AV7 Dc and AV7 Vc Engine Parts
under construction
Motobecane model 50 figure 1
# part# qty price description 1. Engines, gaskets
01 53444 1 N/A engine 1-speed (20mph 6V ’76-77)
01 53949 1 N/A engine 1-speed (25mph 6V ’76-77)
01 52341 1 N/A engine variator (25mph 6V ’76-77)
01 53744 1 N/A engine 1-speed (30mph 6V ’74-77)
01 53745 1 N/A engine variator (30mph 6V ’74-77)
01 54146 1 N/A engine 1-speed (20mph 12V ’78-80)
01 54147 1 N/A engine 1-speed (25mph 12V ’78-80)
01 54148 1 N/A engine variator (25mph 12V ’78-80)
01 54149 1 N/A engine 1-speed (30mph 12V ’78-80)
01 54844 1 N/A engine variator (30mph 12V ’78-80)
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
Motobecane model 50 figure 2
# 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 Ø8 x Ø14 x 18
03 17994 1 $11.0 Flexibloc right Ø8 x ∅32 x 23
04 19888 1 $3.00 ground cable, engine-to-frame
05 21014 2 $3.00 stepped spacer Ø8 x Ø12-17 x 10.5
06 20789 1 $11.0 Flexibloc left Ø11 ∅32 x 23
07 17523 1 $2.50 nut locking M8-1.00
08 16541 1 $0.20 washer Ø8
09 20790 1 $6.00 spacer tube plastic Ø8 x Ø11 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 Ø7
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
Motobecane 50 figure 3
# 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 $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
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)”.
Motobecane 50 figure 4
# 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
Motobecane 50 figure 5
left is for center-mount carb, right is side-mount
# part# qty price description 5. Intake pipe
01 16673 1 N/A intake pipe short (variator 25mph) Ø16
01 16619 1 $18.0 intake pipe short (var. 30 pre-3/77) Ø17
01 00000 1 $21.0 intake pipe short Malossi 022066B Ø19
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
Motobecane 50 figure 6
# 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
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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.
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23 15349 none o-ring 2.5 x 20 (25od)
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