adjustment, and motorcycle should be supported by main stand, and turn adjustment screw on plug Idling speed：1500±150r/min。...

  • Page 13: Fuel System

    Fuel system Notice in maintenance Adjustment for height of float Trouble shooting Installation of carburetor Disassembly for carburetor Adjustment for idling speed Disassembly for float, float needle and injection nozzle Notice in maintenance Summary 1. Be careful when gasoline is in using, keep good air ventilation in working place, and also keep far distance to spark and fire.
  • Page 14 Disassembly of carburetor Close down fuel switch, and remove connection of fuel tube, and then remove covers both sides Loosen fuel drainage screw, and drain off fuel in carburetor. Loosen screw connects clamp of air intake tube and carburetor. Disassembly of float, float needle and nozzle Remove cap of float chamber and its connective Screw.
  • Page 15 Adjust the height of float Measure the height of float by height gauge first Height of float D：17±0.5mm A：Surface of end of float chamber B：Needle of float C：Float Note: No pushing to needle is allowed when Measure the float height. When height adjustment is needed, slowly change the angle of float arm, until end of float arm precisely touched needle of float,...

  • Page 16: Cooling System

    Cooling system Notice in maintenance Disassembly of cooling pump Troubleshooting Assembly of cooling pump Notice in maintenance Assembly and maintenance of cooling pump could be done only after its cover removed No damage on two joint surfaces of cover of cooling pump is allowed. Trouble shooting In case there is failure in water cooling system, the engine may be overheated or undercooled which bad for its performance, in this case, periodic maintenance and...
  • Page 17 Disassembly for cooling pump Before disassembly of cooling pump, lay a box under engine first, and then screw off drainage bolt of engine and drain off coolant in engine. Remove fastening bolt on cover of water pump, and then remove pump cover. Remove impeller of cooling pump.

  • Page 18: Cylinder And Air Valves

    Cylinder head and valves Notice in maintenance Disassembly of cylinder head Inspection for valve seat Troubleshooting Break down cylinder head Inspection for valves Disassembly for cylinder head cover Inspect valve and its guide tube Repair valve seat Remove bracket of cam Inspect cylinder head Assemble cylinder head Remove camshaft...
  • Page 19 Troubleshooting Low air pressure in cylinder： Blue smoke 1. valves 1. Abrasion of valves Incorrect adjustment of valve clearance 2. Damage or leakage of oil drip pan Poor seal of valves 3. Leakage of cylinder head gasket Wrong timing of gas distribution 4.
  • Page 20 Disassembly for cylinder head cover Remove fastening bolt A on cylinder head cover. Remove cylinder head cover B. Remove cam bracket Remove cylinder head cover Remove bolt connects bracket Remove cam bracket Removal of camshaft Remove cylinder head cover Remove tensioner comp. on cylinder head and bolt on cylinder body Remove bolt connects bracket Remove cam bracket...
  • Page 21 Inspection for camshaft Check rising distance of each cam. Measure length A in right picture by micrometer Check abrasion Items Standard date Limits 36.20～36.30 36.10 Height of air intake cam Height of air exhaust 36.17～36.27 36.07 Check neck diameter of each camshaft for confirming abrasion Air intake and exhaust cam Standard data：22.967～22.980...
  • Page 22 Disassembly of cylinder head Press down valve spring by valve puller, remove lock clip of valve. Loosen valve puller, and remove seat of valve spring, spring, inner spring seat and valve. Caution: For avoiding permanent distorsion, excessively press spring is not allowed, only need to remove valve and lock clip.
  • Page 23 Check cylinder head Check crack on valve seat and hole of spark plug. Check distorsion on cylinder head, and inspect Flatness of cylinder head by feeler gauge or Knife straight gauge Limit of maintenance: 0.05 Check valve spring Measure height of inner and outer spring under free condition.
  • Page 24 Check valve seat Measure door line diameter D of valve seat ring, and its width E. Standard of door line diameter D：Intake：28.3～28.5 Exhaust：24.2～24.4 Standard of door line width D： Intake valve, exhaust valve 1.0～1.2 In case diameter or width of door line of seat ring is unqualified, repair seat ring until it meets the demand for correct sealing.
  • Page 25 Mill bottom belt ring area of valve seat by milling cutter of 60° Make fine machining on working surface of valve seat by milling cutter of 45° for its width reaching correct data Standard data of width of working surface：1.0～1.2。 Spread stamp-pad ink on valve seat, and embole valve and turn, and remove valve for observe its contact surface.
  • Page 26 Assembly of cylinder head Install oil drip pan onto valve guiding tube before installing valve. Spread lubricant on rod of air intake and exhaust valves, and then install into guiding tube. Install valve spring and its seat. Caution: Spring’s end with small pitch face to cylinder head when it is installing.
  • Page 27 Install new gasket in the groove on cylinder head cover. Install the cover on cylinder head. Screw up fastening bolts on cylinder head cover. Fastening torque for bolts should be：（8～10）N·m. Note： When seal ring of fastening bolt for cylinder head cover is in installing, the side of seal ring with metal lining faces upwards(This side matches flange face of bolt on cylinder head cover).

