Yamaha MA190 Service Manual Download

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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 with new one.

Standard

Service limit

5.440–5.455 mm

5.310 mm

5.430–5.445 mm

5.300 mm

Valve spring free length

Measure the free length of the valve springs.
If out of the standard or service limit. Please
replace the spring.

Standard

Service limit

30.5 mm

28.5 mm

Valve Guide

Inspection:

a. Inspect the valve guide for smooth,

scratch and damaged in the inner sur-
face, and matching between the valve
guide and cylinder cover for fastness.

b. Using the valve guide reamer clean 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

5.500–5.512 mm

5.562 mm

4-3 Engine

Valve guide
reamer

Summary of Contents for MA190

Page 1: ...SERVICE MANUAL MA190 7JD F8197 E0 2017 10 1 ...

Page 2: ......

Page 3: ...le appear in future editions of this manual HOW TO USE THIS MANUAL PARTICULARLY IMPORTANT INFORMATION Particularly important information is distin guished in this manual by the following nota tions This is the safety alert symbol It is used to alert you to potential personal injury haz ards Obey all safety messages that follow this symbol to avoid possible injury or death DANGER A DANGER indicates...

Page 4: ...ILLUSTRATED SYMBOLS Refer to the illustration SYMBOL DEFINITION SYMBOL DEFINITION T R Tightening torque Wear limit clearance Engine speed Electrical data Special tool ...

Page 5: ... 3 6 Valve clearance adjustment 17 3 7 Governor adjusting 19 IV DISASSEMBLING AND SERVICING 4 1 Troubleshooting 20 4 1 1 Starting difficult 20 4 1 2 Power lack 22 4 1 3 Unstable speed 23 4 1 4 Unable to ignite 23 4 1 5 Engine overheat 24 4 1 6 Abnormal sound 24 4 1 7 Exhaust gas color abnormal 25 4 2 Preparation of servicing 25 4 2 1 Safety precautions 25 4 2 2 Special tools 26 4 3 Engine 27 4 3 1...

Page 6: ...Part description 1 1 1 Feature Muffler Spark plug Starting lever Oil dipstick Drain plug Fuel tank Fuel tank cap Engine switch Air cleaner 1 1 2 Model serial number YAMAHA MA190 7 Engine model Serial number 1 1 Part description ...

Page 7: ... cylinder horizontal 4 stroke OHC Displacement 189 ml Bore Stroke 68 mm 52 mm Theoretical Maximum Power 3 72 kW 3600 r min Recommended Using Power 3 5 kW 3400 r min Maximum Torque 11 2 N m 2500 r min Fuel Consumption 395 g Kw h Cooling System Forced air Ignition System Capacitance discharge type PTO Shaft Rotation Vertical shaft output 1 2 Specification ...

Page 8: ...3 0 28 0 20 0 40 0 150 2 300 1 000 Connecting rod Small end I D Big end I D Big oil clearance Big end side clearance 16 005 16 021 30 000 30 018 0 019 0 049 0 4 0 7 16 090 30 066 0 120 1 100 Crankshaft Crankshaft pin O D 29 969 29 981 29 910 Valve Valve clearance IN EX Stem O D IN EX Guide I D IN EX Stem clearance IN EX Seat width Spring free length 0 10 0 15 0 15 0 20 5 440 5 455 5 430 5 445 5 50...

Page 9: ...4 II DIMENSION AND TORQUE 2 1 Engine dimension 2 1 1 Appearance dimension 360 290 425 2 1 Engine dimension ...

Page 10: ...gure Type 7 8 1 1 1 Type 7 8 1 1 2 4 76 19 5 0 15 0 22 2 0 025 0 0 05 0 7 07 2 5 19 2 5 0 46 3 1 2 28 1 MOUNTING SURFACE 27 M10 1 25 16 4 76 19 5 0 15 0 22 2 0 025 0 0 05 0 7 07 2 5 19 2 5 0 44 45 1 2 MOUNTING SURFACE 27 M10 1 25 16 25 1 0 2 1 Engine dimension ...

