briggs and stratton small engine care

8/9/2019 Briggs and Stratton Small Engine Care

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A step-by-step guide to maintaining your small engine

www.briggsandstratton.com

SMALL ENGINE


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Small engines must burn fuel and induceelectricity. Each of these involves specialsafety considerationsso you need toobserve the precautions for both. Keep inmind all operational procedures as outlinedin your owners manual when working withyour engine. Additionally, by following thesimple safety rules for engine maintenance,you will simplify the job of safely operating,maintaining and repairing your small engine.

Safe maintenance

To make small engine maintenance andrepair 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.

Keep an approved fire extinguisher in afamiliar location near your work area.

Learn engine shutoff procedures so youcan respond quickly in an emergency.

Disengage the cutting blade, wheels orother equipment, if possible, beforestarting the engine.

Disconnect the spark plug wire to preventaccidental starting when you are servicing

the engine. Always disconnect the wire from the

negative terminal when servicing anelectric starter motor.

Check that a spark plug or spark plugtester is attached to the engine beforecranking.

Avoid contact with hot engine parts,such as the muffler, cylinder head orcooling fins.

Never strike the flywheel with a hammeror hard object; it may cause the flywheel toshatter during operation.

INTRODUCTION

W H E R E T O F I N D U S

You never have to look far to find Briggs

& Stratton support and service for your

small engine. Consult yourYellow Pages

under Engines-Gasoline, Gasoline-

Engines, Lawn Mowers or similar

categories. There are over 30,000 Briggs

& Stratton authorized service dealersworldwide who provide quality service.

You can also contact Briggs & Stratton

Customer Service by phone at 1-800-

233-3723, or on the Internet at

http://www.briggsandstratton.com.

Make sure the air cleaner assembly andblower housing are in place before startingthe engine.

Remove any fuel from the tank and closethe fuel shutoff valve before transportingan engine.

Use only the original manufacturersreplacement parts; any other parts maydamage the engine and create safetyhazards.

Keep engine speed settings withinmanufacturer specifications. Higher speedscan ruin the engine.

Protecting your healthFire, electric shock and asphyxiation are notthe only dangers when working with smallengines. Take care to avoid long-term orsudden injury to your eyes, ears, lungs, feetand back:

Keep your feet, hands and clothingaway from moving engine and equip-ment components.

Use eye protection when you work withengines or power tools.

Wear ear protection to reduce the risk ofgradual hearing loss from exposure to

engine noise.

Wear a face mask, if required, whenworking with chemicals.

Wear specially designed gloves toprotect against heat, harmful chemicalsand sharp objects.

Wear safety shoes to protect against fallingobjects; safety shoes have soles that wontdeteriorate when exposed to gasoline or oil.

Use proper lifting techniques and seek helpwith heavy lifting.

Briggs & Stratton has been a majorforce behind the explosion in small enginepopularity. This quintessential Americancompany builds more than two-thirds of alllawn mower engines and is a major producerof four-stroke small engines for almost everyapplication. You may find many brands ofmowers, tractors and other equipment atyour power equipment retailer. Look closely:chances are good the engines are built byBriggs & Stratton. Retailers like to pointthis out because the name stands for qualityand experience.

Briggs & Strattons knowledge and expertiseis second to none. When you learn fromBriggs & Stratton technicians, youre

learning from the company that has setthe industry standard for decades.

Youre also developing skills that applyto more than lawn equipment. With theinformation in this book, you can maintainand repair small engines on a variety of

power equipmentfrom generators andpressure washers, to hydraulic lifts. In thisbooklet, well cover the basic proceduresfor maintaining your small engine. Formore in depth explanation of enginesystems, maintenance and repair,go towww.briggsandstratton.com or lookfor Briggs & StrattonSmall Engine Care& Repairat your local Briggs & Strattonauthorized dealer.

SAFETYContentsIntroduction to Engines &

Engine Components 3

Maintenance Checklist 4

Checking & Changing Oil 5

Checking & ReplacingSpark Plugs 6

Checking & ChangingAir Filters 7

Troubleshooting Guide

2 THE GUIDE TO SMALL ENGINES


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THE GUIDE TO SMALL ENGINES 3

The four-stroke small engine that powersyour lawn mower, tiller, generator and manyother types of equipment is a gasoline enginethat generates the precise amount of powernecessary to get the job done. Heres how thecomponents in your engine interact.

