Yamabiko ECHO SRM-420ES Service Manual Download Page 16

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SRM-420ES, SRM-420TES

T410S, B410S

T410TS, B410TS

IGNITION SYSTEM

3-1 Troubleshooting guide

3 IGNITION SYSTEM

(A) Flywheel

(B) Ignition coil

(D) Spark plug cap coil

(E) Spark plug cap

(F) Spark plug cap cover

(G) High tension lead

(H) Primary leads

(J) Ground

leads

(K) Ignition switch

(L) Woodruff

key

(A)

(B)

(C)

(D)

(F)

(E)

(G)

(H)

(J)

Not
OK

Spark plug

Spark

plug cap/

coil

Ignition

switch

Clean /
Regap /
Replace.

Replace.

Start

S.T.

Not
OK

S.T.

Not
OK

S.T.

Not
OK

Pole

shoe air

gaps

Replace.

Not
OK

S.T.

Replace
ignition
coil.

Leads

connections

Not
OK

S.T.

Repair /
Replace.

Not
OK

Remedy

Inspect

Not
OK

Flywheel

key

R.T.*

End

Not
OK

Flywheel

magnet

Replace.

Not
OK

R.T.

Not
OK

Replace ignition coil and / or inspect other
systems.

Replace flywheel.

Adjust pole shoe air gaps.
(Inspect flywheel magnet
at the same time. Go to

if OK.)

S.T.

Not
OK

S.T.: Spark test.
R.T.: Running test including actual cutting.

Secondary

coil

resistances

(L)

(K)

Summary of Contents for ECHO SRM-420ES

Page 2: ...oubleshooting guide that describes problems testings reme dies and references We recommend you make use of Operator s Manual and Parts Catalogue together with this manual when servicing We are constantly working on technical improve ment of our products For this reason technical data equipment and design are subject to change without notice All specifications illustra tions and directions in this ...

Page 3: ...al settings 30 4 5 3 Adjusting carburetor 31 4 6 Testing carburetor 32 4 7 Inspecting crankcase pulse passage 33 4 8 Inspecting metering lever height 33 4 9 Inspecting inlet needle valve 34 4 10 Inspecting diaphragm and others 34 4 11 Replacing welch plug 35 4 12 Replacing purge bulb 35 4 13 Replacing throttle cable and control parts 36 4 14 Checking and adjusting throttle cable 36 5 CLUTCH SYSTEM...

Page 4: ... with catalyst Starter Type ES start effortless Soft Start Rope diameter x length mm in 3 8 x 910 0 15 x 35 9 Fuel 3 Type 4 Mixed two stroke fuel Mixture ratio 50 1 2 Gasoline Minimum 89 octane Two stroke engine oil ISO L EGD ISO CD13738 JASO FC FD Tank capacity Full tank capacity 0 69 23 3 L U S fl oz Usable capacity 0 60 20 3 Clutch Type Centrifugal 2 shoe pivot Handle Type Front Crescent loop w...

Page 5: ...eter x length mm in 3 8 x 910 0 15 x 35 9 Fuel 3 Type 4 Mixed two stroke fuel Mixture ratio 50 1 2 Gasoline Minimum 89 octane Two stroke engine oil ISO L EGD ISO CD13738 JASO FC FD Tank capacity Full tank capacity 0 69 23 3 L U S fl oz Usable capacity 0 60 20 3 Clutch Type Centrifugal 2 shoe pivot Handle Type Front Crescent loop with cushion grip U handle with integrated control grip Rear Integrat...

Page 6: ... 2 3 8 Throttle adjust screw turn in 2 2 1 8 Engine warm up Idle WOT Total sec 10 50 180 2 Find idle maximum speed Adjust L mixture needle to maximum idle speed 3 3 Set idle maximum speed w TAS r min 3 550 4 Set idle speed by turning L mixture needle CCW r min 2 750 5 Find WOT maximum speed r min Adjust H mixture needle to maximum WOT speed 6 WOT setting Turn H mixture needle CCW to decrease WOT s...

