outdoor power equipment

   Three basic types of ignition systems are used:

1. A flywheel type, having either an internal or external breaker system.
2. The Magna-Matic system, having the armature and rotor beneath the flywheel, and an external breaker system.
3. Electronic ignition system, eliminating the points. (If you have an Electronic Ignition System, please refer only to the Armature instructions within this section below.)

Check Ignition

   Remove the spark plug. Spin the flywheel rapidly with one end of the ignition cable clipped to the #19051 tester and with the other end of the tester grounded on the cylinder head. If spark jumps the .116″ tester gap, you may assume the ignition system is functioning satisfactorily.
   NOTE: If engine runs but misses during operation, a quick check to determine if ignition is or is not at fault can be made by inserting the #19051 tester between the ignition cable and the spark plug. A spark miss will be readily apparent. While conducting this test on Magna-Matic equipped engines, Models 9, 14, 19 and 23, set the tester gap at .060″.

Spark Plug

   The spark plugs recommended for Briggs & Stratton engines are as follows:
   (Required Tool — Deep socket plug wrench – 3/4″ and/or 13/16″)

• Champion –J19LM, CJ-8, J-8, RC12YC, RJ19LM
• Auto-Lite — A-7NX, A-71, AR-7N, AR-80
• A.C. — CS-45, GC-46, R-46

Spark Plug Cleaning

   Clean spark plug with a pen knife or wire brush and solvent and set gap at .030″ for ALL models. If electrodes are burned away, or the porcelain is cracked, replace with a new plug. DO NOT USE ABRASIVE CLEANING MACHINES.

Coil and Condenser Testing – ALL Models

   Use an approved tester to test coils and condensers. Specifications are supplied by the tester manufacturer. (It is usually best to bring the coil and/or condenser in for testing.)

Ignition

Flywheel Type — Internal Breaker

   The flywheel is located on the crankshaft with a soft metal key. It is held in place by a nut or starter clutch. The flywheel key must be in good condition to insure proper location of the flywheel for ignition timing. DO NOT use a steel key under any circumstances! Use only the soft key, as originally supplied.
   The key-way in both flywheel and crankshaft should not be distorted. Flywheels used are made of aluminum, zinc, or cast iron.

Remove Flywheel Nut or Starter Clutch

   On flywheels of 6-3/4″ diameter or less, use flywheel holder #19167, to keep flywheel from turning. On rope starter engines, the 1/2″ diameter thread flywheel nut is left handed and the 5/8″ diameter thread is right handed. Starter clutch used on rewind and wind-up starter has a right hand thread. Use #19114 starter clutch wrench.
   For flywheels of larger diameter, place a block of wood under flywheel fin to prevent flywheel turning while loosening nut or starter clutch.

Remove Flywheel

   Some flywheels have two holes provided for use of a flywheel puller. Leave nut loose on threads of engine for puller to bear against. Small cast iron flywheels do not require a flywheel puller.

Removing Breaker Cover

   Care should be taken when removing breaker cover, to avoid damaging cover. If cover is bent or damaged it should be replaced to insure a proper dust deal.

Breaker Points

   Breaker point gap on all models is .020″. Breaker points should be checked for contact and for signs of burning or pitting. Points set too wide will advance spark timing and may cause kick back when starting. Points gaped too close retard spark timing and decrease engine power.

Remove Breaker Points

   Breaker point assemblies are removed by removing condenser and armature wires from breaker points clip. Loosen adjusting lock screw and remove breaker point assembly.
   Another style of breaker point assemblies are removed by loosening the screw holding the post. The condenser on these models also includes the breaker point. The condenser is removed by loosening the screw holding the condenser clamp.
   If the breaker point plunger hole becomes worn excessively, oil will leak past the plunger and may get on the points, causing burning. To check, loosen breaker point mounting screw and move breaker points out of the way. Remove plunger. If the flat end of the #19055 plug gauge will the plunger hole for a distance of 1/4″ or more, the hole should be re-bushed.

Install Breaker Point Plunger Bushing

   To install the bushing, it is necessary that the breaker points, armature, crankshaft, and starter be removed. Use a reamer #19056, to ream out the old plunger hole. This should be done by hand. The reamer should be in alignment with the plunger hole. Drive the bushing, #23513, with drive #19057 until the upper end of the bushing is flush with the top of the boss. Finish ream the bushing with reamer #19058. All reaming chips or dirt must be removed.

Breaker Point Plunger

   If the breaker point plunger is worn to a length of .870″ or less, it should be replaced. Plungers must be inserted with groove at the top when installed or oil will enter breaker box.

Install Breaker Points

   Most complaints concerning engine operation can be classified as one or a combination of the following:

1. Will not start
2. Hard starting
3. Kicks back when starting
4. Lack of power
5. Vibration
6. Erratic operation
7. Overheating
8. High oil consumption

   When the cause of malfunction is not readily apparent, perform a check of the Compression, Ignition and Carburetion Systems. This check-up, performed in a systematic manner, can usually be done in a matter of minutes. The quickest and surest method of determining the cause of failure. This check-up will point up possible cause of future failures, which can be corrected at the time. The basic check-up procedure is the same for all engine models, while any variation, by model will be shown under the subject heading.
   NOTE: What appears to be an engine malfunction may be a fault of the powered equipment rather than the engine. If equipment is suspect, see Equipment, affecting engine operation.