Page 11: ...0 Type 1 1 Type 1 2 6 35 21 8 0 15 0 25 4 0 025 0 0 05 0 7 03 2 5 25 4 2 5 0 46 03 1 2 MOUNTING SURFACE 27 3 8 24UNF 26 1 0 25 4 6 35 21 8 0 15 0 0 05 0 25 4 0 025 0 7 07 2 5 25 4 2 5 0 61 9 1 2 MOUNTING SURFACE 27 3 8 24UNF 32 1 0 2 5 4 Type 1 3 Type 25 2 6 35 0 05 0 21 8 0 15 0 19 9 0 15 0 5 0 03 0 25 4 0 025 0 7 07 2 5 25 4 2 5 0 61 9 1 2 MOUNTING SURFACE 27 32 1 0 37 0 1 3 8 24UNF 19 2 5 4 6 3...

Page 12: ...7 2 1 Engine dimension Type 25 3 4 76 9 75 0 15 0 0 05 0 5 2 5 80 2 1 2 MOUNTING SURFACE 27 50 1 0 31 min 25 0 05 0 03 7 16 20UNF 19 ...

Page 13: ... 25 8 8 22 2 9 Cylinder head cover M6 12 8 8 8 2 M6 80 8 8 10 Breath groove covering plate M6 12 8 8 10 2 11 Brake M6 12 8 8 10 2 M6 20 8 8 12 Ignition coil M6 20 8 8 10 2 M6 68 8 8 13 Stud supporting bolt M6 80 8 8 10 2 14 Lower shell M6 16 8 8 10 2 15 Muffler stud M8 109 8 8 12 2 16 Muffler nut M8 8 22 2 17 Air cleaner M6 8 8 2 18 Throttle control M6 12 8 8 10 2 19 Governor support lock nut M6 8...

Page 14: ...7 11 5 mm flange bolt 3 6 6 9 6 mm screw 7 11 5 mm flange bolt 3 6 6 9 6 mm flange bolt 10 14 8 mm flange bolt 20 26 10 mm flange bolt 35 45 2 4 Important bolt torque value Item Thread dia mm Torque value N m Kg m Connecting rod bolt M6 1 0 13 1 3 Cylinder head bolt M8 1 5 26 2 6 Flywheel nut M14 1 5 52 5 2 Crankcase cover bolt M6 1 0 10 1 0 Value locking nut M5 0 5 6 0 6 2 3 Standard torque value...

Page 15: ...pection at the intervals shown in the Maintenance schedule below Maintenance schedule Frequency Item Each time First month or 20 hrs Each season or 50 hrs Every 6 month or 100 hrs Each year or 300 hrs Engine oil Oil level check Replace Air cleaner Check Clean replace Spark plug Check clean Adjust Replace Fuel strainer Clean Valve clearance Check adjust Cylinder head Clean Fuel tank Replace Every 3...

Page 16: ... If the oil level is too low add the rec ommended engine oil up to the oil upper limit 5 Reinstall the dipstick and screw down 6 Tighten the oil drain plug MA190 Oil drain plug 20 24 N m TIP Use 4 stroke engine oil API service classifica tion SE class or equivalent Always check the API service label on the oil container to be sure it includes the letters SE or equivalent SAE10W 30 is recommended f...

Page 17: ...g with insuffi cient engine oil may damage the engine severely and it will not be covered the range of the warranty NOTICE Used engine oil may cause skin cancer if repeatedly left in contact with the skin for prolonged periods Although this is unlike ly unless you handle used oil on a daily basis it is still advisable to thoroughly wash your hands with soap and water as soon as possible after hand...

Page 18: ...f the connecting bolt and remove the air cleaner shell 2 Remove foam element or paper element Be careful to prevent dirt and debris from falling into the air cleaner base opening 3 Clean the element Polyurethane element Clean polyurethane with detergent then blow it dry with compressed air or squeeze it dry Dip the element in clean oil then forcefully squeeze it dry and install it back Tap the ele...

