OWNER'S MANUAL
OWNER'S MANUAL
CH640, CH730, CH740
HORIZONTAL CRANKSHAFT
Liquefi ed Petroleum Gas (LPG) or LPG/Natural Gas (NG) Fueled
1
Safety Precautions
To ensure safe operations please read the following statements and understand their meaning. Also refer to your
equipment owner's manual for other important safety information. This manual contains safety precautions
which are explained below. Please read carefully.
WARNING
Warning is used to indicate the presence of a hazard that can cause severe personal injury, death, or substantial
property damage if the warning is ignored.
CAUTION
Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or property
damage if the caution is ignored.
NOTE
Note is used to notify people of installation, operation, or maintenance information that is important but not
hazard-related.
For Your Safety!
These precautions should be followed at all times. Failure to follow these precautions could result in injury to yourself and
others.
WARNING
Accidental Starts can cause severe
injury or death.
Disconnect and ground spark plug
leads before servicing.
Accidental Starts!
Disabling engine. Accidental
starting can cause severe injury or
death. Before working on the engine or
equipment, disable the engine as follows:
1) Disconnect the spark plug lead(s).
2) Disconnect negative (-) ba ery cable
from ba ery.
Before disconnecting the negative (-)
ground cable, make sure all switches are
OFF. If ON, a spark will occur at the
ground cable terminal which could cause
an explosion if hydrogen gas or LPG/NG
fuel vapors are present.
WARNING
Rotating Parts can cause severe
injury.
Stay away while engine is in
operation.
Rotating Parts!
Keep hands, feet, hair, and clothing away
from all moving parts to prevent injury.
Never operate the engine with covers,
shrouds, or guards removed.
CAUTION
Electrical Shock can cause injury.
Do not touch wires while engine is
running.
WARNING
Hot Parts can cause severe burns.
Do not touch engine while operating
or just a er stopping.
Hot Parts!
Engine components can get extremely
hot from operation. To prevent severe
burns, do not touch these areas while the
engine is running, or immediately a er
it is turned off . Never operate the engine
with heat shields or guards removed.
California
Proposition 65 Warning
Engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects, or other reproductive harm.
2
Electrical Shock!
Never touch electrical wires or
components while the engine is running.
They can be sources of electrical shock.
Safety Precautions (Cont.)
WARNING
Explosive Fuel can cause fi res and
severe burns.
If a gaseous odor is detected, ventilate
the area and contact an authorized
service technician.
Explosive Fuel!
LPG is extremely fl ammable and is
heavier than air and tends to se le in
low areas where a spark or fl ame could
ignite the gas. Do not start or operate
this engine in a poorly ventilated area
where leaking gas could accumulate and
endanger the safety of persons in the area.
NG is extremely fl ammable, is lighter
than air, and rises. Do not start or operate
this engine in a poorly ventilated area
where leaking gas could accumulate and
endanger the safety of persons in the area.
To ensure personal safety, installation and
repair of LPG/NG fuel supply systems
must be performed only by qualifi ed
LPG/NG system technicians. Improperly
installed and maintained LPG/NG
equipment could cause fuel supply system
or other components to malfunction,
causing gas leaks.
WARNING
Carbon Monoxide can cause
severe nausea, fainting or death.
Do not operate engine in closed or
confi ned area.
Lethal Exhaust Gases!
Engine exhaust gases contain poisonous
carbon monoxide. Carbon monoxide is
odorless, colorless, and can cause death if
inhaled. Avoid inhaling exhaust fumes,
and never run the engine in a closed
building or confi ned area.
WARNING
Explosive Gas can cause fi res and
severe acid burns.
Charge ba ery only in a well
ventilated area. Keep sources of
ignition away.
Explosive Gas!
Ba eries produce explosive hydrogen
gas while being charged. To prevent a
fi re or explosion, charge ba eries only in
well ventilated areas. Keep sparks, open
fl ames, and other sources of ignition
away from the ba ery at all times. Keep
ba eries out of the reach of children.
Remove all jewelry when servicing
ba eries.
Before disconnecting the negative
(-) ground cable, make sure all switches
are OFF. If ON, a spark will occur at the
ground cable terminal which could cause
an explosion if hydrogen gas or LPG/NG
fuel vapors are present.
Observe federal, state and local laws
governing LPG/NG fuel, storage, and
systems.
