Toro 51638, 51653, 51911, 51912, 51916 Service Manual
...
N-28 ENGINE SERVICE MANUAL
Table of Contents – Page 1 of 1
GENERAL INFORMATION
SPECIFICATIONS AND TORQUES
SAFETY WARNINGS AND NOTES
PRODUCT IDENTIFICATION NUMBERS
STARTING/STOPPING INSTRUCTIONS
SERVICE/MAINTENANCE INSTRUCTIONS
STORAGE INSTRUCTIONS
TROUBLESHOOTING
ENGINE FAILS TO START
ENGINE STARVES ON ACCELERATION
ENGINE IS HARD TO START
ENGINE STALLS
ENGINE FIRES INTERMITTENTLY
ENGINE DOES NOT PRODUCE MAXIMUM POWER
CARBURETOR FLOODS
ENGINE STOPS AFTER RUNNING BRIEFLY
ENGINE WILL NOT IDLE
ENGINE BACKFIRES OR MISFIRES
ENGINE WILL NOT ACCELERATE
ENGINE LACKS POWER OR STOPS DURING OPERATION
DISASSEMBLY, INSPECTION, & REPAIR
TYPICAL DISASSEMBLY SEQUENCE
MAJOR COMPONENTS (CONT.)
ENGINE
REASSEMBLY
TYPICAL DISASSEMBLY SEQUENCE
ENGINE
MAJOR COMPONENTS
GENERAL INFORMATION
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting ..............................
Disassembly, Inspection, and Repair ...................
Reassembly ................................
1
2
3
4
1 - 1
GENERAL INFORMATION
1
SPECIFICATIONS AND TORQUES
Engine - All N28 Engines . . . . . . . . . . . . . . . . . . . . . . 1-4
Engine - Units with Serial Number 102084332 to 302010968 . . . 1-4
Engine - Units with Serial Number 302010969 and Greater . . . . 1-3
Fuel and Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Carburetor Units with Serial Number 102084332 to 302010968 . . 1-5
Table Of Contents
Carburetor Spacer . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Clutch Standard N28 Engines . . . . . . . . . . . . . . . . . . . . 1-5
Clutch Professional N28 Engines . . . . . . . . . . . . . . . . . . 1-5
Crankcase and Cylinder . . . . . . . . . . . . . . . . . . . . . . . 1-5
Drive Housing (Boom) Professional N28 Units . . . . . . . . . . . 1-5
Engine/Styling Cover . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Flex Drive Housing (Boom) - Standard N28 Units . . . . . . . . . . 1-5
Fuel Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Ignition Module . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Muffler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Starter/Starter Housing . . . . . . . . . . . . . . . . . . . . . . . 1-5
1- 2
GENERAL INFORMATION
Safety Warnings and Notes . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Product Identification Numbers . . . . . . . . . . . . . . . . . . . . . . 1-7
Engine Serial Number Significance . . . . . . . . . . . . . . . . . 1-7
Oil and Fuel Recommendations . . . . . . . . . . . . . . . . . . . . . . 1-7
Recommended Oil Type . . . . . . . . . . . . . . . . . . . . . . 1-7
Recommended Fuel Type . . . . . . . . . . . . . . . . . . . . . 1-7
Use of Blended Fuels . . . . . . . . . . . . . . . . . . . . . . . 1-8
Problems with Blended Fuels . . . . . . . . . . . . . . . . . . . . 1-8
Gasohol Use May Require Carburetor Adjustments . . . . . . . . 1-8
Use of Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Fuel and Oil Mixing Instructions . . . . . . . . . . . . . . . . . . 1-8
Starting/Stopping Instructions . . . . . . . . . . . . . . . . . . . . . . . 1-9
To Start the Engine . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
1
To Stop the Engine . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Service/Maintenance Instructions . . . . . . . . . . . . . . . . . . . . . 1-10
Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
