Briggs & Stratton 420000 Series Manual

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Model Series
Covered in
This Manual
420000
460000
Operating & Maintenance
Instructions
Model Type Code
Month Day Year
Note: General Model Series number noted above is inclusive of the specific model
number found on your engine. To get replacement parts or technical assistance in
the future, write your engine Model, Type, Code and date of purchase here.
TABLE OF CONTENTS
Safety 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Information 6. . . . . . . . . . . . . . . . . . . . . . . .
Oil 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel and Starting Information 8. . . . . . . . . . . . . . .
Starting and Stopping 9-10. . . . . . . . . . . . . . . . . . .
Maintenance 11-14. . . . . . . . . . . . . . . . . . . . . . . . .
Adjustments 14-15. . . . . . . . . . . . . . . . . . . . . . . . . .
Parts and Service & Storage 16. . . . . . . . . . . . . . .
Warranty Information 17. . . . . . . . . . . . . . . . . . . . .
WARNING
Briggs & Stratton does not approve or authorize the use of
these engines on 3-wheel All Terrain Vehicles (ATVs), motor
bikes, aircraft products or vehicles intended for use in
competitive events. Use of these engines in such applications
could result in property damage, serious injury (including
paralysis), or even death.
Need assistance? Go to www.briggsandstratton.com
for detailed information regarding
Briggs & Stratton engines.
Or call, 1-800-233-3723, (U.S.A. and Canada)
to hear a menu of pre-recorded messages
offering engine maintenance information.
PRINTED IN U.S.A. Copyright 2003 by Briggs & Stratton Corporation FORM NO. 274796-5/03

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The Power That Works For You.
Look For Relevant Emissions Durability Period and Air Index Informa-
tion On Your Engine Emissions Label
Engines that are certified to meet the California Air Resources Board (CARB) Tier 2 Emission Standards must
display information regarding the Emissions Durability Period and the Air Index. Briggs & Stratton makes this
information available to the consumer on our emission labels. The engine emission label will indicate certification
information.
The Emissions Durability Period describes the number of hours of actual running time for which the engine is
certified to be emissions compliant, assuming proper maintenance in accordance with the Operating &
Maintenance Instructions. The following categories are used:
Moderate: Engine is certified to be emission compliant for 125 hours of actual engine running time.
Intermediate: Engine is certified to be emission compliant for 250 hours of actual engine running time.
Extended: Engine is certified to be emission compliant for 500 hours of actual engine running time.
For example, a typical walk-behind lawn mower is used 20 to 25 hours per year. Therefore, the Emissions
Durability Period of an engine with an intermediate rating would equate to 10 to 12 years.
The Air Index is a calculated number describing the relative level of emissions for a specific engine family. The
lower the Air Index,the cleaner the engine. This information is displayed in graphical form on the emissions
label.
After July 1, 2000, Look For Emissions Compliance Period On
Engine Emissions Compliance Label
After July 1, 2000 certain Briggs & Stratton engines will be certified to meet the United States Environmental
Protection Agency (USEPA) Phase 2 emission standards. For Phase 2 certified engines, the Emissions
Compliance Period referred to on the Emissions Compliance label indicates the number of operating hours for
which the engine has been shown to meet Federal emission requirements. For engines less than 225 cc
displacement, Category C = 125 hours, B = 250 hours and A = 500 hours. For engines of 225 cc or more,
Category C = 250 hours, B = 500 hours and A = 1000 hours.
The displacement of Model Series 420000 engines is 694 cc. The displacement of Model Series 460000 engines
is 745 cc.
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BEFORE OPERATING ENGINE
•Read entire Operating & Maintenance Instructions AND
the instructions for the equipment this engine powers.*
•Failure to follow instructions could result in serious injury
or death.
THE OPERATING & MAINTENANCE INSTRUCTIONS
CONTAIN SAFETY INFORMATION TO
•Make you aware of hazards associated with engines
•Inform you of the risk of injury associated with those hazards, and
•Tell you how to avoid or reduce the risk of injury.
274796
The safety alert symbol ( ) is used to identify safety
information about hazards that can result in personal injury.
A signal word (DANGER, WARNING, or CAUTION) is
used with the alert symbol to indicate the likelihood and the
potential severity of injury. In addition, a hazard symbol
may be used to represent the type of hazard.
DANGER indicates a hazard which, if not
avoided, will result in death or serious injury.
WARNING indicates a hazard which, if not
avoided, could result in death or serious injury.
CAUTION indicates a hazard which, if not
avoided, might result in minor or moderate
injury.
CAUTION,when used without the alert symbol,
indicates a situation that could result in damage
to the engine.
WARNING
The engine exhaust from this prod-
uct contains chemicals known to the
State of California to cause cancer,
birth defects, or other reproductive
harm.
HAZARD SYMBOLS AND MEANINGS
Explosion
Toxic Fumes
Moving Parts
ShockHot Surface
Kickback
Fire
THE INTERNATIONAL SYMBOLS USED
ON THE ENGINE OR
IN THIS MANUAL INCLUDE:
On Off
Fuel Shutoff
Read Owner’s
Manual
Stop Fuel
Choke
Safety Alert
Oil
*Briggs & Stratton does not necessarily know what equipment this engine will power. For that reason, you should carefully read
and understand the operating instructions for the equipment on which your engine is placed.

