Honda GX640 User's Manual
Contents
1. Some conventional gasolines are being blended with alcohol or an ether compound These gasolines are collectively referred to as oxygenated fuels To meet clean air standards some areas of the United Sates and Canada use oxygenated fuels to help reduce emissions If you use an oxygenated fuel be sure it is unleaded and meets the minimum octane rating requirement 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 be marketed under the name Gasohol MTBE methyl tertiary 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 metha nol by 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 f2. SCREEN OIL DRAIN PLUG 5 3 PRE OPERATION CHECK RADIATOR SCREEN and RADIATOR CORE E 2 Allow the radiator to cool then remove the screen from the front of the radiator Clean debris from the screen and radiator core Reinstall the radiator screen RADIATOR SCREEN RADIATOR RADIATOR CORE ENGINE OIL e Engine oil is a major factor affecting engine performance and service life Nondetergent oils and 2 stroke engine oils are not recommended because they have inadequate lubricating characteristics e Check the oil level with the engine on a level surface and the engine stopped Use 4 stroke motor oil that meets or exceeds the requirements for API service classification SF or SG Always check the API SERVICE label on the oil container to be sure it includes the letters SF or SG SAE 10W 30 is recommended for general use TEMP 20020 40 60 Other viscosities shown in the chart may be used when the average temperature in your AMBIENT TEMPERATURE area 15 within the indicated range Oil Level Check Check the oil level with the engine stopped and level 1 Remove the dipstick and wipe it clean 2 Fully insert the dipstick then remove it to check the oil level If the oil level is near below the lower limit mark on the dipstick remove the oil filler cap and fill with the recommended oil to the upper limit mark Reinstall the dipstick and filler cap gt ENGINE OIL FILLER CAP
3. the oil filler cap securely ENGINE OIL REFILL CAPACITY Without oil filter change 2 0 2 2 1 With oil filter change 2 3 2 2 4 ENGINE OIL FILLER CAP UPPER LIMIT LOWER LIMIT ENGINE OIL DIPSTICK OIL DRAIN BOLT Wash your hands with soap and water after handling used oil Please dispose of used motor oil in a manner that doesn t harm the environment We suggest you take it in a sealed container to your local service station for reclamation Do not throw it in the trash pour it on the ground or down a drain 19 OIL FILTER CAHNGE 1 Drain the engine oil and retighten the drain bolt securely see page 19 2 Remove the oil filter with a filter wrench and let the remaining oil drain out Discard the oil filter 3 Clean the filter base Coat the O ring on the new filter with clean engine oil 5 Screw on the new oil filter by hand until the O ring contacts the filter mounting base then use oil filter wrench to tighten the filter an additional 7 8 turn TORQUE 8 N m 0 8 kg m 5 6 ft lb O RING OIL FILTER Use only a Honda genuine oil filter or a filter of equivalent quality specified for your model Using the wrong Honda filter or a non Honda filter which is not of equivalent quality may cause engine damage 6 Pour the specified amount of recommended oil into the engine see page 19 Start the engine and check the filter for leaks 7 Stop the engine and recheck the oil level I
4. 0 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 1 800 meters 6 000 feet with a modified carbure tor may cause the engine to overheat and result in serious engine damage For use at low altitudes have your dealer return the carburetor to original factory specifications 13 5 MAINTENANCE THE IMPORTANCE OF MAINTENANCE Good maintenance is essential for safe economical and trouble free operation It will also help reduce air pollution 4a WARNING 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 inspection and 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 sustain
5. ENGINE OIL DIPSTICK UPPER LIMIT LOWER LIMIT Running the engine with a low oil level can cause engine damage FUEL Use unleaded gasoline with a pump octane rating of 86 or higher This engine is certified to operate on unleaded gasoline Unleaded gasoline produces fewer engine and spark deposits and extends exhaust system life a WARNING Gasoline is highly flammable and explosive and you can be burned or seriously injured when refueling e Stop engine and keep heat sparks and flame away Refuel only outdoors e Wipe up spills immediately Fuel can damage paint and some types of plastic Be careful not to spill fuel when filling your fuel tank Damage caused by spillied fuel is not covered under warranty Never use stale or contaminated gasoline or an oil fuel mixture Avoid getting dirt or water in the fuel tank Occasionally you may hear light spark knock or pinging metallic rapping noise while operating under 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 pinging can cause engine damage Running the engine with persistent spark knock or pinging is misuse and the Distributor s Limited Warranty does not cover parts damaged by misuse Oxygenated Fuels
