Honda GX25, GX35 Owner's Manual
INTRODUCTION
Thank you for purchasing a Honda engine. We want to help you to
get the best results from your new engine and to operate it safely.
This manual contains information on how todo that; please read it
carefully before operating the engine. If a problem should arise, or
if you have any questions about your engine, consult an
authorized Honda servicing dealer.
All information in this publication is based on the latest product
information available at the time of printing. Honda Motor Co., Ltd.
reserves the right to make changes at any time without notice and
without incurring any obligation. No part of this publication may
be reproduced without written permission.
This manual should be considered a permanent part of the engine
and should remain with the engine if resold.
Review the instructions provided with the equipment powered by
this engine for any additional information regarding engine
startup, shutdown, operation, adjustments or any special
maintenance instructions.
United States, Puerto Rico, and U.S. Virgin Islands:
We suggest you read the warranty policy to fully understand its
coverage and your responsibilities of ownership.The warranty
policy is a separate document that should have been given to you
by your dealer.
SAFETY MESSAGES
OWNER’S MANUAL
MANUEL DE L’UTILISATEUR
MANUAL DEL PROPIETARIO
GX25·GX35
The engine exhaust from this product
contains chemicals known to the State of
California to cause cancer, birth defects
or other reproductive harm.
ENGLISHFRANÇAISESPAÑOL
Your safety and the safety of others is very important. We have
provided important safety messages in this manual and on the
engine.Please read these messages carefully.
A safety message alerts you to potentialhazards that could hurt
you or others.Each safety message is preceded by a safety alert
symbol and one of three words, DANGER, WARNING, or
CAUTION.
These signal words mean:
You WILL be KILLED or SERIOUSLY
HURT if you don’t follow instructions.
You CAN be KILLED or SERIOUSLY
HURT if you don’t follow instructions.
You CAN be HURT if you don’t follow
instructions.
Each message tells you what the hazard is, what can happen, and
what you can do to avoid or reduce injury.
DAMAGE PREVENTION MESSAGES
You will also see other important messages that are preceded by
the word NOTICE.
This word means:
Your engine or other property can be damaged if you
don’t follow instructions.
The purpose of these messages is to help prevent damage to your
engine, other property, or the environment.
2005 Honda Motor Co., Ltd. All Rights Reserved
37Z6J601
00X37-Z6J-6010
−
GX25NT·GX35NT
CONTENTS
.......................INTRODUCTION .1
SAFETY INDICATION
................................LOCATION .2
COMPONENT& CONTROL
................................LOCATION .2
................................FEATURES .3
BEFORE OPERATION
....................................CHECKS .4
..............................OPERATION .4
SAFE OPERATING
THE IMPORTANCE OF
MAINTENANCE
............................SCHEDULE .7
...........................REFUELING .8
...........................ENGINE OIL .8
.........................Oil Change .9
......................AIR CLEANER .10
........................Inspection .10
..........................Cleaning .10
ENGLISH
................SAFETY MESSAGES .1
..........SAFETY INFORMATION .2
.....................PRECAUTIONS .4
......STARTING THE ENGINE .4
.....SETTING ENGINE SPEED .5
......STOPPING THE ENGINE .6
.....SERVICING YOUR ENGINE .6
....................MAINTENANCE .6
......MAINTENANCE SAFETY .6
.......SAFETY PRECAUTIONS .7
............RecommendedOil .8
..................Oil Level Check .9
......................SPARK PLUG .11
...................COOLING FINS .11
FUEL FILTER AND FUEL
...................................TANK .12
.............SPARK ARRESTER .12
HELPFUL TIPS &
......................SUGGESTIONS .14
...STORING YOUR ENGINE .14
................TRANSPORTING .15
TAKING CARE OF
....UNEXPECTED PROBLEMS .16
TECHNICAL& CONSUMER
.......................INFORMATION .16
.....Serial Number Location .16
.....Remote Control Linkage .16
Carburetor Modifications for
.....High Altitude Operation .17
...............OxygenatedFuels .17
Emission Control System
.........................Information .17
..............................Air Index .18
.....................Specifications .18
........Tuneup Specifications .19
Quick Reference
.........................Information .19
................Wiring Diagrams .19
.CONSUMER INFORMATION .20
Distributor/DealerLocator
.........................Information .20
CustomerService
.........................Information .20
1
COMPONENT & CONTROL LOCATIONSAFETY INFORMATION
Understand the operation of all controls and learn how to stop
the engine quickly in case of emergency. Make sure the operator
receives adequate instruction before operating the equipment.
Do not allow children to operate the engine. Keep children and
pets away from the area of operation.
Your engine’s exhaust contains poisonous carbon monoxide.
Do not run the engine without adequate ventilation, and never
run the engine indoors.
The engine and exhaust become very hot during operation.
Keep the engine at least 1 meter (3 feet) away from buildings
and other equipment during operation. Keep flammable
materials away, and do not place anything on the engine while it
is running.
SAFETY INDICATION LOCATION
Standard/Pump type:
READ OWNER’S MANUAL BEFORE OPERATION.
Standard/Pump type:
OIL FILLER CAP
AIR CLEANER
PRIMING BULB
SPARK PLUG
(inside the top cover)
TOP COVER
MUFFLER
(inside the top cover)
STARTER GRIP
OIL FILLER CAP/
DIPSTICK
RECOIL STARTER
Standard type:
Tiller type:
READ OWNER’S MANUAL BEFORE OPERATION.
FUEL FILLER CAP
FUEL TANK
ENGINE CONTROLS
CHOKE LEVER
TANK GUARD
(applicable type)
Standard type:
Pump type:
THROTTLE LEVER
The illustrations in this manual are based on:
The illustrations may vary according to the type.
2
GX25
ENGINE SWITCHTHROTTLE LEVER
ENGLISH
Tiller type:
FEATURES
TOP COVER
AIR CLEANER
PRIMING BULB
STARTER GRIP
RECOIL STARTER
FUEL TANK
FUEL FILLER CAP
Centrifugal Clutch (Standard/Tiller type)
The centrifugal clutch automatically engages and transmits power
when engine speed is increased above approximately 4,200 rpm.