Check Compression

   Spin flywheel in reverse rotation (counterclockwise) to obtain accurate compression check. The flywheel should not rebound sharply, indicating satisfactory compression.
   If compression is poor, look for:

1. Loose spark plug
2. Loose cylinder head bolts
3. Blown head gasket
4. Burnt valves and/or seats

   NOTE: The list is greater than 4 possibilities, but further tests would most likely require a qualified service technician.

Check Ignition

   Remove the spark plug. Spin the flywheel rapidly with one end of the ignition cable clipped to the pt. #19051 spark tester and with the other end of the tester grounded on the cylinder head. If spark jumps the .116″ tester gap, you may assume the ignition system is functioning satisfactorily. Try a new spark plug.
   If spark does not occur look for:

1. Incorrect armature air gap
2. Worn bearings and/or shaft on flywheel side.
3. Sheared flywheel key
4. Incorrect breaker point gap (when so equipped)
5. Dirty or burned breaker points
6. Breaker plunger stuck or worn
7. Shorted ground wire (when so equipped)
8. Shorted stop switch (when so equipped)
9. Condenser failure
10. Armature failure
11. Improperly operating interlock system

   NOTE: If engine runs but misses during operation, a quick check to determine if ignition is or is not at fault can be made by inserting the #19051 tester between the ignition cable and the spark plug. A spark miss will be readily apparent. While conducting this test on Magna-Matic equipped engines, Models 9, 14, 19 and 23, set the tester gap at .060″.

Check Carburetion

   Before making a carburetion check, be sure the fuel tank has an ample supply of fresh, clean gasoline. On gravity feed (Flo-Jet) models, see that the shut-off valve is open and fuel flows freely through the fuel line. On all models, inspect and adjust the needle valves (per-set at 1-1/2 turns). Check to see that the choke closes completely. If engine will not start, remove and inspect the spark plug. If plug is wet, look for:

1. Over-chocking
2. Excessively rich fuel mixture
3. Water in fuel
4. Inlet valve stuck open (Flo-Jet carburetor)

   If plug is dry, look for:

1. Leaking carburetor mounting gaskets
2. Gummy or dirty screen or check valve (Pulsa-Jet and Vacu-Jet carburetors)
3. Inlet valve stuck shut (Flo-Jet carburetors)
4. Inoperative pump (Pulsa-Jet carburetors)

   A simple check to determine if the fuel is getting to the combustion chamber through the carburetor is to remove the spark plug and pour a small quantity of gasoline through the spark plug hole. Replace the plug. If the engine fires a few times then quits, look for the same condition(s) as for a dry plug.

Equipment – Effecting Engine Operation

   Frequently, what appears to be a problem with engine operations, such as hard starting, vibration, etc., may be the fault of the equipment powered rather than the engine itself. Since many varied types of equipment are powered by Briggs & Stratton engines, it is not possible to list all of the various conditions that may exist. Listed are the most common effects of equipment problems, and what to look for as the most common cause.

Hard Starting, Kickback, or Will Not Start

1. Loose blade — Blade must be tight to shaft or adaptor.
2. Loose belt — a loose belt like a loose blade can cause a back-lash effect, which will counteract engine cranking effort.
3. Starting under load — See if the unit is disengaged when engine is started; or if engaged, does not have a heavy starting load.
4. Check remote Choke-A-Matic control assembly for proper adjustment.
5. Check interlock system for shorted wires, loose or corroded connections, or defective modules or switches.

Vibration

1. Cutter blade bent or out of balance — Remove and balance.
2. Crankshaft bent — Replace.
3. Worn blade coupling — Replace if coupling allows blade to shift, causing unbalance.
4. Mounting bolts loose — Tighten.
5. Mounting deck or plate cracked — Repair or replace.

Power Loss

1. Bind or drag in unit — If possible, disengage engine and operate unit manually to feel for any binding action.
2. Grass cuttings build-up under deck.
3. No lubrication in transmission or gear box.
4. Excessive drive belt tension may cause seizure.

Noise

1. Cutter blade coupling or pulley — an oversize or worn  coupling can result in knocking, usually under acceleration. Check for fit, or tightness.
2. No lubricant in transmission or gear box.

For Parts Needed for Above Steps

To order the Briggs & Stratton parts you need, see the list below:

• Head Gaskets
• Points, Condensers, Plungers & Flywheel Keys
• Stop Switches
• Armatures / Coils
• Spark Plugs
• Cables & Controls
• Drive Systems & Drive Parts
• Blades

Welcome to the Small Engine ShoppeBriggs & Stratton
Service and Repair Information Center

     Before I delve into the technical information concerning Briggs & Stratton (B&S) engine repair in specific areas pertaining to B&S engines, I would first like to give some important information that the person(s) performing the repairs should know and understand about these engines. Remember, we all want a long life out of all our B&S products. 

