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Motobécane Moby moped — repair and wiring diagrams Service manual
Service manual for Motobécane Moby moped — repair and wiring diagrams. 90 pages in English. Read the original PDF, download or print a copy without registration.
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- Brand
- Motobécane
- Model / document
- Motobécane Moby moped — repair and wiring diagrams
- Document type
- Service manual
- Language
- English
- Pages
- 90
- File size
- 4.8 MB
- Category
- Vehicles & accessories
- Document date
- Not specified in catalog
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Page 4 · Read text
TABLE OF CONTENTS
DESIGNATION PAGES
' r S \
TechnicalSpecifications 1
TooIs (specia'l service) \ 2-6
Use of the Stroke Limiter ' 7 \ei.R:r(EngineRemoval C " \ B'9
- l \Refitting the Engineon the Frame L0,1.L
Disassemblingthe Engine L2,L3 \t €-Piston Cylinder Matching L4
Examinationof the Cylinder Headand Cyli nder 1.5, L6
Reassemblingthe Engine t7 ,L7,19,20,21,22
Decarbonizingthe Engine 23
Removjng-Decarboni zing-Refitti ng the Exhaust 24,25
Testing Ignition Timing 26,27
Removinqand Refitting the FlywheelMaqneto 28,29
Adjustingthe Ignition Points and Ignition Timing 30,31
Removingand Refitting the Carburetor 32,33
Disassemblyand Reassemblyof Carburetor 34,35
Descriptionand 0peration of the MOBYMATICVariator 36
Variator (componentsparts) 37
Remov'ingthe Variator 38,39
Disassemblyand Reassemblyof Variator 40,41,42
Adjustingand Refittjnq the Variator 43,44
Removing-Refitting-Disassembli ng-Reassemb'linq the Clutch 45,46
Removingand Refitting Driven Pulley 47,48
Removingand Refitting the Crankgear,ReplacingCrankgear
Bushings 49,50
Rep'lacing UpperEngine Mounting Fl exi bl e Bushinss 51,52,53
ReplacinqCables 54,55
Replacingthe Frame 56,57,58
Removingthe Main Fork Assembly 59,60
Refitting the Main Fork Assembly,Removinqand Refitting
the Fork Complete 61
ReplacingFork Bushingsand Springs 62
Removingthe Handlebars 63
Removingthe Steering Head 64
Refitting the SteeringHead 65
Removing-andRefitting the Front and Rearl.lheels 66
Rep'lacingthe BrakeShoes 6B
Removjnqthe CenterStand, the Saddle, Replacinqthe
PedalChainand the EngineDrive Chain 69,70
Replac'ingthe Front h|heelAdjustmentCones,Cups,and ' Bolts 77,72
Rep'lac'ingRear WheelBalI Bearings 73,74
CheckWheelA'li gnment 75
Removingand Refitting the Front and Rear Fenders 76,77
Removingand Refittinq the ShockAbsorbersand the
Swing Arm 78,79
TroubleShootingGuide 80,81.,82,83,84
l,liring Diagram6 Volt B5
l{i ri ng Diagram12 Volt B6View original page 4Page 11 · Read text
USE OF THE STROKELIMITER
IMPORTANT
For all types of enginesto be serviced, the use of the stroke
limiter, No. 100004,js required in most disassemblyand reas-
sembling operations.
This tool is designedto lock crankshaftrevolution at mid-stroke
and offers the advantageof leaving both handsfree to perform
the operationsrequired.
DONOTUSETHE STROKELIMITER ON ENGINESFITTEDt',ITHFLAT-TOPPED
PISTONS.
After havingscrewedthe ljmiter into the whole threadedlength
of the spark plug hole, bring the piston to rest against it
gently.
www.butkus.org/information R07View original page 11Page 12 · Read text
ENGI NE REMOVAL
Removeboth side covers (screwdriver).
Disconnectthe suppressorcap.
Free the decompressorcable nipple using a screwdriver(fig. 1) and
disconnectthe cable.
Loosenthe nut securing the carburetor clamp (Bmmsocket) and remove
the carburetor.
Disconnectthe wires at the terminals behind the flywheel magneto
stator plate and slide themout of the guide sprino.
Disconnectthe grey wire at the ignition coil and slide it out ' of the support bracket in the frame.
Removethe belt from the pu'lley grooveand pass it in front of the pedal (fig. 2).
Fis. I Fig.2
ROBView original page 12Page 13 · Read text
ENGI NE REMOVAL
CONT'D,
Loosenthe lower enginemountingnut and wi thdraw the bol t ( tOrnmopen
wrenchand socket).