  • Page 28: Cylinder Body And Piston

    Cylinder body and piston Notice in maintenace Disassembly of piston Troubleshooting Assembly of piston Disassembly of cylinder Assembly of cylinder Notice in maintenance Summary Well install new washer and positioning pin first before installing cylinder, no dust and impurity enter crankcase is allowed. Specification of each part Items Standard（mm）...
  • Page 29 Trouble shooting Low or unstable compression Overheated 1 Abrasion on cylinder or piston ring 1. Carbon buildup in combustion chamber or on piston Smoky Abnormal knock 1.Abrasion on cylinder, piston or its rings 1. Knocking or abnormal sound 2.Incorrect installation of piston rings 2.
  • Page 30 Remove piston Remove circlip of piston pin by pliers Caution: No circlip drop into crankcase is allowed Press piston pin out of piston, and then remove the piston. Piston/Piston rings’ check Measure clearance between piston rings and their grooves by thickness gauge A. Standard data：...
  • Page 31 Measure outer diameter at positon by 5mm above bottom of piston skirt. Standard： 77.950～77.97 Limit：77.805 Calculate clearance between cylinder and piston Limit：0.12 Measure diameter of hole of piston pin： Standard： 17.002～17.008 Limit：17.04 Measure outer diameter of piston pin： Standard： 16.994.0～17.000 Limit：16.96 Installation for piston rings Completely wash and clean up grooves...
  • Page 32 Install piston Install piston, piston pin and new circlip of piston in together. Caution：The side with mark“▲” face to exhaust valve when installing piston. Clearance on end of circlip should interlace opening on piston. New circlip must be used when in re-installation. No circlip drop into crankcase is allowed.

  • Page 33: Clutch Component

    Clutch component Notice in maintenance Install right crankcase cover Troubleshooting Remove clutch and driving gear Disassemble clutch cover Disassemble clutch Install clutch cover Check clutch Disassemble right crankcase cover Assemble clutch and driving gear Notice in maintenance Maintenance work could be done after right crankcase cover removed, without taking down engine from motorcycle.
  • Page 34 Remove clutch cover Remove clutch cable Loosen fastening bolts on clutch Remove clutch cover Caution: No taking out of operation rod A is allowed when removing clutch for avoiding damage oil seal B, in case took out, replace by new oil seal is needed.
  • Page 35 Remove clutch and driving gear Pushing rod Remove pushing rod Remove pushing plate Pushing plate Loosen locking nut on clutch Locking nut Screw off locking nut on primary driving gear Remove clutch component Remove collar and flat washer on clutch Remove primary driving gear Remove semi-round key Disassemble clutch...
  • Page 36 Check flatness of driven plate by thickness gauge ≤0.1 Standard： Limit：0.2 Check spring length under free condition by vernier caliper Standard： 35.5 Limit： 34 Install clutch and driving gear Install woodruff key Install driving gear Install flat washer and shaft sleeve of clutch Install outer case of clutch Install washer of lower surface...
  • Page 37 Install pushing plate of clutch Install pushing rod and washer Install washer of locking nut of driving gear Install locking nut of driving gear Caution: Concave side of washer face to clutch and driving gear when installing washer of locking nut of driving gear and clutch.

  • Page 38: Gearshift System

    Gearshift system Notice in maintenance Install gearshift spindle Remove gearshift device cover Remove check plate Remove gearshift spindle Install check plate Check gearshift spindle Install gearshift device cover Notice in maintenance No damage to joint surface of cover and case of gearshift device is allowed when removing cover of gearshift device, no impurity drop into engine is allowed.
  • Page 39 Check gearshift spindle Check damage or distortion on gearshift spindle A, in case distortion is found, adjustment is needed, in case damaged, replace it. Check damage or distortion on returning spring B, in case damage or distortion is found, replacement is needed.

