Maruyama BL471 Blower Owner’s Manual

(RA VARLIVAMA U.S, INC.
SERVICE MANUAL
FOR BACKPACK POWER BLOWER
MODEL: BL471
P/N 840430
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1/20/94
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TABLE OF CONTENTS
. External view e oscoooococsoooactoorcooonoaaucocosencarcaoecaacemoorenoacocrowresqaccesaaroo 1
. Specifications: -...............m..e.essrcecerereocenoreoaeooaeocercer eran eeeeee. 2
. Periodic inspections ----=-......e....e..eervesneecorao eee Doe enero ene. 3
. Servicing tools, measuring tools
4—1 Servicing ТОО!5 ‘оо ооооооооо оное оо ооо оо ооо во вой оооововооввочовсововсооввее вов нововвововое 4
4—2 Measuring IQO|S:..es-ooacccoraccasreraacareconanecaooarrrrarcanracacaca, .0002000002008 5
. General cautions during assembly and disassembly
5—1 Cautions and prohibitions prior to disassembly +-==--====es=snsoccnrcncccnnes 6
5-2 (Cautions during disassembly eotararereaoreneanaracarecaooeocacaccavecarecacacrece. 6
5—3 (Cautions during cleaning *ocearorrreuororevasonocaocasacadacarcantcouverartrrecanasoo 6
5—4 Cautions during assembly coreNtotavarancorantoavAnAaCAANAtaretartauccoantccdAamaaeeso 6
6. Assembly and disassembly of each component
6—1 Assembly and disassembly of maching +++«=<sscscssocacacacarecacerorenececacan. 7
6—2 Throttle lever ----.--.e.escacrccaccoreccacecornacoasocero ooo reee eoereeorrencoo. 10
6—3 Fuel tank ---==-e=.rerooocccoraoroccaoenenacaoroneec one. eoeroroocenacanceroneaaane. 12
6—4 inspection of air cleaner -+=--.==<sc.0cerccocccooroococcconeoncaroroanerea eee. 13
6—5 Carburetor ---..e...0orcccrconocaooorocro oo oee roce aro ree aroueorrereoecacacorrereaeaoe 14
6—6 Inspection of spark plug eocovococaconrroeranTUarancoeocareaaroaeocaraooaranaenanoco 19
6—7 Inspection Of muffler secssersscecscercess *eoeveraccaceneccancooconecaronecerecceo.... DO
6—8 Inspection of cylinder, piston and piston ring <<<<-<>e. 21
6—9 Crankcase, crankshaff---e.íecococesconcocororeocaocoroocancoocasreno soe cero, 24
7. Tightening torque table:---..........e....e.0.e.ceccrcencecorconenccne.. 1.0.0000... 26
8. Servicing standards table---.…….............…...….…………eecrererseecsercsrses 27
9. Malfunctions and countermeasures PP 28
1. EXTERNAL VIEW
HANDLE
ENGINE
THROTTLE CABLE | \ MUFFLER COVER
AIR CLEANER = 2 FAN CASE(BLOWER HOUSING)
RECOIL STARTER ==
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FUEL TANK | BACKPACK FRAME
2. SPECIFICATIONS
Model name BL471
Dimensions (L X W x H) inch (mm) 17.4 X 20.6 X 20.8 (440 X 520 x 525)
Dry weight los (kg) 19.8 (9.0)
Fuel tank capacity gts (lit) 1.3 (1.2)
External diameter inch (mm) 9.3 (236)
Fan case Glass fiber reinforced plastic
Material
Fan Die-cast aluminum
Blower
Standard blow head Bent blow head
Rotation speed rem 6800
Air volume mM /min 9.8
Name Mitsubishi T310PND
Air cooled, 2-cycle,
Type single cylinder gasoline engine
Displacement 47.1cc
Engine Fuel Gasoline-oil mixture (gasoline-oil ratio — 25:1)
Carburetor Diaphragm piston valve type (Nikki)
Ignition Non-contact points (MTI) magnetic ignition
Spark plug NGK-BM7A
Starting system Recoil system
Type Cable type
Throttle
Positions 8 (including stop)
Attached blow head
Bent pipe, fan-blow head
3. PERIODIC INSPECTIONS
Periodic inspections should be carried out according to the table below:
Inspection and servicing periods
Îtems for inspection and servicing Before y every every every
e eve
starting 25 hours | 50 hours | 100 hours } 200 hours
Fuel-return line O
Fuel suction hose
Bolt, nut
Harness
О ОТО | ©
Anti-vibration rubbers
Blower
& Fan O
Fuel tank
O
Fuel tank
Backpack frame O.
