Toro 71254, 74388, 74616, 74621, 74629 Service Manual

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RESIDENTIAL PRODUCTS

RIDING PRODUCT

ENGINE SERVICE MANUAL

LC1P92F (452cc)

About this Manual

This service manual was written expressly for Toro service technicians. The Toro Company has made every effort to make the information in this manual complete and correct. Basic shop safety knowledge and mechanical/electrical skills are assumed. The Table of Contents lists the systems and the related topics covered in this manual. An electronic version of this service manual is available on the Toro Dealer Portal. We are hopeful that you will find this manual a valuable addition to your service shop. If you have any questions or comments regarding this manual, please contact us at the following address:

The Toro Company Residential and Landscape Contractor Service Training Department 8111 Lyndale Avenue South Bloomington, MN 55420

Chapter 1 – General Service Information

Chapter 2 - Engine Service / Maintenance

Chapter 3 - Engine Disassembly and Service

Chapter 4 - Electrical

NOTES:

Chapter 1 – General Service Information

Safety 2 Service Rules 3

Engine Model / Serial Number Location 3

Engine Fastener Torque Specification 4 General Specifications 5 Engine Specifications 6 Troubleshooting 7

Safety

Safety Information

This symbol means WARNING or PERSONAL SAFETY INSTRUCTION – read the instruction because it has to do with your safety. Failure to comply with the instruction may result in personal injury or even death. This manual is intended as a service and repair manual only. The safety instructions provided herein are for troubleshooting, service, and repair of the Toro engine. The Toro operator’s manual contains safety

information and operating tips for safe operating practices.

Avoid Unexpected Engine Start - Turn off engine and disconnect the spark plug before servicing engine.

Avoid Lacerations and Amputations - Stay clear of all moving parts while the engine is running.

Avoid Burns - Do not touch the engine, muffler, or other components which may increase in temperature during operation, while the unit is running or shortly after it has been running.

Avoid Fires and Explosions - Avoid spilling fuel and never smoke while working with any type of fuel or

lubricant. Wipe up any spilled fuel or oil immediately. Never remove the fuel cap or add fuel when the engine is running. Always use approved, labeled containers for storing or transporting fuel and lubricants.

Avoid Asphyxiation - Never operate an engine in a confined area without proper ventilation.

Avoid Injury From Batteries - Battery acid is poisonous and can cause burns. Avoid contact with skin, eyes, and clothing. Battery gases can explode. Keep cigarettes, sparks, and flames away from the battery.

Avoid Injury Due To Inferior Parts - Use only original equipment parts to ensure that important safety criteria are met.

Avoid Injury To Bystanders - Always clear the area of bystanders before starting or testing power equipment.

Avoid Injury Due To Projectiles - Always clear the area of sticks, rocks, or any other debris that could be picked up and thrown by the power equipment.

Avoid Modifications - Never alter or modify any part unless it is a factory approved procedure.

Service Rules

1. Only use genuine Toro parts and lubrication products.

2. Always install new gaskets, O-rings and seals when assembling engine.

3. Always torque fasteners to specification and in sequence.

4. Always lubricate friction components with clean engine oil or engine assembly lube when assembling engine.

Engine Model and

Serial Numbers

Serial Number

Engine Model

Engine Model / Serial Number Location

The engine model and serial number are stamped into the crankcase.

XXX-XXXX XXXXXXXXXXX

Oil Drain Valve

7 ft-lbs (10 Nm)

Oil Filter Adaptor Bolt

31 ft-lbs (42 Nm)

Spark Plug

20 ft-lbs (28 Nm)

Connecting Rod Bolts

12 ft-lbs (16 Nm)

Crankcase Cover Bolt

20 ft-lbs (28 Nm)

Fuel Pump Asm. Mounting Bolts

7 ft-lbs (10 Nm)

Breather Plate Bolts

7 ft-lbs (10 Nm)

Cylinder Head Bolts

40 ft-lbs (54 Nm)

Rocker Arm Studs

23 ft-lbs (31 Nm)

Rocker Arm Pivot Lock Nut

11 ft-lbs (15 Nm)

Alternator Bolts

7 ft-lbs (10 Nm)

Valve Cover Bolts

7 ft-lbs (10 Nm)

Flywheel Nut

81 ft-lbs (110 Nm)

Ignition Coil Bolts

7 ft-lbs (10 Nm)

Starter Motor Bolts

20 ft-lbs (28 Nm)

Carburetor Mounting Nuts

7 ft-lbs (10 Nm)

Throttle / Choke Bracket Asm.