Engine components &

their function

The rewind cord is pulled to start thecombustion process. On some models, astarter motor replaces the rewind, drawingon battery power to start the engine.

Revolvingmagnetswork in conjunction with theignition armature andspark plug to produce aspark in thecombustion chamber.

Thecarburetordraws in fuel from the fuel tankand outside air to form a combustible vapor thatis fed into the combustion chamber.

Intake and exhaust valves open and close atprecisely timed intervals to let air and fuel enterthe engine and to let spent gases exit.

Thepiston is pushed through thecylinderby theforce of expanding gases. The pistons motioncauses thecrankshaftto turn. Momentum thencarries the piston back toward the top ofthe cylinder.

Oil stored in thecrankcase circulates throughthe engine to lubricate key components like thepiston and crankshaft and to provide generalizedcooling by drawing away heat from internalengine surfaces.

Aflywheelbrake andstop switch are includedon engines for equipment such as mowers thatrequire constant supervision. The two compon-ents are designed to stop the engine if yourelease the controls.

Anair vane orflyweights monitor engine

RPMs so the governor can maintain the selectedengine speed.

Cooling fins help reduce engine tempera-tures when air circulates across the hottestengine surfaces.

INTRODUCTION TO ENGINES

Parts of the small engine front view Parts of the small engine side view

Fuel tank and shroudFuel cap

Air cleaner cover

Cylinder head

Piston

Engine block

Crankshaft

Muffler

Intake valve

Exhaust valve

Rewind rope Rewind

Flywheel brake

Blower housing

Flywheel

Carburetor

Air cleaner element

Fuel tank and s

Spark plug

Cylinder head

Intake valve spring

Intake valve

Exhaust valve spring

Exhaust valve Cran

Di

Connecti

Cran

Oil fBlower housing

Rewind

FlywheelIgnition armature

Spark plug lead

Primer bulb


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MAINTENANCE

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 loador 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 the carburetor.

Check the engine mounting bolts/nuts.

Every 100 hours or every season:

Clean the cooling system.*

Change the oil filter, if equipped.

Decarbonize the cylinder head.

*Clean more often if the engine operates underdusty conditions or in tall, dry grass.

Regular maintenance schedule

You can avoid many small engine problems and save money on parts andrepairs if you follow a regular maintenance schedule. Make good maintenancea habit when your engine is new, and always consult your owners manual for

special guidelines for your make and model. Service the engine morefrequently if you use it heavily or under dusty or dirty conditions.


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Tools & materials:

Socket wrench set, box\wrench or adjustable wrench,

screwdriver or hex key, oil filter or pipe wrench

(for models with filters), oil drain pan, funnel.

Time required:

30 minutes.

Checking the oil

Make it a habit to check the oil level andappearance each time youre about to start asmall engine. Checking the oil while theengine is cold and most of the oil is in thecrankcase yields the most accurate reading.You wont need to change or add oil everytime. But youll ensure a better-runningengine and avoid problems down the road ifyou keep the crankcase full and change theoil on schedule and any time the oil loses itsamber hue.

1. Start by locating the oil fill cap on thecrankcase (photo A). Fill cap locations vary,depending on the make and model of yourengine. On newer models, look for an oil can

symbol or the word oil or fill stamped onthe plug. On small tractors, you may have tolift the hood to locate this cap.

Some engines contain either an extended oilfill tube or a standard fill hole with a dipstickfor inspection. Others require you to removethe fill cap to check that the oil is at the fillline or the top of the fill hole.

2. To prevent dirt and debris from fallinginto the crankcase, wipe the area around thecap with a clean cloth before removing thecap. If there is no dipstick, dab the oil witha clean tip of the cloth to inspect the oil

(photo B).3. If the engine includes a dipstick cap,remove the dipstick and wipe it with a cleancloth. To ensure an accurate reading, reinsertthe dipstick completely. Then, remove itagain and check the oil level. If the dipstickcap is a screw-in type, ensure an accuratereading by screwing it in all the way beforeremov-ing it a second time to check the level.The oil mark on the dipstick should bebetween the lines shown on the dipstick(photo C). It should never be above the FULLline or below the ADD line.