Congratulations – You have selected a fi ne four-cycle, twin cylinder, air-cooled engine. Kohler designs long life
strength and on-the-job durability into each engine...making a Kohler engine dependable...dependability you can
count on. Here are some reasons why:
• Effi cient overhead valve design and full pressure lubrication provide maximum power, torque, and reliability
under all operating conditions.
• Dependable, maintenance free electronic ignition ensures fast, easy starts time a er time.
• Kohler engines are easy to service. All routine service areas (like the dipstick and oil fi ll, air cleaner, spark plugs,
and carburetor) are easily and quickly accessible.
• Parts subject to the most wear and tear (like the cylinder liner and camsha ) are made from precision formulated
cast iron. Because the cylinder liner can be rebored, these engines can last even longer.
• Every Kohler engine is backed by a worldwide network of over 10,000 distributors and dealers. Service support is
just a phone call away. Call 1-800-544-2444 (U.S. & Canada) for Sales & Service assistance.
To keep your engine in top operating condition, follow the maintenance procedures in this manual.
3
Vaporizer
Air Cleaner
Dipstick
Oil Filter
Electric Starter
Oil Drain Plug
Figure 1. Typical Command Horizontal Shaft LPG or LPG/NG Fueled Engine.
Oil Recommendations
Using the proper type and weight of oil in the
crankcase is extremely important. So is checking oil
daily and changing oil regularly. Using oil that is
NOTE: Using other than service class SG, SH, SJ or
higher oil or extending oil change intervals
longer than recommended can cause engine
damage.
incorrect or dirty can cause premature engine wear and
failure. Synthetic oil is recommended for use in LPG/
NG fueled engines because there is less oxidation or
A logo or symbol on oil containers identifi es the API
service class and SAE viscosity grade. See Figure 3.
thickening, and deposit accumulation on intake valves
is substantially reduced. Conventional petroleumbased oil may be used, but valve service will be
required every 500 hours to remove the accumulated
deposits.
Oil Type
Use high quality, oil of API (American Petroleum
Institute) service class SG, SH, SJ or higher. Select
the viscosity based on the air temperature at the time of
operation as shown in the following table.
RECOMMENDED SAE VISCOSITY GRADES
Figure 3. Oil Container Logo.
LPG Regulator
Kohler 10W-30
10W-30
*
5W-20, 5W-30
-20 0
°F
-30 -20
°C
TEMPERATURE RANGE EXPECTED BEFORE NEXT OIL CHANGE
20
-10 0
*Synthetic oils will provide be er starting in extreme
cold below -23°C (-10°F).
Figure 2. Viscosity Grades Table.
4
40 60
32
50
10 20 30
SAE 30
80
100
Refer to Maintenance Instructions beginning on
page 8 for detailed oil check, oil change, and oil fi lter
change procedures.
Fuel Recommendations
CH640 and CH740 engines are certifi ed to operate on
LPG or NG.
40
CH730 engines are certifi ed to operate on LPG.
LPG Engines
LPG from an appropriate LPG fuel tank (supplied
separately) is required to operate this engine.
LPG Operation
Installation of jet in regulator fi ing is required for
LPG operation.
WARNING: Pressurized LPG!
Fuel tanks are fi lled under pressure and should be handled
with care. To prevent tank damage which could endanger the
safety of the operator or persons in the area, do not drop or
drag tanks on any surface. Use a hand truck when moving,
or tilt the tank on its footring in a position slightly off
vertical and roll it.
Avoid personal contact with LPG fuel to prevent frostbite.
See a physician if frostbite occurs.
WARNING: Explosive Fuel!
LPG is extremely fl ammable, is heavier than air and tends
to se le in low areas where a spark or fl ame could ignite the
gas. Do not start or operate this engine in a poorly ventilated
area where leaking gas could accumulate and endanger the
safety of persons in the area.
LPG fuel consists primarily of propane, although the fuel
supplier may sometimes mix other gases with propane.
Fuel tanks must be fi lled only by persons qualifi ed in the
handling of LPG. Tanks are fi lled by weight and should not
be overfi lled (never to more than 80 percent of total capacity).
An air space must be present in the tank to allow fuel to
expand.
Switching from NG to LPG
NOTE: When switching from NG to LPG fuel, the
ba ery must be temporarily disconnected for safety
and to reset the system.
Remove the fuel inlet hose. Inspect the internal threads
of regulator fi ing to ensure they are clean and dry.
Install jet into the fuel elbow orifi ce for LPG operation.
See Figure 4. Reconnect and fully tighten the fuel inlet
hose.