Spark Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
Carburetor Adjustment . . . . . . . . . . . . . . . . . . . . . . . 1-11
Governed Carburetor Check . . . . . . . . . . . . . . . . . . . . 1-12
Storage Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
Storage for 45 to 60 Days . . . . . . . . . . . . . . . . . . . . . 1-13
Storage for More Than 60 Days . . . . . . . . . . . . . . . . . . 1-13
Reactivate Unit for Service . . . . . . . . . . . . . . . . . . . . . 1-13
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
1 - 3
GENERAL INFORMATION
SPECIFICATIONS AND TORQUES
1
Engine Specifications
Item
Engine Type Air-cooled. 2-cycle, Third Port
Displacement 1.7 cu. in. (28.5 cc)
Bore 1.31 in. (33.27 mm) 1.31 in. (33.27 mm)
Stroke 1.28 in. (32.51 mm) 1.28 in. (32.51 mm)
Average Compression 115-125 lbs. (52-57 kg)
Piston Ring(s) Side Clearance 0.004 in. max (0.101 mm)
Piston Ring Width (S/N 102084332 to 302010968) 0.060 in. (1.6 mm)
Piston Ring Width (S/N 302010969 and Greater) 0.046 in. (1.14 mm)
Piston Ring End Gap (S/N 102084332 to 302010968) 0.072 in. (1.8 mm)
Piston Ring End Gap (S/N 302010969 and Greater) 0.057 in. (1.45 mm)
Fuel and Lubrication
Item
Lubrication Fuel/Oil Mixture
Fuel/Oil Ratio 32:1
Approx. Fuel Tank Capacity 18 oz. (530 ml)
Ignition
Item
Ignition Type Electronic
Ignition Module Air Gap 0.010-0.015 in. (0.254-0.381 mm)
Spark Plug Type Champion® RDJ7Y
Spark Plug Gap 0.018-0.023 in. (0.45 to 0.58 mm)
1- 4
SPECIFICATIONS AND TORQUES (cont.)
GENERAL INFORMATION
Torque Specifications
Item
Air Filter Cover Mounting Screws 18-22 in•lb (2.0-2.5 N•m)
Carburetor/Choke Plate Mounting Screws (Initial Torque) 13-17 in•lb (1.5-1.9 N•m)
Carburetor/Choke Plate Mounting Screws (Retorque) 23-27 in•lb (2.6-3.0 N•m)
Throttle Wire Swivel Screw (S/N 102084332 to
302010968)
Carburetor Spacer Screws 55-65 in•lb (6.2-7.3 N•m)
Clutch Cover Mounting Screws 35-40 in•lb (3.9-4.5 N•m)
Clutch Rotor 150-160 in•lb (16.9-18.0 N•m)
Clutch Housing/Drum Assembly Screws 35-40 in•lb (3.9-4.5 N•m)
Clutch Rotor 130-150 in•lb (14.6-16.8 N•m)
Clutch Bolts 60-80 in•lb (6.7-9.0 N•m)
Crankcase (Cylinder) Mounting Screws 50-60 in•lb (5.6-6.7 N•m)
Crankcase Cover Mounting Screws 55-65 in•lb (6.2-7.3 N•m)
Spark Plug 100-120 in•lb (11.2-13.5 N•m)
9-12 in•lb (1.0-1.4 N•m)
1
Boom Clamp Screw 70-80 in•lb (7.9-9.0 N•m)
Anti-Rotation Screw 15-20 in•lb (1.7-2.3 N•m)
Rear Engine Cover to Starter Housing Screw 50-60 in•lb (5.6-6.7 N•m)
Rear Engine Cover to Crankcase Screw 35-40 in•lb (3.9-4.5 N•m)
Engine Styling Cover 35-40 in•lb (3.9-4.5 N•m)
Boom Clamp Nut 70-80 in•lb (7.9-9.0 N•m)
Anti-Rotation Screw 15-20 in•lb (1.7-2.3 N•m)
Fuel Tank Bracket Screws 50-60 in•lb (5.6-6.7 N•m)
Ignition Module Mounting Screws 25-35 in•lb (2.8-3.9 N•m)
Muffler Exhaust Tube Screws 15-25 in•lb (1.7-2.8 N•m)
Muffler Mounting Screws 80-90 in•lb (9.0-10.1 N•m)
Starter Housing Screws 35-40 in•lb (3.9-4.5 N•m)
Starter Pulley Retainer Screw 20-30 in•lb (2.3-3.4 N•m)
1 - 5
GENERAL INFORMATION
SAFETY WARNINGS AND NOTES
The purpose of safety symbols is to attract your
attention to possible dangers. The safety symbols and
1
the explanations with them deserve your careful
attention and understanding. The safety warnings do
not by themselves eliminate any danger. The
instructions or warnings they give are not substitutes
for proper accident prevention measures.
