Briggs & Stratton 28N700 Series Installation and operation manual

Model Series
Covered in
This Manual
28N700
287700
28P700
28Q700
28S700
28U700
310700
311700
312700
313700
Operating & Maintenance
Instructions
Model Type Code
Month Day Year
Note: General Model Series numbers noted above include many specific numbers
like the ones 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 11-13. . . . . . . . . . . . . . . . . . . . . . . . .
Adjustments 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts and Service & Storage 15-16. . . . . . . . . . . .
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.
In the USA and Canada our 24 hour hotline is
1-800-233-3723
Briggs & Stratton Corporation
Milwaukee, Wisconsin 53201
www.briggsandstratton.com
PRINTED IN U.S.A. Copyright 2000 by Briggs & Stratton Corporation FORM NO. 274789-9/00

2
The Power In Power Equipment
Thank you for selecting a Briggs & Stratton engine to power your equipment.
Briggs & Stratton is committed to producing a line of engines which will make your life’s chores easier to perform. We have,
at the same time, improved the design of our engines so they are environmentally friendly. Since 1995, we have succeeded
in reducing smog-forming exhaust emissions from our engines by 70%. Briggs & Stratton’s efforts have not stopped there.
We are also committed to designing and introducing even cleaner engines in the future, while maintaining our reputation for
excellent utility and value.
Briggs & Stratton’s environmental awareness has resulted in the engineering of the “Smart-Fill” gas can, featuring a spill
resistant nozzle which opens only when fully inserted into the gas tank, and which shuts off automatically when the tank is
full. Because refueling spills can harm the environment, the Smart-Fillcontainer helps preserve a stronger ecosystem by
reducing this source of pollution.
We hope you will enjoy your new engine and equipment. We welcome you to our worldwide family of Briggs & Stratton
engine users.
Best Wishes Always,
The Employees of Briggs & Stratton Corporation
Look For Relevant Emissions Durability Period and
Air Index Information 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.
TheEmissions 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 280000 engines is 465 cc. The displacement of Model Series 310000 engines is 501 cc.
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3
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.
274789
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.
HAZARD SYMBOLS AND MEANINGS
Explosion
Toxic Fumes
Moving Parts
Shock
Hot Surface
Kickback
Fire
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.
* 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.

4
SAFETY
WARNING
Gasoline and its vapors are extremely flammable
and explosive.
Fire or explosion can cause severe burns or death.
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.
WARNING
Unintentional sparking can result in fire or electric
shock.
Unintentional start-up can result in entanglement,
traumatic amputation, or laceration.
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.
WARNING
Starting engine creates sparking.
Sparking can ignite nearby flammable gases.
Explosion and fire could result.
•If there is natural or LP gas leakage in area, do not
start engine.
•Do not use pressurized starting fluids because
vapors are flammable.

5
SAFETY
WARNING
Engines give off carbon monoxide, an odorless,
colorless, poison gas.
Breathing carbon monoxide can cause nausea,
fainting or death.
•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
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.
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.