6. ENT DUCT 22 SPARK PLUG SERVICE Recommended spark plugs BPR5ES 11 NGK W16EPR U11 DENSO Incorrect spark plugs can cause engine damage To ensure proper engine operation the spark plugs must be properly gapped and free of deposits 1 Remove the spark plug caps 2 Clean any dirt from around each spark plug base 3 Use the proper size plug wrench to remove the spark plugs CAUTION The muffler becomes very hot during operation and remains hot for a while after stopping the engine Be careful not to touch the muffler while it is hot SPARK PLUG WRENCH 4 Visually inspect the spark plugs Discard them if the insulator is cracked or chipped Clean the spark plugs with a wire brush if they are to be reused 5 Measure the plug gap with feeler gauge Correct as necessary by carefully bending the side electrode 1 0 1 1 mm The gap should be 1 0 1 1 mm 0 039 0 043 in 0 039 0 043 in 6 Check that the spark plug washers are in good condition and thread the spark plugs in by hand to prevent cross threading 7 After the spark plugs are seated tighten with the spark plug wrench to compress the washers If installing new spark plugs tighten 1 2 turn after the spark plugs seat to compress the washers If reinstalling used spark plugs tighten 1 8 1 4 turn after the spark plugs seat to compress the washers Loose spark plugs can overheat and damage the engine Ov
7. SAVE Click SAVE to save this manual to your computer Thank you for choosing Honda RHONDA ENGINES OWNER S MANUAL _GX640 i N gt al WARNING A amp A The engine exhaust from this product contains chemicals known to the State of California to cause cancer birth defects or other reproductive harm Honda Motor Co Ltd 1995 31ZG8611 5009704 00 31 268 6110 1 PRINTED IN JAPAN Thank you for purchasing Honda engine We want to help you get the best results from your new engine and to operate it safely This manual contains the information on how to do that please read it carefully This manual covers the operation and maintenance of GX640 engines and is based on the SD4 Type 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 it if it is resold It is illegal in some areas to operate an engine without a USDA qualified spark arrester Check local laws and regulations An optional spark arrester for this engine is available from authorized Honda servicing dealers Safety Messages Your safety and the safe
8. cts close to the engine Do not allow children to operate the engine Keep children and pets away from the area of operation Know how to stop the engine quickly and understand the operation of all controls Never permit anyone to operate the engine without proper instructions Gasoline is extremely flammable and is explosive under certain conditions Refuel in a well ventilated area with the engine stopped Do not smoke or allow flames or sparks in the area where the engine is refueled or where gasoline is stored Do not overfill the fuel tank there should be no fuel in the filler neck After refueling make sure the tank cap is closed properly and securely Be careful to spill fuel when refueling Spilled fue or fuel vapor may ignite If any fuel is spilled make sure the area is dry before starting the engine Exhaust gas contains poisonous carbon monoxide Avoid inhalation of exhaust gas Never run the engine in a closed garage or confined area The muffler becomes very hot during operation and remains hot for a while after stopping the engine Be careful not to touch the muffler while it is hot Let the engine cool before storing it indoors 2 COMPONENT IDENTIFICATION ENGINE OIL FILLER CAP Ve 3 fun Ws 9 DS 0 lt _ lt ONA 9 gt f AIR CLEANER ENGINE OIL DIPSTICK AS gt CAE Ze SPARK PLUGS OIL FILTER RADIATOR
9. d purpose Sustained high load or high tem perature operation or use in unusually wet or dusty conditions will require more frequent service 17 MAINTENANCE SCHEDULE REGULAR SERVICE PERIOD Perform at every indicated month or operating hour interval whichever comes first Check level Engine oil Change 25 Radiator screen Clean Check Change Every 2 years 2 _ Radiatorcore Cean 1101 Air cleaner Radiator coolant Spam pugs Ceannas fo Replace a Spark arrester optional part Clean g idle speed Check Readjust Valve clearance ___ Check Readjust 0 2 g Engine oil filter Replace O or 200 hrs Check Po Replace O 2 Fuel Check Every 2 years Replace if necessary 2 Emission related items Replace the paper element only 1 Service more frequently when used in dusty areas 2 These items should be serviced by an authorized Honda servicing dealer unless the owner has the proper tools and is mechanically proficient See the Honda Shop Manual 3 For commercial use log hours of operation to determine proper maintenance intervals 18 ENGINE OIL CHANGE Drain the oil while the engine is warm to assure rapid and complete draining 1 Remove the oil filler cap and drain bolt and drain the oil into a suitable container 2 Retighten the drain plug securely 3 Refill to the upper limit mark on the dipstick with the recom mended oil see page 7 Tighten