WARNING: For Your Safety
Highlights instructions which failure to obey can result
in personal injury.
NOTE: Advises of information which may be useful
while performing maintenance or repair of the
equipment. Also highlights instructions which failure to
obey can result in damage to parts or equipment.
WARNING: Spring Under Tension!
The rope starter on these engines contains a flat wire
spring that is under tension. Wear eye and hand
protection when replacing worn or broken spring, in
case it should uncoil as it is handled. Allow spring
tension to be completely relieved and make sure
pulley disengages from spring before removing the
pulley retainer(s), pulley, and starter spring from
housing.
WARNING: Explosive Fuel!
Gasoline may be present in the fuel tank, carburetor,
fuel line, or crankcase. Gasoline is extremely
flammable and its vapors can explode if ignited. Keep
sparks, flames, and other sources of ignition away
from the engine. Do not smoke while servicing the
engine. Never use gasoline as a cleaning agent.
Store gasoline only in approved containers in
well-ventilated, unoccupied buildings away from
sparks, flames, or other sources of ignition. Do not fill
the fuel tank while the engine is hot or running, since
spilled fuel could ignite if it comes in contact with hot
parts or sparks from ignition. Do not start the engine
near spilled fuel. Do not smoke while handling
gasoline or filling the fuel tank.
WARNING: Cracked or Broken FLYWHEEL
Cooling Fins Are A Hazard!
Be careful not to crack or break any flywheel cooling
fins. They could fly off during operation. If cooling fins
are cracked or broken, replace the flywheel.
WARNING: Electrical Shock!
Never touch electrical wires or components while the
engine is running. They can be sources of electrical
shock.
WARNING: HOT SURFACES!
The muffler, cylinder, crankcase, trimmer cutting head,
and other engine surfaces get extremely hot from
operation. These surfaces remain hot for a short
period of time after the engine is stopped. To prevent
severe burns, allow the engine to cool completely
before servicing.
1- 6
GENERAL INFORMATION
PRODUCT IDENTIFICATION
NUMBERS
When ordering parts, or in any communication
involving an engine or product, always give the:
• Model Number and
• Serial Number
These numbers are located on a decal (or decals)
affixed to the unit (Figure 1-1). The identification
decal(s) will be located on the engine, metal boom, or
plastic housing. The actual location will vary
depending on the type of product.
Recommended Oil Type
Toro 2-cycle oil is recommended for use in these
engines (Figure 1-2). If another brand of 2-cycle oil is
used, use a high quality oil that is formulated for small
2-cycle air-cooled engines.
Figure 1-2. Recommended Oil Type.
1
Figure 1-1. Product Identification Decal.
OIL AND FUEL
RECOMMENDATIONS
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can
explode if ignited. Store gasoline only in approved
containers in well-ventilated, unoccupied buildings
away from sparks or flames. Do not fill the tank while
the engine is hot or running, since spilled fuel could
ignite if it comes in contact with hot parts or sparks
from ignition. Do not start the engine near spilled fuel.
Do not smoke while handling gasoline. Never use
gasoline as a cleaning agent.
NOTE: READ THESE INSTRUCTIONS CAREFULLY
BEFORE ATTEMPTING TO START OR OPERATE
THIS UNIT. Using old oil or fuel or improperly mixing
the oil and fuel can cause engine damage. This type
of damage will void the engine warranty.
Recommended Fuel Type
Use clean fresh, regular grade unleaded gasoline.
NOTE: Alcohol blended fuel absorbs moisture (water).
As little as 1% moisture in the fuel can cause fuel and
oil to separate and form acids when stored.
If these types of fuel must be used, use fresh fuel (less
than 60 days old) and mix according to the instructions
in this section.