Fan case O
Cleaning of screen
Blow head
Fuel inspection
Inspection for leakage of fuel and pressurized air
Inspection for loose screws
ОТО ТОО | О | ©
Cleaning of cylinder fins
Cleaning of air cleaner element O
Cleaning and adjustment of spark plug O
Engine | Cleaning of fuel tank O
Tightening of cylinder O
O
Tightening of engine components
Cleaning of carbon on muffler and exhaust port O
Cleaning of fuel filter O
Removal of cylinder head and combustion chamber O
Tightening of muffler cover O
4—1 SERVICING TOOLS
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4. SERVICING TOOLS, MEASURING TOOLS
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No. Name Remarks Main use
1 | Hammer
2 Screwdriver (Phillips) Medium, large | Assembly, disassembly of muffler, handle, rotor case -
3 | Screwdriver (standard) Medium
4 | Pliers Assembly, disassembly of fuel cap clamp
5 | Radio pliers Removal, replacement of throttle cable
6 | Spark plug wrench 19 Removal, replacement of spark plug -
7 | Wrench 8x 10 Assembly, disassembly of gauge plate
8 | Ratchet wrench Large, small
9 | Extension bar For small sizes
10; Socket 8,12,14
11| Box wrench 19 Assembly, disassembly of backpack frame, muffler and rotor
12 Hexagon rod wrench 4mm Assembly, disassembly of cylinder
13 | Grease
14| Oil
15| Emery paper #400
16 { Waste cloth
4—2 MEASURING TOOLS
A |
18 25 26 27 28 29
№ Мате ‘Remarks Main use
17 | Dial indicator Measure eccentricity at end of crankshatt
18 Micrometer Measure journal area of crankshaft |
19! Cylinder gauge ® 6, ¢ 26 |Measure diameter of piston pin hole
20| Gap gauge 0.15—0.5 [Measure piston ring groove gap
21 | Torque wrench Measure flywheel tightening torque
22 | Coil tester
23 | Magnetic indicator gauge table Assembly, disassembly of gauge plate
24 | V-block
25 | Flywheel puller Flywheel removal tool
26 | Rotation clamp | Flywheel removal tool
27 | Revolution counter Measure engine speed
28 | Pressure gauge Check carburetor open/close pressure
29 | Float lever height gauge Adjust float lever height
5. GENERAL CAUTIONS DURING ASSEMBLY AND
DISASSEMBLY
5—1 CAUTIONS AND PROHIBITIONS
PRIOR TO DISASSEMBLY
1) Be sure to extract fuel prior to disassembly. It is
extremely dangerous to disassemble with fuel
remaining in the tank.
2) Remove mud, grease and grass caught in various
parts.
Do not allow dirt to enter major parts of the machine
as it can cause a malfunction.
3) Disassemble the engine after it has cooled. if
disassembly is carried out while the engine is still
hot, there is the danger of burn injury.
4) Disassembiy should be performed in a tidy work
environment. Disregarding this can lead to difficulty
during the reassembiy sequence and also
misplacing parts.
5—2 CAUTIONS DURING DISASSEMBLY
1)When disassembling, follow the individual
instructions and use the correct tools.
2) When disassembling, lay out the parts as major -
components in the order of disassembly, as this will
facilitate smooth reassembly. It is also a good idea
to attach parcel tags to label parts.
3) Gaskets should be replaced during reassembly.
4) Take care not to damage oil seals.
5) Take care not to cause severe Impact to the
crankshaft.
6) With screws, even if the diameter is correct, when
the wrong length screw is used it can lead to
damage. It is recommended that screws are
returned to their original position and hand
tightened.
7) When a part is to be left disassembled for some
time, apply oll to exposed parts to prevent rust
forming.
5—3 CAUTIONS DURING CLEANING
1) Before assembly, wash each part with new cleaning
fluid (paraffin, or light oil).
2) When cleaning, give priority to important parts.
5-4 CAUTIONS DURING ASSEMBLY
1) The circlip of the piston pin should be replaced
during reassembly.
2) Any stuck gasket should be separated carefully and
replaced with a new one.
3) Compare the condition of each part with the
standard values in “9. Servicing Standards Table”
(see P.43) and replace ail parts which are outside
the standard values with new parts.
4) Applying two-cycle oil to rotating areas and rubbing
areas before assembly.
5) The output shaft side (crankcase P) and the recoil
starter side (crankcase R} are fitted together, so
they shouid be replaced as a pair.
6) Areas with more than one screw should be
tightened evenly, with diagonally opposite screws
being tightened alternatively.
7) Screws should be tightened to the torque settings
specified in “8. Tightening Torque Table"(see P.42).
6. ASSEMBLY AND DISASSEMBLY OF EACH
COMPONENT
6—1 ASSEMBLY AND DISASSEMBLY OF
MACHINE
(1) ASSEMBLY/DISASSEMBLY OF FUEL TANK
1) Remove the return pipe and suction pipe which
connects the engine and fuel tank. The return pipe
can be removed by lifting with pliers the clip-which
Is securing the cap, and pushing the cap with a
standard screwdriver. To remove the suction pipe,
push open the resin clamp with a standard
screwdriver, and pull out the suction pipe from the
carburetor.
RETURN PIPE
CLAMP .
AN SUCTION PIPE
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2) Using a Phillips screwdriver, remove the two
screws at the bottom of the backpack frame which
fasten the fuel tank, and the fuel tank can be
removed.
. (2) ASSEMELY/DISASSEMBLY OF HANDLE
1)Using a Phillips screwdriver, remove the four
screws which fasten the handle, and puli up the
handle to remove.
HANDLE
PHILLIPS HEAD SCREW (EE)
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2) There is a packing piece and oil seal packing
which should be replaced if a draft of pressurized
air can be felt from the side of the handle.
Note:
When removing the handle, take care not to lose the
nut in the rotor case.