Page 7: ...3 17 26 Muffler M6 100 140 10 14 90 125 Muffler cover M5 1 30 45 3 4 5 26 40 Muffler stay M5 60 90 6 9 50 80 Others Blade fastening nut LM10 280 320 28 32 245 280 Regular bolt nut and screw M3 6 10 0 6 1 5 9 M4 15 25 1 5 2 5 13 22 M5 25 45 2 5 4 5 22 40 M6 45 75 4 5 7 5 40 65 M8 110 150 11 15 95 130 M10 210 300 21 30 180 260 LM Left hand thread 1 Apply thread locking sealant See 1 4 Special repair...

Page 8: ...plating is worn and aluminum can be seen B Piston outer diameter Min 39 91 1 571 C Piston pin bore Max 10 035 0 3951 D Piston ring groove Max 1 6 0 063 E Piston ring side clearance Max 0 1 0 004 F Piston pin outer diameter Min 9 98 0 3929 G Piston ring width Min 1 45 0 057 H Piston ring end gap Max 0 5 0 02 K Con rod small end bore Max 13 025 0 5128 L Crankshaft runout Max 0 02 0 001 M Clutch drum...

Page 9: ...ing lever gauge Measuring metering lever height on carburetor 11 X644 000020 Piston stopper Locking crankshaft rotation 12 91041 Pressure rubber plug Plugging exhaust port to test crankcase cylinder leakages 13 897826 16131 Pressure rubber plug Plugging intake port to test crankcase cylinder leakages 14 897827 16131 Pressure plate Plugging intake port to test crankcase cylinder leakages 15 91149 P...

Page 10: ...ng D until the accumulated energy is enough to overcome the compression pressure in cylinder 6 When accumulated energy in power spring D overcomes the load from compression pressure in cylinder crankshaft is rotated 7 Power spring D absorbs compression resistance of cylinder and snatch back of engine during starting action 8 When starter rope G is released rope reel C is returned together with pow...

Page 11: ...d rope reel F by hand Loop excess rope in rope reel notch f as shown 5 Rotate rope reel F clockwise to release tension of rewind spring 6 Remove tapping screw G 7 Remove pawl catcher H and power spring J 8 Remove rope reel K with rewind spring L from starter case M slowly to prevent rewind spring L from unwinding WARNING DANGER Wear eye protection and take care when removing rope reel Rewind sprin...

Page 12: ... shown 2 2 Replacing starter rope 1 Pull out and untie knot A 2 Pull knot B to remove rope from rope reel C 3 When installing new starter rope singe both ends of rope to prevent fraying 5 Pass other end of starter rope through starter case from inside to outside 6 Pass starter rope through starter grip Make a knot as shown 7 Tighten knot Push the knot into recess of starter grip A B C D D ...

Page 13: ...nd spring inside rope reel hooking outer hook a to holder b of rope reel B as shown 2 Apply small amount of lithium based grease to outside of rewind spring 2 4 Assembling starter 3 Check for proper engagement of rewind spring and rope reel by turning rope reel A clockwise and counterclockwise A b a 1 Lubricate center post c2 of starter case with lithium based grease 2 Assemble rope reel A with re...

Page 14: ...otch a2 as shown Hold rope reel to prevent it from rewinding and pull out starter grip to take the rope slack a2 F 8 Pull starter several times to check rewind spring tension If starter is not rewinding fully increase spring tension by rotating rope reel one more turn counterclockwise following above step 7 9 Pull out starter rope all the way and check that rope reel can be rotated an additional h...

Page 15: ... plug hole to stop crankshaft rotation and remove bolt easily 3 Install torsion spring D pawl C washer B and bolt A To avoid pinching of torsion spring install these parts without setting the end of torsion spring d1 on starter pawl 4 Using fine wire F or appropriate tool place the end of torsion spring d1 on pawl B by hooking and passing under pawl as shown Remove fine wire or tool 5 Make sure pa...