  • Page 40: Magneto And Electrical Starting Component

    Magneto and electrical starting component Notice in maintenance Install electrical starting gear Remove starting motor Install magneto Remove left front cover Install left front cover Remove magneto Install magneto Remove electrical starting gear Notice in maintenance This section introduce removal and installation of magneto, the work could be done without removing engine, only need remove left front cover.
  • Page 41 Remove left front cover Drain off lubricant in engine Remove installation bolt of left front cover Remove left front cover No damage to joint surface of cover is allowed during removing left front cover Remove magneto Remove installation bolt A of stator Remove installation screw C of wire pressing plate of stator.
  • Page 42 Check big and small double gear and plate shaped gear In case damage and abrasion is found, replacement is needed Install electrical starting gear Install collar A of plate shaped gear Install plate shaped gear Install small double gear and flat washer Install magneto Install rotor comp.
  • Page 43 Install left front cover Install positioning pin of left front cover Install new gasket Install left front cover Fasten installation bolt of left front cover Fastening torque：（8～12）N·m Install starting motor Install starting motor into left cover Fasten installation bolt of starting motor Fastening torque：（8～12）N·m Install big double gear and flat washer, 1 pcs each at upper and lower position of gear...

  • Page 44: Crankshaft And Transmission System

    Crankshaft and transmission device Notice in maintenance Check crankshaft Troubleshooting Check transmission device Break down crankcase Install crankshaft Remove transmission system Install transmission system Remove crankshaft Install crankcase Notice in maintenance This section introduce disassembly and assembly of crankshaft and transmission system, break apart crankcase before working above began.
  • Page 45 Trouble shooting Noisy Oil leakage 1. Abrasion of bearing on bigger end of connecting rod 1. Excessively oiled 2. Distortion of connecting rod 2.Oil seal abrasion or damage 3. Abrasion of bearing on neck of crankshaft 3. Crankcase damaged 4. Abrasion, seizing up or crushing of gear 5.
  • Page 46 Remove crankshaft Remove driven gear A of balancing shaft Remove balancing shaft Remove crankshaft Check crankshaft Measure total clearance B between end face of bigger end of connecting rod and crankshaft by thickness gauge A. Standard： 0.2～0.4 Limit：0.6 Turn the crankshaft by hand and inspect its radial bounce by dial gauge: ≤...
  • Page 47 Check transmission system Check flexibility of turning or axial moving of main or counter shaft and their each gear. Check abrasion or damage on each gear of main and counter shaft. Check width B of fork groove Standard： 5.0～5.18 Limit：5.33 Check thickness A of fork and its plate Standard：...
  • Page 48 Install crankshaft Inductively heat bearing hole of crankshaft on left crankcase to (130～150)℃, and then slightly press crankshaft into crankcase. Turn and check flexibility of crankshaft. The right end of crankshaft face upwards, and sufficiently drop oil into oil hole at right end, and slowly turn the connecting rod until oil overflow from both sides of bigger end of connecting rod.
  • Page 49 Spread lubricant on each gear and turnable parts. Spread sealant on end face of case body. Match up left and right crankcase Screw up installation bolt of crankcase Installation torque of bolt:（8～12）N·m。 Install o-ring B and jacket A on countershaft. Install chain, chain adjustment plate, and chain tensioning plate Install piston comp.

  • Page 50: Fault Diagnosis

    Failure diagnosis Hard staring or starting failure of engine Bad performance when engine is in high speed Insufficient engine power Abnormal sound of engine Bad performance when engine is in low speed or idling Hard starting or starting failure of engine Diagnosis Cause 1.
  • Page 51 2、Gradual acceleration of engine rotation speed→No speed change→ 1. Bad performance of fuel supplying Normal acceleration of engine rotation speed 2. Air filter blocked 3. Ventilation hole on carburetor cover blocked 4. Muffler exhaust blocked 3、Check ignition timing→Wrong ignition switch→ 1、CDI damaged Correct ignition timing 2、Magneto failed...
  • Page 52 Bad performance of engine under low speed or idling speed Diagnosis Cause 1、CDI failure 1、Check ignition timing and valve clearance→Incorrect→ Correct 2、Magneto failure。 3、Sensor failure 4、Too narrow the valve clearance 2、Check joint and leakage of carburetor→Leakage is found 1. Distortion of seal ring of carburetor No leakage 2.
  • Page 53 3、Sensor failure 4、Ignition switch failure 5、Ignition coil failure 6、Spark plug cap failure 7、Spark plug damaged 8、Short circuit is found in power resource circuit Abnormal noise of engine Diagnosis Cause 1、Abnormal noise of valve 1、Wide valve clearance 2、Abrasion of valve 、Abrasion on piston and cylinder body 2、Piston and cylinder knocking 2、...

Table of Contents

Save PDF