Page 19: ...soline is extremely flammable and is explosive under certain conditions 2 Refueling in a well ventilation area with the engine stopped Do not smoke and allow flames or sparks in the area where gasoline is stored or where the fuel tank is refueled 3 Do not overfill the fuel tank The fuel will not exceed 3 4 of the fuel tank After refueling make sure the fuel tank cap is set back securely 4 Be caref...

Page 20: ...fuel when refu eling Any damage due to fuel spilling is not within valid warranty Light knocking or spark exploding sound can be hear when the engine overloading It is normal Do not be worry about that If knocking or spark exploding sound occur at a steady speed under normal load change grade of gasoline if such phenomena still happen consult your dealer for help otherwise the engine may be damage...

Page 21: ... it with plug wrench compress the plug washer Cover the spark plug cap on TIP To avoid cross threading first screw in spark plug by hand then tighten with a spark plug wrench to compress the gasket If a new spark plug is used more twist 1 2 turns after compressing the gasket If reinstalling the used spark plug just more twist 1 8 1 4 turns Spark plug 22 2 N m The spark plug must be tightened secur...

Page 22: ...inder head cover and gasket in order NOTICE After the cylinder head cover is removed engine oil may flow Be sure to wipe up any flowed oil Stud M6 109 Spark plug Cylinder head gasket Dowel 10 14 Stud M6 105 Cylinder head assy Cover gasket Bolt Head cover Bolt M6 12 Bolt M6 80 2 Lightly pull the starting rope and set the piston at top dead center of the compres sion stroke insert screwdriver into t...

Page 23: ...torque Bolt 8 2 N m Adjusting nut screw down small Adjusting nut screw off big NOTICE Clearance too big Intake and exhaust valve opening delay will shorten the intake and exhaust time lower the opening height of the valve and change normal distribut ing phase to result in power lowering from the intake lack and exhaust incomplete Furthermore also make vale train parts knock increasing and wearing ...

Page 24: ...ing speed Don t adjust the speed because it is fixed speed If necessary please have it to the theorized deal er for adjusting If the user has a proper tools and repairing capacity only permit the following operation 1 Start the engine and allow it to warm up to normal operating temperature 2 If the maximum speed is not conformed to specified value adjust throttle control and hole position of the s...

Page 25: ...n bad conditions Too much carbon deposit and dirt around electrodes Clear away Electrodes are burn dam aged seriously or insulators damaged Replace spark plug Improper electrodes gap Adjust to proper value High tension line no spark Normal spark plug High tension line is damaged Replace Ignition coil is damaged Replace Magneto loses magnetism Replace Abnormal gap between the ignition coil and flyw...

Page 26: ...ap with wet hand 9 If having fuel cock turn the fuel cock to OFF position if no fuel cock first drain the gasoline of the fuel tank then drain the gasoline of the carburetor 9 Remove the spark plug and spark plug cap 9 Install the spark plug cap 9 Turn the engine stop switch to I or STOP position 9 Pass negative pole thread of the spark plug through cylinder cover to connect grounding and pull the...

Page 27: ... Air cleaner is clogged up Clean air cleaner filter element Intake pipe is leaking Repair or replace Poor compres sion Intake pipe is leaking Repair or replace Piston or cylinder or piston ring is worn Replace the worn Air leakage from the surface by which cylinder block contacting with cylinder head Replace cylinder gasket Too big or too small valve clearance Readjust Cylinder pressure check 9 Dr...

Page 28: ...electrodes clearance Adjust Something wrong with induced coil and so on Check and replace damaged parts 4 1 4 Unable to ignite TROUBLE CAUSE REMEDY Unable igniting Fuel supply system Fuel tank is empty Refill fuel Carburetor is clogged Check fuel line and dredge Float is leaking Repair Needle valve is stuck Dismantle float chamber and eliminate it Ignition system Spark plug is punctured or short c...

Page 29: ...t 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 Metal beating sound when abnormal com bustion occurs Too much carbon d...

