BigDog Diablo User manual

120124 REV C
BIGDOG®MOWER CO. DIABLO®
General Service Manual
200 South Ridge Road
Hesston, Kansas
67062

REV C 120124
The Engine Owner’s Manual provides information regarding the U.S. Environmental Protection Agency
(EPA) and the California Emission Control Regulation of emission systems, maintenance and warranty.
Keep Engine Owner’s Manual with your unit. Should the Engine Owner’s Manual become damaged or
illegible, replace immediately. Replacements may be ordered per the information found in the Product
Information section of the owner’s manual.
Federal law and California State law prohibit the following acts or the causing thereof:
1. The removal or rendering inoperative by any person other than for purposes of
maintenance, repair, replacement, of any device or element of design incorporated into
any equipment for the purposes of emissions control prior to or after its sales or delivery
to the ultimate purchaser or while it is in use, or
2. The use of the equipment after such device or element of design has been removed or
rendered inoperative by any person.
WARNING
WARNING
The engine exhaust from this product
contains chemicals known to the state
of California to cause cancer, birth
defects or other reproductive harm.
NOTICE OF REQUIREMENT OF SPARK ARRESTER MUFFLER
This equipment may create sparks that can start fires around dry vegetation. California Public Resources Code
Section 4442.6 provides that it is unlawful to use or operate an internal combustion engine on any forest-covered,
brush-covered, or grass-covered land unless the engine is equipped with a spark arrester maintained in effective
working order. A spark arrester is a device constructed of nonflammable materials specifically for the purpose of
removing and retaining carbon and other flammable particles over 0.0232 of an inch in size from the exhaust flow of
an internal combustion engine that uses hydrocarbon fuels or which is qualified and rated by the United States
Forest Service. Other states or federal areas may have similar laws. The Operator Should Contact Local Fire
Agencies For Laws or Regulations Relating to Fire Prevention Requirements. THIS EQUIPMENT DOES NOT HAVE
A SPARK ARRESTER AND YOU SHOULD CONTACT YOUR AUTHORIZED DEALER FOR THE PURCHASE OF
A SPARK ARRESTER.
Inspect spark arrester daily; replace every 500 hours or as needed.

120124 toc-1 REV C
Table of Contents
General Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Service Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Maintenance Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Safe Servicing Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Pre-Operation Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Operation Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Operate Machine Safely. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
General Maintenance Precautions. . . . . . . . . . . . . . . . . . . . . . . 3-2
Maintenance Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Standard Torques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Special Torques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Power Unit Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Steering Adjustments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Park Brake Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Hydraulic Pump Belt Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 5-6
Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
Engine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
General Engine Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Engine Oil and Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Engine Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Fuel Evaporation System Filter . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Fuel & Evaporative System Line Routings. . . . . . . . . . . . . . . . . 6-3
Engine RPM Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Deck Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Deck Leveling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Blades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
Deck Belt Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

REV C toc-2 120124
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1
Electrical Schematic – Kawasaki. . . . . . . . . . . . . . . . . . . . . . . . .8-1
Maintenance Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-1

120124 2-1 REV C
GENERAL INFORMATION
Service Program
This manual is part of a service package for the Big Dog®
Diablo®mowers. Use of this manual in conjunction with
other Big Dog®Diablo®mower and component manuals will
provide the information necessary to service and maintain
Big Dog®Diablo®mowers.
This General Service Manual is a service guide for use by
Service Technicians. It provides the necessary information
needed to perform normal maintenance requirements on
these units.
The Parts Manual provides a complete parts listing for the
unit. Use this manual when ordering parts.
The Operator's Manual provides fundamental operational
information and operational safety that is needed when oper-
ating the mower.
The component manuals are furnished by the various man-
ufacturers to be used for the troubleshooting and servicing
of their components.
Maintenance Introduction
Regular maintenance is the best prevention for downtime
or premature failure. The following pages contain suggested
maintenance information and schedules which the operator/
mechanic should follow on a routine basis.
Remain alert for unusual noises, they could be signaling a
problem. Visually inspect the machine for any abnormal wear
or damage. A good time to detect potential problems is while
performing scheduled maintenance service. Correcting the
problem as quickly as possible is the best insurance.
Clear away heavy build-up of grease, oil and dirt, especially
in the engine compartment and under the seat platform
areas; minute dust particles are abrasive to close-tolerance
engine and hydraulic assemblies.
Daily inspect mower for grass clippings and wire and string
tangles. The underside of the mower deck will collect a build-
up of grass clippings and dirt, especially when grass is wet or
has high moisture content. This build-up will harden, restrict-
ing blade and air movement and will probably show a lesser
quality of cut. Therefore it should be removed routinely.
To do this it will be necessary to raise and block the deck,
using jack stands or blocks, in the full up position and scrape
the build-up from underneath.
Some repairs require the assistance of a trained service
mechanic and should not be attempted by unskilled person-
nel. Consult your Big Dog®Mowers service center when
assistance is needed.
Information included in this manual was current at the time
of printing, but subsequent production changes may cause
your machine to vary slightly in detail. Big Dog®Mowers
reserves the right to redesign and change the machine as
deemed necessary, without notification. If a change has been
made to your machine which is not reflected in this service
manual contact the Customer Service Department at Big
Dog®Mowers for additional information.
Warranty
Warranty repair must be performed by a Big Dog®Mowers
Authorized Dealer before warranty credit can be allowed.

