Briggs & Stratton Engine 277102 Operators Manual

							11
Oil
Check oil level before starting the engine.
Keep oil level at FULL. Do not overfill.
Check level daily, or after every eight (8) hours.
Capacity
Engine oil capacity is 2/3 qt. (22 oz.; 0.65 liter). NOTE: Often residual oil remains in engine. Fill to FULL line on
dipstick.
Oil Recommendation
Use a high quality detergent oil classified “For Service SF, SG, SH, SJ” or higher.
Do not use special additives.
SAE 30 40F and higher (5C and higher)
is good for all purpose use above 40°F,  u s e  b e l o w
40°F will cause hard starting.
10W-30 0 to 100F (−18 to 38C)
is better for varying temperature conditions. This
grade of oil improves cold weather starting, but may
increase oil consumption at 80°F (27°C) or higher.
 
 Check oil level frequently at higher temperatures.
Synthetic 5W-30 −20 to 120F (−30 to 40C)
provides the best protection at all temperatures as
well as improved starting with less oil consumption.
5W-30 40F and below (5C and below)
is recommended for winter use, and works best in
cold conditions.
Checking and Adding Oil
1. Place engine level and clean around oil fill area.
Oil Fill
2. Remove dipstick and wipe with clean cloth. 
3. Replace and tighten dipstick. Remove and check
oil level.
4. Oil level should be at FULL line on dipstick.
FULL
5. If needed, add oil slowly.
6. Re-check oil level. Do not over fill.
7. Replace and tighten dipstick. 
						

							12
Changing Oil
Change oil after first 5 to 8 hours of use, then every 50
hours. Change oil every 25 hours when operating the
engine under heavy load or in high temperatures.
1. Run engine until it runs out of fuel. Otherwise,
fuel can leak out, creating a fire/explosion hazard,
when you tip engine in Step 4.
2. Disconnect spark plug wire and keep it away from
spark plug.
3. With engine OFF but still warm remove dipstick.
4. Drain oil into appropriate receptacle. 
Top oil drain: Keep air cleaner above oil outlet.
Bottom or side oil drain (if equipped): Keep
engine level.
AIR
CLEANERTOP OIL DRAIN
SIDE OIL DRAIN
(IF EQUIPPED)
RATCHET
AND
EXTENSION
CUTTING
BLADEOIL
DRAIN
PLUG BOTTOM OIL DRAIN
DRAIN
PLUGS
PIPE3/8”
SQUARE
Top oil drain is recommended method, however oil can
drain from side (if equipped) or bottom as shown.
5. Place engine level. Add about 20 oz or 0.61 liter
of oil. Note: Often residual oil remains in engine.
Fill to FULL line on dipstick. Do not overfill.
6. Replace dipstick.
Used oil is a hazardous waste product. Dispose
of used oil properly. Do not discard with
household waste. Check with your local
authorities, service center, or dealer for safe
disposal/recycling facilities.
CAUTION
To prevent unintentional starting,
disconnect spark plug wire and keep it away
from spark plug.
Unintentional start-up can result in shock,
entanglement, traumatic amputation, or
laceration.
WARNING
Changing Oil Filter (if equipped)
Replace oil filter after every 100 hours of operation.
OIL FILTER
1. After draining engine of used oil, fill with fresh oil.
2. Before installing new filter, lightly oil gasket with
fresh, clean oil.
3. Screw filter on by hand until gasket contacts oil
filter adapter.
4. Tighten 1/2 − 3/4 turn more.
5. Start and run engine at idle to check for leaks.
6. Stop engine. Re-check oil level. Add oil if
required. 
						