Page 30: ...d cover and fan in time in order to make the engine cool normally 6 The 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 Anyone without training is forbidden to operate the engine Keep periodical maintenance Solve problems in time Do not run the engine in spite of malfunction ...

Page 31: ...sembler handle Installing handle and bearing 3 Inner retainer assembler Assembling ball bearing and time 4 Diamond lap 45 Rectifying valve seat surface 5 Diamond lap 32 Rectifying valve seat surface 6 Flywheel driver Dismounting flywheel 7 Bearing extractor Dismounting flywheel 4 2 Preparation of servicing ...

Page 32: ...r case 3 Starting rope grip 9 Compression spring 15 Stud M6 80 4 Rope guide assy 10 Washer 16 Stud M6 68 5 Starter coil spring 11 Drive guide 17 Cross recessed pan head screw M5 20 6 Rope coil tray 12 Screw 18 Housing NOTICE Wear gloves during disassembly and take care not to allow the return spring to come out When assembling first check starter rope for damaged or broken then assemble it 4 3 Eng...

Page 33: ...to the proper container 9 Remove screw M5 20 fuel tank cover and engine housing 9 Remove the fuel tube fuel strainer and remove the fuel tank 9 Clean the fuel tank and dry it thoroughly 9 Install the strainer on fuel tank after cleaning and connect the fuel tube on 9 Check the fuel tank if there is leakage 9 Install the engine housing fuel tank cover and screw M5 20 TIP 9 Check fuel tank cover ven...

Page 34: ...ion coil flywheel Ser No Description Ser No Description 1 Flywheel nut 5 Hex flange bolt big series B class M6 25 2 Starting cup 6 Ignition coil 3 Impeller 7 Ignition coil stop wire 4 Flywheel assy 8 Clip 4 3 Engine ...

Page 35: ...ew down the bolt Check the ignition coil Primary side Measure the resistance of the primary coil by attaching one ohmmeter lead to the ignition coil s primary terminal while touching the other tester lead to the iron core Primary side resistance value 1 0 1 5 Ω 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...

Page 36: ... is no washer and other foreign material on the magnetic part 2 Set the key in the key groove 3 Install the flywheel over the crankshaft TIP The flywheel may push the key out of its slot check after assembling Flywheel nut 64 4 N m aluminum flywheel 78 4 N m iron flywheel Flywheel cast iron 9 Attach by aligning the four small holes in the flywheel 9 Attach by aligning the lug on the rear side of t...

Page 37: ...ning carbon deposits Replace it if the muffler exist in water and is seriously rusted to make noise increasing NOTICE Don t clean with iron wire or the muffler material out to lower the muffler performance Don t reuse the muffler gasket WARNING 9 The muffler can glow heat Please place the gasoline engine out touch of the passerby and children 9 Don t place the flammable materials near the exhaust ...

Page 38: ...ling direction viewing from the air cleaner side 9 Before assembling check rubber tube for deterioration or damage Replace if neces sary Pay attention to connect the beveled end shorter big head end to the air clean er case while the other end connect to the engine NOTICE 9 Don t wash the foam element with the gasoline acidity alkali or organic sol vent 9 Don t pull and wrest the sponge or it will...

Page 39: ...t 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 having quality defectiveness partly foreign matters will enter into the carburetor Otherwise the gasoline contains some composition which can form the colloid after long sediment and attach in the carburet...

Page 40: ... gasoline and compression air to clean it Ser No Description Ser No Description Ser No Description 1 Throttle valve 11 Pilot jet 21 Float pin 2 Throttle valve shaft 12 Choke stopper spring 22 Float chamber sealing ring 3 Small washer A class 13 Pilot screw 23 Float chamber 4 Cross pan head screw 14 Pilot screw spring 24 Sealing ring 5 Choke shaft 15 Throttle stop screw 25 Oil cup bolt 6 Choke 16 S...