REV C 2-2 120124

120124 3-1 REV C
SAFETY
This safety alert symbol is used to call attention to a mes-
sage intended to provide a reasonable degree of PERSONAL
SAFETY for operators and other persons during the normal
operation and servicing of this equipment.
Safe Servicing Practices
Refer to the Safety section of this manual for more detailed
service safety information.
Understand Correct Service
Be sure you understand a service procedure before
you work on the machine.
Unauthorized modifications to the machine may
impair the function and/or safety and affect machine
life.
If it is necessary to make checks with the engine run-
ning, always use two people—with the operator at the
controls, able to see the person doing the checking.
Pre-Operation Precautions
Fuel Handling
To avoid personal injury or property damage, use
extreme care in handling fuel. Fuel is extremely flam-
mable and the vapors are explosive.
Observe usual fuel handling precautions:
•Do not smoke while refueling. Extinguish all ciga-
rettes, cigars, pipes and other sources of ignition.
• Do not remove fuel cap or fill tank with engine run-
ning or while engine is hot. Clean up any fuel spills.
•Allow engine to cool before storing machine
inside a building.
•Keep fuel away from open flame or spark and
store machine away from open flame or spark or
pilot light such as on a water heater or appli-
ances.
•Use extreme care when handling gasoline and
other fuels. They are extremely flammable and
vapors are explosive. A fire or explosion from fuel
can burn you and others and can damage prop-
erty.
•Refuel outdoors. Never refuel or drain the fuel
from the machine indoors.
•Never attempt to start engine when there is a
strong odor of gasoline or diesel fuel fumes pres-
ent. Locate and correct cause.
•Store fuel in an approved container and keep it
out of the reach of children. Never buy more than
a 30 day supply of fuel.
•Do not fill fuel containers inside a vehicle or on a
truck or trailer bed with interior carpets or plastic
truck bed liners. Always place fuel containers on
the ground away from your vehicle before filling.
•When practical, remove gas or diesel fuel pow-
ered equipment from the truck or trailer and
refuel the equipment with its wheels on the
ground. If this is not possible, then refuel such
equipment on the truck or trailer using a portable
container and not a fuel dispenser nozzle. If a
fuel dispenser nozzle must be used, keep the noz-
zle in contact with the rim of the fuel tank or con-
tainer opening at all times until fueling is
complete. Do not use a nozzle lock-open device.
•Never use gasoline or diesel fuel for cleaning
parts.
•Read and observe safety precautions elsewhere
in this manual.
Gasoline and diesel fuel is harmful or fatal if swal-
lowed.
•Long-term exposure to vapors can cause serious
injury and illness.
•Avoid prolonged breathing of vapors.
•Keep face away from nozzle and gas tank or fuel
container opening.
•Keep fuel away from eyes and skin.
•If fuel is spilled on clothing, change clothing
immediately.
Understand Machine Operation
Only qualified and trained personnel should operate
the equipment.
– denotes immediate hazards which WILL result in
severe personal injury or death.
– denotes a hazard or unsafe practice which
COULD result in severe personal injury or death.
DANGER
WARNING