							13
Fuel
Type of gasoline to use
This engine is certified to operate on gasoline. The
emission control system for this engine is EM (Engine
Modifications).
Always use gasoline that meets these requirements:
•Clean, fresh unleaded gasoline.
•A minimum of 87 octane/87 AKI (91 RON). If
operating at high altitude, see below.
•Gasoline with up to 10% ethanol (gasohol) or up to
15% MTBE (methyl tertiary butyl ether), is
acceptable.
•Use of any gasoline other than those approved
above will void the engine warranty. In some local
areas fuel pumps may be marked if the gasoline
contains alcohols or ethers. If you are unsure about
the gasoline you purchase check with your fuel
provider.
•Do not modify the engine fuel system or carburetor
to run on alternative fuels.
•Never mix oil with gasoline.
All gasoline is not the same. If you experience starting
or performance problems after new gasoline has been
used in your engine, switch to a different fuel provider
or change fuel brands.
Some fuels, called oxygenated or reformulated
fuels, are fuels 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.
CAUTION
Fuel Storage
Fuel can become stale when stored over 30 days. Stale
fuel causes acid and gum deposits to form in fuel
system or on essential carburetor parts. Mix fuel
stabilizer with fuel in tank or storage container. Run
engine for a short time to circulate stabilizer through
carburetor and engine. Engine and fuel can be stored
up to 24 months.
If fuel stabilizer is not used, you need to drain gasoline
from equipment prior to storage.
If the FRESH START™ continuous fuel preserver fuel
cap (concentrated liquid cartridge) is used, there is no
need to drain fuel, as long as cartridge contains
stabilizer for seasonal storage.
Fuel Stabilizer
To protect the fuel system from gum formation, use
Briggs & Stratton FRESH START fuel stabilizer plus,
or FRESH START continuous fuel preserver fuel cap
(concentrated liquid cartridge), or FRESH START
preservative & stabilizer (granular).
High-altitude Use
At higher altitudes (over 5,000 feet), 85 octane/85 AKI
(89 RON) gasoline can be used. Operation at high
altitude may require a high-altitude carburetor jet kit to
improve performance and decrease fuel consumption.
See your local authorized Briggs & Stratton dealer for
more information.
Adding Fuel
1. Turn engine OFF and let engine cool at least 2
minutes before removing gas cap.
2. Remove cap. Fill tank to approximately 1 inch
(25mm) below top of neck to allow for fuel
expansion. Be careful not to overfill.
3. Replace cap before starting.
Fuel cap
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.
•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.
WARNING 
						

							14
Fresh Start Continuous Fuel Preserver - Fuel Cap
Your engine may be equipped with
a Fresh Start™ fuel cap.
Cartridge is shown with tab
partially removed.
Fresh Start fuel cap is designed to
hold a cartridge which contains fuel stabilizer.
1. Place silver foil seal end of cartridge into fuel cap.
2. Press to “snap” cartridge into place.
3. Remove the white tab to expose membrane.
4. Reinstall fuel cap on engine fuel tank.
5. Check periodically − if empty, remove and
replace.
DANGER
•IF SWALLOWED, call physician immediately.
Do not induce vomiting. If inhaled, remove to
fresh air. In case of eye or skin contact, flush
with water for 15 minutes.
•Store unopened cartridges in a cool, dry,
well-ventilated area. Keep open cartridge in
fuel cap, and fuel cap closed on fuel tank when
not in use.
Contents are HARMFUL OR FATAL IF
SWALLOWED. Avoid contact to eyes,
skin, or clothing. Do not take internally.
Avoid breathing the mist or vapor.
Overexposure to eyes or skin can
cause irritation. KEEP STABILIZER
OUT OF THE REACH OF CHILDREN.
Fuel stabilizer is a hazardous
chemical.**
•In case of emergency, contact a physician
immediately and call 1-800-424-9300 for material
safety information.
** Fuel stabilizer contains: 2,6-di-tert-butylphenol
(128-39-2) and aliphatic petroleum distillate
(64742-47-8). 
						