Page 41: ...carburetor in the position as shown and measure the distance between the float top and carburetor body when the float just contacts the seat with out compressing the valve spring Specified float height 13 7 mm If the height is out of specification replace the float valve and recheck the float height Tools Float level gauge 4 3 Engine Float valve Float valve seat Worn Normal Main jet Main nozzle Fl...

Page 42: ... engine stop switch line to crankcase while the other end connects to engine stop switch Governor support Lever rubber sleeve Bolt M6 12 Throttle control Bolt M6 12 Spring Engine stop switch Support fix bolt Hex flange nut M6 NOTICE Don t randomly replace throttle valve returning spring and governor spring hooking posi tion or result in performance of the engine unstable Governor spring hook posit...

Page 43: ...arburetor 7Disassemble throttle control lever 8Disassemble cylinder head cover 9Disassemble crankcase cover Timing chain Disassembly 1 Refer to pages 17 18 loosen the valve adjusting bolt and make an appropriate gap between the valve stem end and the valve bolt 2 Pull out the rocker shaft and remove the intake rocker and the exhaust rocker Chain Appropriate gap Rocker Rocker Rocker shaft 4 3 Engin...

Page 44: ... and pull out the cam shaft spindle NOTICE When pulling out the camshaft spindle be careful not to strike the cylinder head and cylinder block by the camshaft falling off 5 Slide the chain sideways and remove the camshaft Pin Tensioner Spring Bolt Camshaft spindle Chain Camshaft 4 3 Engine ...

Page 45: ...40 4 3 Engine 6 Move the timing chain downward and remove it from the crankcase side Reassembly 1 Timing chain pass through as shown in Figure 1 Chain Figure 1 ...

Page 46: ...shaft by matching the camshaft mating mark and the timing chain mark One piece with different color 4 Confirm that the matching mark of the crankshaft and the camshaft matches the mark of the timing chain Figure 2 Crank mating mark Timing chain mark Camshaft mating mark and timing chain mark Crank mating mark and timing chain mark Timing chain mark Camshaft mating mark 4 3 Engine ...

Page 47: ...he pin while compressing the spring with the finger as shown in the fig ure and attach the tensioner 7 Make sure the pin is inserted until the end 8 Refer to pages 17 18 to install the locker Adjust the valve clearance Bolt Camshaft spindle Spring Pin Pin 4 3 Engine ...

Page 48: ...ld be tightened gradually and evenly up to specified torque Torque 8 2 N m Cylinder head cover Crankshaft Camshaft spindle Sealing ring Chain Tensioner Spring Pin Bolt Assembly disassembly Turn and tighten the bolts in a crisscross pattern in 2 or 3 steps Torque 26 N m Intake valve Don t interchange with the exhaust valve in assembling Intake mark IN Exhaust mark EX Be careful not to damage the va...

Page 49: ...gth of the valve springs If out of the standard or service limit Please replace the spring Standard Service limit 30 5 mm 28 5 mm 3Valve Guide Inspection a Inspect the valve guide for smooth scratch and damaged in the inner sur face and matching between the valve guide and cylinder cover for fastness b Using the valve guide reamer clean the valve guides to remove any carbon deposits before measuri...

Page 50: ... Install the new valve guides from the valve spring side of the cylinder head 9 Exhaust side Drive the exhaust valve guide until the clip is fully seated as shown as fig 9 Intake side Drive the intake valve guide to the specified height measured from the top of the valve guide to the cylinder cover as shown as fig d After installation inspect the valve guide for damage if damaged please replace 4 ...

Page 51: ...centered in the valve guide insert the valve and check opera tion If the valve does not operate smoothly the guide may have been bent during installation Replace the valve guide if it is bent or damaged c Check the valve stem to guide clearance d The valve stem to guide clearance The vale guide bore detract the valve stem outside diameter to get the clearance between the valve guide and valve stem...

Page 52: ...5 cutters to narrow and adjust the valve seat so that it contacts the middle of the valve face 9 The 32 cutter removes material from the top edge contact too high 9 The 45 cutter removes material from the bottom edge contact too low Be sure that the width of the finished valve seat is within specification Standard Service limit 0 8 mm 2 0 mm e Use 45 cutter to remove any possible burrs at the edge...

