MTD 350 Series Service Manual
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MTD 350 Series Service Manual

Single cylinder engine
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See also: Operator's Manual
For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983
Service Manual
2006 MTD Single Cylinder Engine 350/450/650 Series "First Look"
NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power
equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals.
These materials are intended to provide supplemental information to assist the trained technician. Untrained or inexperi-
enced individuals should seek the assistance of an experienced and trained professional. Read, understand, and follow
all instructions and use common sense when working on power equipment. This includes the contents of the product's
Operators Manual, supplied with the equipment. No liability can be accepted for any inaccuracies or omission in this pub-
lication, although care has been taken to make it as complete and accurate as possible at the time of publication. How-
ever, due to the variety of outdoor power equipment and continuing product changes that occur over time, updates will be
made to these instructions from time to time. Therefore, it may be necessary to obtain the latest materials before servicing
or repairing a product. The company reserves the right to make changes at any time to this publication without prior notice
and without incurring an obligation to make such changes to previously published versions. Instructions, photographs and
illustrations used in this publication are for reference use only and may not depict actual model and component parts.
© Copyright 2005 MTD Products Inc. All Rights Reserved
MTD Products Inc - Product Training and Education Department
FORM NUMBER - 769-02092A
10/2005
www.mymowerparts.com

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Summary of Contents for MTD 350 Series

  • Page 1 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 Service Manual 2006 MTD Single Cylinder Engine 350/450/650 Series “First Look” NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals.

  • Page 2: Table Of Contents

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 TABLE OF CONTENTS Introduction........................: 1 Service Intent ........................2 Major failures not covered under warranty ..............3 Minor failures not covered under warranty ..............3 Maintenance and Adjustment Information ...............3 Starter Service .......................13 Ignition System ......................17 Fuel System ........................21 Exhaust .........................29 Governor ........................30...

  • Page 3: Introduction

    The Series 350 and Series 450 share some basic parts. See Figure 1.5. 1.1. MTD has chosen to introduce three MTD exclu- sive engines for walk-behind and self-propelled Series 350 / Series 450 Engine mowers for the 2006 season. See Figure 1.1.

  • Page 4: Service Intent

    2.2. Because MTD is entering a new field, dealers module. can assume that MTD will be very interested in scrutinizing any failed parts that dealers replace • The module is mounted above the cylinder on under warranty during the ‘06 and ‘07 mowing...

  • Page 5: Major Failures Not Covered Under Warranty

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 MAINTENANCE AND ADJUSTMENT INFOR- MAJOR FAILURES NOT COVERED UNDER WARRANTY MATION NOTE: The following is a list of typical non war- 5.1. Fasteners: All threaded fasteners used on the rantable scenarios.
  • Page 6 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 • Wet, black deposits on the insulator and elec- 5.6. Top no-load speed varies with blade length per trodes indicate the presence of oil in the com- ANSI B71.1-1984 standard of 19,000 feet per...
  • Page 7 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 • The regulated blade tip speed is a safety fea- 5.10. Oil can be drained by removing the drain plug ture. A dealer who puts a mower back into ser-...
  • Page 8 • The gasoline can have a maximum of 10% etha- nol or 15% MTBE. • Do not use E85 in MTD engines. 5.13. Valve lash can be checked and adjusted using the following steps: Valves closed 5.14. If the engine has been run, allow it to cool thor- oughly.
  • Page 9 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 5.21. Intake valve lash (top valve) should be .003”- 5.28. Install the valve cover, tightening the valve cover .005” (.10 + .02mm). screws to a torque of 71 in-lb (8 Nm).
  • Page 10 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 • The cable should not bind. Replace the cable if 5.38. Interpreting compression readings: it is kinked, melted frayed, or damaged in any • Near Zero (< 20PSI [1.38 Bar]): most likely a other way that causes it to bind.
  • Page 11 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 5.44. To replace the brake pad, remove the flywheel 5.49. There are two screws that hold the brake as described in the IGNITION section of this assembly to the engine.
  • Page 12 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 5.52. Run and test the mower in a safe area before 5.55. The reading should be high when the bail is returning it to service. pulled down, reflecting the resistance in the pri-...
  • Page 13 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 5.57. If further investigation is required, remove the 5.61. Resistance (Ohms) should be infinite (O.L) with recoil assembly, as described in the STARTER the bail depressed. See Figure 5.61.
  • Page 14 MTD. blade 5.67. Use of non-OEM blades, blade adaptors, and support Blade hardware is not recommended for MTD mowers. adaptor Blade bolt Figure 5.69 CAUTION: At no time should any part of the body be placed in the path that the blade would follow if it were to rotate.

  • Page 15: Starter Service

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 STARTER SERVICE 5.70. When servicing the blade: • Replace any parts that are damaged or suspect. 6.1. To Remove recoil assembly from the mower, remove the fuel cap.
  • Page 16 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 • Replace the rope with 83” (2.1 meters) of #4 6.6. Lift the recoil assembly off of the engine, and place it on a convenient work surface.
  • Page 17 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 6.13. Carefully lift the spring and pulley out of the 6.17. Install the torsion springs and pawls so that the recoil housing. See Figure 6.13. long arm of the spring reaches outside of the...
  • Page 18 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 6.22. Heat fuse the ends of a 9’ (3 meter) length of #4 6.25. If starter rope tension needs to be adjusted, starter rope, and tie a double half-hitch in one there is room between the recoil housing and the end.

