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

This Page Intentionally Left Blankl

2- 8

DISASSEMBLY, INSPECTION, & REPAIR

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting ..............................

Disassembly, Inspection, and Repair ..................

Reassembly ................................

1

2

3

4

3 - 1

DISASSEMBLY, INSPECTION, & REPAIR

Table Of Contents

Typical Disassembly Sequence . . . . . . . . . . . . . . . . . . . . . . 3-4

Major Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Drain Fuel From Tank . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Remove Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Standard N28 Engines . . . . . . . . . . . . . . . . . . . . . 3-5

Professional N28 Engines . . . . . . . . . . . . . . . . . . . 3-6

Remove Styling Cover . . . . . . . . . . . . . . . . . . . . . . . 3-7

Remove Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3

Remove Choke/Carburetor . . . . . . . . . . . . . . . . . . . . . 3-8

Remove Primer Bulb . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Carburetor Disassembly . . . . . . . . . . . . . . . . . . . . . . . 3-9

Fuel Metering Side . . . . . . . . . . . . . . . . . . . . . . . 3-9

Fuel Pump Side . . . . . . . . . . . . . . . . . . . . . . . . 3-11

Carburetor Inspection and Cleaning . . . . . . . . . . . . . . . . . 3-11

Carburetor Reassembly . . . . . . . . . . . . . . . . . . . . . . . 3-12

Fuel Metering Side . . . . . . . . . . . . . . . . . . . . . . . 3-12

Fuel Pump Side . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

Final Carburetor Adjustment . . . . . . . . . . . . . . . . . . . . 3-15

Remove Carburetor Spacer . . . . . . . . . . . . . . . . . . . . . 3-15

Remove Rear Engine Cover . . . . . . . . . . . . . . . . . . . . 3-16

Remove Fuel Tank Bracket, Fuel Tank, and Heat Shield . . . . . . 3-16

Fuel Tank and Lines, Disassembly, Inspection, and Reassembly . 3-16

Fuel Tank and Cap . . . . . . . . . . . . . . . . . . . . . . . 3-16

Fuel Line and Filter Removal . . . . . . . . . . . . . . . . . 3-17

Fuel Line and Filter Installation . . . . . . . . . . . . . . . . 3-17

3- 2

Remove Muffler . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18

Exhaust Exit Tube Removal . . . . . . . . . . . . . . . . . . 3-18

DISASSEMBLY, INSPECTION, & REPAIR

Muffler Inspection and Cleaning . . . . . . . . . . . . . . . . . . 3-18

Muffler Reassembly . . . . . . . . . . . . . . . . . . . . . . . . 3-19

Remove Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19

Standard N28 Engines . . . . . . . . . . . . . . . . . . . . 3-19

Professional N28 Engines . . . . . . . . . . . . . . . . . . 3-20

Clutch Inspection . . . . . . . . . . . . . . . . . . . . . . . . . 3-21

Remove Starter Housing . . . . . . . . . . . . . . . . . . . . . . 3-21

Starter Disassembly, Repair, and Reassembly . . . . . . . . . . . 3-22

Adding Starter Spring Tension . . . . . . . . . . . . . . . . 3-22

Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . 3-23

Inspection and Service . . . . . . . . . . . . . . . . . . . . 3-24

Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . 3-25

Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27

Remove Ignition Module . . . . . . . . . . . . . . . . . . . . . . 3-27

Remove Flywheel . . . . . . . . . . . . . . . . . . . . . . . . . 3-27

FIywheel Inspection and Repair . . . . . . . . . . . . . . . . . . 3-28

Remove Spark Plug, Cylinder, and Piston/Connecting

Rod Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29

Cylinder and Piston Inspection . . . . . . . . . . . . . . . . . . . 3-31

Crankshaft and Crankcase Disassembly . . . . . . . . . . . . . . 3-31

Crankcase Inspection . . . . . . . . . . . . . . . . . . . . . . . 3-33

Crankcase Reassembly . . . . . . . . . . . . . . . . . . . . . . 3-33

3

3 - 3

DISASSEMBLY, INSPECTION, & REPAIR

Typical Disassembly Sequence

The following sequence is suggested for complete
engine disassembly, inspection, and repair. This
procedure can be varied to accommodate individual
requirements for disassembly and repair.

Clean all parts thoroughly as the engine is
disassembled. Only clean parts can accurately be
inspected and gauged for wear or damage. There are
many commercially available cleaners that will quickly
remove oil and grime from engine parts. When such a
cleaner is used, follow the manufacturer’s instructions
and safety precautions carefully. Particular attention
should be given to commercial cleaners compatibility
with plastic parts.

Make sure that the cleaner is wiped off of engine parts

3

and not allowed to air dry as some cleaners leave a
residue on parts which can affect engine lubrication.

Refer to the appropriate parts manual to ensure the
correct replacement parts are ordered.

1. Drain Fuel from Tank*

7. Remove Rear Engine Cover

8. Remove Fuel Tank Bracket, Fuel Tank, and Heat
Shield

9. Remove Muffler*

10. Remove Clutch

11. Remove Starter Housing

12. Remove Ignition Module

13. Remove Flywheel

14. Remove Spark Plug*, Cylinder, and Piston/
Connecting Rod

15. Remove Crankshaft; Disassemble Crankcase

2. Remove Engine from Equipment

3. Remove Styling Cover

4. Remove Air Filter*

5. Remove Choke/Carburetor*

6. Remove Carburetor Spacer

* On some units, these can be removed and
reinstalled without removing the engine from its
normal operating installation.