REV C 3-2 120124
Carefully read the operator’s manual and all manuals
furnished with the attachments. Learn the location
and purpose of all controls, instruments, indicators
and labels.
Wear Protective Clothing
Do not operate or service the equipment while wearing
sandals, tennis shoes, sneakers, shorts or any type of
loose fitting clothing. Long hair, loose clothing or jew-
elry may get tangled in moving parts. Always wear
long pants, safety glasses, ear protection and safety
shoes when operating or servicing this machine.
Always wear adequate eye protection when servicing
the hydraulic system and battery, or when grinding
mower blades and removing accumulated debris.
Prolonged exposure to loud noise can cause impair-
ment or loss of hearing.
•Always wear adequate ear protection, such as
earplugs, when operating this equipment as pro-
longed exposure to uncomfortable or loud noises
can cause impairment or loss of hearing.
•Do not wear radios or music headphones while
operating the machinery. Safe operation requires
your full attention.
Operation Precautions
Avoid Fire Hazards
Clean flammable material from machine. Prevent fires by
keeping engine compartment, top of deck, exhaust area,
battery, hydraulic lines, fuel line, fuel tank and operator’s
station clean of accumulated trash, grass clippings, and
other debris. Always clean up spilled fuel and oil.
Start Engine Safely
Avoid possible injury or death from machine runaway.
Do not start engine by shorting across starter termi-
nals.
Before you start the engine:
•Sit on the operator’s seat.
•Move control levers to the neutral/brake position.
Operate Machine Safely
Refer to the unit’s operator’s manual for complete
safety information on safe machine operation.
Always maintain a safe distance from people and pets
when mowing.
Always be aware of what is behind the machine before
backing up.
Never leave machine unattended with ignition key in
switch, especially with children present.
Follow daily and weekly checklists, making sure hoses
are tightly secured and bolts are tightened.
Always keep engine and machine clean, removing
accumulated dirt, trash and other material from
machine.
Never put hands or feet under any part of the machine
while it is running.
Never attempt to start engine when there is a strong
odor of gasoline fumes present. Locate and correct
cause.
Keep all safety shields and covers in place, except for
servicing.
Do not touch hot parts of machine.
General Maintenance Precautions
Repairs or maintenance requiring engine power should
be performed by trained maintenance personnel only.
Never run the engine in an enclosed area unless
exhaust is vented to the outside. Exhaust gases con-
tain carbon monoxide which is an odorless and deadly
poison.
Unless specifically required, DO NOT have the engine
running when servicing or making adjustments to the
mower.
•Park the mower on level ground
•Disengage the deck clutch.
•Place the steering control levers in the park brake
position.
•Lower the deck.
•Stop the engine.
•Remove the ignition key.
•Disconnect the negative battery cable.
•Wait for all movement to stop before adjusting,
cleaning or repairing.
•Repairs or maintenance requiring engine power
should be performed by trained maintenance per-
sonnel only.
•To prevent carbon monoxide poisoning, operate
the engine in a well ventilated area only.
•Read and observe all safety warnings in this man-
ual.
Before working on or under the deck, make certain
engine cannot be accidentally started. Shut engine off,
remove ignition switch key and disconnect negative
battery cable for maximum safety.
Except when changing or checking belt, always keep
belt covers on mower deck for safety as well as clean-
liness.
Use a stick or similar instrument to clean under the
mower making sure that no part of the body, especially
arms and hands are under mower.
Keep your machine clean and remove any deposits of
trash and clippings, which can cause engine fires and
hydraulic overheating as well as excessive belt wear.

120124 3-3 REV C
Clean up oil or fuel spillage. Allow machine to cool
before storing.
Always wear adequate eye protection when servicing
the hydraulic system and battery, or when grinding
mower blades and removing accumulated debris.
Never attempt to make any adjustments or repairs to
the mower drive system, mower deck or any attach-
ment while the engine is running or deck clutch is
engaged.
Exercise caution when releasing spring tension from
any of the belt idlers or when working with any of the
deck lift components.
Never work under the machine or attachment unless it
is safely supported with jack stands. Make certain
machine is secure when it is raised and placed on the
jack stands. The jack stands should not allow the
machine to move when the engine is running and the
drive wheels are rotating. Use only certified jack stands.
Use only appropriate jack stands, with a minimum
weight rating of 2000 pounds to block the unit up. Use
in pairs only. Follow the instructions supplied with the
vehicle stands.
Keep nuts and bolts tight, especially the blade attach-
ment bolts. Keep equipment in good working condi-
tion.
Never tamper with safety devices. Check their proper
operation regularly.
Exercise caution when working under the deck as the
mower blades are extremely sharp. Wrap the blade(s)
or wear gloves and use extra caution when servicing
them.
Use original Big Dog®Mower replacement parts or
parts that are equivalent in overall performance.
•The mower may not comply with the appropriate
safety standards if aftermarket parts, accesso-
ries, or attachments are used.
Maintenance Precautions
Avoid Fire Hazards
Be prepared if an accident or fire should occur. Know
where the first aid kit and the fire extinguishers are
located and how to use them.
Provide adequate ventilation when charging batteries.
Do not smoke near battery.
Never check fuel level with an open flame.
Never use an open flame to look for leaks anywhere on
the equipment.
Never use an open flame as light anywhere on or
around the equipment.
When preparing engine for storage, remember that fuel
stabilizer is volatile and therefore dangerous. Seal and
tape openings after adding the inhibitor. Keep con-
tainer tightly closed when not in use.
Inspect electrical wiring for worn or frayed insulation.
Install new wiring if wires are damaged.
Prepare For Emergencies
Be prepared if a fire starts.
Keep a first aid kit and fire extinguishers available.
Keep emergency numbers for doctor, ambulance ser-
vice, hospital, and fire department near the telephone.
Prevent Battery Explosions
Battery posts, terminals, and related accessories con-
tain lead and lead compounds, chemicals known to the
State of California to cause cancer and reproductive
harm. Wash hands after handling.
Charge batteries in an open well-ventilated area, away
from sparks and flames. Unplug charger before con-
necting or disconnecting from battery. Wear protective
clothing and use insulated tools.
Avoid skin and clothing contact with battery acid.
•Always wear eye protection when checking the
battery, acid can cause serious injury to skin and
eyes. If contact occurs, flush area with clean
water and call physician immediately. Acid will
also damage clothing.
•Do not drink the battery electrolyte.
•Do not allow open flame near the battery when
charging.
•Hydrogen gas forms inside the battery. This gas
is both toxic and flammable and may cause an
explosion if exposed to flame. Always disconnect
the negative (black) battery cable(s) before dis-
connecting the positive (red) cable(s). Always
connect the positive (red) battery cable(s) before
connecting the negative (black) cable(s).
•Do not overfill battery.
•Electrolyte may overflow and damage paint, wir-
ing or structure. When cleaning the battery, use
soap and water. Be careful not to get soap and
water into the battery. Clean the battery termi-
nals with a solution of four parts water and one
part baking soda when they become corroded.
Shorts caused by battery terminals or metal tools
touching metal mower components can cause sparks.
Sparks can cause a battery gas explosion which will
result in personal injury.
•Prevent the battery terminals from touching any
metal mower parts when removing or installing
the battery.
•Do not allow metal tools to short between the
battery terminals and metal mower parts.
Incorrect battery cable routing could cause damage to
the mower and battery cables. This can cause sparks
which can cause a battery gas explosion which will
result in personal injury. Always disconnect the nega-