Loosenthe self-locking nut of the upperengine mount ( 13nrmwrench) .
Drive out the upperenginemountingaxle only as far as the first
spacer (fig. 3).
Beforeremovingthe engine, carefullynotethe locations of the upper
enginemountspacers.
Tilt the engineand removeit (fig. 4).
Fig. 3
Fis. 4
www.butkus.org/information R09View original page 13Page 14 · Read text
REFI TT I NG THE ENGI NE ON THE FRAME
Inspect the upperenginemountingflexible bushingsand insulation ring
for goodcondition (fig. 1).
Fit the enginethroughuppermountingbolt (operateas for removal).
Checkthat spacersare correctly lined up and makesure to insert the
eye ring of the groundlead betweenthe spacerand cylinder head
(R.H., fig z).
Tighten but do not lock upperenginernountingnut.
Insert the screw into the lower engine mountingbrackets and into the
spacerwhich js fit in with the tension springs (fig. 3).
Fis.1
-
Fig. 3
R0 10View original page 14Page 15 · Read text
REFITTINGTHE ENGINEON THE FRAME
coNT'D,
Tighten and lock lower enginennuntingnut (10nmwrench).
Refit the carburetorall the way onto the inlet pipe and lock-the
carburetor securing clampnut (8rm socket).
Reconnectthe decompressorcable (screwdriver).
Reconnectthe wires to the spadeconnectionsbehind the flywheel mag-
neto stator p'late (pass themthrouqhthe guide spring, if bquipped)-
(fig. 4).
Slide the grey wire through the support bracket on the frame and re-
connectit to the ignition coil (straight femaleterminal).
Lock the upperenginemountingnut (while holding the other end of
the bolt 12mmwrench)after having installed the belt (fig. 5).
NOTE:Makecertain to lock upperenginemountingnut after having in-
stalled the belt. Thenthe engineis in a mediumswingincpositton,
whichwill preventthe flexible bushingsfrom sustainingdamage.
Refit the suppressor.
Refit both side covers.
Fig. 5 Fig. +
R0 11 www.butkus.org/informationView original page 15Page 16 · Read text
D I SASSEMBLI NG THE ENGI NE
Engine removed.
Removethe exhaust usinq 10mmand 1lmmsockets to loosen exhaust clamp
and a 32mmopen wrench to loosen the nut connecting the exhaust to the
cyl i nder.
Set the engine jn a vice by inserting a spacer betweenthe lower enqine
mount plates so that the assemblymay be firmly clamped(fjg.2).
Removebelt cover usinq a screwdriver for variator engines or a LOmm
socket for Dimobyclutch eng'ines.
Removethe flywheel magneto (See page 28).
Removethe variator or the clutch assemblyaccording to the type of
machjneserviced (See pages 38 and 43).
Progressive'lyloosenthe cy1inder head nuts at opposite corners.
Removethe cylinder head and the qasket (tOmmsocket).
Removethe cyljnder and cylinder base gasket.
N0TE: After Ju1y, 1975, our eng.inesare f j tted wi th pi stons havinq LEVELLED
UP RINGSWHICHCOVERTHEL0CATINGPINS (fig. 1).
l^Jithdrawthe piston rings.
'ips Stuff a rag into the crankcasemouth and removethe wrist pin c'l using
flat nose p1iers (fig. 2).
Dri ve out the p.iston p j n usi ng the pi n extractor tool , 100025, (f j g. 3) .
Digitally signed by mike
butkus
DN: cn=mike butkus, mike o=orphancameras,
ou=29,
email=mike@butkus.org,
c=US butkus Date: 2018.03.02 16:02:07
-05'00'
New-sty1e 0l d-style
P.is ton Piston Fjg. 3 Fig. 1
! {
I k
Fi g.RO12View original page 16Page 17 · Read text
DISASSEMBLINGTHE ENGINE
CONT'0,
Withdrawthe needlecage from the con-rod small end.
Loosenall crankcaseretaining nuts.
Removethe crankcasefrom the vice.
Removethe crankcaseretaining bolts and lower enginemountinqstuds
(note uhe position of the studs and of the bracket for the belt guard).
To prevent the crankshaftjournal from overheating,insert the blade,
100015,on it. Repeatthe operationfor the other iournal.
Heat with a propanetorch the crankcasehalf facing the clutch side
aroundthe outside of the crankshaftbearing (beginwith this side be-
causeit js then easy to separatecrankcaseshells) (fig.4).
The crankcasehalf will drop awayon its own (fig. 4).