NOTE: Only disassemble the engine to the extent
necessary to make the desired repairs.

3- 4

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Drain Fuel From Tank

WARNING:

EXPLOSIVE FUEL

WARNING: Explosive Fuel!
Gasoline may be present in the fuel tank,
carburetor, fuel lines, and 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.

3

1. Drain all fuel from the fuel tank and drain into a
suitable container for storing a 2-cycle fuel
mixture.

2. Start the engine and allow it to run until it stalls.
Allow the engine to cool.

2.0415.011

2.6071.015

Remove Engine

Standard N28 Engines

Remove the engine from the equipment as follows:

1. If necessary, remove the air filter cover and base
before the throttle cable is removed from the
carburetor throttle lever.

2 For units with serial number 102084332 to

302010968 - loosen the screw securing the
throttle cable in the swivel on carburetor throttle
lever. Remove the throttle cable from the swivel.

3 - 5

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

3. For units with serial number 302010969 and
greater, remove the Z-bend of throttle cable
from the hole in the carburetor throttle lever.

4. Disconnect the lead wires from the ignition switch.

NOTE: The location of the lead wires and the
removal instructions will vary from model to model.

3

2.6071.016

5. Remove the anti-rotation screw from the drive
housing.

6. Loosen clamp nut and bolt.

7. Remove engine from the drive housing (boom).

Professional N28 Engines

Remove the engine from the equipment as follows:

1. If necessary, remove the air filter cover and base
before the throttle cable is removed from the
carburetor throttle lever.

Anti-Rotation

Screw

Drive Housing

Clamp

3.6071.017

2. Remove the throttle cable from the hole in
carburetor throttle lever.

3- 6

3.6069.004

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

3. Disconnect the lead wires from the ignition
switch.

NOTE: The location of the lead wires and the
removal instructions will vary from model to model.

3.6069.003

3

Clamp
Screw

Anti-Rotation

Screw

4. Remove the anti-rotation screw from the clutch
housing/drum assembly.

5. Loosen clamp screw.

6. Remove engine from the drive housing (boom).

3.6071.016

Remove Styling Cover

Units with a professional N28 engine are equipped
with an engine styling cover. To remove the styling
cover:

2.6071.018

1. Remove the screws securing the styling cover.
Remove the cover.

3 - 7

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Remove Air Filter

Use the following procedures to remove the air filter
cover and element. Service the element as
instructed in Part 1 - General Information.

1. Remove the screws securing the air filter cover.
Remove the air filter cover assembly from the
air filter base.

3

3.6071.019

2. Remove the air filter element from the air filter
cover.

Remove Choke/Carburetor

1. Remove the screws securing the choke
components, air filter base, and carburetor to
the carburetor spacer.

2. Remove the flat washers, wavy washer, choke
lever and choke plate, and spacers.

3.6071.020

3- 8

2.6071.021

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

3. Remove the fuel line from the carburetor fuel inlet
fitting.

4. Remove the fuel line from the fuel outlet fitting on
carburetor (to primer bulb).

Fuel Inlet

Fitting

Fuel Outlet

Fitting

5. Remove the carburetor and carburetor gasket.

2.6071.024

3

Remove Primer Bulb

1. Remove the fuel lines from the fittings on primer
bulb.

2. Squeeze the mounting tabs on the back of the
bulb, and pull the bulb out from the front of the
air filter base.

Inspect the primer bulb for flexibility and cuts or
tears. Replace the primer bulb if necessary.

2.6071.022

2.6071.023

Carburetor Disassembly

Fuel Metering Side

1. Remove the high speed mixture (H) and idle
mixture (L) adjusting needles and springs.

3 - 9

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

2. Remove the fuel metering cover screws and
cover.

3

2.6071.024

3. Remove the fuel metering diaphragm and gasket.

4. Remove the screw securing the metering lever
hinge pin in carburetor body.

Remove the metering lever, hinge pin, metering
lever spring, and fuel inlet needle.

NOTE: These components are under spring tension.
Remove them carefully to prevent loss. Make sure
the spring is not stretched.

2.6071.025

3 - 10

2.6071.026

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Fuel pump Side

1. Remove the idle speed adjusting screw and
spring from fuel pump cover.

2. Remove the fuel pump cover screw and cover.

2.6047.027

3

2.6071.028

3. Remove the fuel pump cover gasket and pump
diaphragm.

NOTE: Further disassembly to remove the throttle
plate, throttle lever, welch plugs, fuel inlet screen,
etc., is not recommended.

Carburetor Inspection And Cleaning

Two carburetor service kits are available: a gasket/
diaphragm kit and a carburetor repair kit.

The gasket/diaphragm kit contains the fuel metering
cover gasket, fuel metering diaphragm, fuel pump
cover gasket, and fuel pump diaphragm.

2.6277.138

The carburetor repair kit contains the gaskets and
diaphragms included in the gasket/diaphragm kit
plus the high speed mixture needle and spring, idle
mixture needle and spring, fuel inlet needle and
spring, fuel metering lever, metering lever hinge pin,
the fuel inlet screen and welch plugs. Refer to the
appropriate parts manual for service kit part
numbers.

3-11

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

1. Inspect the tips of the high speed mixture needle,
idle mixture needle, and fuel inlet needle for
wear or damage. Replace the needles if
necessary.