Page 16: ...ch Clean Regap Replace Replace Start OK OK S T Not OK S T Not OK Not OK S T OK S T Not OK Pole shoe air gaps Replace Not OK OK Not OK S T OK OK Replace ignition coil Leads connections Not OK OK OK Not OK S T Repair Replace Not OK Remedy Inspect Not OK Flywheel key OK R T End Not OK Flywheel magnet Replace Not OK R T Not OK OK OK Replace ignition coil and or inspect other systems Replace flywheel O...

Page 17: ...c tion WARNING DANGER Do not test near spark plug hole without spark plug installed otherwise there is a chance to ignite fuel mixture inside cylinder Do not touch metal parts of spark tester while performing the test to avoid receiving electrical shock Do not check spark in area where gasoline is spilled or flammable gases may exist 3 3 Inspecting spark plug 1 Remove spark plug to inspect for fou...

Page 18: ... or multi me ter to primary lead C of ignition switch side as shown 4 Connect other probe to ground lead D of igni tion switch side as shown 5 When ignition switch is in RUN position tester should indicate infinite resistance 6 When ignition switch is in STOP position tes ter should show that circuit is in conducting state closed circuit 7 If ignition switch is defective replace with a new one B A...

Page 19: ...om drive shaft housing 5 Disconnect end h of throttle cable H from throttle trigger J 6 Remove throttle latch K with torsion spring M throttle latch N with torsion spring P throttle trig ger J with torsion spring Q and throttle latch R 7 Remove ignition switch S with leads cushion T corrugated tube U and throttle cable H 8 Pull out throttle cable from cush ion T and corrugated tube U 9 Pass thrott...

Page 20: ...atch R Install throttle trigger J with torsion spring Q hooking torsion spring end q as shown 15 Install throttle latch N with torsion spring P hooking torsion spring end p as shown Install throttle latch K with torsion spring M hooking torsion spring end m as shown 16 Connect end h of throttle cable H to throttle trigger J 17 Install throttle cable H cushion T and corrugated tube U to rear handle...

Page 21: ... D with torsion spring F 5 Disconnect end g of throttle cable G from throttle trigger C 6 Remove ignition switch H with leads corrugat ed tube J and throttle cable G 7 Remove corrugated tube J from handle shaft together with the cable and leads 8 Pull out throttle cable G from corrugated tube J 9 Pass throttle cable G through corrugated tube J of new ignition switch 10 Route leads behind ignition ...

Page 22: ...p half as shown NOTE Set grooves of corrugated tube J on ribs M of the handle grip half Fig 1 NOTE Make sure throttle cable G is passing inside of hand grip boss L and install the hand grip groove surely as shown 15 Put together both grip halves 16 Reinstall right hand grip on handle 17 Route cable N on handle support P and secure with clip Q NOTE Make sure cable N routes through ribs of handle su...

Page 23: ...ion coil core to confirm that the circuit is in conducting state closed circuit If the circuit is not in conducting state ensure conduction between ignition coil bolt and cylinder 6 If the reading at step 3 or 4 is not in the range of the above replace with a new ignition coil Go to 3 8 Replacing ignition coil A D C 3 7 Replacing spark plug cap and coil 1 Disconnect spark plug cap A from spark plu...

Page 24: ...rank case as shown 7 Tip primary lead B to high tension lead as shown 8 Loosely install new ignition coil primary lead B and grommet C with two bolts A as shown Set pole shoe air gaps Refer to 3 9 Setting pole shoe air gaps Tighten two bolts A D B 3 9 Setting pole shoe air gaps 1 Loosen two bolts A and insert module air gap gauge 91004 B or 0 3 0 4 mm 0 012 0 016 in thick feeler gauge between flyw...

