Echo CS-2511WES Service Manual
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Echo CS-2511WES Service Manual

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CS-2511WES
ECHO:
251Ws
shindaiwa:
(Serial number: 38000001 and after)
Ref. No. 401-44
Copyright C 2019 YAMABIKO Corporation All rights reserved.

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  • Page 1 CS-2511WES ECHO: 251Ws shindaiwa: (Serial number: 38000001 and after) Ref. No. 401-44 Copyright C 2019 YAMABIKO Corporation All rights reserved.
  • Page 2 INTRODUCTION This service manual contains information for ser- vice and maintenance of ECHO CHAIN SAW, model CS-2511WES and shindaiwa CHAIN SAW, model 251Ws. For systematic diagnosis, to avoid extra work, time loss and to meet Emission regulation, please refer to “Troubleshooting guide” that describes problems, testing, remedies and references.

  • Page 3: Table Of Contents

    CS-2511WES 251Ws TABLE OF CONTENTS Page Page 1 SERVICE INFORMATION ........2 6 CHAIN BRAKE SYSTEM ........42 1-1 Specifications ............2 6-1 Replacing brake lever and torsion spring ..42 1-2 Technical data ........... 3 6-2 Inspecting chain brake parts ......44 1-3 Torque limits ............

  • Page 4: Service Information

    CS-2511WES 251Ws SERVICE INFORMATION 1 SERVICE INFORMATION 1-1 Specifications Dimensions Length* mm(in) 400 (15.7) Width mm(in) 213 (8.4) Height mm(in) 210 (8.3) Dry weight* kg(lb) 2.6 (5.7) Engine Type YAMABIKO, air-cooled, two-stroke, single cylinder Rotation Clockwise as viewed from the output end Displacement 25.0 (1.525)

  • Page 5: Technical Data

    CS-2511WES 251Ws SERVICE INFORMATION 1-1 Specifications (continued) Cutting devices Sprocket nose bar Guide bar Type C20S91-35SA C25S91-40SL C30S91-47ML Called length Gauge 0.050 Saw chain Type Carlton N1C-BL, OREGON 91PX Number of drive links Pitch Gauge 0.050 Sprocket Number of teeth...
  • Page 6 CS-2511WES 251Ws SERVICE INFORMATION 1-2 Technical data (continued) Carburetor adjustment Mixed two-stroke Mixed two-stroke Premixed Fuel type regular fuel E10 fuel alkylate fuel 1) Initial setting H mixture needle turn out 1 3/4 2 1/4 L mixture needle turn out...

  • Page 7: Torque Limits

    CS-2511WES 251Ws SERVICE INFORMATION 1-3 Torque limits Descriptions Size kgf•cm N•m in•lbf Starter system Starter pawl Starter case Ignition system Magneto rotor (Flywheel) Ignition coil Ignition switch Spark plug Fuel system Carburetor Intake bellows Clutch Clutch hub Engine Crankcase Cylinder Engine mount Muffler †...

  • Page 8: Service Limits

    CS-2511WES 251Ws SERVICE INFORMATION 1-5 Service limits Description mm (in) A Cylinder bore When plating is worn and aluminium can be seen Piston outer diameter Min. 34. 92 (1.375) Piston pin bore Max. 8. 035 (0.3163) Piston ring groove Max. 1. 3 (0.051)

  • Page 9: Cs-2511Wes 251Ws

    CS-2511WES 251Ws SERVICE INFORMATION 1-6 Special tools 3, 4 Part Number Description Reference 897802-33330 Tachometer PET-1000R Measuring engine speed to adjust Carburetor Y089-000095 Carburetor Adjustment tool Adjusting Carburetor X602-000330 Torx wrench (T25) Removing and installing Torx bolt X602-000340 Torx wrench (T27)

  • Page 10: Starter System (Es-Start / S-Start)

    CS-2511WES 251Ws STARTER SYSTEM 2 STARTER SYSTEM (ES-start / S-start) (A) Starter case (B) Fan cover (C) Rewind spring (D) Rewind spring case (E) Rope reel (F) Power spring (G) Pawl catcher (H) Screw (J) Starter rope (K) Starter grip...