3

3.6179.165

2. Gaskets and diaphragms eventually deteriorate
and become stiff with age and use. It is good
practice to replace gaskets and diaphragms for
each repair. However, if the diaphragm is soft
and flexible, you do not need to replace it unless
a complete carburetor rebuild is being
performed.

3. Clean the metering cover, pump cover, carburetor
body, and filter screen with carburetor cleaner.
Blow out all passages with compressed air.

NOTE: To prevent damage to the carburetor body,
do not use drill bits or wire to clean fuel ports and
passages.

Carburetor Reassembly

Fuel Metering Side

2.6060.152

1. Install the fuel inlet needle, fuel metering lever
spring, metering lever, and metering lever hinge
pin. Secure the hinge pin in carburetor body with
the hinge pin screw.

3 - 12

2.6071.026

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

2. Place a straight edge across the carburetor body.
Use a wire feeler gauge to measure the
distance between the the straight edge and the
top of the fuel metering lever.

The fuel metering lever should be 0.060-0.070 in.
(1.52-1.78 mm) below the straight edge.

2.6071.029

3

DEPRESS
HERE

HIGH

THEN PUSH
NEEDLE
HERE

PR Y UP HERE

LOW

Adjust the metering lever.

If the lever is adjusted too high, the engine will
run rich. If the lever is adjusted too low, the
engine will run lean. Poor acceleration and
erratic operation may also be noted.

3.6071.031

3. Install the metering cover gasket (next to
carburetor body) and metering diaphragm. Make
sure the larger circular plate of diaphragm is
towards the metering lever.

3.6071.032

3 - 13

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

4. Make sure there are no wrinkles in the metering
diaphragm. Install the metering cover and
screws. Tighten the the screws securely.

3

2.6071.033

5. Install the high speed mixture (H) and idle mixture
(L) adjusting needles and springs.

Turn both needles clockwise until they are lightly
seated. Then turn the needles counterclockwise
the following number of turns:

High Speed Mixture Screw: 1¼ turns
Idle Mixture Screw: 1¼ turns

NOTE: Turn the high speed mixture and idle mixture
needles finger-tight. Do not force the needles with a
screwdriver as this can damage the tips of the
needles and the seats in the carburetor body.

Fuel Pump Side

2.6071.034

1. Install the fuel pump diaphragm (next to carburetor
body) and gasket.

.

3 - 14

2.6071.035

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

2. Install the fuel pump cover and cover screw.
Tighten the screw securely.

3. If necessary, install the idle speed adjusting
screw and spring.

Turn the adjusting screw clockwise until it just
touches the throttle lever; then continue turning
2 full turns.

2.6071.036

3

3.6069.010

Final Carburetor Adjustment

Make final adjustments to the carburetor when the
unit is fully reassembled. Refer to “Carburetor
Adjustment” in Part 1 - General Information.

Remove Carburetor Spacer

1. Remove the two (2) screws securing the
carburetor spacer to the crankcase.

2. Remove the carburetor spacer and carburetor
spacer gasket.

2.6071.037

3. If necessary, remove the two (2) hex nuts on the
back of the carburetor spacer.

3 - 15

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Remove Rear Engine Cover

1. Remove the two (2) screws securing the rear
cover to the starter housing and crankcase.

2. Remove the rear engine cover.

3

2.6071.039

Remove Fuel Tank Bracket, Fuel Tank, and Heat
Shield

1. Remove the two (2) screws from the fuel tank
bracket.

2. Remove the bracket, fuel tank, and heat shield.

3. Remove the rubber fuel tank mounting pads.

Fuel Tank and Lines, Disassembly, Inspection
and Reassembly

Fuel Tank and Cap

1. Inspect the fuel tank for cracks, rubbing, or
chaffed spots. Replace the tank if necessary.

2.6071.040

2. Inspect the rubber fuel tank mounting pads (on
either side of the tank) for condition. Replace
the mounts if necessary.

3. Inspect the fuel tank cap for cracks, damaged
vent valve, or other visible signs of damage.
Replace the cap if necessary.

3 - 16

2.6078.085

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Fuel Line and Filter Removal

This unit has two fuel lines to the fuel tank. The
clear line provides normal fuel flow. The blue line
provides a return line for excess fuel flow during the
primer operation. The blue (primer) line is removed/
installed in the same manner as the fuel line except
it does not have a fuel filter.

To remove the fuel lines and fuel filter:

1. Push the fuel fitting, fuel filter, and fuel line out of
the fuel tank through the tank neck.

2.6071.041

3

2.6078.086

2. If the fuel filter is dirty or clogged, replace it with a
new fuel line assembly.

Fuel Line and Filter Installation

1. Insert a piece of trimmer line through the hole in
the bottom of fuel tank to the filler opening. Slide
the fuel line over trimmer line.

2. Working through the filler neck, insert the fuel line
with the fuel filter and fitting attached through
the hole in the bottom of tank.

2.6078.087

3. Work the fuel line from outside of tank, pulling
until the filter lays on the bottom of the tank.

3 - 17

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Remove Muffler

1. Remove the muffler mounting bolts.

2. Remove the muffler and gasket. Discard the old
gasket.

3

3.6071.045

Exhaust Exit Tube Removal

1. Remove the screws securing the exhaust exit tube
to the muffler body.

2. Remove the exhaust exit tube and gasket.

Muffler Inspection and Cleaning

The muffler should be removed periodically to
inspect for excessive carbon build-up. Excessive
deposits around the exhaust ports or exhaust exit
holes will cause poor engine performance.

