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HONDA ENGINES OWNER’S MANUAL GX640 The engine exhaust from this product contains chemicals known to the State of California to cause cancer, birth defects or other reproductive harm. 0 Honda Motor Co., Ltd. 1995 31ZG8611 c9 0 5009704 00X31-ZG8-6110 PRINTED IN JAPAN...
Thank you for purchasing a 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.
Safety Messages 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 potential hazards that could hurt you or ot ers.
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 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.
ENGINE OIL IR CLEANER E SERIAL NUMBER RADIATOR SPARK PLUGS RADIATOR OIL DRAIN PLUG SCREEN...
3. PRE-OPERATION CHECK RADIATOR SCREEN 1. Allow the radiator to cool, then remove the screen from the front of the radiator. 2. Clean debris from the screen and radiator core. 3. Reinstall the radiator screen. and RADIATOR CORE RADIATOR CORE SCREEN...
ENGINE OIL p5YZE-J 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. Check the oil level with the engine on a level surface and the engine stopped.
FUEL Use unleaded gasoline 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.
1 NOTICE ] Running the engine with persistent spark knock or 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 Some conventional 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.
COOLANT If there is no coolant in the reserve tank, check the cooling system for leaks and repair if necessary. 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.
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. 1 NOTICE 1 Operating the engine without air filters, or damaged filters, will allow dirt to enter the engine, causing rapid engine wear.
4. OPERATION 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.
5. MAINTENANCE THE OMPORTANCE OF MAINTENANCE Good maintenance is essential for safe, economical, and trouble- free operation. It will also help reduce air pollution. Improper maintenance, correct a problem before operation, can cause a malfunction in which you can be seriously Always follow the inspection maintenance schedules...
MAINTENANCE SAFETY Some of the most important 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 mainte- nance instructions and precautions can cause you to be seriously hurt or killed.
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.
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.
MAINTENANCE Air cleaner Fuel filter 0 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.
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.
OIL FILTER CAHNGE Drain the engine oil, and retighten the drain bolt securely (see page 19). Remove the oil filter with a filter wrench and let the remaining oil drain out. Discard the oil filter. Clean the filter. base. Coat the O-ring on the new filter with clean engine oil. Screw on the new oil filter by hand, until the O-ring contacts the filter mounting base, then use an oil filter wrench to tighten the filter an additional...
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.
Air Cleaner AIR CLEANER COVER WING NUTS DUCT PAPER ELEMENT FOAM ELEMENT...
SPARK PLUG SERVICE Recommended spark plugs: BPRSES-11 (NGK) 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.
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 l/2 turn after the spark plugs seat to compress the washers.
SPARK ARRESTER MAINTENANCE In some areas, it is illegal to operate Check local laws and regulations. A spark arrester is available from authorized Honda servicing The spark arrester must be serviced every 100 hours to keep it function- ing as designed. 1.
FUEL FILTER INSPECTION AND REPLACEMENT A fuel filter must be installed 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.
6. STORAGE STORAGE PREPARATION 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 1. Stop the engine, and allow it to cool. 2.
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 promote fuel deterioration during storage. If you keep a container of gasoline for refueling, be sure that it contains only fresh gasoline.
Draining the Fuel Tank and Carburetor 1. Drain the fuel tank into an approved gasoline container, follow- ing the manufacturer’s instructions. 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.
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.
7. GENERAL SPECIFICATIONS Dimensions and weight (standard Type: SDl) Overall length Overall width Overall height Dry weight NOTE: Specifications are subject to change without notice. 8. TUNERUP SPECIFICATIONS ITEM Spark plug gap Engine idle speed Valve Clearance (cold) Other specifications 449 mm (17.6 in) 420 mm (16.5 in) 551 mm (21.7 in)
9. WARRANTY SERVICE INFORMATION Honda 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.