Repeatthe operationfor the other crankcasehalf (fig. 4).
While the crankcasehalvesare hot, removethe oil seals with a screw-
driver tapping from the outside to the inside of the crankcasehalf.
Extract the crankshaftbearingsusing the crankshaftbearinqpu11er,
100011(fig. 5).
Note the arrangementof shimsbehindthe crankshaftsupportbearinq if
the crankshaftis so fitted.
Fig. 5 N Fig. 4
www.butkus.org/information R0 13View original page 17Page 19 · Read text
EXAMI NATI ON OF THE CYLI NDER HEAD AND CYLI NDER
Examinatjonof the Cylinder Head:
Checkthat the cylinder headbottombaseis flat (qrina it with a sun-
face plate if necessary).
Refit the spark plug and checkthe decompressorvalve for leakageby
pouringfuel in the combustionchamber(fjg. 1).
Exceptin case of absolutenecessity, the decompressorvalve shouldnot
be removedfrom the cyl inder headassembly.
In case of leakageand if the valve is not worn out, tap the valve head
gently to seat.
Examinationof the Cylinder:
Makesure that the cylinder wall is neither scuffed not scored (lack of
chromiumplated surface).
Measurethe p'iston cl earance(d'ifferencebetweenthe minimumcyl i nder
bore and the maximumpiston diameter),the piston rins end gap (fig . 2)
and the clearancebetweenring and groove.
o
Fis. 1
Fig.2
www.butkus.org/information R0 15View original page 19Page 20 · Read text
EXAMINATION OF TI{E CYLINDERHEADAND CYLINDER
CONT,D .
If insta'lling a new piston, refer to the match'inglist on page 14.
CLEARANCESIN MM STANDARD MAXI MUM
Piston Clearance
(skirt) 0.005 to 0.010 0.050
toP ring Ring end gap + o.10 0.40 secondring 3:13
Ring groove top ring 0.03 to 0.060 0. 15 Side gap secondring
Fit the small end needle cage and insert the wrist pin in it (fiq. 3).
The pin should turn freely without vertical play.
Fis.3
R0 16View original page 20Page 21 · Read text
REASSEMBLINGTHE ENGINE
v NEVERINSTALLUSEDGASKETS;ALWAYSUSENE|r|ONES.
- llhenfitting a newenglnecrankcaseor a newcrankshaft,the side play
shouldbe adjusted.
SIDEPLAYADJUSTMENT:
To effect this operationryou needtwo dunmybearingsthat you can make
yourself.
Useemerycloth on the inner and outer racesof two newbearings(diam.
LGX 42 X 13 - No. 16906)until the bearingscan rotate freely on the
crankshaftjournals and the crankcaseshell housings. This operation
mustbe donewithout crankcaseseals:
- Place the dumy bearingson the crankshaft taperedends.
- PlaCethis assemblyinto the crankcase.
- Fit the crankcasepapergasket.
'N0TE: FromJanuary1, 1976,the papergasketsealing the crankcasehalves
has beensubstitutedby a special sealing compound.Nevertheless,when
servicing an engine,we recbnrnendcleaningthbroughlythe matingiurfaces
andfitting a papergasket.
L,v - Place this assemblyin a vice (over lower 'lugs and crankcaseupper screws).
- Rough'lyassessthe existing side play with a depth caliper gauge.
- Disjoint crankcasehalves and place washersbetweenthe two crankshaft
balanceweights and bearings in order to balancethe con-rod betweenthe
shells'
'IDE pLAy = I/roMM
www.butkus.org/information ROL7View original page 21Page 22 · Read text
REASSEMBLINGTHE ENGINE
CONT'D.
CRANKSHAFTFINALASSEMBLY:
Insert a steel blade (length I20 X 30 X 7mm No. 100005)between
crankshaftbalanceweights (fig. 1).
Install the assembly(without squeezing)jn the jaws of a vice opened
at approximately75mm(fiS. 1).
Install the bearingon crankshaftjournal.
N0TETHEDIRECTI0Nin which the bearingsare facing. The roundedchamfered
sjde must face the crankshaftbalanceweight (fig.2).
Drive the bearing homeagainst the counterweightwith a tube (diam.
18 X 22 X L50mm No. 100014,f i g. 1.) .
Proceedlikewise for the other crankshaftend.
Fig.2
Fig. 1
RO18View original page 22Page 23 · Read text
REASSEMBLINGTHE ENGINE
CONT,D ,
REASSEMBLINGTHECRANKCASE:
0il the crankshafttaperedends, the bearirgS, and the bearingcages.