(3) ASSEMBLY/DISASSEMBLY OF BACKPACK
FRAME
1) Gently lay the machine on its side, and using a box
wrench, remove the screws that fasten the
anti-vibration rubbers at the bottom of the
backpack frame.
2) To remove the backpack from the machine, push
up the two upper fasteners using a standard
screwdriver.
Note:
Take care not to pull the backpack forcibly, as this can
tear the backpack.
3) Using a box wrench, remove the two nuts at the
back of the backpack frame which fasten the
anti-vibration rubbers, and the backpack frame can
be removed from the machine.
|
(4) REMOVAL/REPLACEMENT OF THROTTLE
CABLE
1) Using radio pliers, remove the throttle cable from
the cable housing attached to the throttle lever.
| Note:
When removing the throttle cable, bring the throttle
lever to its lowest position.
RADIO PLIERS
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CABLE HOUSING
(5) REMOVAL/REPLACEMENT OF ROTOR CASES
1)Using a Phillips screwdriver, remove the 12
self-tapping screws that fasten the rotor case S
and remove rotor case S.
Note:
When reassembling, be sure to fasten the throttle
cable clamp together with the self-tapping screw.
2) Removal/replacement of suction cover (to be 3) The drawing on the right shows the condition with
removed when the inside of the suction cover rotor case S being removed. When aligning rotor
becomes dirty). The suction cover can be removed case S with rotor case E at the time of reassembly,
by unscrewing the four screws fastening the mount the bent pipe assembly and the two
suction cover using a Phillips screwdriver. ~ anti-vibration rubbers.
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BENT PIPE ANTI-VIBRATION RUBBERS
PLLILLIP OE ELE ES LOL LO IDOL LILLE ELLE OE ES ALLE LLO SIDO DIEL LID LL EDILES DESDE IES LEO E OELSE DES DELI OELSE ILLES IL IES LILLE ELIO PIELES ILLES DELLE EL LLE LEE
(6) REMOVAL/REPLACEMENT OF ROTOR
Remove the three bolts fastening the rotor while at the
same time pushing the rotor and remove the rotor.
A oe
Note:
When reassembling, align the mark |.
A) MAGNETIC ROTOR B) ROTOR
(ENGINE TOP DEAD CENTER) (NUMBER STAMPING POSITION:LOWER)
| ENGINE TOP
STAMP IS AT THE BACK.
(7) REMOVAL/REPLACEMENT OF ENGINE
1)Using a Phillips screwdriver, remove the two
screws fastening the muffler cover and remove the
muffler cover.
2) After removing the four bolts attaching the engine,
the engine can be separated from the machine.
Note:
When reassembling, hand tighten the four screws to
align with the knock pin, and assemble by aligning the
center so that the rotor case does not foul the rotor.
6-2 THROTTLE LEVER
(TO BE DISASSEMBLED/SERVICED WHEN THE
THROTTLE LEVER AND GAUGE PLATE HAVE
WORN OUT OR WORKED LOOSE).
1) Remove the cap from the grip using a standard
screwdriver.
Note:
When using a siandard screwdriver, take care not to
scratch the cap.
S—
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2) Then using a standard screwdriver, push back the
snap clamp inside the cap, and the grip will come
off the throttle lever.
Note:
The snap clamp is a spring, so be careful not to lose it.
Also, be careful as the spring will open if forced.
= =
- 10 -
3) When the grip slides off the throttle lever, increase
the tension by squeezing the snap clamp with
pliers, as indicated in the diagram. DECREASE TENSION
4) After removal of the two screws which fasten the 6) To remove the cable holder attached to the throttle
gauge plate and gauge plate support, the gauge lever, remove the E-type holding ring using a
plate can be removed. standard screwdriver.
Note: | Note:
For easy removal of the upper pan head screws, bring The elongated hole is to control the maximum engine
the throttle lever to the bottom position for easy speed position of the throttle.
removal.
7) When reassembling, mount the cap and snap on
the grip ahead of time, and then insert over the
throttle lever.
5) As the gauge plate is removed, the throttle lever
can also be removed at the same time. To
increase throttle lever tension, bend the lever in
the direction indicated by the arrow. (see diagram)
Note:
When removing the throttle lever, be careful not to
lose the collar,
-11-
8) Engine speed should be adjusted with the outer
holder of the gauge plate support. When engine
speed cannot be adjusted, loosen the locknut
attached to the lever arm, and move the cable
holder to the left or right.
The engine speed adjustment range is as follows:
Idie: 2,300—2,700 rpm
Maximum: 6,700—7,000 rpm
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6—3 FUEL TANK
(1) INSPECTION
1) The fuel filter can be cleaned by pulling the filte
out through the fuel filling neck using a wire hook.
OUTER HOLDER
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GAUGE PLATE ro el E
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CABLE HOLDER
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AEA EEE LETTE ETL TTS TSS
LILIA
КОРИ РРР ии лены
LLL DLE
HOOKED WIRE
FUEL PICKUP TUBE
PRIMER BULB ASSEMBLY
FUEL FILTER 7
WIRE HOOK
FUEL FILTER
(P/N 912658)
2) Remove the fuel filter from the pick up tube and
clean the filter using gasoline. Normally the fuel
fitter should be cleaned every 50 hours.
