Motobecane Engine Parts

Identification

Parts that are different for each version are listed here.
10 versions have 10 quantity columns. The quantity is 
0 if the part is never on that version.
1 if the part is always on that version.
1 if the part is sometimes on that version.

  E N G I N E   V E R S I O N S
01010 12345 67890   Engines ’74-75 6 volt
52341 00010 00000 engine #4 variator 25 mph
01010 12345 67890   
Engines ’76-77 6 volt       

53444 10000 00000 engine #1 Dimoby 20 mph
53949 01000 00000 engine #2 Dimoby 25 mph
53744 00100 00000 engine #3 Dimoby 30 mph
52341 00010 00000 engine #4 variator 25 mph
53745 00001 00000 engine #5 variator 30 mph
01010 12345 67890   Engines ’78-80 12 volt   
54146 00000 10000 engine #6 Dimoby 20 mph
54147 00000 01000 engine #7 Dimoby 25 mph
54149 00000 00100 engine #8 Dimoby 30 mph
54148 00000 00010 engine #9 variator 25 mph
54844 00000 00001 engine #0 variator 30 mph
01010 12345 67890    Cylinders     
22335 00100 00000 cyl. says 581051, FB2 47
23460 00001 01111 cyl. says 682051, most say nothing
53505 10000 10000 cyl. says 681051, TUM207
54328 01010 00000 cyl.   S25682051, TUM207
01010 12345 67890   Exhausts     
21103 11100 00000 exhaust  
22872 11111 11111 exhaust

01010 12345 67890   Intakes   
16673 00010 00010 intake center ∅16 x 10
16619 00001 00000 intake center ∅17 x 12

21201 01100 01100 intake side    ∅19 x 12
22899 00001 00001 intake side    ∅19 x 13?
53496 10000 10000 intake side    ∅19 x 10
01010 12345 67890   Intake Gaskets   
52646 10000 10000 intake gasket round hole
17073 01111 01111 intake gasket rectangle hole

01010 12345 67890   Carburetors 
20026 00001 00000 carb AR2-12-705 center ∅17
22160 01100 00000 carb AR2-12-729 side-5 ∅19
22160 00000 01100 carb AR2-12-729 side-6 ∅19

52175 00010 00000 carb AR2-10-737 center ∅16
52175 00010 00000 carb AR2-10-759 center ∅16
52175 00000 00010 carb AR2-10-991 center ∅16

54115 10000 00000 carb AR2-10-910 side-5 ∅19
54115 00000 10000 carb AR2-10-910 side-6 ∅19
54973 00001 00000 carb AR2-12-873 side-5 ∅19
54973 00000 00001 carb AR2-12-873 side-6 ∅19
54973 00000 00001 carb AR2-12-978 side-6 ∅19
01010 12345 67890 Model 50, 50V Chains
18368 10000 10000 chain   99L+1 for 12 x 48T
17693 01000 01000 chain   96L+1 for 11 x 44T
18427 00100 00100 chain   97L+1 for 13 x 44T

17785
00011 00011 chain 102L+1 for 11 x 54T
01010 12345 67890 Model 40 Chains
18429 10000 10000 chain   93L+1 for 12 x 48T
20766 01000 01000 chain   90L+1 for 11 x 44T
53874 00100 00100 chain   91L+1 for 13 x 44T

 

 


AV7 Dc and AV7 Vc Engine Parts

  #   part#  qty  price   description  1. Gaskets, bolts      
02   18568    1 $15.0 case bolt set 2 #2.1, 2 #2.2, 3 #2.3
2.1  15276    1 $0.90 bolt M7-1.25 x 45 flange (10 hex)
2.2  14936    1 $0.80 bolt M7-1.00 x 33 (10 hex)
2.3  00366    1 $0.90 bolt M7-1.00 x 48 (10 hex)
2.4  00366.1 1 $1.50 bolt M7-1.00 x 40 (set has 48)
2.5  00366    1 $0.90 bolt M7-1.00 x 48 (10 hex)
2.6  14936    1 $0.80 bolt M7-1.00 x 33 (10 hex)
2.7  15276    1 $0.90 bolt M7-1.25 x 45 flange (10 hex)
2.8  00011    5 $0.50 nut  M7 (10 hex)
03   14854    1 $7.00 gasket cylinder head 
04   14895    1 $6.00 gasket cylinder base
05   16910    1 $3.00 gasket crankcase
06   52646    1  N/A   gasket intake restricted (20mph)
06   17073    1 $3.00 gasket intake (25 and 30mph)
07   16912    1 $15.0 gasket kit 3, 4, 5, 6