REV C 3-4 120124
tive (black) battery cable(s) before disconnecting the
positive (red) cable(s). Always connect the positive
(red) battery cable(s) before connecting the negative
(black) cable(s).
Avoid Acid Burns
Sulfuric acid in battery electrolyte is poisonous. It is
strong enough to burn skin, eat holes in clothing and
cause blindness if splashed in eyes.
Avoid the hazard by:
•Filling batteries in a well-ventilated area.
•Wearing eye protection and rubber gloves.
•Avoiding breathing fumes when electrolyte is
added.
•Avoiding spilling or dripped electrolyte.
If you spill acid on yourself:
•Flush your skin with water.
•Apply baking soda or lime to help neutralize the
acid.
•Flush your eyes with water for 10-15 minutes. Get
medical attention immediately.
If acid is swallowed:
•Drink large amounts of water or milk.
•Then drink milk of magnesia, beaten eggs or veg-
etable oil.
•Get medical attention immediately.

120124 4-1 REV C
TORQUE
Standard Torques
The following chart lists the standard torque values for the threaded fasteners found in this manual. Torque all cap screws, nuts
and set screws to these values unless a different torque is shown in the Special Torques section.
Special Torques
NOTE:
1. Lug nuts only – It is recommended that these be
checked after the first 2 hours of operation and every
50 hours and following removal for repair or replace-
ment.
2. Engine torque values – Refer to the respective engine
owner’s manual.
3. If clutch mounting bolt is loosened or removed, do not
re-use. Replace with a new bolt. Use only hand tools to
install this fastener.
Size ft-lbs N•m Size ft-lbs N•m
#10 32.4 IN.-LBS. 3.6 M3 12 IN.-LBS. 1.3
.250 98.4 IN.-LBS. 11.1 M4 26.4 IN.-LBS. 3
.312 204 IN.-LBS. 23 M5 54 IN.-LBS. 6.1
.375 30 40 M6 92.4 IN.-LBS. 10.4
.438 48 65 M8 222 IN.-LBS. 25
.500 73 99 M10 37 50
.562 105 143 M12 64 87
.625 145 200 M14 103 140
.750 260 350 M16 160 215
.875 420 565 M20 320 435
Description ft-Lbs N•M
Wheel (lug) nuts 170 95
Blade spindle bolt top 70 95
Blade spindle bolt bottom 118 160
Electric clutch mounting bolt 345 – 48 61 – 65
Front wheel axle bolt Tighten the nut, then back it off
until the wheel spins freely
Wheel motor hub nut 230 312
Hydraulic pump pulley screw 14 19
Engine torques 2N/A N/A
Particular attention must be given to tightening the
drive wheel lug nuts and blade spindle bolts. Failure
to correctly torque these items may result in the loss
of a wheel or blade, which can cause serious dam-
age or personal injury.
WARNING