							15
Maintenance
Regular maintenance will improve the performance and
extend the life of the engine. See any Authorized Briggs
& Stratton Dealer for service. Use only genuine
Briggs & Stratton parts. Other parts may notperform as well, may damage the engine, and mayresult in injury. In addition, use of other parts may void
your warranty.
Emission Control
Maintenance, replacement or repair of the emission
control devices and systems may be performed by
any nonroad engine repair establishment or
individual. However, to obtain no charge repairs under
the terms and provisions of the Briggs & Stratton
warranty statement, any service or emission control
part repair or replacement must be performed by a
factory authorized dealer. See Emission Warranty.
Follow the instructions and
schedules indicated below:
Unintentional sparking can result in fire or
electric shock.
Fire or explosion can cause severe burns
or death.
Unintentional start-up can result in
entanglement, traumatic amputation, or
laceration.
•Do not strike the flywheel with a hammer or hard
object because the flywheel may later shatter
during operation.
•Do not tamper with governor spring, links or
other parts to increase engine speed.
Before performing maintenance or repairs:
•Disconnect spark plug wire and keep it away
from spark plug.
•Disconnect battery at negative terminal (only
engines with electric start).
•Use only correct tools.
When testing for spark:
•Use approved spark plug tester.
•Do not check for spark with spark plug removed.
WARNING
Check Valve Clearance
Task
Perform task at hourly or
calendar interval, 
whichever comes first.
Check Oil Level
Service Air Cleaner*
Clean Air Cooling System*** Inspect Spark Arrester (if equipped)
Change Oil **
Change Oil Filter (if equipped)**
Replace Spark Plug
Replace In-line Fuel Filter (if
equipped) Clean Debris*
* Clean more often under dusty conditions or when airborne debris is present. Replace air cleaner, if very dirty.
**Change oil after first 5 to 8 hours of use, then every 50 hours. Change oil every 25 hours when operating the
engine under heavy load or in high temperatures.
*** On string trimmer applications clean debris at each refueling, sooner if needed and have qualified technician clean
air cooling system every 30 hours, every season, or sooner if needed especially in high debris conditions. 
						

							16
Air Cleaner
All engines have an air cleaner cartridge. The cartridge
is either flat or oval. In addition, some engines have a
pre-cleaner.
Do not use pressurized air or solvents to clean
cartridge. Pressurized air can damage cartridge;
solvents will dissolve cartridge.
CAUTION
Removing and Installing Flat Air Cleaner
Flat Air Cleaner
SCREWCOV-
ERBAS
E
CARTRIDGECARTRIDGE LIP
ASSEMBLE SO CARTRIDGE LIP TOUCHES
BASE IN DIRECTION SHOWN
PRE-CLEANER LIP
TABS AND SLOTS
PRE-CLEANER
P/N 493537
1. Loosen screw, tilt cover down and remove air
cleaner.
2. Install clean (or new) air cleaner assembly inside
cover. Lip of pre-cleaner (if equipped) must be at
bottom of cartridge pleats.
3. Insert cover tabs into slots in bottom of base.
4. Tilt cover up into place and tighten screw.
Removing and Installing Oval Air Cleaner
Oval Air Cleaner
ASSEMBLE SO THAT CARTRIDGE
LIP SITS INSIDE BASE
2 SCREWSCOVER
BASECARTRIDGE
P/N 690610
PRE-CLEANER
P/N 273356
ÌÌÌÌ ÌÌÌÌ ÌÌÌÌ ÌÌÌÌ
5. Loosen two screws and lift off cover.
6. Remove air cleaner assembly (pre-cleaner, if
equipped, and cartridge) from base.
7. Install clean (or new) air cleaner assembly in
base. Air cleaner must fit securely in base.
8. Place cover over air cleaner.
9. Tighten screws.
Ensure air cleaner, retainer, and cover are
properly installed before starting engine.
WARNING
Spark Plug
Check the spark plug every 100 hours. Replace the
spark plug if upon inspection the electrode is burned or
worn. Ensure the spark plug is clean. Check the gap
with a feeler gauge and reset to .020 (0.51 mm) if
necessary. Use only Briggs & Stratton Spark Tester
(part number 19368) to check for spark.
Note: In some areas, local law requires using a resistor
spark plug to suppress ignition signals. If this engine
was originally equipped with a resistor spark plug, use
same type for replacement.
.020” (0.51 mm)
WIRE GAUGE 
						