Page 25: ...OTE Do not use power tool to remove nut C Otherwise piston damage may occur 6 Remove starter pawls Then set puller Y089 000110 or Y089 000111 D on flywheel as shown 7 Tighten two nuts d1 on puller alternately to re move flywheel 8 Wipe off oil from taper part of crankshaft and fly wheel before assembling flywheel 9 Inspect woodruff key E for damage or shear ing Replace it as required 10 Install wo...

Page 26: ...e C Fuel strainer O Air cleaner case D Fuel line P Intake gasket E Fuel return line Q Carburetor F Tank vent R Insulator plate G Tank vent line S Cable holder H Fuel line grommet T Intake insulator J Stand U Intake bellows K Air cleaner cover V Intake gasket L Element plate W Purge bulb J K L M N D E G A B F C H P O Q R S T U V W ...

Page 27: ...ay carefully and thoroughly by widening the grooves of filter WARNING DANGER Wear eye protection when working with compressed air Eye damage can occur from flying particles 3 Replace air filter if heavily soiled or damaged 4 2 Inspecting fuel cap and fuel strainer 1 Remove fuel cap 2 Inspect fuel cap for cracks and gasket A for cuts or damage and replace with new one as re quired 3 Replace connect...

Page 28: ...ne The pressure should stay at or above 10 kPa 0 1 kgf cm2 1 5 psi If pressure drops under 10 kPa 0 1 kgf cm2 1 5 psi tank vent or tank vent line is defective NOTE Tank vent prevents a vacuum from forming in fuel tank when fuel in fuel tank is being con sumed When pressure in fuel tank becomes too high tank vent releases the pressure 5 Remove tank vent D from tank vent line and connect pressure te...

Page 29: ... cm2 1 4 6 psi 3 If it is not in the range gently clean tank vent with compressed air or replace with new one NOTE Do not disassemble valves in tank vent as sembly Damage to valves will occur 4 Remove cap F of tank vent D and clean sponge G 5 Cut pipe 363011 00210 H 7x11x170mm and 382011 01110 J 9x13x350 in approximate ly 30mm 1 1 4 in length and connect them to pressure tester as shown Connect ta...

Page 30: ...t line C Fuel strainer can be directly pulled out through grommet hole 3 Remove fuel line E from fuel line A Remove fuel line A fuel return line B and tank vent line C from fuel line grommet D If line is defective replace with a new one 4 Insert new line and adjust length as follows Line A B C Fuel line Fuel return line Tank vent line Black Yellow Transparent Black Length 130 140 140 mm in 5 12 5 ...

Page 31: ... together with pipe connector H and clips J dia 5 5 mm K dia 6 mm as shown 6 Connect tank vent L to tank vent line C with clip M and tank vent cap N as shown Cover tank vent line C by protect tube P as shown 7 Install grommet D with lines and fuel strainer to fuel tank as shown 8 Put tank vent K in place as shown Connect fuel line A to carburetor and fuel return line B to purge bulb D E A F G H J ...

Page 32: ...Throttle adjust screw Confirm WOT engine speed 9 000 to 10 000 r min If engine does not run correctly after this adjustment proceed to the next step 2 2 4 5 2 Throttle adjust screw L mixture needle and H mixture needle initial settings Tools Required Small screwdriver with 2 5 mm blade P N PET304 Tachometer PET 304 and P N X645 000031 Large D shaped A 1 Turn L and H mixture needle clockwise until ...

Page 33: ...ust H mixture needle C to reach maximum WOT engine speed Then turn H mixture needle C counterclockwise to reduce WOT engine speed 120 r min 6 SRM 420ES L T410S Stop engine Install shield with knife Restart engine and verify engine idle speed ranges from 2 400 to 3 200 r min and WOT engine speed ranges from 9 500 to 10 500 r min SRM 420ES U B410S Stop engine and re install shield and the blade Rest...