10. e of the engine MAX COOLANT MIN LOWER LIMIT AIR CLEANER Check that the air cleaner elements are clean and in good condi tion A dirty air cleaner will restrict air flow to the carburetor reduc ing engine performance NOTICE Operating the engine without air filters or damaged filters will allow dirt to enter the engine causing rapid engine wear This type of damage is not covered by the Distributor s Limited Warranty 1 Remove the wing nuts to remove the air cleaner cover and air cleaner elements 2 Inspect the air cleaner elements Clean or replace the elements if necessary If the air cleaner elements need cleaning follow the procedure described on pages 21 22 3 Reinstall the air cleaner elements and air cleaner cover Tighten the wing nuts securely Reinstall the plastic duct 44 AIR CLEANER ELEMENTS DUCT 12 4 HIGH ALTITUDE OPERATION At high altitude the standard carburetor air fuel mixture will be too rich Performance will decrease and fuel consumption will in crease A very rich mixture will also foul the spark plugs and cause hard starting High altitude performance can be improved by specific modifica tions to the carburetor If you always operate your engine at altitudes above 1 800 meters 6 000 feet have your dealer per form this carburetor modification Even with carburetor modification engine horsepower will de crease about 3 5 for each 30
11. ed 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 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 14 MAINTENANCE SAFETY Some of the most important safety precautions follow However we cannot warn you of every conceivable hazard that can arise performing maintenance Only you can decide whether or not you should perform a given task 4 WARNING Failure to properly follow mainte nance instructions and precautions can cause you to be seriously hurt or killed Always follow the procedures and precautions in this owner s manual Safety Precautions e Make sure the engine is off before you begin any maintenance or repairs This will eliminate several potential hazards 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 e Read the instructions before you begin and make sure you have the tools and skills required e To reduce the possibility of fire or explosion be careful when working around gasoline Use onl
12. ertightening the spark plugs can damage the threads in the cylinder head 24 SPARK ARRESTER MAINTENANCE optional part 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 function ing as designed 1 Allow the engine to cool then remove the special screw from the muffler and remove the spark arrester MUFFLER SPARK ARRESTER SPECIAL SCREW ARRESTER SCREEN 3 The spark arrester must be free of breaks and holes Replace if necessary 4 Instali the spark arrester and the muffler in the reverse order of disassembly 25 FUEL FILTER INSPECTION AND REPLACEMENT A fuel filter must be installed between the fuel tank and carburetor to prevent any dirt or sediment from reaching the carburetor The fuel filter available from Honda shown below should be inspected periodically and must be replaced if there is an accumu lation of dirt Additionally scheduled replacement every year or 300 operating hours will help to ensure continued troublefree operation If another type of fuel filter is installed follow the inspection and or replacement recommendations of the filter manufacturer FUEL FILTER 26 le 6 STORAGE STORAGE PREPARATION The following steps will help to keep rust and corrosion from impairi
13. f necessary add oil to bring it up to the proper AIR CLEANER SERVICE A dirty air cleaner will restrict air flow to the carburetor To prevent carburetor malfunction service the air cleaner regularly Service more frequently when operating the engine in extremely dusty areas Operating the engine without air filters or damaged filters will allow dirt to enter the engine causing rapid engine wear This type of damage is not covered by the Distributors Limited Warranty 1 Remove the wing nuts and remove the air cleaner cover Remove the elements and separate them Carefully check both elements for holes or tears and replace if damaged NOTE Be sure to remove the foam element from the air cleaner cover so that you can inspect both sides Foam element Clean in warm soapy water rinse and dry thoroughly Or clean in nonflammable solvent and dry Dip the element in clean engine oil then squeeze out all excess oil engine will smoke when started if too much oil is left in the foam Paper element Tap the element several times on a hard surface to remove loose dirt or blow low pressure 30 psi or less compressed air through the filter from the inside Do not try to brush off dirt Brushing will force dirt into the fibers Reinstall the air cleaner elements Tighten the wing nuts securely 21 Air Cleaner AIR CLEANER 5 PAPER COVER D AA ELEMENT gt WING NUTS ELEM