1 - 7
GENERAL INFORMATION
Use of Blended Fuels
1
If you choose to use a blended fuel or its use is
unavoidable, the following precautions are
recommended:
1. Always use fresh fuel mixed according to the
instructions in this section.
2. Use the special additive Alcohol Protector® (by
Gold Eagle) or equivalent to inhibit corrosion and
reduce oil/fuel separation (mix as directed).
3. Always agitate the fuel mix before fueling unit.
4. Drain the fuel tank and run engine dry before storing
unit.
Problems with Blended Fuels
Some problems associated with blended fuels include:
• Vapor lock
Use of Fuel Additives
The use of fuel additives such as Toro Gas
Stabilizer/Conditioner, STA-BIL® Gas Stabilizer, or an
equivalent, will minimize the formation of fuel gum
deposits. Such an additive should only be used when
fuel/oil mix is prepared. Add 0.4 oz. (11 ml) per gallon
of gasoline or mix per instructions on container.
NEVER add fuel additives directly to the unit fuel tank.
Fuel and Oil Mixing Instructions
NOTE: For proper engine operation and maximum
reliability, pay strict attention to these fuel and oil
mixing instructions. Use a 32:1 fuel/oil ratio when
using Toro or IDC 2-cycle oil. Using improperly mixed
fuel can severely damage the engine. Never mix the
gasoline and oil in the fuel tank of the unit.
Use the following procedures to ensure complete
mixing:
1. Put a small amount of fresh gasoline into a clean
one U.S. gallon (3.785 liter) fuel can.
• Poor warm restart
• Poor performance at high altitudes
• Corrosion of fuel system components
If any of these symptoms occur, switch to regular,
unleaded gasoline.
Gasohol Use May Require Carburetor Adjustments
These engines are lubricated by oil mixed with fuel.
Using blended fuel may alter the air/fuel ratio causing
a lean mix (less fuel, more air).
If this condition is not corrected by adjusting the
carburetor, engine damage due to poor lubrication can
result.
2. Add 4-oz. (118 ml) of Toro 2-cycle engine oil.
3. Fill the remainder of the fuel can with gasoline.
4. Screw the fuel can cap on tightly and SHAKE THE
CAN VIGOROUSLY FOR 30 SECONDS.
1- 8
GENERAL INFORMATION
STARTING/STOPPING
INSTRUCTIONS
To Start the Engine
1. Make sure the switch is in the “START” or “ON”
position (Figure 1-3).
Figure 1-3. Typical Ignition Switch.
2. FULLY PRESS AND RELEASE the primer bulb 5 to
7 times (Figure 1-4).
3.6069.003.
5. Squeeze the throttle trigger to “FULL THROTTLE”
(Figure 1-5). Hold or lock the throttle in this
position.
Figure 1-5. Typical Throttle Control.
6. Pull the starter rope BRISKLY until you hear the
engine sound like it wants to run (normally 2 to 5
pulls).
7. Place the choke lever in the “PARTIAL” choke
position (Figure 1-4).
3.6069.005
1
3. Place the choke lever in the FULL “CHOKE” position
(Figure 1-4).
Primer Bulb
Choke Lever
Figure 1-4. Primer Bulb and Choke Lever.
4. Place the unit in the starting position with the
trimmer cutting head away from yourself and
others.
3.6069.004
8 Pull the starter rope BRISKLY 1 to 3 pulls to start
the engine.
9. If the engine does not start, repeat steps 1
through 8.
10. After the engine warms up for 5 to 10 seconds,
place the choke lever in the “RUN” position.
To Stop the Engine
Place the ignition switch in the “OFF” or “STOP”
position (see Figure 1-3).
1 - 9
GENERAL INFORMATION
SERVICE/MAINTENANCE
INSTRUCTIONS
1
Air Filter
NOTE: CLEAN AND RE-OIL THE AIR FILTER
EVERY 10 HOURS OF OPERATION. The air filter is
one of the most important areas to maintain. If it is not
maintained as follows, severe engine damage can
result:
1 Remove the air filter from the carburetor/air filter
cover assembly. Refer to Part 3 - Engine
Disassembly.
Figure 1-7. Oiling Air Filter Element.