Changing the oil

Once you decide the oil needs changing,check your owners manual to determine thetype of oil, and make sure you have enoughon hand. Then, run the engine for severalminutes. Draining the oil while its warm willcarry off many floating particles that wouldotherwise settle in the engine.

1. Stop the engine, disconnect the sparkplug lead and secure it away from the sparkplug. Then, locate the oil drain plug. Onmowers, the plug is typically below the deckand may be obscured by a layer of grass anddebris.

2.Wipe the area with a rag to prevent debrisfrom falling into the crankcase when youopen the drain plug. Tilt the mower deck andposition some newspaper and an oil pan orjug beneath the mower. Use a socket wrenchto turn the plug counterclockwise, allowingthe old oil to drain (photo A). If the plug also

serves as a fill cap, it may have two prongs soyou can loosen it by hand or use ascrewdriver or hex key for additional torque.Replace the drain plug by twisting clockwiseand tightening with a box wrench oradjustable wrench.

3. If your engine has a filter, replace it atleast once a season, more often under heavyuse. Replace the filter by twisting counter-clockwise on the body, using a filter wrenchor pipe wrench.

4. Lightly oil the filter gasket with cleanengine oil. Install a new filter rated for yourengine. Screw in the filter by hand until the

gasket contacts the filter adapter (photo B).Tighten the filter an additional 12 to 34 turn.

5.Add the appropriate quantity of oil (seeyour owners manual). Then, run the engineat idle and check for leaks.

6.After an oil change, dispose of oil andsoiled rags in accordance with localenvironmental statutes (photo C). In manyareas, oil can be left at curbside with otherrecyclables, provided it is sealed in arecyclable container. Check the regulationsin your area.

C

B

A

CHECKING&CHANGING OIL

C

B

A

When you pour fresh oil into the crankcase, its a golden or ambercolor. Gradually, the heat, dirt particles and agitated air in thecrankcase cause the oil to darken. Dark oil is not only dirty; it has alsolost much of its ability to coat and protect engine components.

Manufacturers recommend changing the oil in your small engine afterevery 25 hours of operation. For a new engine, youll also need to

change the oil after the first five hours of operation. New enginesrequire this extra step to flush out small particles that accumulatenaturally during the break-in period.

Hours of use are just one factor in determining how often the oilshould be changed; the amount of wear and tear is equally important.Just like the oil in a vehicle operated in extremely dirty or dustyconditions or at high speeds, the oil in a lawn mower or other smallengine breaks down faster under tough conditions, such as wet grass,heavy dust, high temperatures and rough or hilly terrain.


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Tools & materials:

Spark tester, spark plug

socket (sizes vary), socket

wrench, wire brush,

plug/point cleaner,

spark plug gauge.

Time required:

15 minutes.

The electrodes on a spark plug must beclean and sharp to produce the powerfulspark required for ignition. The more wornor dirty a spark plug, the more voltageand

the greater the tug on the rewindrequiredto produce an adequate spark.

If you havent tuned your engine recentlyand have to tug repeatedly on the rewind tostart the engine, a damaged spark plug maybe the culprit.

Luckily, a spark plug is one of the easiestengine components to repair and aninexpensive one to replace. And yourstandard socket set may already include themost important toola spark plug socket.

Cleaning and inspecting

a spark plug

1. Disconnect the spark plug lead. Then,clean the area around the spark plug to avoidgetting debris in the combustion chamberwhen you remove the plug.

2. Remove the spark plug using a spark plugsocket.

3. Clean light deposits from the plug with awire brush and spray-on plug cleaner. Then,use a sturdy knife if necessary to scrape offtough deposits. NOTE: Never clean a spark

plug with a shot blaster or abrasives.

4. Inspect the spark plug for very stubborndeposits, or for cracked porcelain orelectrodes that have been burned away. If anyof these conditions exists, replace the sparkplug.