Page 34: ... needle valve for sticking or metering lever height is too low 7 If pressure drops at step 3 or if pressure drops below standard figure at step 5 remove pulse pipe C and purge line D from carburetor then re move carburetor from the unit 8 Submerge carburetor in suitable clean solvent to locate the leak by applying pressure approx 100 kPa 1 kgf cm2 14 psi 9 If air bubbles come out between pump cove...

Page 35: ...y to keep dropped oil in the pulse pipe 4 8 Inspecting metering lever height 1 Remove carburetor 2 Remove screws A metering diaphragm cover B metering diaphragm C and gasket D 3 Inspect metering lever E height by Metering lever gauge 897563 19830 F Metering lever height 1 65 mm 0 065 in lower than diaphragm seat G 4 If necessary gently bend metering lever E up or down to set metering lever to prop...

Page 36: ...as follows 1 Spring is seated in its hole at chamber floor 2 Spring is under dimple of metering lever 3 metering lever fork is holding inlet needle valve 4 10 Inspecting diaphragm and others 1 Inspect metering diaphragm A for hardening distortion or pin hole Replace as required 2 Remove pump cover F pump diaphragm D and pump gasket E 3 Inspect pump diaphragm D and replace if hardened or curled at ...

Page 37: ...ool B is included in welch plug tool 500 500 3 Clean low speed ports with compressed air 4 Place a new welch plug over the opening and gently tap it until flush using welch plug installer C 5 Install all removed parts to carburetor body 4 12 Replacing purge bulb 1 Remove carburetor Disconnect fuel return line A from purge bulb 2 Remove purge bulb B with insulator plate C D and cable holder E 3 Rem...

Page 38: ...placing igni tion switch U handle type 1 Referring to 3 5 Replacing ignition switch re move right handle grip half 2 Remove throttle lockout K and throttle trigger L with torsion springs M throttle cable N igni tion switch O and corrugated tube P from rear handle Check parts and replace with new one if defective 3 Pull out throttle cable N from corrugated tube P Pass new throttle cable through cor...

Page 39: ...S B410S T410TS B410TS CLUTCH SYSTEM 37 5 CLUTCH SYSTEM A Retaining ring B Clutch case C Ball bearing D Retaining ring E Clutch drum F Flat spring G Spring H Clutch shoe J Spacer K Clutch hub L Clutch assembly H F E J C B A G D L K ...

Page 40: ...ston stopper Then release rope 3 Pre assemble spacer B clutch shoes and spring A and flat spring C as shown then tight en them with two bolts D 4 Remove piston stopper and reinstall the parts that have been removed in place 5 1 Removing clutch shoes and spring 1 Remove four bolts and remove clutch case A 2 Check clutch shoes B for wear or damage Replace clutch shoes as follows if they have a de fe...

Page 41: ...clutch case B 2 Remove two ball bearings C together from clutch case B using shaft D and boss E of bearing tool 897701 14732 as shown 5 3 Removing clutch drum 1 Remove retaining ring A from clutch drum shaft b using needle nose pliers 2 Push out clutch drum B using press machine with 12 mm 0 47 in diameter pusher C A B C b A D B C E ...

Page 42: ...ase until those bottom To install bearings A use bearing tool 897701 14732 B as shown Outer diameter of adapter b 27 5 mm 3 Check bearings for rotating smoothly 4 Install retaining ring C in the groove of clutch case bore 5 Push center d of clutch drum D in ball bear ings with press machine until it bottoms 6 Make sure clutch drum rotates freely 7 Install retaining ring E in groove of crutch drum ...

Page 43: ...S ENGINE 41 6 ENGINE A Cylinder B Cylinder gasket C Piston ring D Piston E Piston pin F Snap ring G Piston pin spacer H Needle bearing J Crankshaft assembly K Crankcase gasket L Ball bearing M Oil seal N Crankcase L K H G N J M M E F D C B A F G L N ...