Briggs & Stratton General Information

    All Briggs & Stratton engines are of the same basic 4 stroke cycle design used in automobiles, aircraft, trucks and tractors. As the name indicates, there are four strokes to one complete power cycle:

INTAKE STROKE:
    The piston goes down, creating a vacuum in the cylinder which draws gas  through open intake valve into the space above piston.

COMPRESSION STROKE:
    The piston comes up with both valves closed, highly compressing the gas into the space left between the top of the piston and cylinder head.

POWER STROKE:
    At this point the magneto sends high tension current to the spark plug, firing or exploding the compressed gas and driving the piston down.

EXHAUST STROKE:
    Exhaust valve opens and the upward stroke of the piston forces out all of the burnt gases, thus completing the power cycle.

 Caution

    Exhaust gases contain carbon monoxide, which is odorless and a deadly poison. Proper care must be taken to provide efficient ventilation when running an engine indoors.
    Fill the crankcase and air cleaner(when applicable) with proper oil before starting the engine. See that the oil level is maintained.
    Do not fill the gasoline tank while the engine is running. Avoid spilling gasoline on a hot engine—This may cause an explosion and serious injury. 

 Use Clean Gasoline

    It is recommended “regular” grade gasoline be used for all Briggs & Stratton engines. However, the use of lead-free, or low lead, gasoline will result in reduced combustion deposits and normally will improve engine life. Therefore, lead-free, or low lead, gasoline may be used, wherever available.
    It is also recommended that gasoline be purchased in small quantities, not more than a 30-day supply. FRESH gasoline minimizes gum deposits, and also insures a fuel with volatility tailored for the season.

Correct Lubrication is Important

    Any high quality oil having the American Petroleum Institute classification  “For Service SC, SD, SE or MS” can be used in Briggs & Stratton engines. Detergent oils keep the engine cleaner and retard the formation of gum and varnish deposits.

    The oil recommendations are the result of extensive testing. No special additives should be used.
    The oil should be changed after EACH 25 HOURS of engine operation. (More often under dirty operating conditions). In normal running of any engine, small particles of metal from the cylinder walls, pistons and bearings will gradually work into the oil. Dust particles from the air also get into the oil. If the oil is not changed regularly, these foreign particles cause increased friction and a grinding action which shorten the life of the engine. Fresh oil also assists in cooling, for old oil gradually becomes thick and loses its cooling effect as well as lubricating qualities.
    The air cleaner should be serviced every 25 hours of engine operation. Dirty operating conditions require more frequent servicing.

Clean Cooling System

    Grass particles, chaff or dirt may clog the air cooling system, especially after prolonged service in cutting dry grasses. Continued operation with a clogged cooling system may cause severe overheating and possible engine damage.

Tune – Up Procedure

    A “Tune – Up,” see the steps listed below, would normally be performed on relatively new engines brought in for minor difficulties. By performing these steps you will either be sure that the engine is functioning properly or will know what major repairs should be made.

1. Remove air cleaner, check for proper servicing.
2. Check oil level and drain. (Clean fuel tank and lines if separate from carburetor).
3. Remove blower housing, inspect rope and rewind assembly and starter clutch.
4. Clean cooling fins and entire engine. Rock flywheel to check compression.
5. Remove carburetor, disassemble and inspect for wear or damage. Wash in solvent, replace parts as necessary and assemble. Set initial adjustment (high and low adjustment screws are both pre-set at 1 1/2 turns open).
6. Inspect crossover tube or intake elbow for damaged gaskets (properly named “manifold”).
7. Check governor blade, linkage and governor spring for damage or wear, if mechanical also check adjustment.
8. Remove flywheel, check for seal leakage, both flywheel and PTO sides. Check flywheel key.
9. Remove breaker cover and check for proper sealing.
10. “For older models” – Inspect breaker points and condenser. Replace or clean and adjust. Check breaker point plunger.
11. Check coil, inspect all wires for breaks, damaged insulation. Be sure lead wires do not touch flywheel. Check stop switch and lead.
12. Replace breaker cover, use sealer where wires enter.
13. Install flywheel, time engine if necessary. Set air gap. Check for spark.
14. Remove cylinder head, check gasket, remove spark plug, and clear carbon, inspect valves for seating.
15. Replace cylinder head, torque to specified torque, set spark plug gap or replace plug if necessary.
16. Replace oil and fuel, check muffler for restrictions or damage.
17. Adjust remote control linkage and cable if used, for correct operation.
18. Service air cleaner, check gaskets and element for damage.
19. Run and adjust mixture jet and top speed.

For Parts Needed for Above Steps

    To order the Briggs & Stratton parts you need, see the list below:

• Air Filters
• Fuel Filters
• Starter Springs, Clutches, Ropes and Grips
• Carburetors and carburetor parts
• Mufflers
• Points & Breaker Plungers and Flywheel Keys
• Spark Plugs
• Head Gaskets and Gasket Sets

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