14. gnition Select a well ventilated storage area away from any appliance that operates with a flame such as a furnace or water heater Also avoid any area with a spark producing electric motor or where power tools are operated If possible avoid storage areas with high humidity because that promotes rust and corrosion Unless all fuel has been drained from the fuel tank turn off the fuel supply valve following the manufacturer s instructions With the engine and exhaust system cool cover to keep out dust A hot engine and exhaust system can ignite or melt some materi als Do not use sheel plastic as a dust cover A nonporous cover will trap moisture around the mower promoting rust and corrosion REMOVAL FROM STORAGE Check the engine as described in the PRE OPERATION CHECKS section of this manual lf the fuel was drained during storage preparation fill the fuel tank with fresh gasoline If you keep a container of gasoline for refueling be sure that it contains only fresh gasoline Gasoline oxidizes and deteriorates over time causing hard starting lf the cylinders were coated with oil during storage preparation the engine will smoke briefly at startup This is normal 30 7 GENERAL SPECIFICATIONS ew Displacement 635 cm 38 7 cu in Bore x Stroke 76 x 70 mm 3 0 x 2 8 in 14 7 kW 20 HP at 3 600 rom Max torque 46 N m 4 7 kg m 34 ft lb at 2 500 rom Fuel consumption 306 g kWh 0 503 Ib hph 6 Cooling
15. k with fresh gasoline If only partially filled air in the tank will promote fuel 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 s instructions 2 After adding a gasoline stabilizer run the engine outdoors for 10 minutes to be sure that treated gasoline has replaced the untreated gasoline in the carburetor 28 Draining the Fuel Tank and Carburetor 1 Drain the fuel tank into an approved gasoline container follow ing the manufacturer s instructions WARNING Gasoline is highly flammable and explosive and you can be burned or seriously injured when handling fuel e Stop engine and keep heat sparks and flame away e Handle fuel only outdoors Wipe up spills immediately 2 Loosen the carburetor drain screw and drain the fuel into an approved gasoline container After draining tighten the drain screw securely DRAIN SCREW ra Va 29 3 Engine Oil Change the engine oil see page 19 4 Engine Cylinders Remove the spark plugs see pages 23 24 Pour a tablespoon 5 10 cc of clean engine oil into each cylinder Crank the engine for a few revolutions to distribute the oil in the cylinders Reinstall the spark plugs PLACING IN STORAGE If stored with gasoline in the fuel tank and carburetor it is important to reduce the hazard of gasoline vapor i
16. ne Date of purchase Your name address and telephone number A detailed description of the problem 32
17. ng your engine s function and appearance and will make the engine easier to start when you use it again Cleaning 1 Stop the engine and allow it to cool 2 Clean all exterior surfaces Fuel Gasoline will oxidize and deteriorate in storage Old gasoline will cause hard starting and it leaves gum deposits that clog the fuel system If the gasoline in your fuel system deteriorates during storage you may need to have the carburetor and other fuel system components serviced or replaced 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 whether the fuel tank is partially or completely filled The air in a partially filled fuel tank promotes fuel deterioration Very warm storage temperatures accelerate fuel deterioration Fuel deterioration problems may occur within a few months or less if the gasoline was not fresh when you filled the fuel tank The distributor s Limited Warranty does not cover fuel system damage or engine performance problems resulting from neglected storage preparation 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 27 Adding a Gasoline Stabilizer to Extend Fuel Storage Life When adding a gasoline stabilizer fill the fuel tan