At idle speed, the clutch is disengaged.
Do not run the engine without mounting it on equipment that
includes the centrifugal clutch drum and housing, or centrifugal
force will cause the clutch shoes to contact and damage the
engine case.
OIL FILLER CAP/
DIPSTICK
MUFFLER
(inside the top cover)
ENGINE CONTROLS
GX25
GX35
CHOKE LEVER
SPARK PLUG
(inside the top cover)
THROTTLE LEVER
CHOKE LEVER
THROTTLE LEVER
ENGLISH
3
BEFORE OPERATION CHECKS OPERATION
IS YOUR ENGINE READY TO GO? SAFE OPERATING PRECAUTIONS
For your safety, and to maximize the service life of your
equipment, it is very important to take a few moments before you
operate the engine to check its condition. Be sure to take care of
any problem you find, or have your servicing dealer correct it,
before you operate the engine.
Improperly maintaining this engine, or failure to
correct a problem before operation, can cause a
malfunction in which you can be seriously hurt or
killed.
Always perform a preoperation inspection before
each operation, and correct any problem.
Before beginning your preoperation checks, be sure the engine is
level and the engine switch is in the OFF position.
Always check the following items before you start the engine:
Check the General Condition of the Engine
1.
Look around and underneath the engine for signs of oil or
gasolineleaks.
2.
Remove any excessive dirt or debris, especially around the
muffler and recoil starter.
3.
Look for signs of damage.
Before operating the engine for the first time, please review the
SAFETY INFORMATION
OPERATIONCHECKS
.
section on page and the
2
BEFORE
Carbon monoxide gas is toxic. Breathing it can cause
unconsciousness and even kill you.
Avoid any areas or actions that expose you to carbon
monoxide.
Review the instructions provided with the equipment powered by
this engine for any safety precautions that should be observed
with engine startup, shutdown or operation.
STARTING THE ENGINE
1.
To start a cold engine, move the choke lever to the CLOSED
position.
To restart a warm engine, leave the choke lever in the OPEN
position.
CHOKE LEVER
CLOSED
CCLLOOSSEEDD
OOPPEENN
4.
Check that all shields and covers are in place, and all nuts, bolts,
and screws are tightened.
Check the Engine
1.
Check the fuel level (see page ).Startingwitha full tank will
8
help to eliminate or reduce operating interruptions for refueling.
2.
Check the engine oil level (see page ). Running the engine
9
with a low oil level can cause engine damage.
Check the air filter element (see page ). A dirty air filter
3.
10
element will restrict air flow to the carburetor, reducing engine
performance.
4.
Check the equipment powered by this engine.
Review the instructions provided with the equipment powered
by this engine for any precautions and procedures that should
be followed before engine startup.
OPEN
2.
Press the priming bulb repeatedly until fuel can be seen in the
clear-plastic fuel-return tube.
FUEL RETURN TUBE
(clear plastic tube)
PRIMING BULB
3.
Standard/Tiller type: Turn the engine switch on the equipment
to the ON position.
Pump type: Turn the engine switch to the ON position.
ON
ENGINE SWITCH
4
ENGLISH
ON
4.
Pull the starter grip lightly until you feel resistance, then pull
briskly. Return the starter grip gently.
Standard/Pump type:
Tiller type:
Tiller type
1.
Turn the engine switch on the equipment to the OFF position.
2.
Move the choke lever to the OPEN position.
3.
Hold the throttle lever on the equipmentin the MAX. speed
position.
4.
Pull the starter grip 3 to 5 times.
STARTER GRIP
STARTER GRIP
(EQUIPMENT SIDE)
Do not allow the starter grip to snap back against the engine.
Return it gently to prevent damage to the starter.
5.
If the choke lever was moved to the CLOSED position to start the
engine, gradually move it to the OPEN position as the engine
warms up.
CHOKE LEVER
CCLLOOSSEEDD
OOPPEENN
Follow the STARTING THEENGINE procedure on page andstart
4
the engine with the choke lever in the OPEN position.
Pump type
1.
Turn the engine switch to the OFF position.
2.
Move the choke lever to the OPEN position.
3.
Hold the throttle lever in the MAX. speed position.
4.
Pull the starter grip 3 to 5 times.
Follow the STARTING THEENGINE procedure on page andstart
4
the engine with the choke lever in the OPEN position.
SETTING ENGINE SPEED
Standard/Tiller type:
Positionthe throttle lever for the desired engine speed.
The throttle lever shownhere will be connected to a remote
control on the equipment powered by this engine. Refer to the
instructions provided with the equipment for remote control
information and for engine speed recommendations.
THROTTLE LEVER
MMIINN..
OOPPEENN
Hot Restart
If the engine is operated at higher ambient temperatures, then
turned off and allowed to sit for a short time, it may not restart on
the first pull.
If necessary, use the following procedure:
IMPORTANT SAFETY PRECAUTION
Turn the engine switch to the OFF position before performing the
followingprocedure.This will prevent the engine from starting
and running at maximum speed when the throttle is in the MAX.
speed position. If the engine starts with the throttle in the MAX.
speed position, the equipment can move forward rapidly or the
trimmer attachment can spin at maximum speed. This may result
in personal injury.
MMAAXX..
Pump type:
Positionthe throttle lever for the desired engine speed.
For engine speed recommendations, refer to the instructions
provided with the equipment powered by this engine.
MMIINN..
MMAAXX..
MMIINN..MMAAXX..
ENGLISH
THROTTLE LEVER
5
STOPPING THE ENGINE
SERVICING YOUR ENGINE
Standard/Tiller type:
To stop the engine in an emergency, simply turn the engine switch
on the equipment to the OFF position. Under normal conditions,
use the following procedure.
Move the throttle lever to the MIN. position.
1.
The throttle lever shownhere will be connected to a remote
control on the equipment powered by this engine. Refer to the
instructions provided with the equipment for remote control
information and for engine speed recommendations.