2.6071.043

1. Check the inlet port of muffler for excessive
carbon deposits. Clean as required.

3 - 18

2.6071.046

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

2. Inspect the baffle inside muffler for carbon
build-up. Clean baffle by scraping carbon as
required. Use a piece of wire to clear
obstructions from the small holes in baffle.

3. Inspect the muffler mounting holes for elongation.
Replace the muffler if the holes are elongated.

3.6071.045

3

2.6071.043

Muffler Reassembly

1. Install a new gasket and the exhaust exit tube.
Secure the tube with two (2) screws.

Torque the screws to 15-25 in•lb (1.7-2.8 N•m).

Remove Clutch

Standard N28 Engines

1. Remove the four (4) screws securing the clutch
cover to starter housing. Remove the clutch
cover.

2.6071.046

3 - 19

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Clutch Tool

2. Install flywheel holder, P/N 612470 or 180919.

3. Using clutch tool, P/N 147337 or 180918, remove
the clutch rotor.

4. Remove the spacer sleeve from crankshaft.

3

Flywheel Holder

2.6071.047

Professional N28 Engines

1. Remove the four (4) screws securing the clutch
housing/drum assembly to starter housing.
Remove the clutch housing/drum assembly.

2. Install flywheel holder, P/N 612470 or 180919.

3. Remove the two (2) clutch shoe bolts and
washers.

2.6071.048

3 - 20

2.6071.049

Clutch Tool

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

4. Using the clutch tool for professional N28
engines, remove the clutch rotor.

5. Remove the spacer sleeve from crankshaft.

2.6071.050

3

2.6078.088

Clutch Inspection

1. Check the clutch rotor, shoes, and spring for
wear or damage. Replace if necessary.

Remove Starter Housing

1. If necessary, disconnect the spark plug wire from
spark plug and remove the spark plug.

2. Remove the screws securing the starter housing.
Remove the starter housing.

2.6071.051

3 - 21

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Starter Disassembly, Repalr, and Reassembly

WARNING: Sprlng 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, pulley, and starter spring from
housing.

3

2.6060.153

Adding Starter Spring Tension

If the rope pull handle does not fully return against
the starter housing, the spring may need another
turn of tension. Additional tension can be added
without disassembling the starter.

To add spring tension:

1. Pull the rope out a short distance and hold the
pulley from turning.

2. Wind one or more extra turns of rope onto the
pulley.

NOTE: If necessary, loosen the pulley retainer
screw while holding the pulley down to provide
clearance between the retainer and pulley. Torque
the retainer screw to 20-30 in•lb (2.3-3.4 N•m) after
additional rope is wound onto pulley.

2.6071.052

3 - 22

2.6071.053

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

3. Pull the rope out to its full length and let it return
until the pull handle rests against the starter
housing.

NOTE: Do not add any more tension than is
necessary to make the pull handle return against the
starter housing. Adding excessive spring tension
can cause the spring to break.

If spring pressure is weak and adjustment will not
enable the pull handle to return against the starter
housing, replace the spring.

2.6078.089

3

2.6071.053

Disassembly

1. Relieve the spring tension by removing the pull
handle and allow the pulley to slowly unwind
inside the starter housing. Make sure the spring
tension is fully relieved before proceeding.

2. Remove screw and pulley retainer.

3. Remove the starter pulley from the starter
housing .

2.6071.054

3 - 23

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

4. If necessary, carefully remove the starter spring
from the starter housing using a needle-nose
pliers.

NOTE: Once the starter spring is removed from the
starter housing, a service replacement spring
(prewound and contained in a spring retainer)
should be used to reassemble the starter.
Reinstallation of the old starter spring is not
recommended.

3

2.6071.055

5. Remove the starter rope from the pulley.

6. Remove the rope guide bushing from the starter
housing.

Inspection and Service

1. Inspect the starter rope for wear or frays. Replace
the rope if necessary.

2. Inspect the starter pulley for worn pawl
engagement teeth. Also check for wear on the
surface of pulley that is in contact with the
starter spring.

2.6071.056

3. Make sure old grease and dirt are cleaned from
all starter components before reassembling.

3 - 24

2.6047.092

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

Reassembly

1. Install the starter spring into the starter housing
as follows:

a. Orient the replacement starter spring so the

spring windings are clockwise (the open end
of spring hook is to the left).

2.6071.057

3

2.6071.058

b. Grasp the spring near the spring hook with a

needle-nose pliers and carefully remove the
spring retainer.

c. Place the spring into the starter housing.

Make sure the spring hook is installed over
the post in the starter housing.

d. Make sure the spring windings are laying flat

against the starter housing around the entire
circumference of the spring. Hold the spring
in this position and carefully release the
needle-nose pliers holding the spring.

2.6071.059

3 - 25

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

2. Insert the rope through the hole in starter pulley.
Tie a single knot in the rope approximately

0.5 in. (12.7 mm) from the end.

3. Pull the rope tight, pulling the knot into the pocket
in the pulley. Using a screwdriver, or similar tool,
push the end of the rope into the slot in the
pulley.

3

2.6071.060

4. Hold the pulley with the pawl engagement teeth
towards you. Wrap the rope around the pulley in
the clockwise direction. Make sure all of the
rope is wound onto the pulley.

5. Apply a small amount of grease (Mobilgrease®
HP or equivalent) to the post in starter housing,
spring, and backside of pulley.