 


  #   part#  qty  price   description  2. Engine mounts      
01   19886    1 $6.00 bolt engine mount M8-1.00 x 140     
01   20453    1  N/A   bolt for up-exhaust
M8-1.00 x 145?  
02   20534    1 $4.00 spacer tube ∅8 x ∅14 x 18
03   17994    1 $11.0 R Flexibloc     ∅8.0 ∅32.0 x 23
03a 17994a   1 $8.00 R red rubber  ∅9.7 ∅28.8 x 18
03b 17994b   1 $8.00 R center tube ∅11.3 ∅8.0 x 23
04   19888    1 $3.00 ground cable, engine-to-frame
05   21014    2 $3.00 step spacer  ∅8 x ∅12-17 x 10.5
06   20789    1 $11.0 L Flexibloc    ∅11.0 ∅32.0 x 23
06a 20789a   1 $8.00 L red rubber ∅12.4 ∅28.8 x 18
06b 20789b   1 $8.00 L center tube ∅14.0 ∅11.0 x 23
07   17523    1 $2.50 nut locking M8-1.00
08   16541    1 $0.20 washer ∅8
09   20790    1 $6.00 plastic tube ∅8.0 ∅11.0 x 23
10   17661    1 $3.00 bracket for variator cover
11   00011    4 $0.50 nut  M7 (10 hex)
12   01527    7 $0.50 lock washer ∅7
13   15276    2 $0.90 bolt M7-1.25 x 45 flange (10 hex)
14   14936    2 $0.80 case bolt
15   01526    2 $0.50 nut M6 special?
16   01172    2 $0.20 washer Ø6
17   17120    1 $5.00 bracket spring retainer variator
17   21282    1 $6.00 bracket spring retainer 1-speed
18   00968    2 $0.70 bolt M6 x ??
19   15933    2 $7.00 belt tension springs (each)
20   00366    2 $0.90 case bolt M7-1.00 x 48 (10 hex)
21   00010    2 $0.30 nut M6
22   15934    1 $9.00 Flexibloc lower Ø6 x Ø?? x ??
23   00050    1 $0.70 bolt M6 x 25? 
24   21709    1 $4.00 lower engine mount plate right
25   21710    1 $5.00 lower engine mount plate left
26   17354    1 $3.00 bracket variator cover


Motor Mount Bushings (Flexiblocs)
top: #2 tube, #6 left Flexibloc, #3 right Flexibloc
bottom: #6a red rubber, #3a red rubber 

The red rubbers replace just the old black rubber part. The old bushing metal shell and metal center tube are re-used. The shell is not removed from the frame so no special press tool is needed. Instead the black rubber is removed with a knife. 

But the red rubber holes 9.7 and 12.4 are too small for the center tubes 11.3 and 14.0. The small hole must be widened by drilling. The large hole is a very tight fit without drilling. Drilling is recommended for both.