THROTTLE LEVER
MMIINN..
THE IMPORTANCE OF MAINTENANCE
Good maintenance is essential for safe, economical and troublefree operation. It will also help reduce pollution.
Improper maintenance, or failure to correct a
problem before operation, can cause a malfunction in
which you can be seriously hurt or killed.
Always follow the inspectionand maintenance
recommendations and schedules in this owner’s
manual.
To help you properly care for your engine, the following pages
include a maintenance schedule, routine inspection procedures,
and simple maintenance procedures using basic hand tools. Other
service tasks that are more difficult, or require special tools, are
best handled by professionals and are normally performed by a
Honda technician or other qualified mechanic.
The maintenance schedule applies to normal operating conditions.
If you operate your engine under severe conditions, such as
sustained high-load or high-temperature operation, or use in
unusually wet or dusty conditions, consult your servicing dealer
for recommendations applicable to your individual needs and use.
Turn the engine switch on the equipment to the OFF position.
2.
Pump type:
To stop the engine in an emergency, simply turn the engine switch
to the OFF position. Under normal conditions, use the following
procedure.
Move the throttle lever to the MIN. position.
1.
MMIINN..
MMIINN..
THROTTLE LEVER
Turn the engine switch to the OFF position.
2.
Maintenance, replacement, or repair of the emission control
devices and systems may be performed by any engine repair
establishment or individual, using parts that are ‘‘certified’’ to
EPA standards.
MAINTENANCE SAFETY
Some of the most important safety precautions follow. However,
we cannot warn you of every conceivable hazard that can arise in
performing maintenance. Only you can decide whether or not you
should perform a given task.
Failure to properly follow maintenance instructions
and precautions can cause you to be seriously hurt or
killed.
Always follow the procedures and precautions in this
owner’s manual.
6
OFF
OFF
ENGINE SWITCH
ENGLISH
Make sure the engine is off before you begin any maintenance
or repairs. This will eliminate several potentialhazards:
−
Carbon monoxide poisoning from engine exhaust.
Be sure there is adequate ventilation whenever you operate
the engine.
−
Burns from hot parts.
Let the engine and exhaust system cool before touching.
−
Injury from moving parts.
Do not run the engine unless instructed to do so.
Read the instructionsbeforeyou begin, and make sure you have
the tools and skills required.
To reduce the possibility of fire or explosion, be careful when
working around gasoline. Use only a nonflammable solvent, not
gasoline,to clean parts. Keep cigarettes, sparks and flames
away from all fuel related parts.
Remember that an authorized Honda servicing dealer knows your
engine best and is fully equipped to maintain and repair it.
To ensure the best quality and reliability, use only new genuine
Honda parts or their equivalents for repair and replacement.
MAINTENANCE SCHEDULESAFETY PRECAUTIONS
REGULARSERVICE PERIOD (3)
Perform atevery
indicated month or
operating hour interval,
whichever comes first.
ITEM
Engine oil
Air cleaner
Spark plug
Spark arrester
(Applicable
types)
Engine cooling
fins
Nuts, bolts,
fasteners
(Retightenif necessary)
Clutch shoes
Idle speed
Valve
clearance
Combustion
chamber
Fuel filter
Fuel tank
Fuel tubes
Oil tube
Check level
Change
Check
Clean
Check-adjust
Replace
Clean
Check
Check
Check
Check-adjust
Check-adjust
Clean
Check
Clean
Check
Check
Each
use
Every 2 years (Replace if necessary) (2)
Every 2 years (Replace if necessary) (2)
Every 3
First
months
month
or
or
25 hrs
10 hrs
After every300 hrs. (2)
Every 6
months
(1)
or
50 hrs
(2)
Every
year
or
100 hrs
(2)
(2)
Every 2
years
or
300 hrs
Refer
to
Page
9
10
11
12 14
−
11
4
Shop
manual
Shop
manual
Shop
manual
Shop
manual
12
12
Shop
manual
Shop
manual
(1)
Service more frequently when used in dusty areas.
(2)
These items should be serviced by your servicing dealer,
unless you have the proper tools and are mechanically
proficient. Refer to Honda shop manual for service procedures.
(3)
For commercial use, log hours of operation to determine
proper maintenanceintervals.
Failure to follow this maintenance schedule could result in nonwarrantablefailures.
ENGLISH
7
REFUELING
Recommended Fuel
Unleaded gasoline
U.S.
Except U.S.
Pump octane rating 86 or higher
Research octane rating 91 or higher
Pump octane rating 86 or higher
This engine is certified to operate on unleaded gasoline. Unleaded
gasoline produces fewer engine and spark plug deposits and
extends exhaust system life.
Gasoline is highly flammable and explosive, and you
can be burned or seriously injured when refueling.
Stop engine and keep heat, sparks, and flame away.
Refuel only outdoors.
Wipe up spills immediately.
To refuel, rest the engine on the ground with the fuel filler cap
facing up, as shown. Remove the fuel filler cap, and fill the tank
with gasoline to the bottomof the filler neck. Refuel carefully to
avoid spilling fuel. Do not overfill. There should be no fuel in the
filler neck. After refueling, tightenthe fuel filler cap securely.
Never refuel the engine inside a buildingwhere gasoline fumes
may reach flames or sparks. Keep gasoline away from appliance
pilot lights, barbecues, electric appliances, power tools, etc.
Spilled fuel is not only a fire hazard, it causes environmental
damage. Wipe up spills immediately.
For information regarding oxygenated fuels, please refer to page
17
.
ENGINE OIL
Oil is a major factor affecting performance and service life. Use
4-stroke automotivedetergentoil.
Fuel can damage paint and some types of plastic. Be careful not to
spill fuel when filling your fuel tank. Damage caused by spilled
fuel is not covered under the
Distributor’s Limited Warranty.
Never use stale or contaminatedgasoline or oil/gasoline mixture.
Avoid getting dirt or water in the fuel tank.