Page 44: ...port piston crown and muffler for carbon deposits NOTE Compression pressure varies with volume of compression gauge tip occupying cylinder com bustion chamber When you use other than the tool 91037 A it is recommended to measure and note compression pressure of brand new engines as standard pressure in advance 6 2 Cleaning cooling air passages 1 Inspect air intake grid A If blocked with leaves or ...

Page 45: ...found NOTE When cleaning exhaust port always posi tion piston at Top Dead Center TDC to prevent carbon from entering cylinder Do not use metal tool and be careful not to scratch piston or cylin der 3 Remove three bolts and remove muffler lid D muffler lid gasket E and spark arrestor screen F from muffler A 4 Remove carbon deposits from spark arrestor screen F and muffler lid D If screen has heavy ...

Page 46: ...6 If the reading drops leakage may occur 7 Leakage may occur from crankcase seam or oil seal Use soapy water to locate leakage 8 Then apply negative pressure approx 0 03 MPa 0 3 kgf cm2 4 psi by pressure vacuum tester and leave for 30 seconds 9 If the reading drops leakage may occur from oil seal Inspect oil seal for damage or wear 10 Remove plugs from exhaust port and intake port after this inspe...

Page 47: ...nd D ring grooves and skirt E Clean them with soft cleaning brush C if carbon is found NOTE Do not use square end of broken piston ring when cleaning piston ring groove otherwise piston ring groove might be damaged 4 Remove snap rings F from both sides of piston pin 5 Push piston pin out from piston with piston hold er 897719 02830 G NOTE If piston pin is tight use piston pin tool 897702 30131 H w...

Page 48: ...ankshaft and screw it three turns 6 Screw bolt 900100 08008 D in flange nut C until it bottoms 7 Hold the other crankcase half and tap the bolt head axially using plastic hammer to remove crankshaft 8 Clean inside of crankcase halves if they are dirty Replace them as a set if damaged 9 Inspect connecting rod big end and needle bearing for discoloration or damage Replace crankshaft with a new one a...

Page 49: ...apter D inner dia 12 mm outer dia 27 5 mm as shown 8 Tighten shaft B with a wrench to press ball bearing into the crankcase half NOTE Preheat around bearing housing of crank case using a floodlight or a suitable heater for easier assembly 9 Check that bearing is seated to the bottom and rotates smoothly Install new oil seal A B C A B D 6 8 Replacing oil seal continued 4 Apply lithum based grease o...

Page 50: ...ten four bolts to secure the crankcase halves together and check the crankshaft rotation NOTE Tighten four bolts with standard torque refer to 1 3 Torque limits 6 Carefully remove protruding portion of crank case gasket C with a sharp knife 6 11 Installing piston 1 Place piston over the small end of connecting rod so that the arrow mark A on piston points to ward muffler 2 Insert piston pin guide ...

Page 51: ...e glue for easier installation of cylinder 3 Apply oil to piston ring and internal wall of cylin der 4 Install cylinder over piston ensuring that the ex haust side of cylinder should face the arrow side of piston NOTE When installing cylinder it is convenient to use piston holder 897719 02830 B for stabilizing piston NOTE When installing piston in cylinder do not twist cylinder to avoid breakage o...

Page 52: ...S T410TS and B410TS F Washer G Adapter plate H Drive gear J Driven gear K Gear case L Blade fixture M Cover plate 7 1 Replacing drive shaft 1 Separate main pipe A from engine by loosen ing bolts B NOTE For U handle type refer to 3 5 Replacing ignition switch 2 Pull out drive shaft C from main pipe A 3 Inspect drive shaft for damage distortion and both ends of shaft for wear Replace the shaft as re...

Page 53: ... set 897701 14732 vertically against a flat surface F several times until drive gear with two ball bearings SRM 420TES T410TS and B410TS three ball bearings come out WARNING DANGER When using a heat gun put on gloves Otherwise a burn will result 6 Remove retaining ring G from the groove of gear case using pliers then remove the washer 7 Connect PTO shaft puller P021 044870 H with connector h1 to P...