  • Page 11: Disassembling Starter Assembly

    CS-2511WES 251Ws STARTER SYSTEM 2-1 Disassembling starter assembly 1. Remove three bolts and starter assembly (A) from the unit. 2. Remove fan cover (B) from starter assembly (A). 3. Pull out starter rope about 30cm (12in) and hold rope reel (D) by hand. Loop excess rope in rope reel notch (d) as shown.

  • Page 12: Replacing Starter Rope

    CS-2511WES 251Ws STARTER SYSTEM 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 a new starter rope, singe both ends of the rope to prevent fraying.

  • Page 13: Assembling Starter

    CS-2511WES 251Ws STARTER SYSTEM 2-3 Assembling starter 1. If rewind spring (A) is unwound from rewind spring case (B), wind the spring (A) inside case (B) as shown. NOTE : Apply small amount of lithium based grease to rewind spring case (B), before wind the spring.
  • Page 14 CS-2511WES 251Ws STARTER SYSTEM 2-3 Assembling starter (Continued) 6. Check for proper engagement of rewind spring and rope reel (F) by turning rope reel (F) clockwise and counterclockwise. 7. Apply small amount of lithium based grease to power spring mounting groove (f3) of the rope reel (F).

  • Page 15: Replacing Starter Pawl

    CS-2511WES 251Ws STARTER SYSTEM 2-3 Assembling starter (continued) 13. Pull out starter rope all the way, and check that rope reel (F) can be rotated an additional half or more turn clockwise as shown, to prevent rewind spring from breaking.

  • Page 16: Ignition System

    CS-2511WES 251Ws IGNITION SYSTEM 3 IGNITION SYSTEM (A) Ignition switch (B) Spark plug (C) Spark plug cap coil (D) Spark plug cap (E) Ignition coil (F) Bolt (M4) (G) Collar (H) Flywheel (J) Nut (M8) (K) Woodruff key...

  • Page 17: Troubleshooting Guide

    CS-2511WES 251Ws IGNITION SYSTEM 3-1 Troubleshooting guide Start Remedy Inspect S.T. Pole shoe air Adjust pole shoe air gaps. gaps Clean / Spark plug Regap / S.T. Replace. S.T. Flywheel Replace flywheel. magnet Spark Replace. S.T. plug cap/ coil Ignition Woodruff Replace.

  • Page 18: Testing Spark

    CS-2511WES 251Ws IGNITION SYSTEM 3-2 Testing spark 1. Unhook ring (A) with screwdriver (B) or equiva- lent and open cap cover (C). 2. Remove spark plug cap (D) from spark plug (E). 3. Connect spark plug cap (D) to spark tester 897800-79931 (F), and connect spark tester lead (G) on spark plug (E) as shown.

  • Page 19: Inspecting Spark Plug

    CS-2511WES 251Ws IGNITION SYSTEM 3-3 Inspecting spark plug 1. Remove spark plug from the unit. 2. Inspect for spark plug gap fouling, cracked or broken insulator, cracked outer electrode, or rounded center electrode. Replace spark plug as required. Spark plug gap (A) Standard : 0.9 to 1.0 mm (0.035 to 0.039 in) 3.

  • Page 20: Inspecting Ignition Switch

    CS-2511WES 251Ws IGNITION SYSTEM 3-5 Inspecting ignition switch 1. Remove starter assembly. 2. Connect one probe of ohm-meter or multi-meter to ignition switch terminal (A). Connect the other probe to another ignition switch terminal (B). 3. When ignition switch is “RUN” position, tester should indicate infinite resistance.
  • Page 21 CS-2511WES 251Ws IGNITION SYSTEM 3-6 Replacing ignition switch (Continued) 4. Remove ignition switch (G) from the unit as shown. {Installing} 5. Install new ignition switch. 6. Pass switch lead (h1) through rib (J1) and then pass switch lead (h2) over the lead (h1) as shown.