Occasionally you may hear a light ‘‘spark knock’’ or ‘‘pinging’’
(metallic rapping noise) while operatingunder heavy loads. This is
no cause for concern.
If spark knock or pinging occurs at a steady engine speed, under
normal load, change brands of gasoline. If spark knock or pinging
persists, see an authorized Honda servicing dealer.
Running the engine with persistent spark knock or pinging can
cause engine damage.
Running the engine with persistent spark knock or pinging is
consideredmisuse, and the
Distributor’s Limited Warranty
does
not cover parts damaged by misuse.
1.
Check the fuel level by looking through the translucent fuel tank.
Recommended Oil
SAE Viscosity Grades
Use 4-stroke motor oil that
meets or exceeds the
requirements for API service
classification SJ, SL, or
equivalent.Always check the
API service label on the oil
container to be sure it includes
the letters SJ, SL, or equivalent.
AMBIENT TEMPERATURE
SAE 10W-30 is recommended for general use. Other viscosities
shown in the chart may be used when the average temperature in
your area is within the indicated range.
Standard/Tiller type:
The recommended operating range of this engine is 5°C to 40°C
−
(23°F to 104°F).
Pump type:
The recommended operating range of this engine is 5°C to 40°C
(41°F to 104°F).
2.
If the fuel level is low, refuel in a well-ventilatedarea with the
engine stopped. If the engine has been running, allow it to cool.
Standard/Pump type: Tiller type:
FUEL FILLER CAP
MAXIMUM
FUEL LEVEL
8
ENGLISH
Oil Level Check
Check the engineoil level before each use, or every 10 hours if
operated continuously.
Check the engine oil level with the engine stopped and in a level
position.
1.
Remove the oil filler cap/dipstick and wipe it clean.
2.
Insert and remove the oil filler cap/dipstick without screwing it
into the oil filler neck, then remove it to check the oil level shown
on the dipstick.
3.
If the oil level is near or below the lower limit mark on the
dipstick, fill to the bottom edge of the oil fill hole with the
recommendedoil (see page ).Toavoid overfilling or
8
underfilling, be sure the engine is in a level position, as shown,
while adding oil.
OIL FILLER CAP/DIPSTICK
LOWER LIMIT
OIL FILL HOLE
(bottom edge)
FUEL FILLER CAP
OIL FILLER NECK
4.
With the engine in a level position,fill to the bottom edge of the
oil fill hole with the recommended oil (see page ).
8
Some oil will remain in the engine after draining. When refilling
withfreshoil,startwithlessthan80cm
(2.7 US oz, 2.8 lmp oz).
Slowly add enough oil to fill to the bottom edge of the oil fill
hole as shown below.
UPPER LIMIT
UPPER LIMIT
4.
Reinstall the oil filler cap/dipstick and tightensecurely.
Running the engine with a low oil level can cause engine damage.
Oil Change
Drain the used oil when the engine is warm. Warm oil drains
quickly and completely.
1.
Check that the fuel filler cap is tightened securely.
2.
Place a suitable container below the engine to catch the used oil.
3.
Remove the oil filler cap/dipstick and drain the oil into the
containerby tipping the engine toward the oil filler neck.
Running the engine with a low or excessive oil level can cause
engine damage.
OIL FILLER CAP/DIPSTICK
OIL FILL HOLE (bottom edge)
UPPER LIMIT
UPPER LIMIT
Please dispose of used motor oil in a manner that is compatible
with the environment. We suggest you take used oil in a sealed
containerto your local recycling center or service station for
reclamation. Do not throw it in the trash, pour it on the ground, or
down a drain.
5.
Reinstall the oil filler cap/dipstick securely.
If any oil is spilled, make sure to wipe it up.
ENGLISH
9
A dirty air cleaner will restrict air flow to the carburetor, reducing
engine performance. If you operate the engine in very dusty areas,
clean the air filter element more oftenthan specified in the
MAINTENANCE SCHEDULE.
Operating the engine without an air filter element, or with a
damagedair filter element, will allow dirt to enter the engine,
causing rapid engine wear. This type of damage is not covered by
the
Distributor’s Limited Warranty.
CleaningAIR CLEANER
1.
Clean the filter element in warm soapy water, rinse, and allow to
dry thoroughly. Or clean in nonflammable solvent and allow to
dry.
2.
Dip the filter element in clean engine oil, then squeeze out all
excess oil. The engine will smoke when started if too much oil is
left in the foam.
3.
Wipe dirt from the air cleaner body and cover, using a moist rag.
Be careful to prevent dirt from entering the carburetor.
Inspection
Press the latch tab on the top of the air cleaner cover, and remove
the cover. Inspect the filter element. Clean or replace dirty filter
elements. Always replace damaged filter elements.
Refer to this page for instructions that apply to the air cleaner and
filter service.
Reinstall the filter element and air cleaner cover.
GX25
Tiller type:Standard/Pump type:
AIR CLEANER BODY
CHOKE LEVER
UPPER TAB
AIR CLEANER BODY
UPPER TAB
GX25
Standard/Pump type: Tiller type:
FILTER ELEMENT
GX35
Standard/Tiller type:
FILTER ELEMENT
FILTER ELEMENT
UPPER TAB
LOWER TABS
GX35
Standard/Tiller type:
UPPER LATCH TAB
AIR CLEANER COVER
UPPER LATCH TAB
FILTER ELEMENT
AIR CLEANER COVER
UPPER TAB
LOWER TABS
AIR CLEANER COVER
AIR CLEANER BODY
CHOKE LEVER
Reinstall the filter element and air cleaner cover securely.
4.
10
FILTER ELEMENT
LOWER TABS
ENGLISH
SPARK PLUG
Recommended Spark Plug:
CM5H (NGK) CMR5H (NGK)
,
The recommended spark plug is the correct heat range for normal
engine operating temperatures.
An incorrect spark plug can cause engine damage.
For good performance, the spark plug must be properly gapped
and free of deposits.
1.
Remove the top cover.
Loosen the 5 mm hex bolt with a hexagon wrench, then remove
the top cover.