6. Install the rope guide bushing into the starter
housing.

7. Install the pulley/rope assembly into the starter
housing. Rotate the pulley slightly until the
spring hooks onto the pulley, and the pulley
drops into place.

Post

2.6071.056

8. Route rope through the guide bushing in the
starter housing.

Install the pull handle on the rope and secure it
with a single knot.

3 - 26

2.6071.062

DISASSEMBLY, INSPECTION, & REPAIR

MAJOR COMPONENTS (cont.)

9. Install the pulley retainer and screw. Torque the
screws to 20-30 in•lb (2.3-3.4 N•m).

10. Pull the rope out to its full length and let it return.
Check the spring tension and adjust as
necessary. Refer to “Adding Starter Spring
Tension” above.

2.6071.053

ENGINE

3

2.6071.064

Remove Ignition Module

1. Make sure the spark plug wire and the lead
wires to the ignition module are disconnected.

2. Remove the screws securing the ignition module
to the cylinder. Remove the ignition module.

Remove Flywheel

WARNING: CRACKED OR BROKEN COOLING
FINS ARE A HAZARD!

Be careful not to crack or break any cooling fins.
They could fly off during operation. If cooling fins are
cracked or broken, replace the flywheel.

2.6071.065

1. Using a plastic-faced mallet, tap and pull
flywheel until it breaks free from the crankshaft.

3 - 27

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

2. Remove the flywheel from the crankshaft.

3. Remove the flywheel key from crankshaft.

3

2.6071.066

Flywheel Inspection and Repair

Inspect the flywheel for the following conditions:

• Missing, broken, or cracked fins.

• Oval shaped pawl pin holes.

• Broken, damaged or missing springs, pawls, or

pawl pins. Freedom of movement of pawls.

• Evidence that the Starter Pawl Repair Kit has

been installed (holes in bottom of the flywheel
below pawl pins).

• Other signs of fatigue, wear, or damage to the

flywheel.

Starter Pawl Repair Kit, P/N 180142, is available to
repair the flywheel. This kit contains 2 pawl pins
(oversized*), 2 pawl springs, and 2 pawls. To install
the kit, an arbor press, 0.228 in (5.79 mm) drill and
drill press are required. Installation instructions are
provided in the kit.

2.6060.161

CONTENTS OF KIT

#180142

2 Starter Pawl Pins

(oversized)

2 Starter Pawl Springs

*NOTE: The pawl pins in this kit are oversized.
Once this kit is installed, the flywheel cannot be
repaired a second time.

For all other damage, replace the flywheel.

3 - 28

2 Starter Pawls

2.6078.093

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

Remove Spark Plug, Cylinder, and Piston
Connecting Rod Assembly

1. Remove the spark plug from cylinder.

Service the spark plug as instructed in Part 1 ­General Information.

2.6071.067

3

2.6071.068

2. Remove the four (4) screws securing the
crankcase cover to crankcase. Remove the
crankcase cover and gasket.

3. Remove the four (4) cylinder mounting screws.

2.6071.069

3 - 29

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

4. Remove the connecting rod from crankshaft.

5. Remove the cylinder with piston/connecting rod
assembly from the crankcase as a unit. Remove
the cylinder gasket.

3

2.6071.070

6. Remove the piston/connecting rod assembly from
the cylinder.

NOTE: Units with serial number 102084332 to
302010968 have one (1) piston ring. Units with
serial number 302010969 and greater have two (2)
piston rings.

7. Remove the piston ring(s) from the piston.

NOTE: Do not disassemble the piston/connecting
rod further.

2.6071.071

3 - 30

2.6071.072

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

Cylinder and Piston Inspection

1. Inspect the cylinder, piston, and piston ring(s) for
wear and damage. Refer to the specifications
and tolerances in Part 1 - General Information.
Replace the cylinder, piston, or piston ring(s) if
necessary.

2.6078.090

3

2.6071.073

2. Install the piston ring(s) into the ring groove(s) in
piston, and check the side clearance of piston
ring(s). The maximum side clearance is

0.004 inch (0.101 mm). Replace the ring(s) and
piston if necessary.

NOTE: Units with one (1 ) piston ring have a piston
ring width of 0.060 inch (1.6 mm) minimum.

Units with two (2) piston rings have a piston ring
width of 0.047 inch (1.14 mm) minimum.

3. Inspect the ring groove(s) on piston for carbon
deposits. Clean the ring groove(s) thoroughly.

Crankshaft and Crankcase Disassembly

NOTE: Crankcase disassembly and reassembly

requires the use of an arbor press and suitable drift
punches and bearing supports. If these are not
available, do not attempt to repair the crankcase
assembly. Refer to the appropriate parts manual to
order a complete crankcase/crankshaft assembly.

2.6071.074

1. Using an arbor press, press the crankshaft and
thrust washer out of the crankcase.

3 - 31

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

2. Remove the outer (sealed) bearing from the
flywheel side of the crankcase using a bearing
puller.

3

2.6071.075

3. Remove the inner (unsealed) bearing from the
inside of the crankcase.

4. Remove the snap rings securing the inner seal in
crankcase.

2.6071.076

Snap Rings

3 - 32

2.6071.077

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

5. Remove the inner seal from crankcase.

2.6071.078

3

2.6071.076

Crankcase Inspection

1. Inspect the crankcase for nicks, cracks, and
deformation. Replace if necessary.

2. Inspect the crankshaft for nicks, cracks,
roundness, and deformation. Replace if
necessary.

Crankcase Reassembly

NOTE: To prevent bearing damage, make sure

bearings are fully supported on both the inner and
outer races during all pressing operations. Make
sure the inner surface of crankcase and mating
surfaces of bearings and seal are clean, dry, and
free from grease and oil.