Note:
The fuel filter should be replaced as a complete
assembly.
FUEL FILTER
FUEL PICKUP TUBE
WEIGHT SPONGE
(2) DISASSEMBLY/ASSEMBLY
(THE PRIMING PUMP SHOULD BE REPLACED
WHEN THE PRIMING FUNCTION HAS
DETERIORATED.)
1) Pull out the suction hose while tipping the priming
pump.
Note:
-12-
When reassembling, fix the priming pump with care so
as not to drop the suction hose inside the fuel tank.
2) Pull out the suction hose from the fuel tank
together with the fuel filter, |
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6—4 INSPECTION OF AIR CLEANER
(1) DISASSEMBLY —
1) Remove the band spring which holds the air
cleaner cover.
BAND SPRING
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CLEANER COVER
2) Remove the air cleaner cover and element. When
reassembling after cleaning, be sure to put the nap
side of the element facing out, from the case.
ELEMENT
- 13 -
3)To remove the cleaner case, loosen the two
screws fastening the air cleaner case and
carburetor using a Phillips screwdriver.
"Note;
Remove the cleaner case only when the cleaner case
and grid are excessively dirty.
When removing the air cleaner case, remove it
together with the cap (see P.8).
Be careful not to allow the cap to become separated
from the cleaner case.
CLEANER CASE
| e |
CAP
(2) CLEANING
The element should be cleaned regularly (every
— 25 hours, or as required). After cleaning, soak the
element in two-cycle engine oil and squeeze out the
excess oil.
6—5 CARBURETOR
(1) STRUCTURE
PARTS NAMES
VENTURI PART
1. CHOKE LEVER ; (
3. MAIN DIAPHRAGM
O-RING
7. VALVE SEAT
6. FLOAT VALVE
19. PUMP COVER
20. JOINT
2. MAIN ADJUSTMENT SCREW 11. NEEDLE JET
. INLET VALVE SPRING
5. FLOAT ARM 12. MAIN DIAPHRAGM COVER
18. TICKLER LEVER
<= ¡AR
<Q : FUEL |
<= : AIR-FUEL MIXTURE
8, CLIP
8, THROTTLE VALVE
10. JET NEEDLE
VENTURI PART
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13. SLOW AIR JET
14, PUMP DIAPHRAGM
15. OVERFLOW PIPE
The purpose of the carburetor is to mix air and liquid
(fuel), and supply an air-fuel mixture according to the
engines needs.
1) The pump diaphragm (14) reacts to changes in
pressure inside the engine crankcase, the fuel
from the fuel pipe joint (20).
2) The engine suction air pressure acts on the main
diaphragm (3) through the needle jet (11), and
atmospheric pressure presses the opposite side of
the main diaphragm. This presses the float arm (5)
and lowers the float valve (6), and fuel flows into
the metering chamber.
3) The fuel in the metering chamber, drawn by the
negative pressure cf the venturi area, squirts out
from the needle jet (11) to become an air-fuel
mixture that is supplied to the engine.
4) When the engine stops, the negative pressure of
the venturi area becomes zero. The float arm (5) is
pushed by the inlet valve spring (4), and the float
valve (8) closes. This cuts off the flow of fuel and
prevents overflow.
*When the tickler lever (18) is pushed up and primer
operated, fuel will be forcibly squirted into the
metering chamber via the diaphragm pump (14)
and the float valve (6). The air in the metering
chamber will be mixed with fuel and sprayed out
from the overflow pipe (15).
- 14 -
(2) DISASSEMBLY
1) Remove the air cleaner from the engine unit (see
P.18).
2) Remove the suction pipe and the return pipe which
connects the engine to fuel tank (see P.8).
3) Remove the carburetor from the engine unit. When
dismantling the carburetor, remove the two screws
using a Phillips screwdriver.
f /
Note: ; |
Servicing of the throttle valve should be conducted in
a clean environment, and care should be taken to
prevent dirt from entering.
(3) CHARACTERISTICS AND ADJUSTMENT
1) Throttle valve, Jet needle
a. Characteristics
The throttle valve is a piston type and the transition
from low speed to high speed is good. As for the
shape of the bottom of the throttle valve, it is
tapered from the air inlet side towards the air
exhaust side, which increases the speed of the
air-fuel mixture and improves the atomization of
fuel.
4) Remove the jet needle inside the carburetor.
Loosen the cap that fastens the throttle wire to the
carburetor. |
Hold the cap by hand and pull out together with the
throttle valve,
- 15 -
|
© The cut away (CA) is balanced to stabilize fuel flow
volume during idling.
© Conditions of the air-fuel mixture are created by
the throttle valve, JN and NJ. The supply of the
air-fuel mixture to the combustion chamber is
adjusted with the opening/closing of the throttle
valve. In other words, at the same time as the
volume of sucked air is adjusted, the fuel flow
volume from the needle jet is calculated with the
throttie vaive.
CA:0.5
7 | | Я THROTTLE VALVE
— AIR-FUEL MIXTURE
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JET NEEDLE
NEEDLE JET
b. adjustment
Jet needle
There are three levels of grooves and the standard
is set at the second groove. This is matched to the
engine so that the optimum air-fuel mixture is made
at this position and no adjustment is normally
required.