Do not operate the engine when the top cover is
removed.
Do not pull the recoil starter handle when the top
cover is removed.
4.
Inspect the spark plug.
Replace it if damaged or
SIDE ELECTRODE
badly fouled, if the sealing
washer is in poor condition,
or if the electrode is worn.
5.
Measure the spark plug
electrode gap with a wiretype feeler gauge. Correct the
gap, if necessary, by carefully
−
0.60 0.70 mm
−
(0.024 0.028 in)
SEALING
WASHER
bending the side electrode.
The gap should be:
−−
0.60 0.70 mm (0.024 0.028 in)
6.
Install the spark plug carefully,
by hand, to avoid crossthreading.
7.
After the spark plug is seated, tighten with a 5/8-inch spark plug
wrench to compress the sealing washer.
8.
When installing a new spark plug, tighten 1/2 turn after the spark
plug seats to compress the washer.
You may be injured from the rotating parts or burned
by the muffler.
5mmHEXBOLTTOP COVER
2.
Disconnect the spark plug cap, and remove any dirt from around
the spark plug area.
3.
Remove the spark plug with a 5/8-inch spark plug wrench.
SPARK PLUG
9.
When reinstalling the original spark plug, tighten1/8 1/4 turn
−
after the spark plug seats to compress the washer.
A loose spark plug can overheat and damage the engine.
Overtightening the spark plug can damage the threads in the
cylinder head.
10.
Attach the spark plug cap to the spark plug.
11.
Install the top cover, and tighten the 5 mm hex bolt securely
with a hexagon wrench.
COOLING FINS
Inspection
1.
Loosen the 5 mm hex bolt, then remove the top cover.
2.
Disconnect the spark plug cap.
3.
Inspect the engine cooling fins, and clean out debris if necessary.
SPARK PLUG CAP
SPARK PLUG CAP
COOLING FINS
4.
Reconnect the spark plug cap.
5.
Install the top cover, and tighten the 5 mm hex bolt securely.
ENGLISH
11
SPARK ARRESTER (applicable types)FUEL FILTER AND FUEL TANK
Fuel filter inspection and Fuel tank cleaning
Gasoline is highly flammable and explosive, and you
can be burned or seriously injured when handling
fuel.
Stop engine and keep heat, sparks, and flame away.
Handle fuel only outdoors.
Wipe up spills immediately.
Check that the engine oil filler cap is tightenedsecurely.
1.
Remove the fuel filler cap, and drain the fuel into an approved
2.
gasolinecontainer by tipping the engine toward the fuel filler
neck.
ENGINE OIL FILLER CAP
The spark arrester may be standard or an optional part, depending
on the engine type. In some areas, it is illegal to operate an engine
without a spark arrester. Check local laws and regulations. A spark
arrester is available from authorized Honda servicing dealers.
The spark arrester must be serviced every 100 hours to keep it
functioning as designed.
If the engine has been running, the muffler will be hot. Allow it to
cool before servicing the spark arrester.
GX25
Standard/Pump type:
Spark Arrester Removal
1.
Loosen the 5 mm hex bolt, then remove the top cover (see page
11
).
2.
Remove the 4 mm screws from the spark arrester, and remove
the spark arrester from the muffler.
MUFFLER
SPARK PLUG
FUEL FILLER NECK
3.
Pull the fuel filter out through the fuel filler neck by hooking the
black fuel tube with a piece of wire, such as a partly straightened
paper clip.
4.
Inspect the fuel filter. If the fuel filter is dirty, wash it gently with
nonflammable or high flashpoint solvent. If the fuel filter is
excessively dirty, replace it.
FUEL FILTER
5.
Remove water and dirt from in the fuel tank by rinsing the inside
of the fuel tank with nonflammable or high flash point solvent.
4 mm SCREWS
SPARK ARRESTER
Spark Arrester Cleaning & Inspection
1.
Use a brush to remove carbon deposits from the spark arrester
screen. Be careful to avoid damaging the screen.
The spark arrester must be free of breaks and holes. Replace the
spark arrester if it is damaged.
SPARK ARRESTER SCREEN
2.
Install the spark arrester in the reverse order of disassembly.
When you install the spark arrester, the spark arrester’s outlet
must point to the side opposite the spark plug.
6.
Insert the fuel filter into the fuel tank and tightenthe fuel filler
cap securely.
12
3.
Install the top cover, and tighten the 5 mm hex bolt securely (see
11
page ).
ENGLISH
Tiller type
Spark Arrester Removal
1.
Loosen the 5 mm hex bolt, then remove the top cover (see page
11
).
2.
Remove the 3 6 mm self-tapping screws from the spark
×
arrester, and remove the spark arrester from the muffler.
×
3 6 mm SELF-TAPPING SCREW
GX35
Standard Type:
Spark Arrester Removal
1.
Loosen the 5 mm hex bolt, then remove the top cover (see page
11
).
2.
Remove the 4 6 mm self-tapping screws from the spark
×
arrester, and remove the spark arrester and exhaust filter from
the muffler.
SPARK PLUG
SPARK ARRESTER
OUTLET
EXHAUST
FILTER
MUFFLER
SPARK ARRESTER
MUFFLER
Spark Arrester Cleaning & Inspection
1.
Use a brush to remove carbon deposits from the spark arrester
screen. Be careful to avoid damaging the screen.
The spark arrester must be free of breaks and holes. Replace the
spark arrester if it is damaged.
SPARK ARRESTER SCREEN
2.
Install the spark arrester in the reverse order of disassembly.
3.
Install the top cover, and tighten the 5 mm hex bolt securely (see
11
page ).
×
46mm
SELF-TAPPING
SCREWS
SPARK ARRESTER
Exhaust Filter Cleaning & Inspection
Pinch the exhaust filter, strike lightly with a finger, and remove
carbon deposits. Be careful not to strike strongly.
The exhaust filter must be free of breaks and holes. If it is
damaged or fouled excessively, have it serviced by your Honda
dealer.