Bolts

7 ft-lbs (10 Nm)

Fan Cover Nuts

7 ft-lbs (10 Nm)

Fan Shroud Bolts

7 ft-lbs (10 Nm)

Standard Torque Values

M5 Bolt / Nut – 4.5 ft-lbs (6 Nm)

M6 Bolt / Nut – 7.5 ft-lbs (10 Nm)

M8 Bolt / Nut – 19 ft-lbs (26 Nm)

M10 Bolt / Nut – 28 ft-lbs (38 Nm)

M12 Bolt / Nut – 41 ft-lbs (55 Nm)

Engine Fastener Torque Specifications

General Specifications

Model

1P92F-1

Type

Single Cylinder, 4-Stroke, Forced Air Cooling, OHV

Bore X Stroke (mm)

92×68

Displacement (cc)

452

Compression Ratio

8.8 :1

Lubrication

Oil Pump with Oil Filter

Starting

Electric

Rotation

Counter Clockwise (From P.T.O. Side)

Ignition System

Transistorized Magneto Ignition

Air Cleaner

Foam and Paper

Fuel Type

Unleaded Gasoline, 87 Octane

Oil Capacity

34 oz. (1.0 L) Without Filter Change

36 oz. (1.05 L) With Filter Change

Dimension (L×W×H) (mm)

432×388×300

Weight

68.3 lbs. (31 kg)

Engine Specifications

Part

Item

Standard

Service Limit

Engine

Operating RPM

3350 – 3450 RPM

－

Idle RPM

1700 – 2000 RPM

－

Cylinder Head

Warpage

－

0.00393” (0.10 mm)

Cylinder

Sleeve Taper / Out of Round

(Inside Diameter)

3.6220” - 3.6224” (92-92.01 mm)

3.6259” (92.10 mm)

Piston

Skirt Outside Diameter

3.620 - 3.621” (91.96-91.975 mm)

3.6196” (91.940 mm)

Cylinder Clearance

0.00098 - 0.0017” (0.025-0.045 mm)

0.0032” (0.081 mm)

Piston Pin Bore Inside Diameter

0.7870 - 0.7877” (20.002-20.008 mm)

0.7879” (20.01 mm)

Piston Pin Clearance

0.00016 - 0.00063” (0.004-0.016 mm)

0.0011” (0.029 mm)

Piston Pin

Outside Diameter

0.7871 - 0.7873” (19.992-19.998 mm)

0.7834” (19.9 mm)

Piston Rings

Ring To Groove (Top and Middle)

0.00079 - 0.00236” (0.02-0.06 mm)

0.00433” (0.11 mm)

End Gap (Top and Middle)

0.0059 - 0.0118” (0.15-0.30 mm)

0.0137” (0.35 mm)

Width (Top and Middle)

0.046 - 0.0468” (1.17-1.19 mm)

0.0433” (1.10 mm)

Width (Oil Ring)

0.11 - 0.126” (2.8-3.2 mm)

0.1063” (2.7 mm)

Connecting Rod

Small End Inside Diameter

0.79 - 0.788” (20.07-20.018 mm)

0.7881” (20.02 mm)

Big End Inside Diameter

1.4179 - 1.4183” (36.015-36.025 mm)

1.4185” (36.03 mm)

Big End Oil Clearance

0.00157 - 0.00248” (0.04-0.063 mm)

0.0047” (0.12 mm)

Big End Side Clearance

0.00079 - 0.0138” (0.02-0.35 mm)

0.00157” (0.4 mm)

Crankshaft

Crankpin Outside Diameter

1.417 - 1.4165” (35.966-35.981 mm)

1.415” (35.946 mm)

Valve

Clearance (cold) (Intake)

0.0039” (0.10 mm)

－

Clearance (cold) (Exhaust)

0.0059” (0.15 mm)

－

Stem Diameter (Intake)

0.2584 - 0.2590”(6.565-6.58 mm)

0.2579” (6.550 mm)

Stem Diameter (Exhaust)

0.2577 - 0.2583” (6.545-6.56 mm)

0.2571” (6.530 mm)