5. Use a spark plug gauge to measure thegap between the two electrodes (one straight,one curved) at the tip of your spark plug(photo A). Many small engines require a .030"gap. Check the specifications for your modelwith your power equipment dealer. If

necessary, use a spark plug gauge to adjustthe gap by gently bending the curved elec-trode. When the gap is correct, the gauge willdrag slightly as you pull it through the gap.

6. Reinstall the plug, taking care not toovertighten. Then, attach the spark plug lead.

Checking ignition with

a spark tester

A spark tester offers an inexpensive, easy wayto diagnose ignition problems (see Checkingfor Spark Miss).

If you find a problem, remove and inspect thespark plug. Replace the spark plug if you findevidence of wear or burning at the spark plugtip. Spark plugs are inexpensive and a newone may solve the problem.

1. Connect the spark plug lead to the longterminal of your tester and ground the testerto the engine with the testers alligator clip(photo B).

2. Use the rewind or electric starter to crankthe engine, and look for a spark in the testerswindow.

3. If you see a spark jump the gap in thetester, the ignition is functioning. Theabsence of a visible spark indicates a problemin the ignition system.

Checking for spark miss

A spark plug that is fouled or improperlygapped may not allow sparks to jump the gapbetween electrodes consistently. The sparkplug will fire erratically or may occasionallyfail to spark. Test for this problemknown asspark missif your engine stumbles, with anoticeable decrease in engine sound. Sparkmiss can also cause the engine to emit blacksmoke or a popping sound, as unburned fuelexits with the exhaust and ignites inside themuffler.

1.With the spark plug screwed into thecylinder head, attach the spark plug lead tothe long terminal of the spark tester. Attachthe testers alligator clip to the spark plug(photo C).

2. Start the engine and watch the testersspark gap. Youll recognize spark miss by theuneven timing of the sparks in the tester.

A

B C

CHECKING SPARK PLUGS


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SERVICING AIR CLEANERSA properly maintained air cleaner is your engines first line of defenseagainst the destructive effects of dirt. When the air cleaner is in goodcondition, it keeps airborne dirt particles from entering through thecarburetor. If the air cleaner is not maintained, dirt and dust willgradually make their way into the engine. And dont underestimatedirts potential to cause damage. It can lead to a sharp drop in enginepower, orworsecause premature wear of critical enginecomponents.

Many types of air cleaners are used in small engines. Most contain afoam or pleated-paper element.

Dual-element air cleaners contain a pleated-paper element with afoam pre-cleaner, offering two layers of protection. Discard the paperelement when you can no longer remove dirt from the pleats bytapping the element on a hard, dry surface. You may be able to washand reuse the foam pre-cleaner. Foam elements can be cleaned withhot water and liquid dish detergent that contains a grease-cuttingagent.

Single-element air cleaners should be serviced every 25 hours (or oncea season). In a dual-element system, the pre-cleaner should be cleanedevery 25 hours. The cartridge should be cleaned every 100 hours.

Servicing a foam air cleaner

1. Loosen the screws or wing nuts that holdthe air cleaner assembly in place (photo A).Disassemble.

2. Inspect the foam element. Replace it if itis torn or shows signs of considerable wear.

4. Saturate the element with engine oil

(photo B). Then, squeeze it to spread the oilthroughout.

5. Inspect the rubbery sealing gasketbetween the air cleaner and carburetor.Replace it if it is worn.

6. Reassemble and reinstall the air cleaner.

Servicing a pleated-paper or

dual-element air cleaner

Dual-element air cleaners come in a varietyof designs. Two of the most common are

shown here.

1.With the cover removed, separate the pre-cleaner (if equipped) from the cartridge(photo C).

2. Tap the cartridge gently on a flat surfaceto remove any loose dirt. Inspect the elementand replace it if it is heavily soiled, wet orcrushed.

3. Inspect the pre-cleaner, if equipped. Notethe mesh backing, designed to act as a barrierbetween the oily pre-cleaner and the pleated-paper element. Replace it when soiled orworn.

4. Look for oiling instructions on the pre-cleaner (photo D). If directed, lubricate thepre-cleaner with oil. NOTE: Not all foam pre-cleaners should be oiled.