 

 


  #   part#  qty  price   description  3. Cylinder and head
01   53505    1 $140. cylinder E with piston J (20 mph)
01   53505    1 $140. higher top deck, lower compression

01   23460    1 $180. cylinder AA w/piston AA (25 & 30)
01   23460    1 $180. cylinder AA w/piston AA (25 & 30)
01   23460    1 $180. cylinder C with piston C  (25 & 30)
01   23460    1 $180. cylinder C with piston C  (25 & 30)
01   23460    1 $180. cylinder C with piston C  (25 & 30)
01   23460    1 $180. cylinder E with piston E  (25 & 30)
01   23460    1 $140. cylinder C with piston C good-used
01   23460    1 $140. cylinder C with piston E good-used

02   14721    1 $12.0 decomp valve kit
03   14821    2 $10.0 piston ring (pre-6/76) Ø39 x 2.0 FG
03   22148    2 $12.0 piston ring (6/76-on) Ø39 x 2.0 GI
04   15094    1 $12.0 piston pin Ø13 x 30
05   00658    2 $2.00 piston pin clip Ø13
07   19885    1 $35.0 cylinder head complete
08   00053    2 $1.00 rivet for ID plate
09   21294    1  N/A   engine ID plate   
10   00059    1 $1.00 spark plug gasket ring
11   01547    1 $3.50 spark plug NGK BR6HS
12   15025    1 $8.00 decomp valve bare
13   14919    1 $7.00 mounting lug
14   14855    1 $7.00 guide
15   14897    1 $7.00 gasket
16   14987    1 $4.00 washer
17   15007    1 $4.00 spring 
18   15099    1 $6.00 valve link
19   00018    1  N/A   cottor pin, use small bent nail
21   22156    1 $3.00 wire guide

Cylinders on US models:
53505 is the 20mph cylinder. It says 681051 and TUM207.  The top deck is higher. The exhaust port top is lower.
54328 is the 25mph cylinder. It says S25682051 and TUM207
22340 is the 30mph non-var. It says? 581051 and FB2 47
23460 is the 30mph variator. It says 682051 and most say nothing

Piston (at skirt) to cylinder clearance: new is 0.005 to 0.01 mm (0.0002 to 0.0004″), max is 0.05 mm (0.002″).
This is a very small clearance, measured at the bottom of the piston, allowed by the all-aluminum cylinder. 
Usually pistons are measured at the bottom skirt, called “lower” below, because when cold, that is the widest part.
The bottom is slightly wider than the top, because there is less material, and therefore less thermal expansion.
When the piston is hot, the bottom and top are the same. The whole piston expands, as does the cylinder. 
Motobecane measures just below the rings, called “upper” below. On these pistons lower is 0.02 mm bigger.
Motobecane original pistons have no marks on top, listed below as “(M)”. Inside has the M logo (some also AJ3). 

< Some original replacement pistons have this logo stamped on top, listed as “(Θ)”. Inside says FRANCE.
They also have a size letter stamped on top. These were original replacements from Motobecane USA.
Other vintage aftermarket have no logo on top, listed below as “(O)”.

  # part#    price   description x skirt    4. Piston
73 22273    $70  piston W  38.92 for 38.93 cyl
74 22274    $70  piston AA 38.93 for 38.94 cyl
75 22275    $70  piston A   38.94 for 38.95 cyl
76 22276    n.a.  piston C   38.95 for 38.96 cyl
77 22277    $75  piston E   38.96 for 38.97 cyl
78 22278    n.a.  piston G   38.97 for 38.98 cyl
79 22279    n.a.  piston  J   38.98 for 38.99 cyl
80 22280    n.a.  piston  L   38.99 for 39.00 cyl
81 22281    $75  piston N   39.00 for 39.01 cyl
82 22435    $75  piston P   39.01 for 39.02 cyl
82 22435.1 $75  piston O   39.11 for very worn

 


   #   part#  qty  price   description  5. Intake pipe
01   16673    1  N/A   intake (variator 25mph) Ø16 x 10
01   16619    1 $33.0 intake (var 30 pre-3/77) Ø17 x 12
01   00000    1 $21.0 intake Malossi 022066B Ø19 x 15

02   01176    3 $0.90 lock nut M6
03   01172    3 $0.25 lock washer Ø6
04   52646    1  N/A   intake gasket restricted (20mph)  
04   17073    1 $7.00 intake gasket (25 & 30 mph) 
05   00796    2 $2.50 stud M6 x 31
06   53496    1  N/A   intake pipe thin long (1-sp 20mph) Ø19
06   21201    1 $13.0 intake pipe long (1sp 25&30mph) Ø19
06   22899    1 $16.0 intake pipe long (var. 30 3/77-on) Ø19
07   21202    1 $6.00 support bracket
08   23018    1 $1.50 carriage bolt M6