THROTTLE _ | THREE LEVELS OF
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RECEIVER |
~~ PSTD
CLIP ——— | __»8
GROVE / 3
—
JETNEEDLE — 7
NEEDLE JET
2) Main adjustment screw
a. Characteristics
This is the component that controls the fuel flow so
that it matches the optimum flow volume required
by the engine,
b. Adjustment
The main adjustment screw controls output to
maximum when a load is applied at high speed,
but normally no readjustment is required as it is
pre-adjusted.
| Standard return times: 24 + 14 |
||
||
MAIN
ADJUSTMENT SCREW
(HIGH SPEED FUEL
ADJUSTMENT SCREW)
i: Fully open throttle lever
ii: Adjust main adjustment screw to a position that
gives stable running by turning from left and right
within the range of the standard return times (214
+ 16). |
Turn right : Air-fuel mixture becomes lean
Turn left: Air-fuel mixture becomes rich
iii. Check rapid acceleration/deceleration
Check for smooth acceleration and deceleration by
rapidly opening or closing the throttle lever.
*If the engine stalls or there is inadequate
acceleration, the air-fuel mixture is lean, and the
main adjustment screw requires readjustment.
3) Main diaphragm
a. Characteristics
The main diaphragm converts the pressure
difference in the engine air intake and the
atmosphere into an up-down movement force and
controls the fuel flow into the metering chamber.
This correlates to the movement of the carburetor
float.
b. Servicing
Be careful not to damage the diaphragm or deform
the saucer, and care should be taken regarding
the knock pin hole. Since this is an important part,
special care is required during overhaul.
KNOCK PIN HOLE
No) saw
SAUCER
- 16 -
4) Needle valve
a. Characteristics
The float arm moves following the up-down
movement of the main diaphragm, and fuel from
the fioat valve flows into the metering chamber.
The float valve controls the fuel flow volume.
SEAT(RUBBER) HOOK
b. Servicing
It is essential that the float valve operates smoothly
and makes an air-tight seal when the valve is fully
open. Therefore, when the seat is damaged or
worn after an extended period of use, overflow
occurs, and the engine malfunctions. In this
situation the float valve should be replaced.
c. Cautions during assembly/disassembly
i: The free length of the inlet valve spring should not
be altered by stretching. Be careful to avoid
distorting. |
Also check that the spring fits firmly in the float arm
guide (protruding part).
FLOAT ARM
=]
UIDE PROTRUSION
INLET VALVE SPRING
| FLOAT ARM HOOK
NEEDLE VALVE
li: Check that the hook at the end of the float arm is
correctly fitted in the needie valve.
fil: Tightening of the float pin should be carried out by
bringing the float pin as far as possible towards the
float pin set screw.
OVERFLOW VALVE SEAT
FLOAT ARM [ INLET VALVE
\
SPRING GUIDE
FLOAT PIN
\
| NEEDLE VALVE
FLOAT PIN SET SCREW
BODY CONTACT AREA
- 17 -
iv: Float arm height has a critical effect on engine
performance, so height adjustment should be
performed accurately using a measuring gauge.
© When the float arm is too high, excess fuel will be
supplied.
O When the float arm is too low, insufficient fuel will
be supplied. (Lack of output, poor acceleration)
Adjust to 1.4 to 1.6mm from the carburetor body.
1.4 TO 1.6mm FROM THE
FLOAT ARM CARBURETOR BODY
INLET VALVE SPRING
“
N
f FLOAT VALVE
FLOAT ARM GAUGE
FR 15330
MATERIAL: SK5 t2
GAUGE
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5) Diaphragm pump
a. Characteristics
When the function of the diaphragm pump
deteriorates, it will cause malfunctions such as
poor siarting, poor acceleration and engine
stalling.
The pump diaphragm operates according to
b. Servicing
The check valves of the pump diaphragm should
be free from damage or distortion and should be
flat.
- Therefore, when assembling the diaphragm,
direction and gasket order should be corrected.
pressure variation inside the crankcase. (4) ASSEMBLY
i) After installing the insulator together with the
gasket, refit the carburetor using a Phillips
screwdriver.
CHECK VALVE
2) Install the return pipe and suction pipe that
connects the carburetor and fuel tank. |
-18-
Note:
As for the cap installation position, the tickler lever
should not foul the return pipe and the clamp should
be installed ensuring that the cap is not under excess
tension.
3) Attach the air cleaner case to the main unit using a
Phillips screwdriver.
A д / 7
AZ
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| NES
7
4) After fitting the air cleaner case, attach the element
cover. -
Note:
The element should be fitted with the nap side
outwards.
5) Finally, fasten the air cleaner with the spring.
6—6 INSPECTION OF SPARK PLUG
(1) DISASSEMBLY
Pull the spark plug cap off the spark plug, then
remove the spark plug with a plug wrench.
-19-
(2) INSPECTION
The plug gap is 0.024—0.028 when the piug is new.
However, through use it becomes narrower or wider,
and adjustment is required. When the plug gap is
incorrect it will cause starting problems or reduced
output.
When replacing the spark plug, use an NGK-BM7A.