3.6069.008
2. Wash the air filter in detergent and water
(Figure 1-6). Rinse the air filter thoroughly in clean
water and allow it to dry.
Figure 1-6. Washing Air Filter Element.
3. Apply clean SAE 30 oil to the air filter (Figure 1-7).
3.6069.006
4. Squeeze the air filter to ensure that the oil is spread
throughout the entire filter (Figure 1-8).
Figure 1-8. Squeezing Excess Oil from Air
Filter Element.
5. Reinstall the air filter in the carburetor/air filter cover
assembly. Refer to Part 4 - Engine Assembly.
3.6069.008
1 - 10
Spark Plug
Every 50 hours of operation remove the spark plug,
check its condition, and reset the gap or replace with a
new plug as necessary.
WARNING: Electrical Shock!
Never touch electrical wires or components while the
engine is running. They can be sources of electrical
shock.
GENERAL INFORMATION
Carburetor Adjustment
1. Before removing the spark plug, clean the area
around the base of the spark plug to keep dirt and
debris out of the engine.
2. Disconnect the spark plug wire and remove the
spark plug from engine.
3. Inspect the spark plug for carbon buildup and clean
if necessary. Replace the plug if it is badly burnt or
if reuse is questionable.
NOTE: Do not clean the spark plug in a machine
which uses abrasive grit. Some grit could remain
on the spark plug and enter the engine causing
extensive damage.
4. Check the spark plug gap using a wire feeler gauge.
Set the gap to 0.018-0.023 inch (0.45 to 0.58 mm)
(Figure 1-9).
5. Reinstall the spark plug and torque to 100-120 in•lb
(11.3 - 13.5 N•m).
These engines are equipped with a diaphragm-type
carburetor. The carburetor has been carefully
calibrated at the factory. In most cases, no further
adjustment will be required.
The condition of the air filter is very important to the
operation of the trimmer. A dirty air filter will restrict the
air flow to the carburetor. This, in turn, upsets the
fuel-air mixture in the carburetor. The resulting
symptoms are often mistaken for an out-of-adjustment
carburetor. Therefore, check the condition of the air
filter before adjusting the carburetor. Refer to “Air
Filter” Service/Maintenance Instructions.
If the following conditions are experienced, it may be
necessary to adjust the carburetor:
• The engine will not idle.
• The engine hesitates or stalls on acceleration.
• The loss of engine power, which is not corrected
by cleaning the air filter.
• The engine operates in an erratic or fuel-rich
condition (indicated by excessive exhaust smoke
from the muffler).
NOTE: Follow these carburetor adjustment
procedures carefully. An incorrectly adjusted
carburetor can cause severe engine damage.
1
0.018 - 0.023 in.
(0.45 - 0.58 mm)
Figure 1-9. Spark Plug Gap.
Make sure the unit is fully assembled before making
carburetor adjustments.
For trimmers and brushcutters, make sure the boom,
cutting head, and line guard are installed and the
cutting line is extended to its full cutting length.
The carburetor has three basic adjustments: idle
speed adjustment, idle mixture adjustment, and high
speed mixture adjustment (Figure 1-10).
3.6069.009
1-11
GENERAL INFORMATION
(H) High
Speed
1
Mixture
Figure 1-10. Carburetor Adjustments.
1. Initial Idle Speed Setting: Turn idle speed screw
counterclockwise until it does not touch the throttle
lever. Now turn the screw clockwise until it just
touches the throttle lever; then continue turning 2
full turns.
(L) Idle Mixture
Needle
Idle
Speed
Screw
3.6069.010
5. Final High Speed Mixture Setting: Squeeze the
throttle trigger to the FULL (WIDE OPEN)
THROTTLE position. Turn the high speed mixture
needle clockwise or counterclockwise to set the
high speed RPM: 6,800 to 7,200.
6. Release the throttle trigger and let the engine idle.
If the engine stops, turn the idle speed screw
clockwise 1/8 turn at a time until the engine idles.
7. Final Idle Mixture and Idle Speed Settings: Adjust
the the idle mixture and idle speed as follows:
a. Turn the idle mixture needle clockwise until the
fastest idle RPM is reached; then turn the
needle counterclockwise 1/8 turn.
b. Squeeze the throttle trigger. If the engine falters
or hesitates as it accelerates, turn the idle
mixture needle counterclockwise 1/16 turn at
a time until the engine accelerates rapidly.