  • Page 22: Replacing Ignition Coil

    CS-2511WES 251Ws IGNITION SYSTEM 3-7 Replacing ignition coil 1. Remove starter assembly. 2. Disconnect spark plug cap from spark plug. 3. Remove front handle (A) with two bolts (Refer to 9-2 Replacing front handle and spring). 4. Remove bolt (B) and spring (C). 5. Remove two bolts (D). Disconnect ignition switch terminal (E) from ignition coil (F).

  • Page 23: Setting Pole Shoe Air Gaps

    CS-2511WES 251Ws IGNITION SYSTEM 3-8 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 flywheel (C) and ig- nition coil shoes (D).
  • Page 24 CS-2511WES 251Ws IGNITION SYSTEM 3-9 Inspecting flyweel and woodruff key (Continued) 5. Remove nut (E) by rotating counterclockwise. NOTE: Do not use power tool to remove nut (E). Otherwise, piston damage may occur. 6. Remove starter pawls. Then set puller Y089- 000111 (F) on flywheel (A) as shown.

  • Page 25: Fuel System

    CS-2511WES 251Ws FUEL SYSTEM 4 FUEL SYSTEM (K2) (K1) (R2) (K3) (R1) (T) (U) (A) Air cleaner cover (N) Joint (black) (B) Air filter (P) Purge line (L-shaped) (C) Fuel cap (Q) Purge bulb (D) Gasket (R1)Fuel return line (3x5x58mm)

  • Page 26: Inspecting Air Filter

    CS-2511WES 251Ws FUEL SYSTEM 4-1 Inspecting air filter 1. Close choke shutter. Remove air cleaner cover. 2. Remove air filter (A), twisting as shown in the picture. 3. Inspect the air filter. If blocked with dirt or dust, remove the obstruction using brush.

  • Page 27: Replacing Air Cleaner Cover Latch

    CS-2511WES 251Ws FUEL SYSTEM 4-2 Replacing air cleaner cover latch 1. Remove air cleaner cover. 2. Remove air cleaner cover latch (A) from rear handle. 3. Install air cleaner cover latch (A) to bar (B) of rear handle as shown. NOTE: Check air cleaner cover latch (A) for mov- ing smoothly.
  • Page 28 CS-2511WES 251Ws FUEL SYSTEM 4-4 Inspecting fuel tank and line 1. Clean fuel tank inside as required. 2. Remove rear handle (Refer to 9-3 Replacing rear handle and springs). 3. Remove dust cover (A) from enigne cover. 3. Connect fuel line (B) with black joint (C) to pres- sure tester 897803-30133 (D) as shown.

  • Page 29: Inspecting And Replacing Tank Vent

    CS-2511WES 251Ws FUEL SYSTEM 4-5 Inspecting and replacing tank vent 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. 1. Remove dust cover (Refer to 4-4 Inspecting fuel tank and line).
  • Page 30 CS-2511WES 251Ws FUEL SYSTEM 4-5 Inspecting and replacing tank vent (continued) NOTE: Inspection using 897803-30133 If pressure tester 91149 is not available, tank vent can be inspected with pressure tester 897803- 30133 as follows. 1. Connect tank vent (A) to pressure tester 897803-30133 (B).

  • Page 31: Replacing Purge Bulb

    CS-2511WES 251Ws FUEL SYSTEM 4-6 Replacing purge bulb {Removing} 1. Remove rear handle (Refer to 9-3 Replacing rear handle and springs ). 2. Press leg (a1) of purge bulb (A) with screwdriver to remove purge bulb (A) from rear handle. 3. Disconnect parge line (B) and fuel return line (C) from purge bulb (A).