EXTERNAL ELECTRODE
0.024---0.028 inch
—
“A
CENTRAL
ELECTRODE
(3) ASSEMBLY
o Tighten using a plug wrench.
0 The correct tightening torque is 110—170kg.cm.
Note:
When the spring that is connected to the secondary
circuit of the ignition coil is not properly inserted on the
spark plug, the area where the terminal touches the
- Spring will generate heat leading to burning and
creating holes. This can cause electrocution, so the
plug cap should be properly inserted in the following
manner. |
o When inserting the cap, do not just push from the
top, but also twist to the right. Twist to the left when
removing.
SECONDARY CIRCUIT CABL
TERMINAL R Е
SPRING
CAP
AREA WHERE
LOCALIZED
HEATING OCCURS
WHEN PRESSED
BY HAND ONLY
INSERTION
CONDITION BAD
INSERTION
CONDITION GOOD
6—7 INSPECTION OF MUFFLER
(1) DISASSEMBLY
1) It is dangerous to disassemble the muifler while,
stili hot. Furthermore, it can damage the screws.
The muffler should be disassembled after the
engine has cooled.
2) Loosen the two pan head screws that fasten the
muffler cover and remove the muffler cover (see
P.12).
3) Loosen the two nuts that fasten the muffler to the
engine using a box wrench.
4)Loosen the pan head screws that fasten the
muffler to the engine using a Phillips screwdriver,
TT
N
5) Move the muffler to the right as shown in the
drawing, and remove from the engine. At this time
take care to avoid carbon entering the cylinder.
IGNITER
(2) CLEANING
1) To clean carbon from the muffler, clean the
cylinder side port and tail pipe.
When a lot of carbon is deposited, clean from both
the tail pipe and entrance of the pipe, using a thick
wire. Carbon can also be burned off using a blow
torch.
- 20 -
2) After removing the muffler, remove the carbon
deposited around the exhaust port area standard
screwdriver, until the aluminum material is
exposed. Take care not to scratch the chrome
plating.
Note:
When removing carbon, take care not to scratch the
piston.
==
Ро
Jil
FEE ET EEE EET TETRIS TERPS PR EFF ETRE EE TI EE TFET ALTER EEE рты
DEEE RE AE AE EEE EE RE LESTER ESTEE EEL ETE ELS SLT ETT TLL TTT ELSES ESTES
6—8 INSPECTION OF CYLINDER,
PISTON AND PISTON RING
(1) CLEANING OF CYLINDER FINS
After removing the muffler from the engine, loosen the
hexagon bolts that attach the cylinder cover and
remove the cylinder cover.
Clean the cooling fins when the cover is removed.
-21-
(3) ASSEMBLY
Assemble | in the reverse order of disassembly.
Note:
. The gasket should be assembled bringing the side
with holes to the bottom, as shown in the diagram.
MUFFLER
GASKET
FF yr rE ry yrreE
LLE ALELLA LLL Ep dd rr PEL Er Err EAR Pr SE TEAR FREE FFP LE FEE Federer
HAE LL TFET ESET EE TALLEST SLES TESTES ETAT EFTPS TPES TFL ASF STARE ASST FLL ESAT
(2) DISASSEMBLY OF CYLINDER
1) Remove the four bolts that attach the cylinder to
the crankcase, using a hexagon rod wrench.
Tap with a plastic hammer on the carburetor side
or muffler side, and remove the cylinder from the
crankcase.
2) Pull the cylinder parallel to the piston. (Take care
not to twist the cylinder as this will damage the
piston ring.)
2) Hold the piston in one hand, and insert the piston
pin puller {option), and tap lightly with a hammer to
draw out the piston pin. Take care to prevent
damage to the connecting rod.
(3) INSPECTION AND CLEANING OF CYLINDER
Remove carbon deposits around the combustion
chamber and exhaust area until the aluminum base
material is, exposed. Take care not to scratch the
chrome plating.
(4) DISASSEMBLY OF PISTON
1) Remove the circiip on both sides of the piston pin.
PISTON PIN
PULLER
3) Remove the piston while taking care not to drop
the needie bearing.
4) Cpen the piston ring slightly and take it off from the
piston. The piston ring may be damaged when itis
opened too wide.
PISTON RING
1
=D
ES
(5) INSPECTION AND CLEANING OF PISTON
- 22 -
(6) INSPECTION AND REPLACEMENT STANDARD
OF PISTON
1) Gap between piston ring and ring groove
Insert a gap gauge between the piston ring and the
ring groove of the piston. When the gap exceeds
the service limit, the piston and piston ring should
be replaced.
>
O)
GAP GAUGE
4) The little-end needle bearing should be replaced
when it is worn or has harmful marks. Also replace
when the hole diameter of the piston exceeds the
service limit.
MICROMETER
PISTON
2) Piston ring gap
Put the piston ring horizontally in the cylinder skirt
(use the piston). Measure the gap using a gap
gauge. When it exceeds the service limit, replace
the piston ring.
GAP GAUGE
PISTON RING
5) Gap between piston and cylinder
Measure the maximum diameter of the piston
using a micrometer. Calculate the difference
between the maximum internal diameter of the
cylinder (called piston gap), and when it exceeds
the service limit, replace the piston. |
3) When there is wear or marks on the outer surface
of the piston pin, replace the piston pin. Also
replace when the measurement exceeds the
service limit.