Valve Guides

Inside Diameter (Intake, Exhaust)

0.2362 - 0.2604” (6.0-6.615 mm)

0.2606” (6.620 mm)

Stem to Guide Clearance (Intake)

0.00079 - 0.00197” (0.02-0.05 mm)

0.0047” (0.12 mm)

Stem to Guide Clearance (Exhaust)

0.00157 - 0.00275” (0.04-0.070 mm)

0.00669” (0.17 mm)

Valve Seat

Seat Width

0.03149 - 0.0393” (0.8-1.0 mm)

0.0591” (1.5 mm)

Valve Spring

Free Length

1.555 - 1.594” (39.5-40.5 mm)

1.535” (39.0 mm)

Camshaft

Height (Intake)

1.282 - 1.284” (32.563-32.603 mm)

1.276” (32.40 mm)

Height (Exhaust)

1.262 - 1.264” (32.049-32.099 mm)

1.256” (31.9 mm)

Journal (Bearing)

0.6298 - 0.6293” (15.996-15.984 mm)

0.6266” (15.916 mm)

Crankcase Cover

Camshaft Hole Diameter

0.6299 - 0.6306” (16.0-16.018 mm)

0.6338” (16.1 mm)

Crankshaft Hole Diameter

2.8330 - 2.8338” (71.949-71.979 mm)

2.8366” (72.05 mm)

Spark Plug

Gap

0.0275 - 0.0314” (0.7-0.8 mm)

－

Ignition Coil

Resistance (Primary)

1.0-1.6 Ω

－

Resistance (Secondary)

10.5 KΩ +/- 15%

－

Gap to Flywheel

0.011 - 0.019” (0.3-0.5 mm)

－

Troubleshooting

Hard Starting / Poor Running

- Incorrect Fuel (Level, Age, Octane, Ethanol Content)

- Fuel System Contamination and / or Debris in Carburetor

- Incorrect Oil Level

- Weak Battery / Charging System

- Spark Plug (Incorrect Gap, Fouled, Loose or Faulty)

- Air Filter Restriction

- Air Intake System Leaks

- Ignition Coil to Flywheel Gap Incorrect

- Weak / No Spark

- Incorrect Fuel Solenoid / Fuel Pump Operation

- Choke / Governor Linkage

- Operating RPM Incorrect

- Governor Adjustment Incorrect

- Engine Valve Clearance out of Specification

- Low Compression or Excessive Leakdown

Overheating

- Incorrect Oil Level

- Cylinder Head Gasket Leak

- Debris Build-Up Restricting Air Flow

NOTES:

Chapter 2 – Engine Service / Maintenance

Engine Oil Change Procedure 10 Air Cleaner Service 11 Spark Plug Service 12 Valve Clearance Inspection and Adjustment 13 Engine Governor – Zero Point Setting 14 Engine Idle Speed / Operating RPM Adjustment 15 Fuel Filter Replacement 16

Engine Oil Change Procedure

1. Warm engine, then remove the ignition key before changing the engine oil.

2. Drain oil through the drain valve / hose into an approved container.

3. When oil has drained completely, close the oil drain valve. Remove the oil drain hose and wipe up any excess oil on the frame.

Note: Properly dispose of used engine oil.

4. Remove the oil filter from the engine and clean the filter adapter gasket surface.

5. Apply a thin coat of new oil to the rubber gasket on the new oil filter.

6. Install the new oil filter onto the filter adapter and turn the oil filter clockwise until the rubber gasket contacts the filter adapter. Tighten the oil filter an additional 1/2 to 3/4 turn.

7. Remove the dipstick from the oil fill / check tube. Add the appropriate amount of approved engine oil.

8. Install the oil fill cap/dipstick.

9. Start engine and let run for 1-3 minutes. Shut off the engine.

10. Remove the dipstick from the oil fill / check tube. Wipe it clean and reinstall it.

11. Unscrew the dipstick and inspect the oil level. If the oil level is low, pour oil into the fill hole to raise the level to the Full mark on the dipstick.

Important: Do not overfill the crankcase

Engine Oil Capacity:

Max. Fill: 34 oz (1.0 l) without oil filter change Max. Fill: 36 oz (1.05 l) with oil filter change

Engine Oil Type: Detergent oil - API classification of SF,SG, SH, SJ, SL, or higher

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