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SUPPLEMENTARY
SERVICE MANUAL
LIT-19616-01-88
MZ250
MZ300
7VB-F8197-11

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Summary of Contents for Yamaha MZ250 2012

  • Page 1 SUPPLEMENTARY SERVICE MANUAL MZ250 MZ300 LIT-19616-01-88 7VB-F8197-11...
  • Page 3 7VB-F8197-10. LIT-19616-01-80 ards. Obey all safety messages that follow this symbol to avoid possible injury or This Manual Was Written By The Yamaha death. Motor Powered Products Co., Ltd. primarily for use by Yamaha dealers and their qualified WARNING mechanics.
  • Page 4 HOW TO USE THIS MANUAL This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid out with the individual steps in sequential order. 9 The manual is divided into chapters and each chapter is divided into sections.
  • Page 5 ILLUSTRATED SYMBOLS (Refer to the illustration) SYMBOL DEFINITION SYMBOL DEFINITION Periodic checks and General information adjustments Engine Carburetor Electrical Troubleshooting Specifications Filling fluid Lubricant Special tool Tightening torque Wear limit, clearance Engine speed Electrical data Replace the part with a new one. Lithium-soap base grease Molybdenum disulfide grease Engine oil...
  • Page 7 INDEX GENERAL INFORMATION INFO ENGINE ELECTRICAL ELEC SPECIFICATIONS SPEC...
  • Page 8: Table Of Contents

    CHAPTER 1. GENERAL TORQUE SPECIFICATIONS ........4-10 GENERAL INFORMATION LUBRICATION POINTS AND TYPE MACHINE IDENTIFICATION .....1-1 OF LUBRICANTS ........4-11 ENGINE SERIAL NUMBER ....1-1 STARTING SERIAL NUMBER ....1-1 WIRE ROUTING DIAGRAM ....4-12 UPPER SIDE VIEW ......4-12 DIMENSIONS ..........1-2 ENGINE SWITCH AND OIL DIMENSION CHART ......1-2 WARNING UNIT .........4-13 TOP (MZ250A/MZ300A) .......1-3...
  • Page 9: Chapter 1. General Information

    MACHINE IDENTIFICATION INFO GENERAL INFORMATION MACHINE IDENTIFICATION ENGINE SERIAL NUMBER The serial number is printed on the label 1 affixed to the position 2 of the multi-purpose engine as shown in the illustration. The first three digits identify the model, and the remaining digits indicates the production number.
  • Page 10: Dimensions

    DIMENSIONS INFO DIMENSIONS DIMENSION CHART Unit: mm Model (Code) PTO shaft dimensions (Type) Mounting face dimensions 94.5 å MZ250 AAIA0 7/16 -20UNF-2B (7KBJ) 88.5 6.31 72.2 MZ300 AAIA0 (7VBJ) 1.25  DEPTH18 3/8 -16UNC2B     DEPTH18 MZ250 KHID0 94.5 å (7KBN) 29.5 5/16 -24UNF-2B MZ300 KHID3 (7VBN) ∫...
  • Page 11: Top (Mz250A/Mz300A)

    DIMENSIONS INFO TOP (MZ250A/MZ300A) Unit: in (mm) 16.77 (426) LEFT SIDE (MZ250A/MZ300A) Unit: in (mm) 4.06 (103) 0.05 (1.25) DEPTH 0.71 (18)
  • Page 12: Right Side (Mz250A/Mz300A)

    DIMENSIONS INFO RIGHT SIDE (MZ250A/MZ300A) Unit: in (mm) 4.13 (105) 3.56 (90.5)
  • Page 13: Front (Mz250A/Mz300A)

    DIMENSIONS INFO FRONT (MZ250A/MZ300A) Unit: in (mm) 15.24 (387) 7.20 (183) 3.50 (89) 0.83 0.43 (11) (HOLE) (21) 2 0.43 (11) 1.06 (27) (SLOT HOLE) 2.32 1.46 2.26 (59) (37) (57.5) MOUNTING BASE (MZ250A/MZ300A) Unit: in (mm) 0.63 (16) 1.46 (37) 2.32 (59)
  • Page 14: Top (Mz250K/Mz300K)

    DIMENSIONS INFO TOP (MZ250K/MZ300K) Unit: in (mm) LEFT SIDE (MZ250K/MZ300K) Unit: in (mm) 7.09 (180) 5.75 (146) 10.63 (270) 7.09 (180.2) 5.61 (142.5) 4.06 (103) 0.05 (1.25) DEPTH 0.71 (18)
  • Page 15: Right Side (Mz250K/Mz300K)

    DIMENSIONS INFO RIGHT SIDE (MZ250K/MZ300K) Unit: in (mm)
  • Page 16: Front (Mz250K/Mz300K)