  • Page 32: Replacing Fuel Line And Fuel Return Line

    CS-2511WES 251Ws FUEL SYSTEM 4-7 Replacing fuel line and fuel return line {Removing} 1. Remove dust cover (Refer to 4-4 Inspecting fuel tank and line). 2. Disconnect fuel line (A) from black joint (B) and (C). Inspect fuel line (A) and replace with new one if defective. 3. Disconnect fuel return line (D) from grommet (E) and white joint (F).
  • Page 33 CS-2511WES 251Ws FUEL SYSTEM 4-7 Replacing fuel line and fuel return line (continued) 12. Reinstall fuel line (G) through grommet (E) as shown. 13. Connect fuel line (A) and (G), using black joint (B). NOTE: Make sure of black joint (B) direction.

  • Page 34: Adjusting Carburetor

    CS-2511WES 251Ws FUEL SYSTEM 4-8 Adjusting carburetor 4-8-1 General adjusting rules A. Before starting the unit for adjustment, check the following items. 1. The correct spark plug must be clean and properly gapped. 2. The air filter element must be clean and properly installed. 3. The muffler exhaust port must be clear of carbon.

  • Page 35: Adjusting Carburetor

    CS-2511WES 251Ws FUEL SYSTEM 4-8 Adjusting carburetor (continued) 4-8-3 Adjusting carburetor PI controller installed model has 2 mode; Carburetor adjustment mode and Operation mode. When adjusting carburetor, must be changed from Operation mode to Carburetor adjustment mode in the following steps. 1. Start engine without brake activated. Do not touch throttle lever.

  • Page 36: Testing Carburetor

    CS-2511WES 251Ws FUEL SYSTEM 4-9 Testing carburetor NOTE: To perform this test, carburetor interior should be wet with fuel. If dry, a little leakage may occur. 1. Remove air cleaner cover, air filter and carbure- tor. 2. Connect pressure tester 897803-30133 (A) to carburetor fitting (B).

  • Page 37: Inspecting Crankcase Pulse Passage

    CS-2511WES 251Ws FUEL SYSTEM 4-10 Inspecting crankcase pulse passage 1. Remove carburetor. 2. Drop a little oil in pulse hole (A). 3. Remove spark plug and pull starter grip several times. Oil should spit back from the hole (A). 4. If not, remove collar (B) and inspect whether pulse passage of collar (B), intake bellows (C) and cylinder are clogged.

  • Page 38: Inspecting Inlet Needle Valve

    CS-2511WES 251Ws FUEL SYSTEM 4-12 Inspecting inlet needle valve 1. Remove metering lever (A) and pivot pin. Re- move spring (B) and inlet needle valve (C). 2. Inspect inlet needle valve if worn or sticky. Clean or replace as required.

  • Page 39: Inspecting Diaphragm And Others

    CS-2511WES 251Ws FUEL SYSTEM 4-13 Inspecting diaphragm and others 1. Inspect metering diaphragm (A) for hardening, distortion, or pin hole. Replace as required. 2. Remove pump cover (B), pump diaphragm (C) and pump gasket (D). 3. Inspect pump diaphragm (C) and replace if hardened or curled at valve tabs.

  • Page 40: Installing Carburetor

    CS-2511WES 251Ws FUEL SYSTEM 4-15 Installing carburetor 1. Connect throttle rod (A) to throttole lever (B), passing under choke knob (K) as shown. 2. Connect purge line (C) and joint (D) of carbure- tor and install fuel inlet (E) of carburetor to fuel line (F).