2.6071.077

1. Install outer snap ring (nearest flywheel).

3 - 33

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

2. Make sure the race of the outer (sealed) bearing
is packed with grease. If necessary, apply a
small amount of a high quality grade 2 lithium
based (or equivalent) bearing grease to the
bearing. Keep the grease off of the inner and
outer bearing surfaces that mate against the
crankcase and crankshaft.

3. Press the outer (sealed) bearing into the
crankcase until it is flush with the crankcase
surface. Make sure the rubber seal is to the
outside.

3

4. Press the inner seal into the crankcase to a depth
of 0.400 in. (10.2 mm). Make sure the lips of the
inner seal face away from the outer bearing.

Outer (Sealed)

Bearing

2.6071.079

Lightly lubricate the lips of the inner seal with
2-cycle engine oil.

5. Install the inner snap ring (nearest crank cheek).

6. Install the thrust washer onto the crankshaft.

7. Press the inner (unsealed) bearing onto the
crankshaft until it makes light contact with the
thrust washer.

2.6071.080

Bearing Support

3 - 34

2.6071.081

Crankshaft/Bearing

DISASSEMBLY, INSPECTION, & REPAIR

ENGINE (cont.)

8. Press the crankshaft/bearing assembly into the
crankcase until the bearing is flush with the
inner surface of the crankcase.

2.6071.082

3

2.6071.083

9. Check the clearance between the inner surface of
the crankcase and the crankshaft counterweight
at several points.

Recommended clearance is 0.030 in.
(0.762 mm). Adjust the location of the
crankshaft/bearing if necessary.

3 - 35

This Page Intentionally Left Blank

3 - 36

REASSEMBLY

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting .............................

Disassembly, Inspection, and Repair ..................

Reassembly ...............................

1

2

3

4

4 - 1

REASSEMBLY

Typical Assembly Sequence . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Install Piston/Connecting Rod . . . . . . . . . . . . . . . . . . . . 4-4

Install Cylinder To Crankcase . . . . . . . . . . . . . . . . . . . . 4-5

Install Spark Plug . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

Major Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Install Flywheel . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Install Ignition Module . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Table Of Contents

4

Install Starter Housing . . . . . . . . . . . . . . . . . . . . . . . . 4-8

Install Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

Standard N28 Engines . . . . . . . . . . . . . . . . . . . . . 4-9

Professional N28 Engines . . . . . . . . . . . . . . . . . . . 4-10

Install Muffler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11

Install Carburetor Spacer . . . . . . . . . . . . . . . . . . . . . . 4-11

Install Heat Shield, Fuel Tank, and Bracket . . . . . . . . . . . . . 4-12

Install Rear Engine Cover . . . . . . . . . . . . . . . . . . . . . . 4-12

Install Primer Bulb . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

Install Carburetor, Choke, and Connect Fuel Lines . . . . . . . . . 4-13

Install Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

Install Styling Cover . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

Install Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

Standard N28 Engines . . . . . . . . . . . . . . . . . . . . . 4-14

Professional N28 Engines . . . . . . . . . . . . . . . . . . . 4-16

4- 2

Prepare the Unit for Operation . . . . . . . . . . . . . . . . . . . . 4-17

Typical Disassembly Sequence

REASSEMBLY

The following sequence is suggested for complete
engine REASSEMBLY. This procedure assumes that
all components are new or have been reconditioned
and all component subassembly work has been
completed. This procedure can be varied to
accommodate individual requirements for assembly
and repair.

NOTE: Make sure the engine is assembled using all
specified torque values and clearances. Failure to
observe specifications can cause severe engine wear
or damage.

Always use new gaskets.

1. Install Piston/Connecting Rod

2. Install Cylinder to Crankcase

3. Install Spark Plug

4. Install Flew

7. Install Clutch

8. Install Muffler*

9. Install Carburetor Spacer*

10. Install Heat Shield, Fuel Tank, and Bracket

11. Install Rear Engine Cover

12. Install Carburetor and Choke; Connect Fuel Lines*

13. Install Air Filter*

14. Install Styling Cover

15. Install Engine

4

16. Prepare the Unit for Operation

5. Install Ignition Module

6. Install Starter Housing

* On some units, these can be removed and
reinstalled without removing the engine from its normal
operating installation.

4 - 3

REASSEMBLY

ENGINE

Install Piston/Connecting Rod

For units with one (1) piston ring, use the following
instructions

1. If necessary, install the piston ring onto the piston.
Make sure the ring end gap is located over the
anti-rotation pin in the piston ring groove.

2.6071.072

4

2. Lubricate the piston and piston ring with 2-cycle
engine oil. Compress the piston ring and insert
the piston into the cylinder.

3. Position the piston ring anti-rotation pin/end gap
so it faces away from the exhaust port of
cylinder.

NOTE: With the exhaust port on the right and intake
port on the left, the text on the piston rod should
face towards you.

2.6071.071

4- 4

2.6078.095

2.6078.096

REASSEMBLY

ENGINE (cont.)

For units with two (2) piston rings, use the following
instructions.