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SAFETY
Gasoline and its vapors are extremely
flammable and explosive.
Fire or explosion can cause severe burns
or death.
WARNING
WHEN ADDING FUEL
•Turn engine OFF and let engine cool at least 2
minutes before removing gas cap.
•Fill fuel tank outdoors or in well-ventilated area.
•Do not overfill fuel tank. Fill tank to approximately
1-1/2 inches below top of neck to allow for fuel
expansion.
•Keep gasoline away from sparks, open flames,
pilot lights, heat, and other ignition sources.
•Check fuel lines, tank, cap, and fittings frequently
for cracks or leaks. Replace if necessary.
WHEN STARTING ENGINE
•Make sure spark plug, muffler, fuel cap and air
cleaner are in place.
•Do not crank engine with spark plug removed.
•If fuel spills, wait until it evaporates before starting
engine.
•If engine floods, set choke to OPEN/RUN position,
place throttle in FAST and crank until engine starts.
WHEN OPERATING EQUIPMENT
•Do not tip engine or equipment at angle which
causes gasoline to spill.
•Do not choke carburetor to stop engine.
WHEN TRANSPORTING EQUIPMENT
•Transport with fuel tank EMPTY or with fuel shut-off
valve OFF.
WHEN STORING GASOLINE OR EQUIPMENT
WITH FUEL IN TANK
•Store away from furnaces, stoves, water heaters or
other appliances that have pilot light or other
ignition source because they can ignite gasoline
vapors.
Starting engine creates sparking.
Sparking can ignite nearby flammable
gases.
Explosion and fire could result.
WARNING
•If there is natural or LP gas leakage in area, do not
start engine.
•Do not use pressurized starting fluids because
vapors are flammable.
WARNING
Rapid retraction of starter cord (kickback) will
pull hand and arm toward engine faster than
you can let go.
Broken bones, fractures, bruises or sprains
could result.
•When starting engine, pull cord slowly until
resistance is felt, then pull rapidly.
•Remove all external equipment/engine loads
before starting engine.
•Direct coupled equipment components such as,
but not limited to, blades, impellors, pulleys,
sprockets, etc., must be securely attached.
WARNING
Rotating parts can contact or entangle
hands, feet, hair, clothing, or accessories.
Traumatic amputation or severe laceration
can result.
•Operate equipment with guards in place.
•Keep hands and feet away from rotating parts.
•Tie up long hair and remove jewelry.
•Do not wear loose-fitting clothing, dangling
drawstrings or items that could become caught.

