ROVER—-—SCOTT BONNAR LTD.
LAWN MOWER ENGINE M120X
SERVICE SEMINAR
(21/19/97
SUZUKI MOTOR 'RPORATION
IGNITION SYSTEM
The M120X has a pointless transistorized ignition system.
This 1gnition system does not required the periodic reconditioning of
contact point surfaces or point gap adjustment. A strong spark is
produced, even at low speed, so that maximum reliability can be
ensured.
1. WIRING DIAGRAN
| IGNITOR |]
| UNIT
Le) E Los | | y
| 5 | 4 | SPARK PLUG
ENGINE }
STOP
SWITCH |
777
77
2. OPERATION OF IGNITION SYSTEM
ECONDARY COIL "e
FLYWHEEL (b= | |
MAGNETO is |
\ I | J
| \ SD TRI Sw
ENGINE 4 Y = PRIMARY COIL
STOP | SPARK PLUG | в : %
SWITCH lo À 4 E
| lc |
ca ||
177 777
5)
When the recoil starter grip 1s pulled, the flywheel turns.
As the flywheel turns, a voltage 1s induced within the primary
coll.
Due to this voltage, the base current flows through the transistor
TRl and then turn the transistor on allowing the current Ic to
flow.
As the current Ic increases, the collector-emitter voltage also
increases which then raises the TR2 base voltage. When the TR2
base votage rises to a predetermined level being controled by
R2/R3 ratio, the TR2 is turned on and then the TR1 is turned off.
To stop the engine, the engine stop switch 1s closed for
stopping the current Ic and shutting off the spark.
3. INSTALLATION OF IGNITOR UNIT
When
shou
T (PC
sa 1 a
f | HH
‘ol | О
|| CLEARANCE 0.5mm
installing the ignitor unit, the clearance to the flywheel
ld be set to 0.5 mm.
CARBURETOR SYSTEM
1. SPECIFICATION
TYPE
MAIN JET
MAIN AIR JET
PILOT JET
PILOT AIR JET
PILOT OUTLET
THROTTLE VALVE
BY-PASS
VALVE SEAT
2. FLOAT SYSTEM
MIKUNI BVI8-15
176.3
Pl. 1mm
#35
Dl, Omm
PO. 7mm
#150
#0. 7mm, 0. 7mm
dl. omm
FLOAT
<—— FUEL
“FUEL INLET
VALVE SEAT
NEEDLE VALVE
MOTOS UTRIO jany
MAIN AND PILOT SYSTEM
3.
jor urey
É _
2ATEA 83009
LA
|
PATEA 9131014]
SSEd
LL
yop dry 30114”
aTZZON ULEN |
+9130 10171
Jl. малое 207114
19 1011d
Aly PUR PUNT wae icon
div ------ >
1904 — >
4, TROUBLESHOOTING
Check Sheet on functioning of carburetors for general-purpose engines
[ТПО | = тот Pn ely ——>[_ Fuel leak —_}——p>[Exterior | HEE os
Ш FAA Aintertor } — — [air roue
В > Rise of Fuel Level gress Som — ‘ — — Effects on accidents leading
| Vibration | ——{1 Luoseness o Talfünctionin. Le — — to injury or death
Hear A coming off of parts es = Vehicle running out of control
Drop of Fuel Level | EA о Damage to the engine ……
| _ Effects on accidents
[ Movement ]- —— Y ear |-— — ‘leading to injury or death
__ Г X Moving Parts Hd | ‘
Rust |— ca > Damage > Fuel System f— ——=c- -
р т к
Water — —— ST Rust — i i ÉL
| (droplet) | Jo ts into the | _ |
N inside of engine | | 5 || Poor starting
[ Dust | —— >i ear | — —— The engine doesn't work well
_ a The engine stalls
> Damage — |
High temp. & | & Lo temp, (> Looseness || | 14 у _
>{ Deformation | -t>{ Hal functioning |— CE N 3 ий)
_ — 7 SLicking - | |
Пса! || | |
(high/low temperatures) | Hoh temp. В |
>| Percolation |} > bvaporation —
on temp,
в —3{ Icing and others ]-—— re -— om >
us Mal functioning |--
>| Expansion |} — pe CH - — — >
caer ны ——— Lf Damage |
[Fuel, chemicals | 7 EE = ——>Alr_feak |— a ?