NOTE: Turn on fuel supply and check all fuel line
connections with soapy water before starting
or pu ing engine/system into service.
Outlet pressure should be checked and if required, set
at the secondary regulator to 4.0 to 5.0 PSI by qualifi ed
personnel.
NG Operation
Removal of jet from regulator fi ing is required for
NG operation.
Switching from LPG to NG
NOTE: When switching from LPG to NG fuel, the
ba ery must be temporarily disconnected for safety
and to reset system.
Tanks must be removed from equipment before fi lling.
NG Engines
NG from an approved system or source of supply can
be used to operate this engine.
WARNING: Explosive Fuel!
NG is extremely fl ammable, is lighter than air, and rises. Do
not start or operate this engine in a poorly ventilated area
where leaking gas could accumulate and endanger the safety
of persons in the area.
Fuel Conversion
Some engines are equipped to convert between LPG
and NG. The models with the fi ing and jet shown
below should follow these instructions for conversion.
Other metering valves should be installed following
the instructions given by the equipment it powers. Shut
off fuel supply before any servicing is performed.
NOTE: Engines with a DSAI system will have leads
located near the fuel regulator. Connect the
leads for NG and leave disconnected for LPG.
Remove the LPG fuel jet from the regulator fi ing.
Disconnect the hose, remove the jet from the orifi ce
(Figure 4), and reconnect the hose.
NOTE: Turn on fuel supply and check all fuel line
connections with soapy water before starting
or pu ing engine/system into service.
Recommended fuel inlet pressure for NG systems is 11
in. water (engine off ). Reduced pressure could result
in hard starting.
Figure 4. Fitting and Jet.
5
Model Designation
Model CH730 for example: C designates Command
engine, H designates horizontal cranksha , and 730
indicates the numerical model designation.
Engine Identifi cation Numbers
When ordering parts, or in any communication
involving an engine, always give the Model,
Specifi cation, and Serial Numbers of the engine.
The engine identifi cation numbers appear on a decal
affi xed to the engine shrouding. Include le er suffi xes,
if there are any.
Emission Compliance Period
The Emission Compliance Period referred to on the
Emission Control or Air Index label indicates the
number of operating hours for which the engine has
been shown to meet CARB emission requirements.
The following table provides the Engine Compliance
Period (in hours) associated with the category
descriptor which may be found on the certifi cation
label.
CARB
Refer to certifi cation label for engine displacement.
Exhaust Emission Control System for gaseous fuel
models CH640, CH730, and CH740, is EM for U.S.
EPA, California, and Europe.
Moderate
125 hours
Intermediate
250 hours
Extended
500 hours
Operating Instructions
Also read the operating instructions of the equipment this
engine powers.
• Check that any clutches or transmissions
are disengaged or placed in neutral. This
is especially important on equipment with
hydrostatic drive. The shi lever must be exactly
in neutral to prevent resistance which could keep
the engine from starting.
WARNING: Lethal Exhaust Gases!
Engine exhaust gases contain poisonous carbon monoxide.
Carbon monoxide is odorless, colorless, and can cause death
if inhaled. Avoid inhaling exhaust fumes, and never run the
engine in a closed building or confi ned area.
Although LPG/NG burns more effi ciently and emits less
carbon monoxide than gasoline, some carbon monoxide is
produced. Avoid inhaling exhaust gases, especially over
prolonged periods of time. Do not allow engine to run
una ended.
Cold Weather Starting Hints
1. Be sure to use the proper oil for the temperature
expected. See Figure 2 on page 4.
2. Disengage all possible external loads.
3. Be sure the ba ery is in good condition. A warm
ba ery has much more starting capacity than a
cold ba ery.
Starting
1. Place the thro le control in the idle position.
Place the choke control (if equipped) into the on
position. See Figure 5.
Pre-Start Checklist
• Check oil level. Add oil if low. Do not overfi ll.
• Check fuel gauge on LPG tank. Tanks should be
fi lled to a specifi c weight. To ensure safety and
proper fuel system operation, tanks must not be
overfi lled.
• Check fuel lines, regulator, and other system
components for leaks. Do not start engine until
leaks are eliminated.
• Check cooling air intake areas and external
surfaces of engine. Make sure they are clean and
unobstructed.
• Check that the air cleaner components and all
shrouds, equipment covers, and guards are in
place and securely fastened.
6
Figure 5. Optional Engine Mounted Throttle and
Choke Controls.
2. Slowly turn the fuel valve on the LPG (propane)
tank or the NG line (if equipped) to full open
position.
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