Morini Franco Motori S6-C COMPETITION User manual

SERVICE MANUAL
S6-C COMPETITION
50cc – 2 stroke - liquid cooled

Page 1
S6 /C
ENGINE
INDEX
TECHNICAL SPECIFICATIONS 2
SPECIAL TOOLS 3 - 4
PERIODIC MAINTENANCE 5
LUBRICANTS 6
TROUBLESHOOTING 7 - 14
TIGHTENING TORQUE TABLE 15
ENGINE DISASSEMBLY 16 - 24
ENGINE REASSEMBLY 25 - 37
SPECIAL 3-SHOE CLUTCH DISASSEMBLY/REASSEMBLY 38 - 39
SPECIAL 3-SHOE CLUTCH ADJUSTMENT PROCEDURE 40
ENGINE COMPONENT INSPECTION AND SERVICE 41 - 43
GENERAL PARTS LIST + EXPLODED VIEW TABLES xx

Page 2
S6 /C
ENGINE
SPECIFICATIONS
CYCLE ......................................................... -2stroke
Nr. of CYLINDERS....................................... -1
DISPLACEMENT.......................................... -49.908cc.
BORE AND STROKE mm............. - 39 X 41.8
CYLINDER MATERIAL ................................. - AluminiumwithNi/Sicarbidecoating
COMPRESSION RATIO................................ -(15.5±0.3):1
SPARK PLUG .............................................. -CHAMPIONC53
TIMINGSYSTEM .......................................... -Reed valve with 4 carbon fibre flaps
MAX.R.P.M. .................................................. - 14500 (rpm) MAX
CARBURETOR ............................................ -12/14/19mmdiameter
INTAKE MANIFOLD ..................................... - Adjustable
FUEL............................................................ -EURO UNLEADED NC 623/02 - R.O.N. 95
LUBRICATION OIL MIXER TYPE ................. -2% AGIP2TCITY
LUBRICATION WITH OIL PUMP .................. -On request
IGNITION ...................................................... -Electronicwithmicrochip
PRIMARY DRIVE GEAR ............................... -Straight-toothgearsZ14/59
..................................................................... withsafetycoupling
..................................................................... Ratio1:4,21
SECONDARY DRIVE GEAR......................... - Sprocket Z 10 or Z11
..................................................................... Chaintype 1/2x3/16roller 7.75
CLUTCH ...................................................... -Automaticcentrifugalclutchinoilbath
..................................................................... Adjustable
TRANSMISSION GEAR OIL ......................... -SAE20W quantity250 cc
STARTER...................................................... - Kickstarter
COOLING ...................................................... -With liquid pump
TECNICALSPECIFICATIONS

Page 3
S6 /C
ENGINE
143154
143176
143156
143179
143180
143181
CodeFigure Description
SPECIAL TOOLS
BEARINGINSTALLER
output shaft
BEARINGINSTALLER
crankshaft
BEARINGINSTALLER
output shaft
OILSEAL INSTALLER
output shaft
OILSEAL INSTALLER
crankshaft (flywheel + clutch)
OILSEAL MOUNTING PROTECTION
crankshaft (flywheel + clutch)

Page 4
S6 /C
ENGINE
140558
143162
143155
SPECIAL TOOLS
CodeFigure Description
OIL PUMP SHAFT INSTALLER
(pre-assembled)
FLYWHEEL REMOVER
CRANKCASE PULLER
143294 SPECIAL CLUTCHADJUSTMENTTOOL

Page 5
S6 /C
ENGINE
PERIODICMAINTENANCE
RUNNING-IN RECOMMENDATIONS:
During the running-in period, i.e.forapprox.the first 500 km on theroad,please note as follows:
-Do neverrunthe engineatmaximum revolutions.
-Do never keep thevehicleatmaximum speed.
-Do not keep the engine at idle speed forlonger time.
FIRST MAINTENANCE SERVICE:
to be carried out after 500 - 600 km.
-Replacetheengineoil
-Check the carburation and adjustifnecessary
-Check thetightnessof nutsandbolts.
(Seetable“tighteningtorques”pag.15)

Page 6
S6 /C
ENGINE
LUBRICANTS
N.B.
Use original MORINI FRANCO MOTORI spare parts only
N.B. TRANSMISSION OIL LEVEL CHECK
Remove the oil filler cap on the clutch cover and check the transmission oil level
through window.
RECOMMENDED LUBRICANTS / ADHESIVES
DESCRIPTION CHARACTERISTICS
Transmission oil AGIP RADULA 68 SAE 20W
Assembly of various parts GR/SM2 GREASE
Special assembly GRAPHITISED MOLYCOTE type GREASE
Thread-locking glue LOXEAL 82-21
Clamping glue LOXEAL 83-54

Page 7
S6 /C
ENGINE
TROUBLESHOOTING
Possible CAUSE of the fault
The following flow charts give a general outline of the causes and effects when the engine is not
running correctly.
Descriptions of solutions for a specific cause are general; for more details the reader should
consult the disassembly-reassembly manual.
LEGEND OF SYMBOLS
EFFECT (fault noticed by the user)
Possible general SOLUTION to the fault

Page 8
S6 /C
ENGINE
YES
NO
NO
Starting problems
Faulty spark plug
orwrongsparkplug
heatrating
YES Check spark plug and
replace if necessary.
Engineflooded YES Start the engine with the
throttle fully open.
Removethe spark plug,
revthe engine,installa
dryspark plug and restart
theengine.
The engine
starts
Sparking starts at
highr.p.m. Replace the ignition coil
NO

Page 9
S6 /C
ENGINE
YES
YES
YES
NO
NO
YES
NO
Maximum indicated running
speed cannot be reached
Soiled or
clogged
filter
Disassemble,wash sponge with a
50% solution of petrol and 2T oil;
leave to dry. Clean the filter box
using compressed air; re-
assemble.
Silencer
obstructed Checkthe silencer forclogging.
Replaceif necessary.
Cylinder
exhaustport
soiled with
carbon
deposits
Disassemble the cylinder and check
that the exhaust pipe is clean. If the
exhaust pipe is partly obstructed by
carbon deposits, clean it thoroughly
usingascraper.
Poor
compression
Disassemble the cylinder head,
cylinderandpiston.
Remove the piston rings, place
theminthecylinderlinerandcheck
theamountofwear.
Replaceifexcessivelyworn.