							17
Cleaning Debris
Daily or before every use, clean accumulated debris
from engine. Keep linkage, spring and controls clean.
Keep area behind muffler free of any combustible
debris.
On string trimmer applications, clean accumulated
debris at each refueling, sooner if needed.
Do not use water to clean engine parts. Water could
contaminate fuel system. Use a brush or dry cloth.
CAUTION
CLEANCLEAN
Finger Guard
CLEAN
CLEAN
Linkage, Springs,
Controls
CLEAN
Muffler
Fuel System
Replacing In-line Fuel Filter (if equipped)
Disconnect spark plug wire and keep away from spark
plug.
Drain Fuel tank or close fuel shut-off valve before
replacing fuel filter. Otherwise, fuel can leak out
creating a fire/explosion hazard.
FUEL FILTER
FUEL HOSE CLAMPS
Replacement parts for fuel system (cap, hoses,
tanks, filters, etc.) must be the original parts, other-
wise fire can occur.
WARNING
Muffler
If muffler is equipped with spark arrester screen,
remove screen for inspection. Replace screen if
damaged or plugged.
Replacement parts for muffler must be the same
and installed in the same position as the original
parts, otherwise fire can occur.
WARNING
Air Cooling System
Over time debris may accumulate in cylinder cooling
fins and cannot e observed without partial engine
disassembly. For this reason, we recommend that you
have an authorized Briggs & Stratton Service Dealer
clean the air cooling system per recommended
intervals (See Maintenance Schedule). Equally
important is to keep top of engine free from debris. See
cleaning debris below.
Engine parts should be kept clean to reduce the risk
of overheating and ignition of accumulated debris.
WARNING 
						

							18
Storage
Equipment stored with fuel can become stale when
stored over 30 days. Stale fuel causes acid and gum
deposits to form in fuel system or on essential
carburetor parts. Mix fuel stabilizer with fuel in tank or
storage container. Run engine for a short time to
circulate stabilizer through carburetor and engine.
Engine and fuel can be stored up to 24 months.
If fuel stabilizer is not used, you need to drain
gasoline from equipment prior to storage.
If the FRESH START™ continuous fuel preserver fuel
cap (concentrated liquid cartridge) is used, there is no
need to drain fuel, as long as cartridge contains
stabilizer for seasonal storage.Perform the following before long-term storage of
equipment.
1. While engine is still warm, change oil.
2. Remove spark plug and pour about 1/2 oz (15ml)
of engine oil into spark plug cavity which puts oil
into cylinder. Replace spark plug securely.
3. Pull starter rope slowly. This turns the engine’s
crankshaft and distributes oil through the engine.
4. Add fuel stabilizer or drain fuel from engine.
5. Clean dirt and chaff from engine, cylinder head
fins, blower housing and rotating screen areas.
6. Store in a clean, dry area.
Do not store engine in same area as a stove,
furnace, water heater or other appliance that uses a
pilot light or has a device that can create a spark.
WARNING
Service
See an Authorized Briggs & Stratton Service Dealer for
all your engine service needs. Each one carries a stock
of Genuine Briggs & Stratton Parts and is equipped
with special service tools. Trained mechanics assure
expert repair service on all Briggs & Stratton engines.
Only dealers advertising as “Authorized Briggs &
Stratton” are required to meet Briggs &
Stratton standards.
When you purchase equipment
powered by Briggs & Stratton, you
are assured of highly skilled,
reliable engine service at more
than 30,000 Authorized Service
Dealers worldwide, including
more than 6,000 Master
Service Technicians. Look
for these signs wherever
Briggs & Stratton service is
offered.
You may fi n d th e ne a r e s t Au t h o r i z e d Se r v i c e De a l e r in
our dealer locator map at
 ww.briggsandstratton.com or
by calling 1-800-233-3723.
PARTIAL LIST OF 
GENUINE BRIGGS & STRATTON
PARTS
PARTPART NO.
Flat Air Cleaner Cartridge 491588 −OR− 5043 . . . . . . . . 
Flat Air Cleaner Pre-cleaner 493537. . . . . . . . . . . . . . . . 
Oval Air Cleaner Cartridge 697029. . . . . . . . . . . . . . . . . . 
Oval Air Cleaner Pre-cleaner 273356. . . . . . . . . . . . . . . . 
Oil 100005 −OR− 100028 . . . . . . . . . . . . . . . . . . . . . . . . . . 
Synthetic Oil 1000074. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
Fuel Filter 298090 −OR− 5018 . . . . . . . . . . . . . . . . . . . . . 
Gas Additive 5041. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
Resistor Spark Plug 491055. . . . . . . . . . . . . . . . . . . . . . . 
Spark Plug Wrench 89838. . . . . . . . . . . . . . . . . . . . . . . . . 
Spark Tester 19368. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
Oil Pump Kit 5056. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
(uses standard electric drill to remove oil from engine
quickly.)
An illustrated shop manual includes common
specifications and detailed information covering
adjustment, tune-up and repair of Briggs & Stratton
single cylinder, 4 cycle engines. It is available for
purchase from an Authorized Briggs & Stratton Service
Dealer or you can order it from
www.briggsandstratton.com 
						