    DIMENSIONS INFO FRONT (MZ250K/MZ300K) Unit: in (mm) 15.91 (404) 7.87 (200) 4.15 (105.5) 0.83 0.43 (11) (HOLE) (21) 2 0.43 (11) 1.06 (27) (SLOT HOLE) 2.32 1.46 2.26 (37) (59) (57.5) MOUNTING BASE (MZ250K/MZ300K) Unit: in (mm) 0.63 (16) 1.46 (37) 2.32 (59)
  • Page 17: Chapter 2. Engine

    GOVERNOR ENGINE GOVERNOR MZ250A/MZ300A 1.1 Nm (0.11 m · kgf , 0.80 ft · lbf) 8 Nm (0.8 m · kgf, 5.8 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) Order Job/Parts to remove Q’ty Remarks Removing the governor Remove the parts in the order listed.
  • Page 18: Mz250K

    GOVERNOR MZ250K 8 Nm (0.8 m · kgf, 5.8 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) Order Job/Parts to remove Q’ty Remarks Removing the governor Remove the parts in the order listed. Engine switch and oil warning unit Refer to “ENGINE SWITCH AND OIL WARNING UNIT”...
  • Page 19: Mz300K

    GOVERNOR MZ300K 8 Nm (0.8 m · kgf, 5.8 ft · lbf) 16 Nm (1.6 m · kgf, 12 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) Order Job/Parts to remove Q’ty Remarks Removing the governor Remove the parts in the order listed.
  • Page 20: Adjusting The Governor

    GOVERNOR ADJUSTING THE GOVERNOR 1. Remove: 9 Fuel tank (Refer to “FUEL TANK, CANISTER” in 7VB-F8197-10 chapter 3.) 2. Adjust: 9 Governor Adjustment steps: a. Loosen the governor arm bolt 1. b. Turn the governor arm 2 clockwise until it stops. c.
  • Page 21: Chapter 3. Electrical

    ELEC CIRCUIT DIAGRAM ELECTRICAL CIRCUIT DIAGRAM MZ250/MZ300...
  • Page 22: General Specifications

    SPEC GENERAL SPECIFICATIONS SPECIFICATIONS GENERAL SPECIFICATIONS Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Dimensions: Overall length mm (in) 387 (15.24) 404 (15.91) 387 (15.24) 404 (15.91) Overall width mm (in) 426 (16.77) 416 (16.38) 426 (16.77) 416 (16.38) Overall height mm (in) 294.5...
  • Page 23 SPEC GENERAL SPECIFICATIONS Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Electrical: Ignition system Ignition timing (3600 r/min) BTDC 20° ± 3° BPR4ES (NGK) Spark plug type 0.7–0.8 (0.028–0.031) Spark plug gap mm (in) * The power rating of the engine indicated in the SPECIFICATIONS is the net power output tested on an engine model and measured at 3600 r/min.
  • Page 24: Maintenance Specifications

    SPEC MAINTENANCE SPECIFICATIONS MAINTENANCE SPECIFICATIONS ENGINE Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Piston: mm (in) Piston clearance 0.023–0.037 0.033–0.047 (0.0009–0.0015) (0.0013–0.0019) <Limit> 0.05 (0.0020) 0.06 (0.0024) Piston skirt diameter “D” 73.97–73.99 79.960–79.980 (2.9122–2.9130) (3.1480–3.1488) <Limit> 73.92 (2.910) 79.91 (3.146) Measuring point “H”...
  • Page 25 SPEC MAINTENANCE SPECIFICATIONS Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Cylinder: mm (in) 74.000–74.020 80.000–80.020 Inside diameter “D” (2.9134–2.9142) (3.1496–3.1504) <Limit> 74.040 (2.915) 80.040 (3.151) Taper limit 0.05 (0.002) Warpage limit 0.05 (0.002) Crankshaft: mm (in) Big end side clearance “A”...
  • Page 26 SPEC MAINTENANCE SPECIFICATIONS Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Valve: mm (in) Head diameter “A” 27.9–28.1 31.9–32.1 (1.0984–1.1063) (1.2559–1.2638) 26.9–27.1 28.9–29.1 (1.0591–1.0669) (1.1378–1.1457) Stem diameter “B” 5.948–5.963 (0.2342–0.2348) 5.940–5.955 (0.2339–0.2344) <Limit> 5.918 (0.2330) 5.910 (0.2327) Stem length “C”...
  • Page 27 SPEC MAINTENANCE SPECIFICATIONS Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Valve spring: mm (in) Free length 36.2 (1.4252) 36.2 (1.4252) <Limit> 34.39 (1.3539) 34.39 (1.3539) Installed length 29 (1.1417) 29 (1.1417) Installed compression spring force N (kgf, lbf) 91.20–104.93 (9.30–10.70, 20.50–23.59) N (kgf, lbf) 91.20–104.93 (9.30–10.70, 20.50–23.59)
  • Page 28: Electrical