SYSTEM
GOVERNOR
[HONY3A09]
y | | ONILSAP OV _
A [VHS WYO] «(5 INOLMIOA3| | [бмНаб]|
vi a à jue
y JAIYA | dana
3711LL0YHL| |104H1NO9
[ONJINO9 3dAL 1V9NÍHIN39
ENGINE TROUBLESHOOTING
ENGINE DOES NOT START
| CAUSE REMEDY
Fuel tank empty | Fill tank. a
Fuel cock closed Open cock.
Fuel hose obstructed Clean fuel filter and hose,
remove and clean carburetor.
Fuel tank cap vent Remove obstruction.
| obstructed
Gasoline contaminated Clean tank and entire delivery
system.
Overchoked Close fuel cock and pull
starter until engine starts.
Open fuel cock again for normal
fuel flow.
Carburetor adjusted Adjust carburetor.
incorrectly
| Magneto wire shorting Repair, replace or connect
| or disconnected wire.
Flywheel magnets weak Replace flywheel.
Ignition coll assy. Replace coil assy.
defective
Spark plug fouled or damaged | Clean or replace spark plug.
Engine stop switch | Replace stop switch.
malfunction |
| Se Se LL EA читов о Е к = E и 7 FE «вен
Spark plug tightened | Tighten to specified torque or
incorrectly or faulty gasket | replace spark plug.
| Compression leak Replace gasket.
Worn piston, ring or Replace ring and piston,
cvlinder Rebore or replace cylinder.
ENGINE MISSES UNDER LOAD
CAUSE
REMEDY
Spark plug fould or damaged
Spark plug gap improper
Carburetor adjusted
incorrectly
| Clean or replace spark plug.
| Adjust carburetor.
ENGINE LACKS POWER
CAUSE
REMEDY
| Choke partially closed
Carburetor adjusted
incorrectly
Piston rings worn
Air cleaner clogged
Fuel filter clogged
Carburetor jets clogged
Air leaking at carburetor
gasket
| Open choke.
Adjust carburetor.
Replace rings.
Clean air cleaner.
Clean filter element.
Disassemble and clean jets.
Replace gasket.
ENGINE KNOCKS
CAUSE
REMEDY
Carbon deposit in combustion
chamber
Flywheel lcose
Cvlinder worn
Improper spark plug gap
causing slapping noise
Remove carbon.
| Check flywheel key and replace
|1t if necessary. Tighten
flywheel nut to proper torque.
Replace cylinder,
Adjust gap.
ENGINE OVERHEATS
CAUSE
REMEDY
Carburetor adjusted
incorrectly
Cooling air flow obstructed
Cooling fins obstructed
Excessive icad on engine
| Carbon deposit in combustion
chamber
Adjust carburetor.
Remove obstruction.
Clean cooling fins.
| Reduce excessive load.
Remove carbon.
ENGINE SURGES OR RUNS UNEVENLY
CAUSE
REMEDY
Fuel tank cap vent
obstructed
\ Governor parts sticking or
binding
Carburetor throttle linkage
sticking or binding
Intermittent spark
Carburetor adjusted
incorrectly
Dirt in carburetor
Fuel filter clogged
Air leaking at carburetor
gasket
| Clean,
Remove obstruction.
Clean, and if necessary repair
| governor part.
| lubricate or adjust
Lincage.
Repair or replace coil assy.
Adjust carburetor,
Clean carburetor.
| Clean filter element.
Replace gasket.
ENGINE VIBRATES EXCESSIVELY
CAUSE
REMEDY
| Engine not securely mounted | Tighten mounting bolts.
Crankshaft bent
Replace crankshaft.
Associated equipment out of | Check associated equipment.
| balance
ENGINE USES EXCESSIVE AMOUNT OF OIL
CAUSE
REMEDY
| Engine speed too fast
Cylinder wall worn or
glazed
Piston rings and grooves
worn excessively
Piston Worn
Adjust engine rpm to spec,
Bore hole, or deglaze as
necessary.
| Replace piston and rings.
Measure and replace as
necessary.
- 10 -
">
