SMALL ENGINE ®
A step-by-step guide to maintaining your small engine
www.briggsandstratton.com
I NTRODUCTION Briggs & Stratton has been a major force behind the explosion in small engine popularity. This quintessential American company builds more than two-thirds of all lawn mower engines and is a major producer of four-stroke small engines for almost every application. You may find many brands of mowers, tractors and other equipment at your power equipment retailer. Look closely: chances are good the engines are built by Briggs & Stratton. Retailers like to point this out because the name stands for quality and experience. Briggs & Stratton’s knowledge and expertise is second to none. When you learn from Briggs & Stratton technicians, you’re
learning from the company that has set the industry standard for decades. You’re also developing skills that apply to more than lawn equipment. With the information in this book, you can maintain and repair small engines on a variety of power equipment—from generators and pressure washers, to hydraulic lifts. In this booklet, we’ll cover the basic procedures for maintaining your small engine. For more in depth explanation of engine systems, maintenance and repair, go to www.briggsandstratton.com or look for Briggs & Stratton Small Engine Care & Repair at your local Briggs & Stratton authorized dealer.
S AFETY
Contents Introduction to Engines & Engine Components
3
Maintenance Checklist
4
Checking & Changing Oil
5
Checking & Replacing Spark Plugs
6
Checking & Changing Air Filters
7
Small engines must burn fuel and induce electricity. Each of these involves special safety considerations—so you need to observe the precautions for both. Keep in mind all operational procedures as outlined in your owners manual when working with your engine. Additionally, by following the simple safety rules for engine maintenance, you will simplify the job of safely operating, maintaining and repairing your small engine.
Safe maintenance
Troubleshooting Guide
To make small engine maintenance and repair tasks easier and safer: • Make sure you have ample work space, with easy access to the tools you need. • Use the correct tools for each job. W H
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You never have to look far to find Briggs & Stratton support and service for your small engine. Consult your Yellow Pages under “Engines-Gasoline,” “GasolineEngines,” “Lawn Mowers” or similar categories. There are over 30,000 Briggs & Stratton authorized service dealers worldwide who provide quality service. You can also contact Briggs & Stratton Customer Service by phone at 1-800233-3723, or on the Internet at http://www.briggsandstratton.com.
2 THE GUIDE TO SMALL ENGINES
• Keep an approved fire extinguisher in a familiar location near your work area. • Learn engine shutoff procedures so you can respond quickly in an emergency. • Disengage the cutting blade, wheels or other equipment, if possible, before starting the engine. • Disconnect the spark plug wire to prevent accidental starting when you are servicing the engine. • Always disconnect the wire from the negative terminal when servicing an electric starter motor.
• Make sure the air cleaner assembly and blower housing are in place before starting the engine. • Remove any fuel from the tank and close the fuel shutoff valve before transporting an engine. • Use only the original manufacturer’s replacement parts; any other parts may damage the engine and create safety hazards. • Keep engine speed settings within manufacturer specifications. Higher speeds can ruin the engine.
Protecting your health Fire, electric shock and asphyxiation are not the only dangers when working with small engines. Take care to avoid long-term or sudden injury to your eyes, ears, lungs, feet and back: • Keep your feet, hands and clothing away from moving engine and equipment components. • Use eye protection when you work with engines or power tools. • Wear ear protection to reduce the risk of gradual hearing loss from exposure to engine noise. • Wear a face mask, if required, when working with chemicals.
• Check that a spark plug or spark plug tester is attached to the engine before cranking.
• Wear specially designed gloves to protect against heat, harmful chemicals and sharp objects.
• Avoid contact with hot engine parts, such as the muffler, cylinder head or cooling fins.
• Wear safety shoes to protect against falling objects; safety shoes have soles that won’t deteriorate when exposed to gasoline or oil.
• Never strike the flywheel with a hammer or hard object; it may cause the flywheel to shatter during operation.
• Use proper lifting techniques and seek help with heavy lifting.
I NTRODUCTION TO ENGINES T he four-stroke small engine that powers your lawn mower, tiller, generator and many other types of equipment is a gasoline engine that generates the precise amount of power necessary to get the job done. Here’s how the components in your engine interact.
Engine components & their function The rewind cord is pulled to start the combustion process. On some models, a starter motor replaces the rewind, drawing on battery power to start the engine. Revolving magnets work in conjunction with the ignition armature and spark plug to produce a spark in the combustion chamber.
The carburetor draws in fuel from the fuel tank and outside air to form a combustible vapor that is fed into the combustion chamber.
Intake and exhaust valves open and close at precisely timed intervals to let air and fuel enter the engine and to let spent gases exit. The piston is pushed through the cylinder by the force of expanding gases. The piston’s motion causes the crankshaft to turn. Momentum then carries the piston back toward the top of the cylinder.
Rewind rope
An air vane or flyweights monitor engine RPMs so the governor can maintain the selected engine speed.
Cooling fins help reduce engine temperatures when air circulates across the hottest engine surfaces.
Oil stored in the crankcase circulates through the engine to lubricate key components like the piston and crankshaft and to provide generalized cooling by drawing away heat from internal engine surfaces.
Parts of the small engine – front view Fuel cap
A flywheel brake and stop switch are included on engines for equipment such as mowers that require constant supervision. The two components are designed to stop the engine if you release the controls.
Parts of the small engine – side view Fuel tank and shroud
Fuel tank and shroud
Rewind
Rewind Oil fill cap
Blower housing Blower housing
Air cleaner element
Flywheel
Primer bulb Carburetor Ignition armature Flywheel
Flywheel brake
Dipstick
Spark plug lead Intake valve spring Intake valve
Piston Cylinder head
Air cleaner cover
Connecting rod Crankcase
Piston
Spark plug Cylinder head Muffler
Engine block Crankshaft
Intake valve Exhaust valve
Exhaust valve Exhaust valve spring
THE GUIDE TO SMALL ENGINES 3
Crankshaft
M AINTENANCE Regular maintenance schedule You can avoid many small engine problems and save money on parts and repairs if you follow a regular maintenance schedule. Make good maintenance a habit when your engine is new, and always consult your owner’s manual for special guidelines for your make and model. Service the engine more frequently if you use it heavily or under dusty or dirty conditions.
After the first five hours of use: • Change the oil and filter.
After each use: • Check the oil. • Remove debris around the muffler.
Every 25 hours or every season: • Change the oil if operating under heavy load or in hot weather. • Service the air cleaner assembly. • Clean the fuel tank and line. • Clean the carburetor float bowl, if equipped. • Inspect the rewind rope for wear. • Clean the cooling fins on the engine block. • Remove debris from the blower housing. • Check engine compression. • Inspect governor springs and linkages. • Inspect ignition armature and wires. • Inspect the muffler. • Check the valve tappet clearances. • Replace the spark plug. • Adjust t

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