18. system Liquid cooled Ignition system PTO shaft rotation Counterclockwise Dimensions and weight standard Type 501 Gveral length Overall with Overall height NOTE Specifications are subject to change without notice 8 TUNERUP SPECIFICATIONS ITEM SPECIFICATION PAGE Spark plug gap 1 0 1 1 mm 0 039 0 043 in See your authorized Intake 0 12 0 02 mm Honda Exhaust 0 20 0 02 mm servicing dealer Other specifications No other adjustments needed 31 Valve Clearance cold 9 WARRANTY SERVICE INFORMATION power equipment dealership personnel are trained profes sionals They should be able to answer any question you may have If you encounter a problem that your dealer does not solve to your satisfaction please discuss it with the dealership s management The Service Manager or General Manager can help Almost all problems are solved in this way lf you are dissatisfied with the decision made by the dealership s management contact the Honda Power Equipment Customer Relations Office You can write to American Honda Motor Co Inc Power Equipment Division Customer Relations Office 4475 River Green Parkway Duluth Georgia 30136 2565 Or telephone 770 497 6400 When you write or call please give us this information Model and serial numbers see page 5 Name of dealer who sold the engine to you Name and address of dealer who services your engi
19. ty 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 potential hazards that could hurt you or others Each safety message is preceded by a safety alert symbol and one of three words DANGER WARNING CAUTION These 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 NOTICE Your engine or other property could 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 1 ENGINE SAFETY Honda engines are designed to give safe and dependable service if operated according to instructions Read and under stand this Owner s Manual before operating the engine Failure to do so could result in personal injury or equipment damage To prevent fire hazards and to provide adequate ventilation keep the engine at least 1 meter 3 feet away from building walls and other equipment during operation Do not place flammable obje
20. uel containing more than the percentages of oxygenates mentioned above are not covered under warranty 10 COOLANT if there is no coolant the reserve tank check the cooling system for leaks and repair if necessary WARNING Removing the radiator cap while the engine is hot can cause the coolant to spray out seriously scalding you Always let the engine and radiator cool down before removing the radiator cap Add coolant to the radiator and the reserve tank then check the coolant level in the reserve tank after the engine reaches operating temperature When the engine is at operating temperature the coolant level should be between the MIN and MAX marks on the reserve tank If the level is near the MIN mark add coolant to bring it up to the MAX mark Coolant Recommendation Use high quality ethylene glycol antifreeze that is specifically formulated for use in aluminum engines Mix the antifreeze with low mineral drinking water or distilled water A 50 50 mixture of ethylene glycol antifreeze and water is recommended tor most temperatures and provides good corrosion protection A higher concentration of antifreeze decreases cooling efficiency and is recommended only if additional protection against freezing is needed A concentration of less than 40 antifreeze will not provide proper corrosion protection The use of unsuitable antifreeze hard water or salt water may cause corrosion damage that will shorten the lif
21. xhaust systems e 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 e Hard starting or stalling after starting e Rough idle e Misfiring or backfiring under load Afterburning backfiring Black exhaust smoke or high fuel consumption 16 Replacement Parts The emission control systems on your Honda engine were de signed built and certified to conform with EPA and California emission regulations We recommend the use of genuine Honda parts whenever you have maintenance done 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 Maintenance Follow the maintenance schedule on page 18 Remember that this schedule is based on the assumption that your machine will be used for its designe
22. y nonflammable solvent not gasoline to clean parts Keep cigarettes sparks and flames away from all fuel related parts Remember that your 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 15 EMISSION CONTROL SYSTEM 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 carburetor settings and other systems to reduce the emissions of carbon monoxide oxides of nitrogen and hydrocarbons The U S and California Clean Air Acts EPA and California regulations require all manufacturers to furnish written instructions describing the operation and maintenance of emission control systems The following instructions and proce dures must be followed in order to keep the emissions from your Honda engine within the emission standards Tampering and Altering Tampering with or altering the emission control system may increase emissions beyond the legal limit Among those acts that constitute tampering are e Removal or alteration of any part of the intake fuel or e
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