 


  #   part#  qty  price   description  6. Crank and case
01   19608    1  N/A   crankcase with seals (25 & 30)
1.1  19608.1 1 $15.0 left case half bare (25 & 30)
1.2  19608.2 1 $15.0 right case half bare (25 & 30)
1.3
  19608.3 1  N/A   crankcase (20mph) with a ridge that
1.3  19608.3 1  N/A   only allows a 20mph cylinder to fit

02   00011    4 $0.50 head nut M7-1.0 thick, 10hex
03   18921    4 $0.30 washer M7
04   14716    4 $4.00 cylinder stud
05   19089    2 $7.00 crank seal Ø15 x Ø21 x 4
06   54977    2 $14.0 special crank bearing 6302QR
07   15855    1 $15.0 needle bearing Ø13 x Ø16 x 14(13.6)
08   19609    1 $150. crankshaft Ø16 Ø15 pre-’80 for 6302QR
08   19609    1 $150. less threads for dome square-hole nut
8.1
  19609.1 1 $150. crankshaft Ø16 Ø15 ’80-on for 6302QR
8.1  19609.1 1 $150. more threads for large hex flywheel nut
8.2  19609.2 1 $150. crankshaft Ø15 Ø15 ’80-on for 6302
8.2  19609.2 1 $150. machined to take regular bearings

09
10
11
12
13

 

Crankshafts: top 19609, bottom 19609.2

Motobecane Crankshafts: are the same for variator and non-variator pulley-clutches.
Top is used, pre-1980, shorter right side threads. Takes special 16mm bearings 6302QR 16x42x13.
Bottom is new 1980-later original, machined to 15mm at bearings, to take ordinary bearings 6302 15x42x13.

Myrons offers new pre-1980 crankshafts, that take special 6302QR bearings.

Myrons offers a new original 1980-later crankshaft that has been machined from 16mm to 15mm at the center where the bearings press on. The press fit is precise and correct. The piston pin and needle bearing are new, included, and factory sealed in wax, that peels off. Two 6302 bearings, and two 15x21x4 seals are included. Price is $180.

It is long enough to take the 1980-later hex nut, sold separately at $10. But it will also take the pre-1980 square-hole nut, if the extra threads are ground off.

 



# qty part# price   7. Variable Pulley-Clutch
0
1 1 23695 
0
1 1 24659
02 1 16845
03 1 17797
04 1 19262
05 1 20638
05 1 23398

06 3 16723
07 4 15356
08 2 22401
09 1 16842
10 2 14562
10 x 14931
10 x 14932
10 x 14933
11 1 14561 $2.00 external circlip 15 x 1.0
12 1 22925
13 1 17455
14 1 14587
14 1 22896
15 1 20683
16 1 21946
17 1 22924
18 2 22402 
19 1 15187
20 2 20456 $0.00 rivet post
21 1 14712 $0.00 needle bearing
22 1 14563 $2.00 internal circlip 22 x 1.0
23 1 15349 none  o-ring 2.5 x 20 (25od)
24 1 19851
25 1 17426
26 1 17425

 

 


Pedal and Pulley Parts

# qty  MB#
5   1  14158  circlip external 16 x 1
6   1  15998  washer 16-26 x 1.0
7   2  14179  pedal shaft bushing 16-24 x 19
8   1  16566  circlip inverted external 16 x 1
9   1  14863  shim washer 16-30 x 0.1
9   1  14865  shim washer 16-30 x 0.3
9   1  15001  shim washer 16-30 x 0.75
11 1  14153  washer 16-27 x 2.0
15 1  00006  pedal pin 9.0
16 1  20738  spacer 16-20 x 13
17 2  20697  pedal cap for original pedal