  • Page 41: Clutch System

    CS-2511WES 251Ws CLUTCH SYSTEM 5 CLUTCH SYSTEM (A) Clutch assembly (B) Clutch hub (C) Clutch shoe (D) Spring (E) Clutch plate (F) Clutch drum (G) Needle bearing 5-1 Inspecting clutch parts 1. Loosen nut (A) and remove sprocket guard (B).
  • Page 42 CS-2511WES 251Ws CLUTCH SYSTEM 5-1 Inspecting clutch parts (continued) 4. Rotate clutch assembly (D) clockwise by hand until it cannot be rotated further. 5. Remove clutch assembly (Left-hand thread) (D), rotating with wrench (E). NOTE: Do not use power tools. Otherwise, piston damage may occur.

  • Page 43: Replacing Clutch Parts

    CS-2511WES 251Ws CLUTCH SYSTEM 5-2 Replacing clutch parts 1. Install clutch springs (A) to clutch shoes (B). NOTE : Make sure to have ends of clutch springs (A) face clutch hub (C) 2. Set one arm of clutch hub (C) to one clutch shoe (B).

  • Page 44: Chain Brake System

    CS-2511WES 251Ws CHAIN BRAKE SYSTEM 6 CHAIN BRAKE SYSTEM (A) Brake lever (B) Bolt (M5) (C) Torsion spring (D) Collar (E) Sprocket guard (F) Collar (G) Brake connector (H) Pin (J) Brake band (K) Spacer (L) Compression spring (M) Brake cover...
  • Page 45 CS-2511WES 251Ws CHAIN BRAKE SYSTEM 6-1 Replacing brake lever and torsion spring (continued) 3. Remove bolt (D) using torx wrench (T25). 4. Remove collar (E), then remove brake lever (F). WARNING DANGER Wear eye protection and take care when re- moving brake lever. Torsion spring may come out suddenly and cause personal injury. 5. Remove torsion spring (G) from brake lever (F) 6.

  • Page 46: Inspecting Chain Brake Parts

    CS-2511WES 251Ws CHAIN BRAKE SYSTEM 6-2 Inspecting chain brake parts WARNING DANGER Wear eye protection and safety gloves when disassembling or assembling chain brake to protect eye and hand from injury. {Disassembling} 1. Remove sprocket guard. 2. Move brake connector (A) with ring wrench (B) or other suitable tool as shown. And make brake connector engaging position. NOTE: Make sure that brake connector (A) is in engaging position before removing brake cover (C), otherwise compression spring may jump out.
  • Page 47 CS-2511WES 251Ws CHAIN BRAKE SYSTEM 6-2 Inspecting chain brake parts (continued) 8. Apply molybdenum grease to collar (J). and then put collar (J) on boss (K) of sprocket guard. 9. Set brake connector (A), brake band (H) with pin (G) and spacer (M) in sprocket guard as shown .

  • Page 48: Saw Chain Lubrication System

    CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7 SAW CHAIN LUBRICATION SYSTEM (A) Oil cap (B) Gasket (C) Connector (D) Oil tank (E) Oil tank vent (F) Oil strainer (G) Oil line (H) Auto-oiler assembly (J) Oil line (K) Bolt (M4)

  • Page 49: Inspecting Oil Tank Vent

    CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-2 Inspecting oil tank vent NOTE: Oil tank vent prevents a vacuum from forming in oil tank when chain oil in the tank is con- sumed. 1. Remove starter assembly. 2. Push oil tank vent (A) into oil tank using suitable tool and take out vent (A) from oil tank.

  • Page 50: Inspecting And Replacing Oil Line

    CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-3 Inspecting and replacing oil line {Inspecting and removing oil line} 1. Remove sprocket guard, clutch assembly, clutch plate, clutch drum and needle bearing (Refer to 5-1 Inspecting clutch parts). 2. Remove two bolts and muffler cover (A). 3. Remove oiler cover (B).

  • Page 51: Inspecting Worm Gear

    CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-4 Inspecting worm gear 1. Remove sprocket guard, clutch assembly, clutch plate, clutch drum and needle bearing (Refer to 5-1 Inspecting clutch parts). 2. Remove worm gear (A) and circular washer (B). 3. Inspect worm gear (A) and circular washer (B) for damage, wear or deformation.

