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 to 3/77
21201 01100 01100 intake side ∅19 x 12
22899 00001 00001 intake side ∅19 x 13? 3/77 on
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
Sources
1977 Motobecane America Dealer Manual
’76-’77 40TS, 40TL, 50S, 50L engines 1, 2, 3
’76-’77 50VL 0000, 0000, 00 engines 4, 5
’76-’77 Solex 4600
1978 Motobecane America Dealer Manual
’76-’77 40TS, 40TL, 50S, 50L engines 1, 2, 3
’76-’77 50VL 0000, 0000, 00 engines 4, 5
’76-’77 Solex 4600
1979 Motobecane America Dealer Manual
’78-’80 40T, 50S, 50L, Traveler engines 6, 7, 8
’78-80 50VL, 50VLA, 50VLS xx engines 9, 0
’78-80 50VLX, Moby, Le Moped engines 9, 0
’78-80 Model 7, Sebring, Solex 4600
Discussion
Porting: The deepest secret is that there are four different cylinders, all identical on the outside. The different cylinders could have different port widths and heights (duration’s). Much more needs to be learned and explained. Why does a 2 hp one-speed model have a different cylinder than a 2 hp variable speed model?
Gearing: The drive belt is the same for all versions. The 1-speed front pulley is the same for all versions. The 2-speed front pulley is the same for all versions. The rear pulley (without the front sprocket) is the same for all versions. Therefore, the pulley ratio is the same for all versions. The variator models in “low gear” have the same pulley ratio as the Dimoby models. As the rear wheel speed increases, the variator makes the front pulley bigger. The engine swings back as the front pulley grows, until it is in “high gear”. In high gear the pulley is about 40% bigger. So even though the variator models are geared low (small front and large rear) in chain sprockets, the variator makes up for it, above 18mph, by making the overall gearing about the same.