REV C 4-2 120124

120124 5-1 REV C
POWER UNIT MAINTENANCE
Steering Adjustments
Steering Control Lever Neutral Adjustment
The mower’s steering has been factory adjusted to elimi-
nate creeping when the steering control levers are in the neu-
tral position. However, should the mower begin to creep, the
steering control lever linkage can be adjusted.
Before considering any adjustment, check the tire air pres-
sure. Unequal tire pressure will cause the mower to drift to
one side. Refer to tire pressure information in the “Tires” sec-
tion for detailed information.
NOTE: Proper park brake adjustment must be completed
before the steering control lever neutral adjustment can be
done. Refer to the “Park Brake Adjustment” section for
detailed information.
Fine adjustment to the unit’s steering is made with the
transmission’s control rod.
Neutral is properly adjusted when the steering control
levers are in the park brake position and the transmissions
do not “whine”.
If this occurs, the steering control linkage may be adjusted
as follows:
1. Raise the rear of the mower and block with certified
jack stands. The rear wheels need to be able to rotate
freely and clear of all obstructions.
2. Chock the front tires.
3. Raise the seat platform and disconnect the mower har-
ness from the seat switch. Bypass the seat switch by
connecting the two mower harness female spades
together. Figure 5-1
4. Start the engine.
5. Position the steering control lever in the neutral posi-
tion and observe which way the wheels are rotating.
Figure 5-2
6. If wheel(s) are rotating forward, loosen the jam nuts on
the pump linkage rods and rotate the rod to lengthen
the steering control linkage until the wheel(s) come to
a stop. Figure 5-3
7. Repeat for the opposite side if necessary.
Never work under the machine or attachment
unless it is safely supported with jack stands.
•Make certain machine is secure when it is
raised and placed on the jack stands.
• Use only certified jack stands. Use only
appropriate jack stands, with a minimum
weight rating of 2000 pounds (907 kg) to
block the unit up.
•Use in pairs only.
•Follow the instructions supplied with the
jack stands.
•The jack stands should not allow the
machine to move when the engine is running
and the drive wheels are rotating.
•Do not allow the wheels to come in contact
with the floor or any object that would permit
the unit to propel itself.
•To prevent injury stay clear and exercise cau-
tion when rotating the wheels.
Keep hands, hair, clothing, etc., clear of the cooling
fans on top of the transmissions. Exercise extreme
caution.
WARNING
WARNING
Untrained maintenance personnel should never
attempt to make any adjustments or repairs to the
mower’s drive system while the engine is running.
The following procedures should be performed by
trained maintenance personnel only.
A. Female spades
B. Seat switch C. Mower harness
Figure 5-1
WARNING
A
C
A
B

REV C 5-2 120124
8. If wheel(s) are rotating in reverse then loosen the jam
nuts on the pump linkage rods and rotate the rod to
shorten the steering control linkage until the wheel(s)
come to a stop. Figure 5-3
Repeat for the opposite side if necessary
9. When both wheels remain in neutral, tighten the jam
nuts to lock the turnbuckle in place.
10. Test again by moving the steering control levers for-
ward and backward before returning them to the neu-
tral position. If the tires are in neutral, the unit is now
ready for operation.
11. After adjusting for neutral it may be necessary to re-
adjust the control lever stop and/or damper.
12. IMPORTANT: With the engine off, disconnect the two
female spade connectors from each other (from step
#3) and reconnect them to the seat switch. This must
be completed so that the safety circuit is functioning
properly. Figure 5-1
13. Check to make sure all tools or obstructions are
removed from under the mower.
14. Raise the rear of the mower and remove the jack
stands. Lower the mower.
15. Lower and secure the seat platform.
Control Lever Stops
The steering control lever stops (see Figure 5-4) are
designed to do two things: First, and most important, they
must keep the pumps from bottoming out internally. Sec-
ondly, the stops may be adjusted to help drive straight when
the steering control levers are pushed forward against the
stops.
To keep the pumps from bottoming out internally use
the following procedure:
This adjustment is only required if the hydraulic pump(s)
have been replaced.
1. To make the first adjustment the mower engine must
not be running.
2. Check to make sure the steering control levers are
against the stops before the pumps are bottomed out
internally.
3. To do this, gently and slowly move the steering control
levers forward and feel if there is some resistance on
the pump lever before the control levers hit the stops.
Check one side at a time. If you sense that the pump
arms are stopping the forward motion of the control
arms, loosen the jam nut on the adjustable stop of the
Steering control lever in neutral position
A. Park brake slot B. Steering control lever
Figure 5-2
A. Jam nut
B. Pump linkage rod C. Pump
Figure 5-3
A
B
A
C
B
Do not operate the mower without plugging the
mower’s wiring harness into the seat switch. This
switch is an important part of the safety start inter-
lock system. Serious injury can result if the seat
switch is not plugged into the mower’s wiring har-
ness.
Never operate the mower with a non-functioning
seat switch. Always reconnect the seat switch to the
mower harness.
Pump damage will occur if these stops are set incor-
rectly.
WARNING
WARNING
WARNING