Spark Arrester Cleaning & Inspection
Use a brush to remove carbon deposits from the spark arrester
1.
screen. Be careful to avoid damaging the screen.
The spark arrester must be free of breaks and holes. Replace the
spark arrester if it is damaged.
SPARK ARRESTER SCREEN
2.
Install the exhaust filter and spark arrester in the reverse order
of disassembly.
When you install the spark arrester, the spark arrester’s outlet
must point to the side opposite the spark plug.
3.
Install the top cover, and tighten the 5 mm hex bolt securely (see
11
page ).
ENGLISH
13
Tiller type:
Spark Arrester Removal
1.
Loosen the 5 mm hex bolt, then remove the top cover (see page
11
).
2.
Remove the 4 6 mm self-tapping screws from the spark
×
arrester, and remove the spark arrester from the muffler.
SPARK ARRESTER
46mm
×
SELF-TAPPING
SCREWS
MUFFLER
SPARK PLUG
Spark Arrester Cleaning & Inspection
1.
Use a brush to remove carbon deposits from the spark arrester
screen. Be careful to avoid damaging the screen.
HELPFUL TIPS & SUGGESTIONS
STORING YOUR ENGINE
Storage Preparation
Proper storage preparation is essential for keeping your engine
trouble-free and looking good. The following steps will help to
keep rust and corrosion from impairing your engine’s function and
appearance, and will make the engine easier to start when you use
it again.
Cleaning
If the engine has been running, allow it to cool for at least half an
hour before cleaning. Clean all exterior surfaces, touch up any
damaged paint, and coat other areas that may rust with a light film
of oil.
Using a garden hose or pressure washing equipment can force
water into the air cleaner or muffler opening. Water in the air
cleaner will soak the air filter, and water that passes through the
air filter or muffler can enter the cylinder, causing damage.
Fuel
Gasoline will oxidizeand deteriorate in storage. Deteriorated
gasoline will cause hard starting, and it leaves gum deposits that
clog the fuel system. If the gasoline in your engine deteriorates
during storage, you may need to have the carburetor and other
fuel system components serviced or replaced.
The spark arrester must be free of breaks and holes. Replace the
spark arrester if it is damaged.
SPARK ARRESTER SCREEN
2.
Install the exhaust filter and spark arrester in the reverse order
of disassembly.
When you install the spark arrester, the spark arrester’s outlet
must point to the side opposite the spark plug.
Install the top cover, and tighten the 5 mm hex bolt securely (see
3.
page ).
11
The length of time that gasoline can be left in your fuel tank and
carburetor without causing functional problems will vary with
such factors as gasoline blend, your storage temperatures, and
whetherthe fuel tank is partially or completely filled. The air in a
partially filled fuel tank promotesfuel deterioration. Very warm
storage temperatures accelerate fuel deterioration. Fuel problems
may occur within a few months, or even less if the gasoline was
not fresh when you filled the fuel tank.
Fuel system damage or engine performance problems resulting
from neglected storage preparation are not covered under the
Distributor’s Limited Warranty
.
You can extend fuel storage life by adding a gasoline stabilizer
that is formulated for that purpose, or you can avoid fuel
deterioration problems by draining the fuel tank and carburetor.
Adding a Gasoline Stabilizer to Extend Fuel Storage Life
When adding a gasoline stabilizer, fill the fuel tank with fresh
gasoline.If only partially filled, air in the tank will promotefuel
deterioration during storage. If you keep a container of gasoline
for refueling, be sure that it contains only fresh gasoline.
1.
Add gasoline stabilizer following the manufacturer’sinstructions.
2.
After adding a gasoline stabilizer, run the engine outdoors for 10
minutesto be sure that treated gasoline has replaced the
untreated gasoline in the carburetor.
14
3.
Stop the engine.
ENGLISH
Gasoline is highly flammable and explosive, and you
can be burned or seriously injured when handling
fuel.
Stop engine and keep heat, sparks, and flame away.
Handle fuel only outdoors.
Wipe up spills immediately.
1.
Make sure the engine oil filler cap is tightenedsecurely.
Storage PrecautionsDraining the Fuel Tank and Carburetor
If your engine will be stored with gasoline in the fuel tank and
carburetor, it is important to reduce the hazard of gasoline vapor
ignition. Select a well-ventilated storage area away from any
appliance that operates with a flame, such as a furnace, water
heater, or clothes dryer. Also avoid any area with a sparkproducing electric motor, or where power tools are operated.
If possible, avoid storage areas with high humidity, because that
promotes rust and corrosion.
Keep the engine level in storage. Tilting can cause fuel or oil
leakage.
2.
Remove the fuel filler cap and drain the fuel into an approved
gasolinecontainer by tipping the engine toward the fuel filler
neck.
3.
Press the primingbulb several times until there is no more fuel
in the fuel return tube.
4.
Tip the engine towardthe fuel filler neck again to drain the fuel.
FUEL RETURN TUBE
5.
After all fuel has drained, reinstall the fuel filler cap securely.
ENGINE OIL FILLER CAP
PRIMING BULB
FUEL FILLER NECK
Engine Oil
With the engine and exhaust system cool, cover the engine to
keep out dust. A hot engine and exhaust system can ignite or melt
some materials. Do not use sheet plastic as a dust cover.
A nonporous cover will trap moisture around the engine,
promoting rust and corrosion.
Removal from Storage
Check your engine as described in the
CHECKS
section of this manual (see page ).
BEFORE OPERATION
4
If the fuel was drained during storage preparation, fill the tank with
fresh gasoline. If you keep a container of gasolinefor refueling, be
sure it contains only fresh gasoline. Gasoline oxidizes and
deteriorates over time, causing hard starting.
If the cylinder was coated with oil during storage preparation, the
engine will smoke briefly at startup. This is normal.
TRANSPORTING
If the engine has been running, allow it to cool for at least 15
minutes before loading the engine-powered equipment on the
transport vehicle. A hot engine and exhaust system can burn you
and can ignite some materials.
1.
Change the engine oil (see page ).
2.