  • Page 52: Cleaning And Replacing Auto-Oiler Assembly

    CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-5 Cleaning and replacing auto-oiler assembly {Cleaning and disassembling} 1. Remove sprocket guard, clutch assembly, clutch plate, clutch drum and needle bearing (Refer to 5-1 Inspecting clutch parts). 2. Remove muffler cover, oiler cover, worm gear and circular washer (Refer to 7-4 Inspecting worm gear ).
  • Page 53 CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-5 Cleaning and replacing auto-oiler assembly (continued) 14. When plunger gear (E) cannot be rotated, ap- ply nail-polish remover (N) to plunger gear (E) on auto-oiler (B) and leave it a few minutes. 15. Tap 5-mm (M5 - Pitch 0.8mm) thread in the hole of plug (P).
  • Page 54 CS-2511WES 251Ws SAW CHAIN LUBRICATION SYSTEM 7-5 Cleaning and replacing auto-oiler assembly (continued) 26. Push in plunger gear (E) with small screw- driver, and hold plunger gear (E) to direction of arrow with finger. Remove screwdriver. 27. Install adjuster needle (K) with spring (L) into oiler body.

  • Page 55: Engine

    CS-2511WES 251Ws ENGINE 8 ENGINE (V) (W) (X) (A) Crankcase (L) Snap ring (V) Bolt (M5) (B) Oil seal (M) Piston (W) Spark arrester screen (C) Ball bearing (N) Piston ring (X) Screw (M4) (D) Gasket (Crankcase) (O) Cylinder (Y) Engine cover...

  • Page 56: Testing Cylinder Compression

    CS-2511WES 251Ws ENGINE 8-1 Testing cylinder compression NOTE: Test cylinder compression when engine is cold. 1. Move ignition switch to STOP position. 2. Open cap cover and remove spark plug (Refer to 3-2 Testing spark). 3. Remove valve core (A) from compression gauge 91037 (B) and insert valve core (A) to adapter X681-000000 (C) with valve core driver (D).

  • Page 57: Cleaning Cooling Air Passages

    CS-2511WES 251Ws ENGINE 8-2 Cleaning cooling air passages 1. Remove starter assembly (A) and fan cover (B). 2. Inspect starter assembly (A) and fan cover (B) for blockage with dirt and/or saw dust. Clean them with wooden or plastic stick or brush or com- pressed air as required.

  • Page 58: Inspecting Muffler And Exhaust Port

    CS-2511WES 251Ws ENGINE 8-3 Inspecting muffler and exhaust port 1. Remove sprocket guard and muffler cover. 2. Remove three bolts (A), muffler (B), exhaust gasket (C) and exhaust plate (D) from cylinder (E) NOTE : If exhaust gasket (C) stays on muffler (B), keep them as it is to reuse.

  • Page 59: Testing Crankcase And Cylinder Sealings

    CS-2511WES 251Ws ENGINE 8-4 Testing crankcase and cylinder sealings 1. Remove air cleaner cover, air filter and carbure- tor from the unit (Refer to 4-9 Testing carburetor ). 2. There are two ways to seal intake port and crankcase pulse passage. Choose convenient one from followings. Way1 : Install pressure plate 897827-16131 (A) and tighten M5 bolts (B) of 8-10 mm (0.3-0.4 in)

  • Page 60: Removing Engine Block

    CS-2511WES 251Ws ENGINE 8-4 Testing crankcase and cylinder sealings (continued) 7. Open cap cover and remove spark plug. 8. Install pressure connector A131-000160 (K) to spark plug hole (L). 9. Connect suitable pipe (inner dia. 4mm) (M) between pressure connector (K) and pressure/vac- cum tester 91149 (N) as shown.