120124 5-3 REV C
corresponding side, turn the stop (set screw) inward to
stop the steering control levers slightly before the
pump bottoms out. Lock in place when the adjustment
is correct by re-tightening the jam nut. Do this for each
side.
To adjust the stops for driving straight when steering
control levers are against the stops during operation:
1. Determine which drive tire is rotating too fast when
both steering control levers are against the stops in
the control panel (see Figure 5-5).
2. Then, stop the mower and loosen the lock nut on the
side which is rotating too fast and turn the stop (set
screw) inward to stop the steering control lever
sooner. Tighten the lock nut on the stop and test
again.
3. Repeat this procedure until unit drives straight.
NOTE: Since this is a hydrostatic drive, variables such as
temperature of oil, efficiency of pumps and motors, tire pres-
sure etc. may affect the consistency of the ability to rely on
the stops to drive straight without the operator making minor
steering adjustments with the control arms.
Steering Damper
The steering dampers are spring loaded to return the con-
trol levers to the neutral position from the reverse position.
This gives the operator a sense of neutral during operation.
To set the steering dampers in the correct operating posi-
tion follow these steps:
1. Shut engine off, place steering control levers in the
park brake position, disengage deck clutch, remove
ignition switch key and disconnect negative battery
cable before doing any adjustments.
2. Place the steering control lever in the neutral position.
Figure 5-5
3. Loosen the steering damper’s front ball stud.
Figure 5-6
4. Pull the damper spring housing past the point that the
internal spring is engaged. Figure 5-6
5. Release the damper spring housing and allow the
internal spring to bring the housing back to the neutral
position.
6. Tighten the nut on the steering damper’s front ball
stud.
NOTE: The damper must not bottom out when the pump
lever is fully stroked in either direction.
7. Reconnect the negative battery cable.
8. Lower and secure the seat platform.
9. To check, move the steering control lever to the
reverse position and release. The steering control lever
should return to the neutral position. If not, repeat
steps 1 through 6.
A. Stop screw B. Steering lever support
Figure 5-4
B
A
Shown with steering control levers in neutral position
A. Steering control lever
Figure 5-5
A. Steering damper spring
housing B. Front ball stud
Figure 5-6
A
B
A

REV C 5-4 120124
Steering Control Lever Adjustment
The steering control levers can be adjusted for operator
comfort.
1. By loosening the nuts that attach the upper control
lever to the lower lever the upper control lever can be
pivoted to fit the operator’s personal preference.
Figure 5-7
2. The steering control levers should be adjusted so that
they align vertically with each other when in the neu-
tral position. Figure 5-8
Park Brake Adjustment
1. Shut engine off, place steering control levers in the
park brake position, disengage deck clutch, remove
ignition switch key and disconnect negative battery
cable before doing any adjustments.
2. Raise the rear of the mower and block with certified
jack stands. The rear wheels need to be able to rotate
freely and clear of all obstructions.
3. Chock the front tires.
4. Position the steering control levers in the neutral posi-
tion.
NOTE: The front brake link is not to be adjusted.
Figure 5-9
5. Open the hydraulic pump’s bypass valve, on the side
that is being adjusted, by turning the bypass valve
A. Nuts
B. Lower control lever C. Upper control lever
Figure 5-7
A. Align steering control lever ±.125” (3.175mm)
Figure 5-8
B
C
A
A
Never work under the machine or attachment
unless it is safely supported with jack stands.
•Make certain machine is secure when it is
raised and placed on the jack stands.
• Use only certified jack stands. Use only
appropriate jack stands, with a minimum
weight rating of 2000 pounds (907 kg) to
block the unit up.
•Use in pairs only.
•Follow the instructions supplied with the
jack stands.
•The jack stands should not allow the
machine to move when the engine is running
and the drive wheels are rotating.
•Do not allow the wheels to come in contact
with the floor or any object that would permit
the unit to propel itself.
•To prevent injury stay clear and exercise cau-
tion when rotating the wheels.
A. Brake link
Figure 5-9
WARNING
A