Loosen the 5 mm hex bolt, then remove the top cover (see page
11
).
3.
Remove the spark plug (see page ).
4.
Apply a couple of drops of clean engine oil into the cylinder.
5.
Install the top cover temporarily.
6.
Pull the starter grip several times to distributethe oil in the
9
11
cylinder.
7.
Remove the top cover, then reinstall the spark plug.
8.
Install the top cover, and tighten the 5 mm hex bolt securely (see
page ).
11
Pull the starter grip slowly until resistance is felt.
9.
ENGLISH
15
TAKING CARE OF UNEXPECTED PROBLEMS TECHNICAL & CONSUMER INFORMATION
ENGINE WILL
NOT START
1.
Check control
positions.
2.
Check fuel.
3.
Remove and
inspect spark
plug.
4.
Take engine to
an authorized
Honda
servicing
dealer, or refer
to shop
manual.
Possible Cause Correction TECHNICAL INFORMATION
Choke open.
Engine switch
OFF.(on the
equipment)
Out of fuel.
Bad fuel; engine
stored without
treatingor
draining
Move lever to
CLOSED position
unless the engine
is warm.
Turn engine switch
to ON position.
Refuel (p. 8).
Drain fuel tank and
carburetor (p. 15).
Refuel with fresh
gasoline(p. 8).
Serial Number Location
Record the engine serial
number, type and purchase
date in the space below. You
will need this informationwhen
ordering parts and when
making technical or warranty
inquiries.
gasoline, or
refueled with
bad gasoline.
Spark plug faulty,
fouled, or
Gap or replace
spark plug (p. 11).
Engine serial number: __ __ __ __ __ __ __ __ __ __ __
Engine type: ___ ___ ___ ___
improperly
gapped.
Spark plug wet
with fuel
(flooded engine).
Allow the spark
plug to dry. After
drying, install the
Date Purchased: ______ / ______ / ______
Remote Control Linkage
spark plug and
start the engine
Standard/Tiller type:
(p. 4).
Fuel filter
restricted,
carburetor
malfunction,
ignition
Replace or repair
faulty components
as necessary.
The throttle control lever is provided with a fitting for cable
attachment.
Remove the air cleaner cover (see page ) for access to the
throttlelever and cable fitting.
malfunction,
valves stuck, etc.
Attachthe throttle cable as shown in the illustration.
ENGINE TYPE
ENGINE SERIAL NUMBER
−
10
POWER
1.
Check air filter.
2.
Check fuel.
3.
Take engine to
an authorized
Honda
servicing
dealer, or refer
to shop
manual.
Filter element
restricted.
Bad fuel; engine
stored without
treatingor
draining
gasoline, or
refueled with
bad gasoline.
Fuel filter
restricted,
carburetor
malfunction,
ignition
malfunction,
valves stuck, etc.
CorrectionPossible CauseENGINE LACKS
Clean or replace
filter element
(p. 10).
Drain fuel tank and
carburetor (p. 15).
Refuel with fresh
gasoline (P. 8).
Replace or repair
faulty components
as necessary.
To adjust the throttle cable, follow the equipment manufacturer’s
instructions.
CABLE ATTACHMENT FITTING
LOCK NUT
STAY
THROTTLE CABLE
ADJUST NUT
16
ENGLISH
Carburetor Modifications for High Altitude Operation
At high altitude, the standard carburetor air-fuel mixture will be
too rich. Performance will decrease, and fuel consumption will
increase. A very rich mixture will also foul the spark plug and
cause hard starting. Operation at an altitude that differs from that
at which this engine was certified, for extended periods of time,
may increase emissions.
High altitude performance can be improved by specific
modifications to the carburetor. If you always operate your engine
at altitudes above 1,500 meters (5,000 feet), have your servicing
dealer perform this carburetor modification. This engine, when
operated at high altitude with the carburetor modifications for
high altitude use, will meet each emission standard throughout its
useful life.
Even with carburetor modification, engine horsepower will
decrease about 3.5% for each 300-meter (1,000-foot)increase in
altitude. The effect of altitude on horsepower will be greater than
this if no carburetor modification is made.
When the carburetor has been modified for high altitude operation,
the air-fuel mixture will be too lean for low altitude use. Operation
at altitudes below 1,500 meters (5,000 feet) with a modified
carburetor may cause the engine to overheat and result in serious
engine damage. For use at low altitudes, have your servicing
dealer return the carburetor to original factory specifications.
Oxygenated Fuels
Some conventional gasolines are being blended with alcohol or an
ether compound. These gasolines are collectively referred to as
oxygenatedfuels. To meet clean air standards, some areas of the
United States and Canada use oxygenatedfuels to help reduce
emissions.
If you use oxygenated fuel, be sure it is unleaded and meets the
minimum octane rating requirements.
Before using an oxygenated fuel, try to confirm the fuel’s contents.
Some states/provinces require this information to be posted on
the pump.
The following are the EPA approved percentages of oxygenates:
ETHANOL
(ethyl or grain alcohol) 10% by volume
You may use gasoline containing up to 10%
ethanol by volume. Gasoline containing
ethanol may be marketed under the name
Gasohol.
MTBE
(methyltertiary butyl ether) 15% by volume
You may use gasoline containing up to 15%
MTBE by volume.
METHANOL
(methyl or wood alcohol) 5% by volume
You may use gasoline containing up to 5%
methanolby volume as long as it also
contains cosolvents and corrosion inhibitors
to protect the fuel system. Gasoline
containing more than 5% methanol by
volume may cause starting and/or
performance problems. It may also damage
metal, rubber, and plastic parts of your fuel
system.
If you notice any undesirable operating symptoms, try another
service station or switch to another brand of gasoline.
Fuel system damage or performance problems resulting from the
use of an oxygenated fuel containingmore than the percentages
of oxygenates mentioned above are not covered under the
Distributor’s Limited Warranty
.