Page 54: ...ing needle nose pliers 2 Lubricate inside of new ball bearings with small amount of lithium based grease and then install them on new drive gear using oil seal tool 897726 21430 F Install new retaining ring to the drive gear 3 Remove ball bearing G from PTO shaft us ing bearing wedge 897701 06030 H or two screw drivers and remove driven gear J from PTO shaft 4 If PTO shaft or ball bearing K is dam...

Page 55: ...aft 7 Insert PTO shaft in a new ball bearing P until the end of shaft is flush with bearing For SRM 420TES T410TS and B410TS 5 If retaining ring L is defective replace with a new one 6 Install a new ball bearing M to PTO shaft us ing oil seal tool 897714 24330 F 7 Install a new driven gear N to PTO shaft 8 Install a new ball bearing P to PTO shaft un til it becomes slightly lower than groove Q as ...

Page 56: ...4 Install new retaining ring C to the groove of gear case 5 Insert drive gear assembly D into gear case NOTE 28 mm diameter main pipe cut to a suitable length can be used as a pusher NOTE Make sure the gears can move smoothly If it does not reheat up gear case to bring the gears back into correct position 6 Install new retaining ring E to the groove of the gear case bore 7 Fill gear case with abou...

Page 57: ...1 Needle bearing 6 11 Cylinder cover Inner cylinder cover Fan cover Piston 6 6 Crankcase 6 7 Ball bearings 5 4 Ball bearings 6 9 Crankshaft 6 7 Oil seal clutch side 6 8 Oil seal starter side 6 8 Flywheel 3 10 6 6 Piston rings Muffler cover 5 3 Clutch drum Stand Carburetor 4 6 Cylinder 6 5 Muffler 6 3 Starter assembly 2 1 Ignition coil 3 8 Fuel tank Clutch case 5 1 ...

Page 58: ...re extremely noisy Fuel consumption is excessive Vibration is excessive Engine does not stop Nylon cord head does not rotate Nylon cord head does not cut well CHECKING Starter system Starter pawl spring Rewind spring Ignition system Sparks Spark plug Spark plug cap coil Ignition switch Ignition coil Pole shoe air gaps Flywheel 2 5 2 3 3 2 3 3 3 7 3 4 3 5 3 6 3 8 3 9 3 10 Continued 15 Starter drum ...

Page 59: ...haust system Cooling air passage Muffler exhaust port Cylinder compression Crankcase cylinder seal Cylinder crankcase Piston piston ring 7 1 6 2 6 3 6 1 6 4 6 5 6 7 6 10 6 6 6 11 6 12 Gears Bearings 7 2 7 3 7 4 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 Crankcase pulse passage 4 7 Throttle control parts 3 5 4 13 Purge bulb 4 12 Clutch Cutter drive system Clutch shoes spring Clutch drum Clutch dr...

Page 60: ...spect Clean 6 2 Spark plug Clean Regap 3 3 Inspect Replace Fuel strainer Clean Replace 4 2 Leads and connections Inspect Repair 3 5 Fuel tank Clean inside Muffler and exhaust port Clean 6 3 Starter system Inspect Repair 2 2 2 5 Daily Inspecting in every services IMPORTANT Service intervals shown above are maximum Actual use and your experience will determine the frequency of required maintenance R...

Page 61: ...59 SRM 420ES SRM 420TES T410S B410S T410TS B410TS MEMORANDUM 59 ...

Page 62: ...SRM 420ES SRM 420TES T410S B410S T410TS B410TS 60 MEMORANDUM 60 ...

Page 63: ...61 SRM 420ES SRM 420TES T410S B410S T410TS B410TS MEMORANDUM 61 ...

Page 64: ...Published by YAMABIKO Corp Tokyo Japan 1805 ...

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Yamabiko ECHO SRM-420ES, Service Manual

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