6
ENGINE PARTS
1. Oil drain
2. Oil fill/Dipstick
3. Rotating screen
4. Blower housing
5. Muffler/(Muffler guard, if equipped)/
(Spark arrester, if equipped)
6. 12 V electric starter
7. Air cleaner
8. In-line fuel filter (if equipped)
9. Carburetor
10. Oil filter (if equipped)
11. Spark plug wire
12. Engine Model Type Code
xxxxx xxxx xx xxxxxxxx
34
5
6
2
9
7
8
10
11
1
12
GENERAL INFORMATION
ENGINE MODEL
This is a single cylinder, overhead valve (OHV), air-cooled
engine. It is a low emissions engine.
In the state of California, OHV Model Series 280000 and
310000 engines are certified by the California Air Re-
sources Board to meet emissions standards for 250 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 280000
Bore 3-7/16 in. (87.31 mm). . . . . . . . . . . . . . . . . . . . . . . . . .
Stroke 3-1/16 in. (77.78 mm). . . . . . . . . . . . . . . . . . . . . . . .
Displacement 28.42 cu. in. (465.7 cc). . . . . . . . . . . . . . . .
MODEL SERIES 310000
Bore 3-9/16 in. (90.60 mm). . . . . . . . . . . . . . . . . . . . . . . . . .
Stroke 3-1/16 in. (77.78 mm). . . . . . . . . . . . . . . . . . . . . . . .
Displacement 30.59 cu. in. (501.2 cc). . . . . . . . . . . . . . . .
Note: For practical operation, the horsepower loading should
not exceed 85% of rated horsepower. Engine power will de-
crease 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).
Engine will operate satisfactorily at an angle up to 15°.
THE INTERNATIONAL SYMBOLS USED
ON THE ENGINE OR
IN THIS MANUAL INCLUDE:
On Off
Fuel Shutoff
Read Owner’s
Manual
Stop
FuelChoke
Safety Alert
Oil
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 272147 or 274008.
Intake 0.003 –0.005 in. (0.08 –0.13 mm). . . . . . . . . . . . .
Exhaust 0.005 –0.007 in. (0.13 –0.18 mm). . . . . . . . . . .

7
OIL
274789
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 liters). 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: Air cooled engines run hotter than
automotive engines. The use of non-synthetic
multi-viscosity oils (5W-30, 10W-30, etc.) 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 and
clean around oil fill area. [2] Remove dipstick and wipe clean with cloth.
[3] Replace and tighten dip-
stick. Remove and check
oil level.
Oil Fill
[4] Oil level should be at
FULL line on dipstick. [5] If needed, add oil slowly - recheck. Do not over fill. [6] Replace and tighten dip- stick.

8
FUEL
TYPE OF FUEL TO USE
•Use clean, fresh, regular unleaded gasoline with a
minimum of 85 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] Fill fuel tank outdoors or in well-ventilated area,
away from sparks, open flames, pilot lights, heat,
and other ignition sources.
[2] If fuel spills, wait until it evaporates before starting
engine.
[3] Turn engine OFF and let engine cool at least 2
minutes before removing gas cap.
[4] 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, reducing
spills and emissions.
[5] Replace cap before starting.
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 light 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.

9
STARTING AND STOPPING
REWIND (MANUAL) STARTER (auxiliary)
TO START ENGINE
[1] Check oil level (see p. 7).
[2] Open fuel shut-off valve
(if equipped) 1/4 turn.
[3] If choke and throttle con-
trols are separate, move
choke control to CHOKE.
Move throttle to FAST.
[4] If choke and throttle are
on the same control,
move control to CHOKE
or START
Choke Throttle Choke/throttle control
1/4 TURN
[5] Insert key and turn to
RUN.
[6] Grasp rope handle. Pull
slowly until resistance is
felt, then pull rapidly to
start engine and avoid
kickback.
[7] Let engine warm up.
Choke Equipped: Move
choke control off or
toward FAST 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
throttle in FAST.
WARNING
TO STOP ENGINE
CAUTION: Do not stop engine by moving choke
control to CHOKE. Backfire, fire or engine damage
could occur.
[1] With throttle in FAST, turn key to OFF.
Remove key and store out of reach of children. [2] Close fuel shut-off valve (if equipped).
1/4 TURN

10
STARTING AND STOPPING
ELECTRIC (KEY) STARTER (if equipped)
TO START ENGINE
[1] Check oil level. [2] If choke and throttle con-
trols are separate, move
choke control to CHOKE.
Move throttle to FAST.
[3] If choke and throttle are
on the same control,
move control to CHOKE
or START
Choke Throttle Choke/throttle control
[4] Open fuel shut-off valve
(if equipped) 1/4 turn. [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
recommendations for charging battery.
[6] Let engine warm up.
Choke Equipped: Move
choke control off or
toward FAST 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 throttle in FAST.
1/4 TURN
TO STOP ENGINE
[1] With throttle in FAST, turn key to OFF.
Remove key and store out of reach of children. [2] Close fuel shut-off valve (if equipped).
1/4 TURN