2. If so equipped, remove the rubber cap from the
high speed mixture adjustment needle.
3. Initial High Speed Mixture and Idle Mixture Settings:
Turn both the high speed mixture and idle mixture
needles clockwise until they are lightly seated.
Then turn the needles counterclockwise the
following number of turns:
High Speed Mixture Needle : 1¼ turns
Idle Mixture Needle: 1¼ turns
NOTE: Turn the high speed mixture and idle
mixture needles finger-tight. Do not force the
needles with a screw driver as this can damage
the tips of the needles and the seats in the
carburetor body.
4. Start engine and allow it to warm up for 3 to 5
minutes.
NOTE: For the following steps, use a magnetic
pick-up 2-cycle engine tachometer to monitor
engine speed.
c. If the idle speed has changed significantly
because of steps a. and b. above, readjust the
idle speed screw.
The recommended idle speed for all products is
3,000 to 3,200 RPM.
8. Make sure the air filter cover is reinstalled securely
before placing the unit back into service.
Governed Carburetor Check
Some units are equipped with fuel-governed
carburetors. If so equipped, and after adjusting the
carburetor, check the operation of the governor on
trimmers and brush cutters as follows:
1. Clip or wind the cutting line so it is inside the cutting
head (not extended to its full cutting length).
2. Start the engine and run it at FULL (WIDE OPEN)
THROTTLE.
The maximum high speed RPM should not exceed
8,800 RPM.
1 - 12
GENERAL INFORMATION
3. If the high speed RPM exceeds 8,800 RPM, the
governor assembly in the carburetor must be
cleaned or replaced and the carburetor readjusted.
STORAGE INSTRUCTIONS
WARNING: Explosive Fuel!
Gasoline is extremely flammable and its vapors can
explode if ignited. Store gasoline only in approved
containers in well-ventilated, unoccupied buildings
away from sparks or flames. Do not fill the fuel tank
while the engine is hot or running, since spilled fuel
could ignite if it comes in contact with hot parts or
sparks from ignition. Do not start the engine near
spilled fuel. Do not smoke while handling gasoline.
Never use gasoline as a cleaning agent.
Storage for 45 to 60 Days
Use the following storage procedure for equipment or
fuel that will be stored for more than 45 days and less
than 60 days:
Equipment - Empty the fuel tank and run the unit until
the fuel system is empty. When starting the unit after
storage, refill the fuel tank with freshly mixed gasoline
and oil.
Fuel - Do not use fuel that has been stored for more
than 60 days. Dispose the old fuel in a safe manner
and use a fresh mix.
5. Store the unit in a dry, well ventilated area.
To Reactive Unit for Service
1. Remove the spark plug and drain the oil from the
cylinder by slowly pulling the starter rope.
2. Reinstall the spark plug.
3. Refuel the unit with a fresh gasoline/oil mixture.
Start engine in accordance with the Starting
Instructions.
SPECIAL TOOLS
In addition to typical hand tools, the following special
tools are required to properly service these engines:
• Clutch Tool, (Standard N28 Engines) P/N 147337
(Figure 1-11).
• Clutch Tool, (Professional N28 Engines)
(Figure 1 -12).
• Flywheel Holder, P/N 612470 (Figure 1- 13).
• 0-250 in•lb (0-28.1 N•m) Torque Wrench
(commercially available).
• Torx® Screwdriver or Bit Set (commercially
available).
1
Storage for More Than 60 Days
1. Drain all fuel from the fuel tank into an approved
fuel container.
2. Start the engine and run it until it stalls.
3. Allow the engine to cool. Remove the spark plug
and put about 1 oz. (39 ml) of any high quality
motor or 2-cycle oil into the cylinder. Pull the
starter rope slowly to distribute the oil. Reinstall
the spark plug.
4. Clean the unit and inspect for any loose or
damaged parts. Repair or replace damaged parts
and tighten loose screws, nuts, or bolts.