Emission Control System Information
Source of Emissions
The combustion process produces carbon monoxide, oxides of
nitrogen, and hydrocarbons. Control of hydrocarbons and oxides
of nitrogen is very important because, under certain conditions,
they react to form photochemical smog when subjected to
sunlight. Carbon monoxide does not react in the same way, but it
is toxic.
Honda utilizes lean carburetorsettings and other systems to
reduce the emissions of carbon monoxide, oxides of nitrogen, and
hydrocarbons.
The U.S., California Clean Air Acts and Environment Canada
EPA, California and Canadian regulations require all
manufacturers to furnish written instructions describing the
operation and maintenance of emission control systems.
The following instructions and procedures must be followed in
order to keep the emissions from your Honda engine within the
emission standards.
Tampering and Altering
Tamperingwith or altering the emission control system may
increase emissions beyond the legal limit. Among those acts that
constitute tampering are:
Removal or alteration of any part of the intake, fuel, or exhaust
systems.
Altering or defeating the governor linkage or speed-adjusting
mechanism to cause the engine to operate outside its design
parameters.
Problems That May Affect Emissions
If you are aware of any of the following symptoms, have your
engine inspected and repaired by your servicing dealer.
Hard starting or stalling after starting.
Rough idle.
Misfiring or backfiring under load.
Afterburning (backfiring).
Black exhaust smoke or high fuel consumption.
Replacement Parts
The emission control systems on your Honda engine were
designed, built, and certified to conform with EPA, California and
Canadian emission regulations. We recommend the use of
genuine Honda parts whenever you have maintenancedone.
These original-design replacement parts are manufactured to the
same standards as the original parts, so you can be confident of
their performance. The use of replacement parts that are not of the
original design and quality may impair the effectiveness of your
emission control system.
A manufacturer of an aftermarket part assumes the responsibility
that the part will not adversely affect emission performance. The
manufacturer or rebuilder of the part must certify that use of the
part will not result in a failure of the engine to comply with
emission regulations.
ENGLISH
17
Follow the maintenance schedule on page . Remember that this
7
schedule is based on the assumption that your machine will be
used for its designed purpose. Sustained high-load or hightemperature operation, or use in unusually wet or dusty conditions,
will require more frequent service.
Air Index
An Air Index Information hang tag/label is applied to engines
certified to an emission durability time period in accordance with
the requirements of the California Air Resources Board.
The bar graph is intended to provide you, our customer, the ability
to compare the emissions performance of available engines. The
lower the Air Index, the less pollution.
The durability description is intendedto provide you with
informationrelatingthe engine’s emission durabilityperiod. The
descriptive term indicates the useful life period for the engine’s
emission control system. See your
Warranty
for additional information.
Emission Control System
Descriptive Term Applicable to Emissions Durability
Period
Moderate
Intermediate
Extended
50 hours [0 65 cm
−−
(0 65cc)]
125 hours [greater than 65 cm
125 hours [0 65 cm
−−
(0 65cc)]
250 hours [greater than 65 cm
300 hours [0 65 cm
−−
(0 65cc)]
500 hours [greater than 65 cm
(65 cc)]
(65 cc)]
(65 cc)]
SpecificationsMaintenance
GX25 (Basic types)
Type
Power equipment
description code
Length
Width
Height
Dry weight
(Without clutch)
Engine type
Displacement
[Bore Stroke]
×
Max. output
Max. torque
Engine oil
capacity
Fuel tank
capacity
Fuel consumption
Coolingsystem
Ignition system
PTO shaft rotation
S3
(Standard)
T3
(Tiller)
W3
(Pump)
(Without tank
guard)
GCART
192 mm
(7.6 in)
221 mm
(8.7 in)
230 mm
(9.1 in)
2.78 kg
(6.13 lbs)
192 mm
(7.6 in)
210 mm
(8.3 in)
236 mm
(9.3 in)
2.96 kg
(6.53 lbs)
247 mm
(9.7 in)
221 mm
(8.7 in)
230 mm
(9.1 in)
3.10 kg
(6.83 lbs)
4-stroke, overhead camshaft, single cylinder
25 cm
[3526mm(1.41.0in)]
××
(1.5 cu-in)
0.81 kW (1.1 PS, 1.1 bhp) at 7,000 rpm
1.25 N·m (0.13 kgf·m, 0.92 lbf·ft) at
5,000 rpm
(0.08 US qt , 0.07 Imp qt)
0.08
0.55
(0.145 US gal , 0.121 Imp gal)
340 g/kWh (250 g/PSh, 0.55 lb/hph)
Forced air
Transistorized magneto
Counterclockwise
The Air Index Information hang tag/label must remain on the
engine until it is sold. Remove the hang tag before operating the
engine.
GX35 (Basic types)
Type
Power equipment
description code
Length
Width
Height
Dry weight
(Without clutch)
Engine type
Displacement
[Bore Stroke]
×
Max. output
Max. torque
Engine oil
capacity
Fuel tank
capacity
Fuel consumption
Coolingsystem
Ignition system
PTO shaft rotation
S3
(Standard)
T3
(Tiller)
TR3
(Tiller)
(Without tank
guard)
GCAST
198 mm
(7.8 in)
234 mm
(9.2 in)
240 mm
(9.4 in)
3.33 kg
(7.34 lbs)
198 mm
(7.8 in)
243 mm
(9.6 in)
242 mm
(9.5 in)
3.52 kg
(7.76 lbs)
198 mm
(7.8 in)
243 mm
(9.6 in)
242 mm
(9.5 in)
3.52 kg
(7.76 lbs)
4-stroke, overhead camshaft, single cylinder
35.8 cm
××
[3930mm(1.51.2in)]
(2.18 cu-in)
1.2 kW (1.6 PS, 1.6 bhp) at 7,000 rpm
1.9 N·m (0.19 kgf·m, 1.4 lbf·ft) at 5,500 rpm
0.10
(0.11 US qt , 0.09 Imp qt)
0.65
(0.172 US gal , 0.143 Imp gal)
360 g/kWh (265 g/PSh, 0.59 lb/hph)
Forced air
Transistorized magneto
Counterclockwise
18
ENGLISH
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