120124 5-5 REV C
counter clockwise one-half to one revolution.
Figure 5-10
6. Try to rotate the tire by hand. The tire should rotate.
Remember hydraulic oil resistance will prevent the tire
from rotating freely even with the bypass valves open.
There should be no resistance from the brakes at this
point.
7. Move the steering control lever to where it is just
inside (1/8" [3.175mm]) the park brake slot.
Figure 5-11
NOTE: When the steering control lever is against the out-
side edge of the slot, the brakes should not be engaged.
8. Rotate the tire. If the brake is adjusted properly the tire
will still rotate but friction will start to become notice-
able here. However, if no brake resistance is noticed,
the brake needs adjusted as follows:
a. Loosen the brake linkage jam nuts. (Figure 5-12)
Rotate the tire and at the same time rotate the
turnbuckle to shorten the length of the brake linkage
to increase the brake pressure. When you feel the
brake begin to engage, stop adjusting the turnbuckle.
Re-tighten the jam nuts on the turnbuckle.
b. Place the control lever in the park brake slot. The tire
should not rotate when the control lever is in the park
brake position. Figure 5-11
c. Place the control lever in the neutral position. The tire
should rotate freely.
9. Close the hydraulic pump’s bypass valve. Figure 5-10
10. Repeat steps 4 through 9 for the other side.
11. Check to make sure all tools or obstructions are
removed from under the mower.
12. Raise the rear of the mower and remove the jack
stands. Lower the mower.
13. Reconnect the negative battery cable.
14. Lower and secure the seat platform.
Belts
Inspect belts frequently for wear and serviceability.
Replace a belt that shows signs of:
•severe cuts
•tears
•separation
•weather checking
•cracking
•burns caused by slipping.
Slight raveling of belt covering does not indicate failure,
trim ravelings with a sharp knife.
Inspect the belt pulley grooves and flanges for wear. A new
belt, or one in good condition, should never run against the
bottom of the groove. Replace the pulley when this is the
case, otherwise, the belt will lose power and slip excessively.
A. Bypass valve
Figure 5-10
A. Control lever
B. Park brake slot C. Outside edge
D. 1/8" (3.175mm)
Figure 5-11
A
A
B
C
D
A. Jam nuts
Figure 5-12
A

REV C 5-6 120124
Never pry a belt to get it on a pulley as this will cut or dam-
age the fibers of the belt covering.
Keep oil and grease away from belts, and never use belt
dressings. Any of these will destroy the belt composition in a
very short time.
Hydraulic Pump Belt Adjustment
The transmission drive belt tension remains constant by
means of a tension idler and spring. There is no tension
adjustment of this belt. Figure 5-13
Inspect the belt every 100 hours and replace as needed.
Replace the belt every 400 hours or every two (2) years
whichever comes first.
Hydraulic System
IMPORTANT: Never use hydraulic or automatic transmis-
sion fluid in this system; use only motor oil as specified.
Remember, dirt is the primary enemy of any hydraulic sys-
tem.
Check oil level in hydraulic system after every 50 hours of
operation or weekly, whichever occurs first. Check more
often if system appears to be leaking or otherwise malfunc-
tioning.
The mower ships from the factory with SAE 20W50 motor oil
in the system. Use SAE 20W50 motor oil or 15W50 synthetic oil
when changing the system oil and filter. Do not mix SAE 20W50
motor oil with 15W50 synthetic oil.
Fluid level should be 1" (25.4mm) from top of reservoir.
NOTE: The reservoir will require approximately 3.50 U.S.
quarts (3.3 liter) of SAE 20W50 motor oil or 15W50 synthetic
oil when replacing the oil after an oil and filter change. Do not
overfill the reservoir.
Initial system oil and filter change must be after the first 50
hours of mower operation. Thereafter, replace filter and oil in
reservoir annually or every 500 hours, whichever comes first.
IMPORTANT: It is necessary to drain the system oil from
the hydraulic reservoir, using the reservoir drain plug, before
removing the hydraulic filter. Replace the drain plug before
adding system oil.
The system filter is located in front of the hydraulic reser-
voir. Use a Big Dog®approved filter element only. A standard
oil filter wrench is used to change filter. The threads are right
hand. Figure 5-14
If the transmission belt fails, loss of control will
occur especially when operating on a slope. If you
lose steering control while operating the machine,
place the steering control levers in the park brake
position immediately. Inspect the machine and
involve your dealer to resolve the problem.
Bottom view
A. Hydraulic pump belt
B. Spring C. Tension idler
Figure 5-13
WARNING
C
B
A
Hydraulic fluid escaping under pressure may have
sufficient force to penetrate skin and cause seri-
ous injury. Foreign fluid injected into the skin must
be surgically removed within a few hours by a doc-
tor, familiar with this form of injury, or gangrene
may result.
Before applying pressure to hydraulic system,
make sure all connections are tight and all hoses
and lines are in good condition. To find a leak
under pressure, use a piece of cardboard or wood
— never use your hands. Relieve all pressure in the
system before disconnecting or working on
hydraulic lines. To relieve pressure, lower all
attachments and shut off engine.
WARNING