• Two-stroke, Magnetic Pick-up Tachometer
(commercially available).
• Arbor or Hydraulic Press (commercially available).
• Bearing and Seal Pullers (commercially available).
• Hex Wrench Clutch Rotor Tool, P/N 180918.
• Flywheel Holding Tool, P/N 180918.
• 0-250 in•lb (0-28.1 N•m) Torque Wrench
(commercially available).
• Torx® Screwdriver or Bit Set (commercially
available).
• Two-stroke, Magnetic Pick-up Tachometer
(commercially available).
1 - 13
GENERAL INFORMATION
1
Figure 1-11. Clutch Tool P/N 147337.
Figure 1-12. Clutch Tool for Professional
N28 Engines.
3.6069.011
3.6069.012
Figure 1-13. Flywheel Holder, P/N 612470.
1 - 14
3.6069.013
TROUBLESHOOTING
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting .............................
Disassembly, Inspection, and Repair ...................
Reassembly ................................
1
2
3
4
2 - 1
TROUBLESHOOTING
Engine Fails to Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Engine Starves on Acceleration . . . . . . . . . . . . . . . . . . . . . . 2-4
Engine is Hard to Start . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Table of Contents
2
Engine Stalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Engine Fires Intermittently . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Engine Does Not Produce Maximum Power . . . . . . . . . . . . . . . . 2-5
Carburetor Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Engine Stops After Running Briefly . . . . . . . . . . . . . . . . . . . . . 2-6
Engine Will Not Idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Engine Backfires or Misfires . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Engine Will Not Accelerate . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Engine Lacks Power or Stops During Operation . . . . . . . . . . . . . . 2-7
2- 2
TROUBLESHOOTING
When difficulties occur, be sure to check for simple causes which, at first, may seem too obvious to beconsidered.
A starting problem, for example, could be caused by an empty fuel tank.
The following table lists some common causes of operating troubles and the possible causes and remedies.
Engine Fails to Start
Possible Cause Remedy
Ignition switch OFF Turn switch ON
Out of fuel or water in fuel Drain tank and blow out fuel lines to remove
water. Refuel tank with fresh fuel mixture.
Dirty or plugged air filter Clean or replace air filter
Loose spark plug lead wire Reconnect lead wire
Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to
0.018-0.023 inch (0.45 to 0.58 mm)
Plugged fuel tank cap vent Clean fuel tank cap vent
Plugged or waterlogged fuel filter Replace fuel filter
Improperly adjusted carburetor Adjust carburetor
Plugged muffler Clean or replace muffler
Faulty primer or primer/fuel lines improperly installed Correctly install primer/fuel lines or
replace primer
Incorrect fuel mixture Drain tank; refill with correct fuel mixture
Plugged fuel line Blow out fuel line
Faulty carburetor diaphragm Replace diaphragm
2
Plugged fuel pump filter screen Clean or replace filter screen
Faulty fuel pump diaphragm Replace pump diaphragm
Plugged carburetor/fuel pump passages Clean out passages
Incorrect air gap between flywheel and ignition Set ignition module air gap to
(0.010-0.015 in (0.254-0.381 mm)
Faulty ignition module Replace ignition module
Low compression Replace piston ring(s) or cylinder
2 - 3
TROUBLESHOOTING
Engine Starves on Acceleration
Possible Cause Remedy
Plugged fuel filter Replace fuel filter
Improperly adjusted carburetor Adjust carburetor about 1/8 turn
2
Engine is Hard to Start
Possible Cause Remedy
Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to
0.018-0.023 in. (0.45 to 0.58 mm)
Plugged or waterlogged fuel filter Replace fuel filter
Improperly adjusted carburetor Adjust carburetor
Clogged muffler Clean or replace muffler
Faulty primer or primer/fuel lines improperly installed Correctly install primer/fuel lines or
replace primer
Incorrect air gap between flywheel and ignition module Set ignition module air gap to
0.010-0.015 inch (0.254-0.381 mm)
Faulty ignition module Replace ignition module
Worn or improperly adjusted carburetor jet needle Adjust or replace needle
Faulty carburetor diaphragm Replace carburetor diaphragm