1. If necessary, install the piston rings onto the piston.

2. Make sure the ring end gaps are located over the
anti-rotation in the piston ring grooves.

Spark Plug

Port

2.6071.071

3. Lubricate the piston and piston rings with 2-cycle
engine oil. Compress the piston rings and insert
the piston into the cylinder.

NOTE: With the exhaust port on the right and intake
port on the left, the text on the piston rod should
face towards you.

Install Cylinder to Crankcase

1. Put a new cylinder gasket on the cylinder.

2. Position the cylinder so the spark plug port is on
the left side of the cylinder.

4

2.6071.070

3. Lubricate the pin on crankshaft counterweight
with 2-cycle engine oil. Slip the connecting rod
bearing over the pin.

4 - 5

REASSEMBLY

ENGINE (cont.)

4. Secure the crankcase to the cylinder with four (4)
screws.

Torque the screws to 50-60 in•lb (5.6-6.8 N•m).

2.6071.069

5. Install a new crankcase cover gasket, the

4

crankcase cover, and attaching screws.

Torque the screws to 55-65 in•lb (6.2-7.3 N•m).

Install Spark Plug

1. Make sure the spark plug gap is set to

0.018-0.023 inch (0.045 to 0.058 mm) using a

wire feeler gauge.

2. Install the spark plug into cylinder and torque to
100-120 in•lb (11.2-13.5 N•m).

2.6071.068

4- 6

2.6071.067

2.6071.066

REASSEMBLY

MAJOR COMPONENTS

Install Flywheel

WARNING: Cracked or Broken Cooling Fins Are
A Hazard!

Be careful not to crank or break any cooling fins.
They could fly off during operation. If cooling fins are
cracked or broken, replace the flywheel.

1. Install the crankshaft key into the key way on
crankshaft.

2.6078.097

4

2. Position the flywheel so that the key slot in the
flywheel aligns with the crankshaft key. Place
the flywheel onto the crankshaft.

Install Ignition Module

1. Install the ignition module ground lead tab

terminal and module fastening screws.

2.6078.098

4 - 7

REASSEMBLY

MAJOR COMPONENTS (cont.)

2. Move the ignition module away from the flywheel
as far as possible. Tighten the fastening screws

slightly

3. Insert a 0.010-0.015 in (0.254-0.381 mm) feeler
gauge or shim stock between the ignition
module and flywheel magnet surfaces.

NOTE: Brass or plastic feeler gauge or shim
stock is more suitable for this application
because of the magnetic forces.

4. Loosen the module fastening screws and push the
ignition module tight against the feeler gauge or
shim stock.

.

2.6078.099

4

Torque the screws to 28-35 in•lb (3.2-3.9 N•m).
Remove the feeler gauge or shim stock.

5. Connect ignition switch lead wires as necessary.

Install Starter Housing

1. Install the starter housing and secure with two (2)
screws.

Torque the screws to 35-40 in•lb (3.9-4.5 N•m).

2.6078.098

NOTE: It may be necessary to pull the starter rope
slightly to enable the starter housing to drop into
position.

4- 8

2.6071.051

2.6078.100

REASSEMBLY

MAJOR COMPONENTS (cont.)

Install Clutch

Standard N28 Engines

1. Install the spacer sleeve over the crankshaft.

2. Install the clutch rotor to the crankshaft. Make
sure the side marked “OUT” is facing away from
the starter housing.

Clutch Tool

Flywheel Holder

2.6078.101

3. Install the flywheel holder, P/N 612470 or

180919.

Using clutch tool, P/N 147337 or 180918, torque
the clutch rotor to 150-160 in•lb (16.9-18 N•m).

4. Remove the flywheel holder.

5. Position the raised boss inside the “snout” of the
clutch cover towards the rope pull handle. Install
the clutch cover/clutch drum to the starter
housing and secure with four screws.

4

2.6071.046

Torque the screws to 35-40 in•lb (3.9-4.5 N•m).

4 - 9

REASSEMBLY

MAJOR COMPONENTS (cont.)

Professional N28 Engines

1. Install the spacer sleeve over the crankshaft.

2. Install the flywheel holder, P/N 612470.

3. Install the clutch rotor to crankshaft.

4. Using the TORO clutch tool for the professional
N28 engine, torque the rotor to 130-150 in•lb
(14.6-16.8 N•m).

4

5. Install flat washer, clutch shoes, spring, and two
(2) clutch shoe bolts.

Clutch Tool

Flywheel Holder

2.6071.050

Torque the bolts to 60-80 in•lb (6.7-9 N•m).

6. Install the clutch housing/drum assembly and
secure with four (4) screws.

Torque the screws to 35-40 in•lb (3.9-4.5 N•m).

NOTE: Make sure the anti-rotation screw is
towards the top (rope pull handle) of the engine.

2.6078.102

4 - 10

2.6071.048

2.6078.042

REASSEMBLY

MAJOR COMPONENTS (cont.)

Install Muffler

1. Install a new muffler gasket, muffler, and muffler
mounting screws.

Make sure the extended edge of the muffler­cylinder gasket is between the muffler body and
crankcase.

Torque the muffler mounting screws to
80-90 in•lb (9.0-10.1 N•m).

2.6078.104

4

Install Carburetor Spacer

1. Insert the two (2) hex nuts into the pockets on the
back of the carburetor spacer.

2. Install the carburetor spacer gasket and the two
attaching screws to the carburetor spacer. Install
the carburetor spacer and gasket to the engine
crankcase.