120124 5-7 REV C
IMPORTANT: Pre-fill the filter element with clean oil
before installing, to prevent drawing air into the system
pump.
Hydraulic Pump Flow Test
The design purpose of the Bi-Directional Flow Test Kit is to
allow the technician to isolate the pump from the wheel
motor and determine if the pump is acceptable. The follow-
ing information can be used to install and test the pump by
simulating a wheel motor load.
Bi-directional Flow Test Kit Installation
Disconnect the system hoses at the wheel motor, or sys-
tem hoses from the pump and connect the Bi-Directional
Flow Test Kit. (Special care should be taken to prevent con-
tamination debris from entering pump or wheel motor sys-
tem ports).
NOTE: Using the Bi-Directional Flow Test Kit, determina-
tion of directional flow is not necessary. The flow meter may
be connected in either direction into the forward and reverse
high pressure system lines.
NOTE: The following adapter fittings will be required when
connecting the Bi-Directional Test Kit (Excel P/N 783886 or
Hydro-Gear P/N 70661):
PK (12) Series Pumps require two 771311 adapter
fittings.
CAUTION: Ensure all fittings and hoses are attached
securely. This test is being completed on the vehicle’s high
pressure system lines. Failure to perform this properly could
result in bodily injury.
Bi-directional Flow Testing Procedures
1. Use approved jack stands to raise the drive wheels off
the floor.
2. Open the restriction valve all the way.
A. Hydraulic reservoir B. Hydraulic filter
Figure 5-14
Potential for serious injury! Never work under the
machine or attachment unless it is safely sup-
ported with jack stands. To prevent possible injury
to the servicing technician and/or bystanders, insure
the vehicle is properly secured.
•Make certain machine is secure when it is
raised and placed on the jack stands.
• Use only certified jack stands. Use only
appropriate jack stands, with a minimum
weight rating of 2000 pounds (907 kg) to
block the unit up.
•Use in pairs only.
•Follow the instructions supplied with the
jack stands.
•The jack stands should not allow the
machine to move when the engine is running
and the drive wheels are rotating.
•Do not allow the wheels to come in contact
with the floor or any object that would permit
the unit to propel itself.
•To prevent injury stay clear and exercise cau-
tion when rotating the wheels.
A
B
WARNING
Do not attempt any adjustments with the engine
running. Use extreme caution while working in or
around all vehicle linkage! High temperatures can
be generated. Follow all safety procedures outlined
in the mower’s operator’s manual!
Never work under the machine or attachment
unless it is safely supported with jack stands.
•Make certain machine is secure when it is
raised and placed on the jack stands.
• Use only certified jack stands. Use only
appropriate jack stands, with a minimum
weight rating of 2000 pounds (907 kg) to
block the unit up.
•Use in pairs only.
•Follow the instructions supplied with the
jack stands.
•The jack stands should not allow the
machine to move when the engine is running
and the drive wheels are rotating.
•Do not allow the wheels to come in contact
with the floor or any object that would permit
the unit to propel itself.
•To prevent injury stay clear and exercise cau-
tion when rotating the wheels.
WARNING
WARNING

REV C 5-8 120124
3. Bring the engine to maximum operating speed.
CAUTION: Damage to the flow meter and/or re-
calibration may result from testing at input speeds that
exceed the above recommendations.
4. For the pump being tested, move the steering control
levers in full forward motion. (It will be necessary to
lock the steering control levers into full forward posi-
tion to prevent false readings).
5. Operate without any load for approximately 30 sec-
onds to 1 minute. This allows the system oil tempera-
ture to rise.
NOTE: Raising the system oil temperature will make a
difference in the readings you receive. It has been deter-
mined that to complete this test accurately, the oil tem-
perature must be near system operating temperatures.
Suggested temperature range 160°–210°F (71.1°–
98.9° C).
6. Tighten the flow meter restriction valve until the gauge
reads 300 psi (21 bar).
Record the flow reading on the Bi-Directional Flow Meter.
7. Increase the pressure to 1100 PSI (76 bar).
Record the flow reading on the Bi-Directional Flow Meter.
8. The acceptable gpm “flow droop” or “difference” is:
If the difference exceeds these values the pump would
not be operating efficiently and should be replaced or
repaired. See the following example.
Pumps Engine full throttle rpm setting
PK (12) 3600
PK (12) 2.0 gpm (7.6 l/min)