Page 10
S6 /C
ENGINE
YES
YES
NO
Poor acceleration / pickup
Clutch
Irregular
acceleration
Check the cluth shoe thickness and
the clutch springs for stretching.
If excessively worn they should be
replaced.
Checkthe exactnumberof turns
of the air adjusting screw on the
carburetor.

Page 11
S6 /C
ENGINE
YES
YES
YES
YES
NO
NO
YES
YES
Incorrect idling speed
Idlingspeed
too high or
too low
Adjustthe RPM of the idling speed
(withenginewarm)byadjustingthe
screw on the throttle valve of the
carburetor.
Disassemble the carburetor and
cleanallparts(nozzles,throttleval-
ve, jet needle, float chamber and
body)withsolventanddrybyusing
compressedair.
False air
intakefrom
carburetor
manifold
Checkthe integrity ofthe
carburetormanifold gaskets.
Check the integrity of the rubber
couplingsleeve that connects the
carburetorandairfilterbox.
Checkthe reed valve gasket.
False air
intake
fromengine
crankshaft
oil seals
Checkthe integrity ofthe
crankshaftoil seals. Replace
evenif onlyslightlydamaged.

Page 12
S6 /C
ENGINE
YES
YES
NO
NO
YES
Noisy engine
Incorrect
transmission
gears
assembly
Loose
transmission
nut
Transmission
noiseandrear
wheeldrag at
idlingspeed.
Checktheassemblyofallgearsand
partsof thetransmission.
Checkthe tightening torque of the
clutchnut.
Checktheclutchunit

Page 13
S6 /C
ENGINE
YES
YES
YES
YES
NO
NO
Noisy engine
Noisy gears
Checkthe oil level.
Refillif necessary.
Checkthe teeth of the drive gears
visually.
Replace if signs of damage or
wearare evident.
Noisy
cylinder
unit
Checkthe clearance betweenthe
piston and the cylinder. If it does
not correspond to the prescribed
value, replace the cylinder and
piston.
Noisy
crankshaft
bearings
BEARINGINSPECTION
Rotatethebearinginnerracebyfin-
gertoinspectforabnormalplay,noise
and smooth rotation while the
bearings are mounted in the
crankcase.
Replace the bearing if anything
unusualisfound.

Page 14
S6 /C
ENGINE
YES
YES
YES
NO
NO
YES
NO
Smokey exhaust
Percentageof
mixer oil Replacethe fuel in the tank with
newfuelmixedwith2%ofthetype
ofoil indicated in the handbook.
Mixer oil Checkthat the oil is 100%
syntheticfor separate oilmixer
pumpuse.
Carbon
deposits
Disassemble the cylinder and
remove any carbon deposits;
checkthesilencerforclogging.
Oilmixer
pump Disassemble the oil mixer pump
andchecktheflowrate.

Page 15
S6 /C
ENGINE
TIGHTENINGTORQUES
DENOMINATION TORQUE
(Nm)
Cranckcase bolts 10 - 12
Clutch cover bolts 10 - 12
Flywheel cover bolts 3 - 4
Carburetor manifold bolts 9 -10
Stator clamping bolts 3 - 4
Oil pump clamping bolts 5 - 6
Carburetor clamping screw 3 - 4
Kick starter lever bolt 8 - 10
Oil drain plug 8 - 10
Clutch nut 50 - 55
+ Loxeal 83-54
Flywheel nut 8 -10
+ Loxeal 83-54
Head nuts 12 - 14
Head clamping bolts 10 - 12
Pulley clamping bolts 3 - 4
+ Loxeal 83-54
Water pump rotor 5 - 6 + Loxeal 83-54
Spark plug 20 - 25

S6 / C
Page 16
ENGINE
ENGINE DISASSEMBLY
CARBURETOR UNIT
TOOL
CODE
DIAGRAM DESCRIPTION NOTES
DisassembletheCARBURETOR
Loosen the SCREWS andremovethe
CARBURETORMANIFOLD
Removethe CARBURETOR
MANIFOLD BASE including the
REEDVALVE
BEFORELOOSEN
THESCREWS
CHECKACTUAL
MANIFOLDANGLE
POSITION
THE MANIFOLD IS
COMPOSEDBY4
ELEMENTS.

S6 / C
Page 17
ENGINE
CYLINDER HEAD - CYLINDER - PISTON
Removethe SPARKPLUG
Removethe4 CYLINDERHEAD
BOLTS
Removethe 4CYLINDERHEAD
NUTS
Removethe CYLINDER HEAD PAYATTENTION TO
THE DOWEL PINS
TOOL
CODE
DIAGRAM DESCRIPTION NOTES
Check the condition of the O-RING
(HEAD GASKET).
Replace if excessively worn.

S6 / C
Page 18
ENGINE
Disassemblethe CYLINDER and
removetheCYLINDERBASE
GASKET
TOOL
CODE
DIAGRAM DESCRIPTION NOTES