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SAFETY
Engines give off carbon monoxide, an
odorless, colorless, poison gas.
Breathing carbon monoxide can cause
nausea, fainting or death.
WARNING
•Start and run engine outdoors.
•Do not start or run engine in enclosed area, even if
doors or windows are open.
WARNING
Running engines produce heat. Engine
parts, especially muffler, become extremely
hot.
Severe thermal burns can occur on contact.
Combustible debris, such as leaves, grass,
brush, etc. can catch fire.
•Allow muffler, engine cylinder and fins to cool
before touching.
•Remove accumulated combustibles from muffler
area and cylinder area.
•Install and maintain in working order a spark
arrester before using equipment on forest-covered,
grass-covered, brush-covered unimproved land.
The state of California requires this (Section 4442
of the California Public Resources Code). Other
states may have similar laws. Federal laws apply
on federal land.
WARNING
Unintentional sparking can result in fire or
electric shock.
Unintentional start-up can result in en-
tanglement, traumatic amputation, or lac-
eration.
BEFORE PERFORMING ADJUSTMENTS OR
REPAIRS
•Disconnect spark plug wire and keep it away from
spark plug.
•Disconnect battery at negative terminal (only
engines with electric start).
WHEN TESTING FOR SPARK
•Use approved spark plug tester.
•Do not check for spark with spark plug removed.
ENGINE INFORMATION
TECHNICAL INFORMATION
POWER RATINGS: The power ratings for an individual engine
model are initially developed by starting with SAE (Society of Auto-
motive Engineers) code J1940 (Small Engine Power & Torque
Rating Procedure) (Revision 2002-05). Given both the wide array
of products on which our engines are placed, and the variety of en-
vironmental issues applicable to operating the equipment, it may
be that the engine you have purchased will not develop the rated
horsepower when used in a piece of power equipment (actual “on-
site” power). This difference is due to a variety of factors including,
but not limited to, the following: differences in altitude, tempera-
ture, barometric pressure, humidity, fuel, engine lubrication, maxi-
mum governed engine speed, individual engine to engine variabil-
ity, design of the particular piece of power equipment, the manner
in which the engine is operated, engine run-in to reduce friction
and clean out of combustion chambers, adjustments to the valves
and carburetor, and other factors. The power ratings may also be
adjusted based on comparisons to other similar engines utilized
in similar applications, and will therefore not necessarily match the
values derived using the foregoing codes.

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ENGINE INFORMATION
1. Spark plug wire
2. Carburetor
3. Air cleaner
4. Rotating screen
5. Emission label and Engine
Model Type Code label
xxxxxx xxxx xx xxxxxxxx
6. Oil drain plug
7. Crankshaft
8. 12V electric starter
9. Fuel filter
10. Oil fill/Dipstick
11. Blower housing
35
1
2
4
8
10
9
6
7
11
GENERAL INFORMATION
ENGINE MODEL
This is a twin cylinder, L-head, air-cooled engine. It is a low
emissions engine.
In the state of California, the 420000 and 460000 series
engines covered in this manual are certified by the
California Air Resources Board to meet emissions stan-
dards for 125 hours. Such certification does not grant the
purchaser, owner or operator of this engine any additional
warranties with respect to the performance or operational
life of this engine. This engine is warranted solely according
to the product and emissions warranties stated elsewhere
in this manual.
MODEL SERIES 420000
Bore 3-7/16 in. (87.31 mm). . . . . . . . . . . . . . . . . . . . . . . . . .
Stroke 2-9/32 in. (57.94 mm). . . . . . . . . . . . . . . . . . . . . . . .
Displacement 42.33 cu. in. (694.0 cc). . . . . . . . . . . . . . . .
MODEL SERIES 460000
Bore 3-9/16 in. (90.49 mm). . . . . . . . . . . . . . . . . . . . . . . . . .
Stroke 2-9/32 in. (57.94 mm). . . . . . . . . . . . . . . . . . . . . . . .
Displacement 45.48 cu. in. (745.2 cc). . . . . . . . . . . . . . . .
TUNE-UP SPECIFICATIONS
Armature air gap 0.010 – 0.014 in. (0.25 – 0.36 mm). . .
Spark plug gap 0.030 in. (0.76 mm). . . . . . . . . . . . . . . . . .
Valve clearance with valve springs installed and piston 1/4 in.
(6 mm) past top dead center (check when engine is cold).
See Repair Manual P/N 271172.
Intake 0.006 – 0.008 in. (0.15 – 0.20 mm). . . . . . . . . . . . .
Exhaust 0.009 – 0.011 in. (0.23 – 0.28 mm). . . . . . . . . . .
Note: For practical operation, the horsepower loading
should not exceed 85% of rated horsepower. Engine power
will decrease 3-1/2% for each 1,000 feet (300 meters)
above sea level and 1% for each 10°F (5.6°C) above 77°F
(25°C). It will operate satisfactorily at an angle up to 15°.