  • Page 61: Inspecting Cylinder

    CS-2511WES 251Ws ENGINE 8-5 Removing engine block (continued) 4. Pull out engine block (B) as shown. 8-6 Inspecting cylinder 1. Remove four bolts securing cylinder (A) and re- move cylinder (A). NOTE : If it’s hard to remove cylinder (A), gently...

  • Page 62: Inspecting Piston And Piston Ring

    CS-2511WES 251Ws ENGINE 8-7 Inspecting piston and piston ring {Disassembling} 1. Inspect piston ring (A) and replace it if broken, scored, or exceeded service limits (Refer to 1-5 Service limits). 2. Inspect piston crown (B). Clean with fine sand paper, oil stone, and soft cleaning brush (C) if car- bon is found.

  • Page 63: Replacing Oil Seal

    CS-2511WES 251Ws ENGINE 8-7 Inspecting piston and piston ring (continued) NOTE: Make sure to place piston with piston arrow mark (P) pointing as shown. 10. Insert pin guide tool (Q) stamped “8”, through piston (H), with needle bearing (L) and piston pin spacers (M) set at step 9.

  • Page 64: Inspecting Crankcase And Crankshaft

    CS-2511WES 251Ws ENGINE 8-9 Inspecting crankcase and crankshaft 1. Remove cylinder, gasket and piston. 2. Remove woodruf key (A) from crankshaft fly- wheel end (B). 3. Remove three bolts (C) from crankcase assem- bly (D). 4. Set puller Y089-000111 (E) on crankcase as- sembly (D) as shown.

  • Page 65: Replacing Oil Seal And Ball Bearing

    CS-2511WES 251Ws ENGINE 8-10 Replacing oil seal and ball bearing {Disassembling} 1. After disassembling crankshaft, check ball bear- ing for smooth rotation. If rough, replace it (them) with new one. NOTE: At the same time, replace oil seal with new one. 2. Remove ball bearing (C) from crankcase half using bearing tool 897701-14732 as follows.

  • Page 66: Assembling Crankshaft And Crankcase

    CS-2511WES 251Ws ENGINE 8-11 Assembling crankshaft and crankcase 1. Clean mating surface of each crankcase half. 2. Heat ball bearing for easier installation. Then insert crankshaft clutch end (A) into clutch side crankcase half (B) until properly seated. WARNING DANGER When using a heat gun, wear gloves. Other- wise, a burn will result. 3. Put new crankcase gasket (C) on clutch side crankcase half (B).

  • Page 67: Installing Piston Ring And Cylinder

    CS-2511WES 251Ws ENGINE 8-12 Installing piston ring and cylinder 1. Completely remove gasket residue on mating surfaces of cylinder and crankcase. 2. If cylinder piece (A) came off from cylinder (B), reinstall it (A) to starter side scavenging port (b1) of cylinder as shown. 3. Set new cylinder gasket (C) on cylinder (B), as notch (c1) of gasket (C) aligns pulse hole (b2).

  • Page 68: Handle And Control System

    CS-2511WES 251Ws HANDLE AND CONTROL SYSTEM 9 HANDLE AND CONTROL SYSTEM (A) Front handle (B) Rear handle (C) Rear handle lid (D) Torsion spring (E) Throttle trigger (F) Throttle lockout (G) Throttle rod (H) Spring holder (J) Bolt (M4) (Q) Bolt (M4)

  • Page 69: Replacing Throttle Control Parts

    CS-2511WES 251Ws HANDLE AND CONTROL SYSTEM 9-1 Replacing throttle control parts {Disassembling} 1. Remove air cleaner cover, air filter and carbure- tor from the unit. 2. Remove ignition switch from rear handle lid (A). 3. Remove bolt (B) and then remove throttle con- trol parts.