    SPEC MAINTENANCE SPECIFICATIONS ELECTRICAL Model name: MZ250 MZ300 Model code number: 7KBJ 7KBN 7VBJ 7VBN Electrical: Ignition system Ignition timing at 3600 r/min BTDC 20° ± 3° Primary coil resistance (Ω ±20 %) Secondary coil resistance (kΩ ±20 %) 11.7 Spark plug cap resistance kΩ...
  • Page 29: Tightening Torques

    SPEC TIGHTENING TORQUES TIGHTENING TORQUES Tightening torque Item Thread size Nm (m·kgf, ft·lbf) Air filter cover screw — 1.6 (0.16, 1.2) Air filter case bolt M6 × 1.0 10 (1.0, 7.2) Air filter case nut M6 × 1.0 9 (0.9, 6.5) Fuel tank bolt M6 ×...
  • Page 30 SPEC TIGHTENING TORQUES Oil level switch clamp bolt M6 × 1.0 10 (1.0, 7.2) Oil drain bolt M12 × 1.5 27 (2.7, 20) Connecting rod cap bolt M8 × 1.25 20 (2.0, 14) Float chamber bolt — 9 (0.9, 6.5) Float chamber bolt —...
  • Page 31: General Torque Specifications

    SPEC GENERAL TORQUE SPECIFICATIONS GENERAL TORQUE Tightening torque Tread size SPECIFICATIONS m·kgf ft·lbf This chart specifies torque for standard fas- teners with standard I.S.O. pitch treads. Torque specifications for special components or assemblies are included in the applicable sections of this book. To avoid warpage, tight- 11.1 en multi fastener assemblies in a crisscross 22.1...
  • Page 32: Lubrication Points And Type Of Lubricants

    SPEC LUBRICATION POINTS AND TYPE OF LUBRICANTS LUBRICATION POINTS AND TYPE OF LUBRICANTS Part name Type of lubricant Oil seal lip Governor shaft oil seal lip Bearing Connecting rod big end Crank pin Crankshaft journal Connecting rod cap bolt Piston pin Piston Crankshaft gear teeth Valve stem...
  • Page 33: Wire Routing Diagram

    SPEC WIRE ROUTING DIAGRAM WIRE ROUTING DIAGRAM UPPER SIDE VIEW 1 Spark plug cap B Route the TCI unit lead as E Fasten the ground terminal 2 TCI unit lead shown. and engine switch together. 3 Oil level switch lead C Pass through the leads to the wire harness protector, and Color code...
  • Page 34: Engine Switch And Oil Warning Unit

    SPEC WIRE ROUTING DIAGRAM ENGINE SWITCH AND OIL WARNING UNIT Color code 1 Oil warning light B Make sure that the gap 2 Wire harness protector between the end of the wire B ..Black 3 Oil warning unit lead (ground) harness protector and end of Gy ..Gray 4 Oil warning unit...
  • Page 35: Tci Unit And Charging Coil

    SPEC WIRE ROUTING DIAGRAM TCI UNIT AND CHARGING COIL 1 High tension code 2 Flywheel 3 Charging coil 4 Clamp 5 TCI unit A Make sure that the high ten- sion cord is not pinched when installing the flywheel cover. B Adjust the TCI unit air gap between 0.4–0.6 mm (0.0157–...
  • Page 36: Oil Level Switch (Crankcase Cover)

    SPEC WIRE ROUTING DIAGRAM OIL LEVEL SWITCH (CRANKCASE COVER) 1 Clamp 2 Oil level switch A Touch the tube (gray) with the grommet. B Route the oil level switch lead as shown. 4-15...
  • Page 37: Upper Side View (Mz250Khid0/Mz300Khid3)

    SPEC WIRE ROUTING DIAGRAM UPPER SIDE VIEW (MZ250KHID0/MZ300KHID3) Color code 1 TCI unit lead 2 Oil level switch lead Gy ..Gray A Route the TCI unit lead as shown. 4-16...
  • Page 38 SPEC WIRE ROUTING DIAGRAM UPPER SIDE VIEW (MZ300KHIDM) Color code 1 Spark plug cap C Install the TCI unit and wire 2 TCI unit lead harness into the base of the B ..Black 3 Wire harness crank case guide. Make sure Gy ..Gray 4 Oil level switch lead that the TCI lead is installed...
  • Page 39: Carburetor And Charging Coil (Mz300Khidm)

    SPEC WIRE ROUTING DIAGRAM CARBURETOR AND CHARGING COIL (MZ300KHIDM) Color code 1 Clamp 2 Carburetor G/R ..Green/Red 3 Charging coil lead 4 Charging coil A Route the wire harness under the breather hose. B Install the clamp as shown. C Position the wire harness so that it does not contact with the cylinder head.
  • Page 40 SPEC 4-19...
  • Page 41 MZ250/MZ300 2012 CIRCUIT DIAGRAM...
  • Page 42 2012_09×1 !

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