Heat moderatelythe shell (facing the f'lywheelmagneto)aroundthe
bearinghousinguntiI smokeappears.
Fit a newoil seal with the crankcaseseal fitting tool , No. 10001.0,
fig. 3.
N0TE: Seals must be fitted with the spring and lips facing outwards.
Very quickly fit the crankshaftassembly(flywheel masnetoside) in
the crankcasehalf; the bearingwill locate itself correctly.
Fit the oiled papergasketto the crankcasehalf (see N0TEon page 17).
Repeatthe operation for the other crankcasehalf.
Tighten but do not lock the two upper screwsafter havinq mountedthe
lug for securingthe belt cover (variator engines)(fig. 4).
Clamp(modenately)tfre enginein a vice over the crankcaselower bosses.
Makesure the cylinder-crankcasemating surfaces are completelyfree
from distortion; if necessary,tap on the upperpart of a stud (assem-
b'ling cyljnder and cylinder head)with a mallet.
Trim the papergasketwith a scraper.
NOTE: As far as variator enginesare concerned,w€ recommendthe positioning
of the belt cover uppermountinglug before locking the crankcasehalf upper
mountingscrew. The top of this mountinglug will rest against the cylinder's
lowest radjation fins (fig. 4).
Fig. 4
Fig. 3
R0 19
www.butkus.org/informationView original page 23Page 24 · Read text
REASSEMBLINGTHE ENGINE
CONT,D ,
Lock the two uppermountingscrews.
Fit the lower enginemountingbracketsand the dual lug securingthe
belt cover (variator engines).
Fit and lock the crankcasemountingnuts (nuts on flywheel magneto
side) with a 10mmwrench.
Place a spacerbetweenthe lower enginemountingbrackets to hold the
enginefirmly in the vice (fig. 5).
Rotatethe crankshaft. If it doesnot retate freely, slightly tap on
the crankcaseshell (clutch side and variator side) with an aluminum
mallet to position the bearing.
REASSEMBLINGTHEPISTON:
Smearthe needlecagewith oil and insert it in con-rodsmall end.
Position the p'iston over the con-rod in such a way that the ring groove
pegs face the exhaustport.
Insert the dummywrist pin which comeswith Tool No. 100008to allign
the assembly(rig. 6).
'F'ig. 6
F,ig. 5
R0 20View original page 24Page 25 · Read text
REASSEMBLINGTHE ENGINE
CONT,D.
Fit the replacementwrist pin using piston pin assemblerNo. 100008.
Heat (moderate'ly)tne pi ston dome(torch) untj I smokeappears. (This
is not necessaryfor a newwrist pin that is an easy sliding fit.)
Insert the assemblertip into the wrist pin (fig . 7).
Pushhomewhile pressingagainst the oppositesjde of the piston to
preventunnecessarypressureon the big-endbearing. The assembler
stop will comect'lyposition the pin in the piston (fig. 7)
Place the cyljnder on the heatedpiston without the rings or piston
pin clips jnstalled. The cylinder wjll slide downas the temperature
evensout. This operationpreventspiston distortion while cooling
(fig. B).
Whenthe piston/cylinderassemblyhas cooledoff, checkcon-rodalign-
ment.
CHECKINGRODALIGNMENT:
Securethe cy'linder with two washersand two opposite cylinder head
nuts. Bring the piston to T.D.C.
Slide in a tapered0.07mmfeeler gaugebetweenthe piston (at pin
holes) and cylinder.
If the gaugeslides freely throughone side and not throughthe other,
the rod provesto be out of a'lignment. Removethe cy1inder and pro-
ceedwith straightening.
Fig. 7
Fig. B
R0 2t
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REASSEMBLINGTHE ENGINE
CONT,D .
STRAIGHTENINGCONNECTINGROD:
Clampthe crankcasein the vice and insert a bar throughpiston pin as
shownin figure 9.
To straighten the rod, apply force to the bar.
Checkrod alignmentand straighten again until the piston is comectly
centeredin the cylinder.
Fit newwrist pjn lock rings using flat nosepliers.
Smearthe piston rings with oil and fit themon the piston.
REASSEMBLINGCYLINDERCYLINDERHEAD:
Bring the piston to T.D.C. and makecertain that the piston rings seat
firmly jn grooves.
Fit the oiled gasketon the baseof the cylinder.
Place the cylinder on the mountingstuds, smeartheborewith oil and
lower gently.
Fit the newcylinder headgasket.
Fit the cylinder headmakingsure its bottombase is perfectly clean.