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7
OIL
274796
CAUTION: This engine is shipped from Briggs &
Stratton without oil. Check oil level before starting
engine. If you start the engine without oil, the engine
will be damaged beyond repair and will not be
covered under warranty.
OIL CAPACITY
Engine without oil filter holds approximately 1-1/2 quarts
(48 ounces; 1.4 liter).
Engine equipped with oil filter holds approximately
1-3/4 quarts (56 ounces; 1.7 liters).
TYPE OF OIL TO USE
•Use a high quality detergent oil classified “For Service
SF, SG, SH, SJ” or higher, such as Briggs & Stratton
30W, Part Number 100005 (20 oz) or 100028 (48 oz).
•Do not use special additives.
•Choose a viscosity according to the table opposite.
Note: Synthetic oil meeting ILSAC GF-2, API
certification mark and API service symbol
(shown at left) with “SJ/CF ENERGY CON-
SERVING” or higher, is an acceptable oil at all
temperatures. Use of synthetic oil does not
alter required oil change intervals.
°F-20 0 20 40 60 80 100
°C-30 -20 -10 0 10 20 30 40
STARTING TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE
*
**
32
*CAUTION: Use 5W-30 oil or synthetic oil if anticipated
temperatures are below 40°F (4°C) to prevent
internal engine damage at startup due to inadequate
lubrication. Air cooled engines run hotter than
automotive engines. The use of non-synthetic
multi-viscosity oils, e.g. 5W-30, in temperatures
above 40°F (4°C) will result in higher than normal oil
consumption. When using a multi-viscosity oil, check
oil level more frequently.
** CAUTION: SAE 30 oil, if used below 40°F (4°C), will
result in hard starting and possible engine bore
damage due to inadequate lubrication.
SAE Viscosity Grades
CHECKING AND ADDING OIL
•Check oil level before starting the engine.
•Check level daily, or after every eight (8) hours.
•Keep oil level at FULL.
•Do not overfill.
[1] Place engine level. Clean
around oil fill and dipstick.
[2] Remove dipstick and wipe clean with cloth.
[3] Then push dipstick back in and remove to check oil level.
FULL
ÏÏ
ÏÏ
ÏÏ
Oil Fill
Dipstick
[4] Remove dipstick. Pour oil
slowly.
[5] Fill to FULL line on dipstick
– recheck. [6] Replace dipstick firmly.
FULL
ÏÏ
ÏÏ