							19
Specifications
All the components used to build this engine
assembly must remain in place for the proper
operation of this engine.
CAUTION
We recommend that you use an authorized Briggs &
Stratton Service Dealer for all maintenance and service
of the engine and engine parts. Use only genuine
Briggs & Stratton parts.
General Information
This is a single cylinder, overhead valve (OHV),
air-cooled engine. It is a low emissions engine.
In the state of California, OHV Model 120000 engines
are certified by the California Air Resources Board to
meet emissions standards 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, Type and Code Number
To get replacement parts or technical assistance in the
future write your engine Model, Type and Code number
along with the date of purchase here. These numbers
are located on your engine. For the location, see
page 3, Engine Features.
Model
Type
Code
Model 120000
Bore 2-11/16 in. (68.26 mm). . . . . . . . . . . . . . . . . . . . . . . . 
Stroke 2-3/64 in. (52.00 mm). . . . . . . . . . . . . . . . . . . . . . . 
Displacement 11.58 cu. in. (189.7 cc). . . . . . . . . . . . . . . 
Tune-up Specifications
Armature air gap 0.006 − 0.014 in. (0.15 − 0.36 mm) . . 
Spark plug gap 0.020 in. (0.51 mm). . . . . . . . . . . . . . . . . 
Valve clearance with valve springs installed and piston 1/4
in. (6 mm) past top dead center (check when engine is
cold). Consult with an Authorized Dealer or repair
manual.
Intake 0.004 − 0.008 in. (0.10 − 0.20 mm) . . . . . . . . . . . . 
Exhaust 0.004 − 0.008 in. (0.10 − 0.20 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°.
Technical Information
Engine Power Rating Information
The gross power rating for individual gas engine
models is labeled in accordance with SAE (Society of
Automotive Engineers) code J1940 (Small Engine
Power & Torque Rating Procedure), and rating
performance has been obtained and corrected in
accordance with SAE J1995 (Revision 2002−05).
Actual gross engine power will be lower and is affected
by, among other things, ambient operating conditions
and engine−to−engine variability. Given both the wide
array of products on which engines are placed and the
variety of environmental issues applicable to operating
the equipment, the gas engine will not develop the
rated gross power when used in a given piece of powerequipment (actual “on−site” or net horsepower). This
difference is due to a variety of factors including, but
not limited to, accessories (air cleaner, exhaust,
charging, cooling, carburetor, fuel pump, etc.),
application limitations, ambient operating conditions
(temperature, humidity, altitude), and engine−to−engine
variability.  Due to manufacturing and capacity
limitations, Briggs & Stratton may substitute an engine
of higher rated power for this Series engine. 
						

							20
Emission Information
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.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
Category B = 250 hours
Category A = 500 hours
For engines of 225 cc or more displacement.
Category C = 250 hours
Category B = 500 hours
Category A = 1000 hours.