Fit washerson the studs and tighten progress'ive1ythe nuts at opposite
cornersto 9 ft. lbs.
Install the variator or clutch (Seepage43).
Fjg. 9
R0 2?View original page 26Page 27 · Read text
DECARBONIZINGTHE ENGINE
Removethe exhaust (See page 24).
Removeleft and right handcovers. I
Removethe suppressorc3p.
Disconnectthe decompressorcable using a screwdriver.
Loosenbut do not removecylinder headnuts.
Loosenthe upperenginemountingnut.
Drive out the upper enginemountingaxle as far as the first spaceronly.
Tilt the engine and removeit from the axle.
Disconnectthe wires at the terminals behind the flywheel magnetostator
plate and slide themthroughthe guide spring.
- Place a block under the engine to prevent the lower mountingflexible bush-
ing from being damaged.
Removethe cylinder head nuts using a l0nrmsocket,
Removethe cylinder headand the gasket.
NEVERUSEHARDENEDTOOLSTHATWILL SCRATCH
ORNICKTHECOMBUSTIONCHAMBERANDPISTON
DOME.
Bring piston to T.D.C.
Scrapethe carbon deposits from the ex-
haust port (fig. l.).
A'lwaysfit a newcylinder, head, and ex-
haust gasket.
REASSEMBLINGANDREINSTALLINGTHEENGINE:
Seepages8, 9, 15, 16, 22.
Fig. 1
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REMOVING, DECARBONIZING, REFITTING THE EXHAUST
REM0VINGTHEEXHAUSTPIPE(Blunderbusstype Fig.'1) I
Loosenthe nut (tOmmand llnm wrenches)and removethe exhaust clamp
nut, but do not removethe spacerbetweenthe enginemountings(fig. 2).
Loosenthe nut (32nrmwrench)threaded into the cyl'inder and removethe
exhaustcompletely(fig. 3).
DECARBONIZING:
Loosenthe locknut and the nut securingthe exhausttail cap.
Removethe baffle plate and the tail cap.
Cleanout the holes in the inner baffle plate and tail pipes (fig.4).
Scrapeout the exhaustpipe entry.
II
L - - . - . - F
I
i
@ i
Fig. 1
Fig.2
Fig. 3
R0 24View original page 28Page 29 · Read text
REMOVING,DECARBONIZING,REFITTINGTHE EXHAUST
CONT'D,
REM0VINGTHEEXHAUSTPIPE (Oval type with crossedchambers,Fig. 5)
Removethe two bolts on the exhaust clamp using a 10nrnsocketo
Loosenthe nut connectingthe exhaust to the cyl inder (32nmwrench)and
removethe exhaustcompletely.
DECARBONIZING:
Loosenthe nut on the clampsecurinq the muffler to the pipe (10mmwrench).
Removethe muffler.
Insert a triangularr scraper through the hole and scrapeaIl carbondeposits
from aroundthe edgesas shownin figure 6.
I nsert a steel cable (di am. 7mm l ength: 250nrm)i nto the tai I pi pe and
clean it out.
- LastJy, shakethe exhaustvertically to removedeposits from the entry
hole
REFITTING:
Reversethe procedureand fit a new sealing washerin the exhaustport of
\-, the cyl inder.
.Insert a steel
cable (diam. 7mm)
into the tail pipe.
Scrapeal I carbon depositswith
a scraper.
Fis. 6
Fis. 5
www.butkus.org/information R0 25View original page 29Page 30 · Read text
TESTIIIGIGNITION TIMING
(w r rHour REMovr NGTHEnoron)
Removeright handside cover.
Disconnectthe grey wire from the ignition coil (fig. 1).
Attach one probe from the ohmmeter to the grey wire (fig. 4)
Attach the other ohmmeter lead to a groundpoint. (Example: Cylinder
head) (fig.4)
Disconnectthe bl ack wi re (l i qhti ng system)f rom the strai grht female
6. 35mmterminal at the stator p1ate.
Removethe radio suppressorand spark plug.
1. Screwif, the timing tool (No. 100013)in place of spark plug (fig. 2).
2. Bring piston to T.D.Cby rotating the rotor in the nonnalrunningdi-
recti on.
Fig. 1
NOTE: l^lhentesting and resetting the
ignition timing on the machine
w.ith a 12 volt lighting system
(manufacturedafter JanuaryL,
1978), a timing liSht tester,
Part No. 100031,must be used.
An ohmmeterwill not register
an accuratereading.
Fig.2
R0 26View original page 30From the M. Butkus archive. Original publisher and archive notices are retained.
Check the model and edition against your equipment.
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