  • Page 70: Replacing Front Handle And Spring

    CS-2511WES 251Ws HANDLE AND CONTROL SYSTEM 9-2 Replacing front handle and spring {Disassembling} 1. Remove bolt (A) and screw (B). 2. Remove clutch side (d1) of front handle (D) from rear handle. 3. Remove front handle (D), turning the handle as shown. 4. Remove bolt (E) and spring (F).

  • Page 71: Replacing Rear Handle And Springs

    CS-2511WES 251Ws HANDLE AND CONTROL SYSTEM 9-3 Replacing rear handle and springs {Disassembling} 1. Remove starter assembly, air cleaner cover and air filter. 2. Remove front handle and spring (Refer to 9-2 Replacing front handle and spring). 3. Remove sprocket guard, muffler cover, chain...
  • Page 72 CS-2511WES 251Ws HANDLE AND CONTROL SYSTEM 9-3 Replacing rear handle and springs (continued) 14. Install intake pipe (P) into groove (q1) of en- gine cover (Q) and then assemble rear handle. NOTE: Make sure boss (R) of rear handle insert to hole (q2) of enigne cover (Q) as shown.

  • Page 73: Guide Bar Mounting System

    CS-2511WES 251Ws GUIDE BAR MOUNTING SYSTEM 10 GUIDE BAR MOUNTING SYSTEM (A) Nut (B) Hook (C) Sprocket guard (D) Bevel gear (E) Tensioner screw (F) Chain tensioner (G) Bevel gear (H) Cover (J) Sprocket guard plate (K) Bolt (M4) (L) Bolt (M5)

  • Page 74: Replacing Chain Tensioner

    CS-2511WES 251Ws GUIDE BAR MOUNTING SYSTEM 10-2 Replacing chain tensioner {Disassembling} 1. Remove bolt (A), sprocket guard plate (B), cover (C), tensioner screw (D), chain tensioner (E), bevel gear (F) and (G) from sprocket guard (H). 2. Check removed parts for damage or wear. Re- place with new part(s) as required.

  • Page 75: Replacing Guide Bar Stud

    CS-2511WES 251Ws MAINTENANCE GUIDE 10-3 Replacing guide bar stud {Disassembling} 1. Remove chain catcher and sprocket guard plate from engine cover. 2. Install two nuts on defective stud (A) and tighten them against each other. 3. Turn nut (B) counterclockwise to remove stud. NOTE: If it is hard to remove or broken stud is too...

  • Page 76: Maintenance Guide

    CS-2511WES 251Ws MAINTENANCE GUIDE 11 MAINTENANCE GUIDE 11-1 Troubleshooting guide TROUBLE Engine does not crank. Engine does not start. Fuel leaks. Idling is not stable. Acceleration is poor. Engine stalls at high speed. Engine lacks power. Engine seizure / overheat Engine misfires.
  • Page 77 CS-2511WES 251Ws MAINTENANCE GUIDE 11-1 Troubleshooting guide (continued) INSPECTING Inspecting first. REFERENCES Fuel system / Carburetor 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 Air filter Fuel cap / strainer Carburetor adjustment Fuel tank/line/vent, Purge bulb...

  • Page 78: Disassembly Chart

    CS-2511WES 251Ws MAINTENANCE GUIDE 11-2 Disassembly chart Starter Sprocket assembly guard (2-1) Chain Air cleaner tensioner Starter cover (10-1) pawl Sprocket guard plate, (2-4) Chain catcher (6-1) Clutch Chain brake Muffler Air filter Flywheel assembly parts cover ( 5-1 to 5-3) (4-1)

  • Page 79: Service Intervals

    CS-2511WES 251Ws MAINTENANCE GUIDE 11-3 Service intervals Intervals Inspecting point Service Reference 3 months 6 months Daily or or 100 hours 300 hours Screws and bolts * Retighten / Replace Air filter Clean Inspect / Replace Carburetor Inspect / Repair 4-8 to 4-15...
  • Page 80 Published by YAMABIKO Corp. Tokyo Japan 1910...

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