5. Clean the cartridge housing with a drycloth (photo E). Do not clean with solvents orcompressed air.

6. Reassemble the air cleaner. If the pre-cleaner is the oiled type, take care to insertthe mesh toward the paper element so thatthe paper is never exposed to the oil.

7. Reinstall, making sure that any tabs on

the cartridge are in their slots on the enginehousing. Gaps around the cartridge permitunfiltered air and damaging dirt particles toenter the engine.

Tools & materials:

Engine oil, screwdrivers, liquid detergent.

Time required:

30 minutes.

E

D

C

A B

Dont wait until your airleaner element looks likehis to replace it. If yourlement has becomeermanently discoloredr has begun to breakown or tear, extend thefe of your small enginey installing a new one.

Pleats in a paper element that are discolored, bent orwater-damaged can no longer provide adequate airto the carburetor. Replace the element when itapproaches this condition.

Pleated-paper

element

Pleated-p

elem

Pre-cleaner

Pre-cleaner


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TROUBLESHOOTING

If the answeris yes:

If the engine wont start

(Fuel line) Fill fuel tank; if engine

is still hot, wait until itcools before filling tank.

Open fuel shut-off valve.

Empty tank, replace fueland check for leaks infuel tank cap.

Disconnect inlet screenfrom engine and cleanusing compressed air.Do not use compressedair near engine.*

Make sure cap is ventedand air holes are notclogged.*

Remove spark plug leadand spark plug; pourteaspoon of fuel directlyinto cylinder; reinsertspark plug and lead;start engine; if it runsshortly before quitting,overhaul carburetor.*

Adjust float in fuel bowl,if adjustable; make surechoke isnt set too high.*

Remove spark plug;clean contacts orreplace plug.

Remove spark plug;reset gap.

Test lead with sparktester, then test engine.

Repair or replace killswitch.*

Replace flywheel key,then try to start engine;if it still wont start,check ignition arma-ture, wire connectionsor points.*

Perform compressiontest. If test indicatespoor compression,inspect valves, pistonand cylinder for damageand repair as needed.*

(Engine smokes)

(Engine overheats)

(Engine knocks)

(Spark plug missesunder load)

(Carburetor)

(Ignition)

(Compression)

Is the fuel tankempty?

Is the shut-offvalve closed?

Is the fuel dilutedwith water?

Is the fuel lineor inlet screenblocked?

Is the fuel tankcap clogged orunvented?

Is the engine

flooded?

Is the spark plugfouled?

Is the spark pluggap set incorrectly?

Is the spark pluglead faulty?

Is the kill switchshorted?

Is the flywheelkey damaged?

Are the valves,piston, cylinderor connectingrod damaged?

Is the carburetorblocked?

Adjust the carburetor.*

Replace the air cleaner.

Clean the engine.*

Add oil to the engine.NOTE: Never add oil tothe gasoline for a four-stroke engine.*

Install new parts asneeded.*

Adjust the carburetor.*

Replace the gasket.*

Clean the fuel tank ventand fuel tank screen.*

Clean carbon from thepiston and head.*

Inspect the flywheel andkey; replace as needed.*

Clean the spark plug.

Replace the spark plugor adjust the sparkplug gap.

Install a solid-stateignition.*

Adjust the carburetor.

Replace the valve spring.

Adjust the valveclearance torecommended settings.

Is the fuel mixture

too rich?

Is the air filterplugged?

Is the engine dirty?

Is the oil level low?

Are any shrouds orcooling finsmissing or broken?

Is there a leakygasket?

Is the fuel tankvent or fuel tankscreen plugged?

Does the combust-

ion chamber containexcess carbon?

Is the flywheelloose?

Is the spark plugfouled?

Is the spark plugfaulty or gapincorrect?

Are the breakerpoints faulty?

Is the carburetorset incorrectly?

Is the valvespring weak?

Is the valveclearance setincorrectly?

Is the fuel mixturetoo lean?

Ask thisquestion:

If the engine runs poorly

Ask thisquestion:

If the answeris yes:

*Refer to Briggs & StrattonSmall EngineCare & Repairfor complete procedures.

Printed in U.S.A. 2001 Briggs & Stratton Corporation Form MS-6605-2/01

briggs and stratton small engine care

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