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8
FUEL
TYPE OF FUEL TO USE
•Use clean, fresh, regular unleaded gasoline with a
minimum of 77 octane. Fresh fuel prevents gum from
forming in the fuel system or on essential carburetor parts.
Purchase fuel in quantity that can be used within 30 days.
•Do not use gasoline which contains Methanol.
•Do not mix oil with gasoline.
•For engine protection use Briggs & Stratton Gasoline
Additive available from your Authorized Briggs &
Stratton Dealer (P/N 5041 or single use pouch).
•This engine is certified to operate on gasoline. Exhaust
Emission Control System: EM (Engine Modifications).
CAUTION: Some fuels, called oxygenated or reformu-
lated gasoline, are gasoline blended with alcohols or
ethers. Excessive amounts of these blends can damage
the fuel system or cause performance problems. If any
undesirable operating symptoms occur, use gasoline
with a lower percentage of alcohol or ether.
ADDING FUEL
WARNING
[1] Remove cap. Fill tank to approximately 1-1/2
inches below top of neck to allow for fuel
expansion. Be careful not to overfill.
Briggs & Stratton Smart-fill)fuel can fills to the
correct level and automatically shuts off, reduc-
ing spills and emissions.
[2] Replace cap before starting.
•Turn engine OFF and let engine cool at least 2
minutes before removing gas cap.
•Fill fuel tank outdoors or in well-ventilated area.
•Keep gasoline away from sparks, open flames,
pilot lights, heat, and other ignition sources.
•If fuel spills, wait until it evaporates before
starting engine.
STARTING
WARNING
•Do not use pressurized starting fluids.
•Vapors are flammable.
OIL PRESSURE SWITCH
If engine is equipped with an oil pressure switch, the switch
will either activate a warning device or stop the engine
when the engine runs low on oil. (Read the operating
instructions supplied by the equipment manufacturer to
determine which way your engine is equipped because the
equipment manufacturer supplies the oil pressure gauge.)
See oil pressure on page 12 for oil filling instructions.
STARTING AND OPERATING TIPS
♦Store and fuel equipment in level position.
♦Use fresh fuel. (See Fuel.)
♦Use correct type of oil for expected starting
temperature. (See Oil.)
♦Remove external equipment/engine loads. (See
equipment operating instructions.)
♦Start lawn mower on hard surface or over previously
cut grass.
♦Periodically remove grass buildup under mower
deck. (See Maintenance.)
♦After engine has started, let it warm up several
seconds to several minutes, depending on outside
temperature.
♦For maximum performance and life, operate engine
with choke in RUN and throttle in FAST.

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9
STARTING AND STOPPING
REWIND (MANUAL) STARTER
TO START ENGINE
[1] Check oil level (see p. 7).
[2] Open fuel shut-off valve
(if equipped).
[3] Move choke control to CHOKE or
START.
[4] Move throttle to FAST
(if equipped). Operate en-
gine with throttle in FAST.
Choke
FULL
Ï
ÏÏ
ÏÏ
[5] Grasp rope handle. Pull slowly
until resistance is felt, then pull
rapidly to start engine and avoid
kickback.
[6] Let engine warm up.
Choke Equipped: Move
choke control lever
toward RUN a short dis-
tance at a time over sev-
eral seconds in warm
weather or minutes in cold
weather. Let engine run
smoothly before each
change. Operate with
choke in RUN.
WARNING
Rewind starter Rope starter
TO STOP ENGINE
[1] Move throttle
(if equipped) to
SLOW, then to STOP.
[2] Close fuel shut-off
valve
(if equipped).
CAUTION:
Do not stop engine
by moving choke
control to CHOKE.
Backfire, fire or en-
gine damage
could occur.

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10
STARTING AND STOPPING
ELECTRIC (KEY) STARTER (if equipped)
TO START ENGINE
[1] Check oil level.
[2] Open fuel shut-off valve
(if equipped).
[3] Move choke control to CHOKE or
START.
[4] Move throttle to FAST (if
equipped). Operate en-
gine with throttle in FAST.
Choke
FULL
Ï
Ï
ÏÏ
ÏÏ
[5] Insert key and turn to
START.
CAUTION:
To prolong starter life,
use short starting cycles
(5 seconds maximum,
then wait one minute).
Follow equipment
manufacturer’s recom-
mendations for charging
battery.
[6] Let engine warm up. Choke
Equipped: Move choke
control lever toward RUN a
short distance at a time over
several seconds in warm
weather or minutes in cold
weather. Let engine run
smoothly before each
change. Operate with choke
in RUN.
TO STOP ENGINE
[1] Move throttle
(if equipped) to SLOW.
[2] Turn key to OFF.
Remove key and
store out of reach of
children.
[3] Close fuel shut-off
valve (if equipped).