Make sure the hex nuts do not fall out of the
spacer during the installation of the carburetor
spacer.

2.6078.105

Torque the screws to 60-65 in•lb (6.8-7.3 N•m).

4-11

REASSEMBLY

MAJOR COMPONENTS (cont.)

Install Heat Shield, Fuel Tank, and Bracket

1. Install the rubber fuel tank mounting pads to the
fuel tank (on front and rear of the tank).

2. Place the heat shield over the muffler and hook
into the crankcase.

2.6078.106

4

3. Install the fuel tank, fuel tank bracket, and two (2)
attaching screws.

Torque the screws to 50-60 in•lb (5.6-6.7 N•m).

Install Rear Engine Cover

1. Install rear engine cover with two (2) screws.

Torque the upper screw (into starter housing) to
50-60 in•lb (5.6-6.7 N•m).

2.6078.107

Torque the lower screw (into crankcase) to
35-40 in•lb (3.9-4.5 N•m).

4 - 12

2.6071.039

2.6078.108

REASSEMBLY

MAJOR COMPONENTS (cont.)

Install Primer Bulb

1. Install primer bulb into air filter base.

To Carburetor

Return Line

3.6078.110

Install Carburetor, Choke, and Connect
Fuel Lines

Use the following procedures to install carburetor,
fuel lines, and choke:

NOTE: This unit has two fuel lines to the fuel tank.
The clear line provides normal fuel flow. The blue
line provides a return line for excess fuel flow during
the primer operation. The primer return line is
connected to the longer fitting of the primer bulb.

1. Connect the fuel lines to the carburetor and
primer bulb.

2. Install the carburetor gasket, carburetor, air filter
base, choke lever, wavy washers, flat washers,
and carburetor mounting screws.

4

2.6078.109

Torque the screws to 23-27 in•lb (2.6-3.0 N•m).

4 - 13

REASSEMBLY

MAJOR COMPONENTS (cont.)

Install Air Filter

Make sure the air filter element is cleaned and oiled
as instructed in Part 1 - General Information.

1. Install the air filter element into the air filter cover.

2. Install the air filter cover and attaching screws to
air filter base.

Torque the screws to 15-25 in•lb (1.7-2.8 N•m).

CHOKE

PARTIAL

RUN

3.6069.004

Install Styling Cover

4

Units with professional N28 engines are equipped
with an engine styling cover. To install the styling
cover:

1. Install the styling cover and secure it with two
screws.

Install Engine

Standard N28 Engines

1. Slip the upper drive housing (boom) clamp
assembly onto the clutch cover.

2.6071.018

Anti-Rotation

Screw

2. Install the engine onto the trimmer drive housing.
Make sure the flex drive shaft mates with the
square drive of engine. Make sure the slot in
the flex drive housing aligns with the boss in the
clutch cover.

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Drive Housing

Clamp

3.6071.017

3.6078.111

REASSEMBLY

MAJOR COMPONENTS (cont.)

3. Install the anti-rotation screw through clamp and
into boom.

Torque the anti-rotation screw to 15-20 in•lb
(1.7-2.3 N•m).

Torque the nut and bolt of clamp to 70-80 in•lb
(7.9-9 N•m).

2.6071.015

4

4. For units with serial number 102084332 to
302010968, install the throttle control cable and
insert it through the hole in the swivel on
carburetor throttle lever. Torque the screw in the
swivel to 9-12 in•lb (1.0-1.4 N•m).

5. For units with serial number 302010968 and
greater, insert the Z-bend end of the throttle
control cable into the third hole from the end of
the carburetor throttle lever.

6. Adjust the throttle control cable in the lever for full
range of throttle travel.

2.6071.016

Make sure the outer cover of the throttle cable
seats in the back of the carburetor spacer.

4 - 15

REASSEMBLY

MAJOR COMPONENTS (cont.)

Professional N 28 Engines

1. Install the engine onto the trimmer drive housing.
Make sure the drive shaft mates with the square
drive of the engine. Make sure the slot in the
flex drive housing aligns with the boss in the
clutch housing/drum assembly.

2.6078.112

2. Install the anti-rotation screw through the clutch
housing/drum assembly and into the boom.

4

Torque the anti-rotation screw to 15-20 in•lb
(1.7-2.3 N•m).

Torque the clamp screw to 70-80 in•lb
(7.0-9.0 N•m).

3. Insert the Z-bend end of the throttle control cable
into the third hole from the end of the carburetor
throttle lever.

4. Install the throttle control cable in the swivel on
carburetor throttle lever.

Anti-Rotation

Screw

Clamp Screw

3.6071.016

Make sure the outer cover of the throttle cable
seats in the back of the carburetor spacer.

5. Adjust the throttle control cable in the swivel for
the full range of the throttle travel.

6. Connect lead wires to ignition switch.

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2.6071.016

2.6071.015

REASSEMBLY

MAJOR COMPONENTS (cont.)

Prepare The Unit For Operation

Before placing the unit back into service, be sure to
do the following:

• Make Sure all fasteners are tightened securely.

• Fill the fuel tank with a fresh gasoline and

2-cycle oil mix. Refer to the “Fuel
Recommendations” in Part 1 - General
Information.

• Adjust the carburetor high speed mixture, idle

mixture, and idle speed settings. Refer to
“Carburetor Adjustment” in Part 1 - General
Information.

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