MEASURING TOOL
MICROMETER
(7) ASSEMBLY OF PISTON
1) Assemble piston onto the connecting rod
I. Position the piston so that the circled mark at the
top of the piston comes to the air suction side.
ii: Do not force the piston pin into place.
iil: If the piston pin circlip is deformed, replace it.
iv: Apply oil to the needle bearing.
Install the piston pin circlip, into the groove using radio
pliers.
2) Install the piston ring into the ring groove.
I: Align the piston ring and knock pin in the ring
groove.
RADIO PLIERS
INSERT SO THAT Í
THE FLANGE IS =
PARALLEL TO ESS ES
THE CRANKSHAFT >,
NL | CRANKSHAFT
1) Attach cylinder packing
o Match to the shape of the case.
2) Attach cylinder
i: Secure the piston to the crank case so that it does
not wobble.
ii. When inserting the piston, make sure that the
flange to attach the carburetor to the cylinder
becomes paraile! to the crankshaft. The cylinder
should not be turned after insertion. If it is turned
by mistake, the piston ring will be caught in the
cylinder port and may break.
li: After tightening the cylinder screws, check that the
crankshaft rotates smoothly.
. 6—9 CRANKCASE, CRANKSHAFT
(1) DISASSEMBLY |
1) Remove the ignition coll and the MTI unit
assembly.
2) Separate the case and remove the crankshaft
assembly,
Note:
When separating the case, take care not to damage
the gasket.
3) Remove the piston from the connecting rod.
Remove the piston pin circlip.
(2) INSPECTION
1) Eccentricity at crankshaft end
Eccentricity is as follows when rotated while
beingsupporting at a—a’. When the service limit is
exceeded, replace the crankshaft assembly.
CONNECTING ROD
CRANKSHAFT
30 gos
*5.5 *5.5
DIAL GAUGE
- 24 -
2) Crankshaft and connecting rod
Side gap
Push the connecting rod to one side. Insert the
gap gauge into the opposite side, measure the gap
at four places and if it exceeds the service limit,
replace the crankshaft assembly.
GAP GAUGE
3) Gap between crank pin and connecting rod
Secure the crankshaft, put the dial gauge against
the small-end of the connecting rod, move the
connecting rod laterally, and if the dial gauge
reading exceeds the service limit, replace the
crankshaft assembly.
DIAL GAUGE
MOVE BY HAND
(ATTACH
(A N SUPPORT SHAFT)
| FIX ON TEST TABLE |
- 25 -
4) Gap between crankshaft and main bearing
Measure the journal area of the crankshaft with a
micrometer, and when the fitting gap between the
main bearing exceeds the service limit, replace the
crankshaft assembly and ball bearing.
(4) ASSEMBLY
1) Insert the crankshaft in the drive side case
o. Apply grease to the oil seal lip.
o Bring the circle mark at the top of the piston to the
air suction side.
o Be careful not to damage the oil seal lip when
inserting the crankshait.
2) Insert the gasket and assemble the crankshaft.
o When the gasket is damaged, replace it.
3) Assemble the ignition coil and MTI unit assembly.
7. TIGHTENING TORQUE TABLE -
(1) ENGINE
Part om nal Qty TL © — Remark
Crankcase attaching element M5 x 30 4 34.7—43.4 (0.4—0.5) | Pan head screws
Cylinder attaching element M5 4 34.7—43.4 (0.4—0.5) | Bolt with hexagon hole
Flywheel attaching element M8 1 69.4— 86.8 (0.8—1.0) Conical SPG nuts
Starter pulley attaching element M10 1 | 164.9—182.3 | (1.9—2.1)
Insulator attaching element M5 x 25 2 21.7—39.1 | (0.25—0.45) | Pan head screws
Carburetor attaching element M5 x 45 2 21.7—39.1 (0.25—0.45) | Pan head screws
Air cleaner attaching element M4 x 20 2 17.4—26.0 (0.2—0.3) | Pan head screws
M6 2 69.4—86.8 (0.8—1.0) | Hexagon nuts with flange
Muffler attaching element
M5 x 12 1 34.7—43.4 {0.4—0.5) | Pan head screws
Recoil starter attaching element M5 x 16 4 34.7—43.4 (0.4—05) ; Pan head screws
Spark plug attaching element M14 1 104.2 (1.2)
Ignition coil attaching element M5 x 20 2 34.7—43.4 (0.4—0.5) | Hexagonal bolts
Cylinder cover attaching element M5 x 12 2 34.7—43.4 (0.4—0.5) | Pan head screws
M4 17.4—26.0 | (0.2-—0.3)
Other attaching element
M5 34.7 —43.4 (0.4—0.5)
(2) MAIN UNIT
Part Nominal Qty Tightening torque | Remark ;
Ib-inch kg-m
Engine attaching element M6 x 30 4 52.1—69.4 (0.6—0.8) | Hexagonal bolts
Rotor attaching element M6 x 25 3 60.8—78.1 (0.7—0.9) | Hexagonal bolts
Rotor case attaching element | M5 x 25 12 34.7—43.4 (0.4—0.5) | Self-tapping screws
Anti-vibration attaching element M6 4 34.7—47.7 | (0.4—055) Spring washer attached
Handle attaching element M5 x 18 4 34.7—47.7 ( 0.4—0.55 ) | Pan head screws