  • Page 19: Ignition System

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 IGNITION SYSTEM 7.5. Hold the safety bail down using a spring clamp, and remove the flywheel using an appropriate 7.1. The ignition system is a transistorized magneto, puller.
  • Page 20 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 • One leg of the module is secured by a stud that 7.8. The ignition module for the Series 650 engines mounted off-set from cylinder. also supports the fan shroud, the second leg is See Figure 7.8.
  • Page 21 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 7.18. Simple spark-testers are readily available and 7.20. At pull-over speed (~ 600 RPM), voltage should inexpensive. Thexton Part # 404 is available be at least 8,000. See Figure 7.20.
  • Page 22 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 7.25. Spark plug: refer to steps 5.2 through 5.4 in the 7.22. Resistance in the secondary windings of the ignition module, measured between the spark MAINTENANCE AND ADJUSTMENT INFOR- plug terminal and the laminations, was observed MATION section of this manual.

  • Page 23: Fuel System

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 FUEL SYSTEM 8.3. tank vented through cap. See Figure 8.3. CAUTION: When working around the fuel sys- tem, do not bring any sources of heat, spark, or...
  • Page 24 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.7. If the choke plate fails to close fully when the 8.5. The tank should not hold any pressure nor any vacuum. knob is pulled, the mower will be difficult or impossible to start when cold.
  • Page 25 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.10. Remove the drain bolt from the carburetor float 8.12. The air filter assembly is easily removable using bowl using a 10mm wrench, and let the fuel flow a 10mm wrench.
  • Page 26 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.17. After the second stud is removed, the carburetor 8.14. Note or mark the orientation of the plate. Notches in the plate allow air to reach emulsion can be maneuvered to disconnect the linkages.
  • Page 27 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.19. Pivot the carburetor to disengage the Z-fitting on 8.21. Between the carburetor and the cylinder head is the end of the choke rod. See Figure 8.19.
  • Page 28 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.25. When inverted, the float should rest in a level 8.22. There is a corresponding passage recessed into the mating surface where the throttle end of the position.
  • Page 29 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.29. A square cross-section gasket seals the bowl to 8.32. The throttle stop screw has a large pliable lip the body of the carburetor. around the head of the screw. That lip secures a metering plug for the pilot and transition ports.
  • Page 30 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 8.36. The pilot screw regulates how much of this pre- 8.34. Examining the metering plug: See Figure 8.34. mixed fuel/air emulsion is allowed to enter the...

  • Page 31: Exhaust

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 EXHAUST 9.3. The muffler gasket extends well beyond the port, to act as a heat shield and cooling air guide 9.1. The muffler and muffler cover are secured to the...

  • Page 32: Governor

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 10.4. The governor shaft is splined. If it is necessary to GOVERNOR remove the governor arm, make an index mark 10.1. The engine speed is controlled by a balance to orient the shaft to the arm on installation.

  • Page 33: Crankcase Ventilation

    The cause of this oil burning can be mistaken for a worn-out engine, if proper diagnosis (compres- sion, leak-down, and case pressure) is not per- formed. 11.5. Experimentation by MTD’s Training and Educa- tion department has revealed the following char- acteristics: •...
  • Page 34 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 11.9. The disc acts as a check valve: pressure pulses 11.6. The PCV chamber is accessible by removing the flywheel, as described in steps 7.2 through 7.6...

  • Page 35: Cylinder Head Removal

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 11.13. Vigorous pumping with a hand pump vacuum / CYLINDER HEAD REMOVAL pressure tester will result in a slight build-up of 12.1. It is recommended that the mower be positioned pressure within the chamber.
  • Page 36 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 12.3. Remove the four screws securing the valve 12.7. Double-nut and remove the exhaust studs, simi- cover using a 10mm wrench. See Figure 12.3. lar to the method used to remove the carburetor studs in the FUEL SYSTEM section of this man- ual.
  • Page 37 For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 12.13. For inspection purposes, the valve retainers can 12.15. Position new cylinder head gasket and dowels removed with light finger pressure. on engine block. See Figure 12.15.

  • Page 38: Torque Specifications

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 TORQUE SPECIFICATIONS Fastener Torque Table Fastener Torque, SAE Torque, metric Nuts, muffler 84 in-lb 10 Nm Nuts, carburetor 84 in-lb 10 Nm Screw, dipstick tube 84 in-lb...

  • Page 39: Maintenance Specifications

    For Discount White Outdoor Parts Call 606-678-9623 or 606-561-4983 MTD Engine - Series 350/450/650 MAINTENANCE SPECIFICATIONS Item Specification Setting. SAE Setting, Metric Ignition module air gap .008"-.016" .2-.4mm Spark plug .024"-.032" .6mm-.8mm Spark plug type Torch F7TC Oil type SAE 30 SF/CD 32 to 104 deg.

This manual is also suitable for:

450 series650 series

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