Faulty fuel pump diaphragm Replace fuel pump diaphragm
Low compression Replace piston ring or cylinder
Engine Stalls
Possible Cause Remedy
Dirty or plugged air filter Clean or replace air filter
Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to
0.018-0.023 in. (0.45 to 0.58 mm)
Plugged fuel tank cap vent Clean fuel tank cap vent
Incorrect fuel mixture Drain tank; refill with correct fuel mixture
Improperly adjusted carburetor Adjust carburetor
Plugged muffler Clean or replace muffler
Plugged fuel line Blow out fuel line
Faulty ignition module Replace ignition module
2- 4
TROUBLESHOOTING
Engine Fires Intermittently
Possible Cause Remedy
Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to
0.018-0.023 in. (0.45 to 0.58 mm)
Incorrect air gap between flywheel and ignition module Set ignition module air gap to
0.010-0.015 inch (0.254-0.381 mm)
Faulty ignition module Replace ignition module
Incorrect fuel mixture Drain tank; refill with correct fuel mixture
Engine Does Not Produce Maximum Power
Possible Cause Remedy
Plugged air filter Clean or replace filter
Incorrect fuel mixture Drain tank; refill with correct fuel mixture
Plugged muffler Clean or replace muffler
Plugged or waterlogged fuel filter Replace fuel filter
Improperly adjusted carburetor Adjust carburetor
Air leak at carburetor base gasket Tighten carburetor fasteners or replace
carburetor base gasket
Intermittent spark Replace ignition module
Low compression Replace piston ring or cylinder
Leaking crankcase seals Replace crankcase seals
Scored piston and/or cylinder Replace piston cylinder assembly
2
Worn piston rings or low compression Overhaul engine
Carburetor Floods
Possible Cause Remedy
Faulty primer or improperly installed primer/fuel lines Correctly install primer/fuel lines or
replace primer
Improperly adjusted carburetor Adjust carburetor
Damaged carburetor Replace carburetor
Leaking fuel inlet needle Replace fuel inlet needle
2 - 5
TROUBLESHOOTING
Engine Stops After Running Briefly
Possible Cause Remedy
Partially plugged fuel tank cap vent Clean fuel tank cap vent
Dirty or plugged air filter Clean or replace air filter
Water in fuel mixture Drain tank and blow out lines
Air leak at carburetor base gasket Tighten carburetor mounting fasteners
or replace carburetor base gaskets
2
Dirty carburetor fuel inlet needle or passage Replace fuel inlet needle or clean out
carburetor
Faulty carburetor diaphragm Replace diaphragm
Losing compression Replace piston ring or gaskets or
overhaul engine
Engine Will Not Idle
Possible Cause Remedy
Improperly adjusted carburetor Adjust carburetor
Faulty carburetor diaphragm Replace carburetor diaphragm
Faulty carburetor inlet seat gasket Replace carburetor inlet seat gasket
Leaking crankshaft seals Replace crankshaft seals
Scored cylinder or low compression Overhaul engine
Engine Backfires or Misfires
Possible Cause Remedy
Improper or contaminated fuel mix Drain tank; refill with fresh fuel mixture
Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to
0.018-0.023 in. (0.45 to 0.58 mm)
Shorted ignition module leads Check for loose or bare wires or loose
assembly and correct or replace ignition
module.
2- 6
TROUBLESHOOTING
Engine Will Not Accelerate
Possible Cause Remedy
Carburetor improperly adjusted Adjust carburetor
Air filter clogged Clean or replace air filter
Spark plug fouled Clean or replace spark plug; set gap to
0.018-0.023 in. (0.45 to 0.58 mm)
Plugged muffler Clean or replace muffler
Carburetor diaphragm gasket leaking Replace gasket
Engine Lacks Power or Stops During Operation
Possible Cause Remedy
Faulty primer causing flooding Replace primer
2
Dirty or plugged air filter Clean or replace air filter
Plugged muffler Clean or replace muffler
Scored cylinder or low compression (below 90 psi) Overhaul engine
2 - 7
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2- 8
DISASSEMBLY, INSPECTION, & REPAIR
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting ..............................
Disassembly, Inspection, and Repair ..................
Reassembly ................................
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2
3
4
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