Muffler cover attaching element M5 x 15 2 26.0—34.7 (0.30.4) |[ Pan head screws
Gauge panel attaching element M6 x 14 2 43.4—56.4 (0.5—0.65) | Pan head screws
Gauge panel support attaching element M5 x 14 4 34.7— 43.4 {0.4—0.5) | Self-tapping screws
Fuel tank attaching element MS x 12 2 34.7—43.4 (0.4—0.5) | Pan head screws
- 26 -
8. SERVICING STANDARDS TABLE
Standard value Service limit
Item - - Remark
inch mm inch mm
Internal diameter of eylinder ¢ 1.654%" ($ 42%") onl or
Gap between cylinder and piston
(Gap between maximum diameter of | 0.001—0.003 (0.03—0.07) 0.004 (0.1)
cylinder and external diameter of piston)
Gap between piston and piston pin 0.0004—0.0020 | (0.01—0.005) 0.002 (0.05)
Piston ring gap 0.006—0.014 (0.15—0.35) 0.028 (0.7)
Gap between piston ring and ring groove | 0.001—0.003 (0.03—0.07) 0.006 (0.15)
Gap between big-end of connecting rod
and crank pin 0.0003—0.0008 | (0.007—0.021) 0.002 (0.05)
Gap between small-end of connectin
rod and piston pin 9 0—0.0007 (0—0.019) 0.002 (0.05)
Play in crankshaft in axial direction 0—0.0118 (0—0.3) 0.020 (0.5)
Gap between crankshaft and bearing 0.0001—0.005 | (0.003—0.012) 0.002 (0.05)
Gap between crankshaft and big-end of
connecting rod 0.0063—0.0138 (0.16—0.35) 0.022 (0.55)
Eccentricity at crankshaft end 0.0020 (Lesst han 0.05) 0.002 (0.06)
Spark plug electrode gap 0.0236—0.0276 (0.6-—0.7) 0.031 (0.8)
With repair parts, these shouid be replaced when they
exceed service limits, except for adjustment of spark
plug electrode.
- 27 -
—9. MALFUNCTIONS AND COUNTERMEASURES
(1) ENGINE
Symptom Area to be checked Measures
Is there fuel in the fuel tank? ——— Check and add if required
| Is the gasoline-oil mixture at the (more than 28 monthey > period
[Fuel system] correct ratio(25:1)? should be replaced
Г Is fuel tank cap ventilation blocked? — Check and clean
Is the fuel filter blocked? —~—————— Check and clean
Is the ignition coil in good condition? — Test coil with tester
er not Is the spark plug damaged? — — Check, clean, replace
| Is there any abnormality in the Check, clean, replace
o Does not | primary and secondarycircuits? (check spark plug cap)
Does not start — detonate [Electrical system]
o Detonates Is there no excess sucking of fuel? — Remove spark plug and clean
occasionally
Spark Plug is __1. 1s the gasoline-oil mixture good? Replace a nord re when
Is the air cleaner blocked? ——— Disassemble and clean
_ Is there any gas leak ЩИ .
from the oil seal? Check and replace if lip is defective
— Is the piston ring stuck or worn? Check and replace
; _ Compression__|_ Is there any gas leak Tighten cylinder attaching bolts,
[Compression system] deficiency from cylinder joints? check packing
Is there any gas leak :
from the spark plug? Check and tighten
_ is the gasoline-oil mixture correct ; “qo
(too lean; 25:1)? —— Replace with new gasoline-oil mixture
is the ignition failure due to a
o No power dirty/damaged spark plug? Check and clean
© Detonation sound is is the exhaust area and muffler |
intermittent _
Malfunction during orifice blocked with carbon? Check and clean
operation |
+ ; Is the exhaust area or muffler
oO Engine backfires orifice blocked with carbon? Check and clean
Spark at spark plug -— Is fuel filter blocked? ——- Check and clean
. — 9 Tank contains fuel — Soark ol Malfuncti
“ine stalls whil park plug ~ __ Malfunction o .
ln Speratio о voue does not always fire. electrical system Check electrical parts
o Abnormalsoundirom Malfunction of engine Overhaul and check each part
inside the engine
(2) MAIN UNIT
Symptom Area to be checked Measures
Is the blow head in place? Attach up to bent blow head
Are the blow head and bent pipe worn out? Check, replace
Engine speed does not increase Is there a pressurized air leak from handle and rotor case? — Check, replace
| Is engine adjustment correct? See engine items
Is throttle lever adjustment correct? (See P. )
Is blow head crushed? Check, replace
; Is suction cover blocked? Check, replace
Engine speed over run . .
Is engine adjustment correct? See paragraph on engine
Is throttie lever adjustment correct? (See P. )
- 28 -
For a complete line of Professional Trimmers,
Brushcutters, Hedgetrimmers, Handheld &
Backpack Blowers, Pumps and Sprayers,
contact-
MARUYAMA U. S., INC.
301 — 30 Street NE, Suite 118
Auburn, WA 98002 —.
PO Box 309, Auburn, WA 98071
Phone (253) 735-7368 Fax (253) 735-1416