Page 53: ...48 g Apply the abradant to the valve seat face suitable for running in when rotating valve seat with valve seat cutter h After reassembling check the valve clear ance 4 3 Engine Valve lapping tool ...

Page 54: ...nkcase cover with special tool without damaging the edge of the oil seal d Apply the special lubrication oil onto oil seal after assembling 9 Don t reuse the oil drain plug washer as can as possible use new one 9 Bolt M6 30 Loosen and tighten the bolts in a crisscross pattern especially when tightening all bolts should be tightened gradually and evenly up to specified torque Bolt torque 10 2 N m 9...

Page 55: ... 13 Gasket 23 Pin 4 Oil dipstick 14 Flat washer A class 24 Connecting rod 5 Bolt M6 16 15 Governor arm 25 Connecting rod body 6 Lower cover 16 Oil seal 6 11 4 26 Connecting rod cover 7 Deep groove ball bearing 17 Split pin 27 Connecting rod bolt 8 Oil seal 25 35 6 18 First ring 28 Woodruff key 9 Bolt M6 20 19 Second ring 29 Crankshaft 10 Groove covering plate 20 Oil ring assy 4 3 Engine ...

Page 56: ... 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 Do not align the end gap of the clip with the cutout in the piston pin bore c Connecting rod cap Install by aligning the alignment marks on the connecting rod cap Connecting rod bolt 13 1 N m Maker mark Top ring Second ring Oil ring Mark Connection rod Reassembly Mak...

Page 57: ...il seal 9 Apply oil to the circumference of an oil seal 9 Drive the oil seal in the cylinder barrel using following tool Tools Driver handle Retainer assembler 9 Apply the lubrication oil on after reas sembling f Piston 9 Apply oil to the piston and cylinder 9 Install the piston with the mark on the piston head toward the tensioner hole side 4 3 Engine Retainer assembler Driver handle Oil seal Pis...

Page 58: ...850 mm b Piston pin bore to piston clearance Separately measure the piston pin bore I D and O D with inside micrometer and outside micrometer Then calculate clear ance by measuring results Standard Service limit 0 004 0 016 mm 0 060 mm c Piston cylinder clearance Difference between cylinder maximum diameter and piston skirt should be con sidered as piston cylinder clearance Check with piston conve...

Page 59: ...place the piston into the cylinder with pushing the piston head to working position Measure the opening clearance with 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 heat ing and blocked in the cylinder thus causing piston broken and sticking If opening clearance is too small file the open...

Page 60: ...necting rod Standard Service limit 16 005 16 021 mm 16 090 mm b Check big end diameter If out of the standard or exceed service limit replace the connecting rod Standard Service limit 30 000 30 018 mm 30 066 mm c Connecting rod big end oil clearance 9 Wipe oil off the crank pin and connect ing rod bearing mating surface 9 Set the plastic gauge on the crank pin connecting rod and bolt to specified ...

Page 61: ...haft height for damaged and camshaft and bearing for loosening and wearing replace as required 9 Check camshaft for height dimension If out of the service limit replace the camshaft Standard Service limit IN lifter 23 98 mm 23 730 mm EX lifter 27 88 mm 27 630 mm 9 Check inner diameter of the camshaft hole if less than the service limit replace the camshaft Standard Service limit 9 00 9 04 mm 9 090...

Page 62: ... the relative part produce deviation face to make abnormal wearing 5Crankshaft Push the bearing until it con tacts the crankshaft with care not to dam age the crankshaft output end and timing gear 9 Check timing gear for engagement clear ance of the chain The camshaft timing chain guide tensioner and crankshaft tim ing gear should be sufficiently matched with chain and contact governor driven gear...

Page 63: ...58 4 4 Electric diagram 4 4 Electric diagram Engine switch Engine switch Spark plug Ignition coil Black ON OF ...

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Page 66: ...SERVICE MANUAL MA190 7JD F8197 E0 2017 10 1 ...

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