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BSA C15
BSA C15
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BSA
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BSA SERVICE SHEET No. 428 |
Reprinted October. 1964 |
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USEFUL DATA |
C15 |
CI5T |
C15S |
Cl5 |
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Engine Number |
Left-hand side of the engine below cylinder | |||
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Frame Number |
At the top of the steering head tube | |||
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ENGINE: |
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Capacity (c.c.) |
249 |
249 |
249 |
249 |
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Cylinder bore (mm.) |
67 |
67 |
67 |
67 |
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Stroke (mm.) |
70 |
70 |
70 |
70 |
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Compression ratio |
8 to 1 |
8 to 1 |
10 to 1 |
8.75 to 1 |
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Inlet opens B.T.D.C. |
26 |
41.5 |
41.5 |
51 |
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Inlet closes A.B.D.C. |
70 |
62.5 |
62.5 |
68 |
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Exhaust opens B.B.D.C. |
61.5 |
62.5 |
62.5 |
78 |
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Exhaust closes A.T.D.C |
34.5 |
41.5 |
41.5 |
37 |
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Piston rings (compression) (in.) |
0.0625 wide |
0.0625 wide |
0.0625 wide |
0.0625 wide |
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Piston rings (scraper) (in.) |
0.125 wide |
0.125 wide |
0.125 wide |
0.125 wide |
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Piston ring gaps: |
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Minimum (in.) |
0.009 |
0.009 |
0.009 |
0.009 |
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Maximum (in.) |
0.013 |
0.013 |
0.013 |
0.013 |
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Sparking plug |
N5 Champion |
N5 Champion |
N3 Champion |
N4 Champion |
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Plug points gap: |
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Minimum (in.) |
0.02 |
0.02 |
0.02 |
0.02 |
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Maximum (in.) |
0.025 |
0.025 |
0.025 |
0.025 |
| After Engine C15T-1251 and C15S-2112 valve timing is:- | ||||
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Inlet opens B.T.D.C. |
51 deg |
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Inlet closes A.B.D.C. |
68 deg |
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Exhaust opens B.B.D.C. |
78 deg |
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Exhaust closes A.T.D.C. |
37 deg |
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TRANSMISSION: |
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Gear ratios--Top |
5.98 |
9 |
9 |
6.36 |
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Third |
7.65 |
14.67 |
10.8 |
7.64 |
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Second |
10.54 |
22 |
14.94 |
10.54 |
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First |
15.96 |
28.53 |
19 |
13.44 |
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Clutch friction plates |
4 |
4 |
4 |
4 |
| Clutch Spring Free Length | 1.66" | 1.66" | 1.66" | 1.66" |
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Chain sizes-Front (in.) |
3/8 Duplex |
3/8 Duplex |
3/8 Duplex |
3/8 Duplex |
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(70 pitches) |
(70 pitches) |
(70 pitches) |
(70 pitches) |
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Rear (in.) |
1/2 x .335 |
1/2 x .335 |
1/2 x .335 |
1/2 x .335 |
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(112 pitches) |
(122 pitches) |
(122 pitches) |
(112 pitches) |
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Teeth on--Engine sprocket |
23T |
23T |
23T |
23T |
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Gearbox sprocket. |
17T |
15T |
15T |
16T |
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Clutch sprocket |
52T |
52T |
52T |
52T |
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Rear chain wheel |
45T |
60T |
60T |
45T |
| Alternatives:- Gearbox Sprockets 17, 18, 19 & 20 Rear chain wheel 52, 56 & 60 | ||||
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CAPACITIES: |
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Fuel tank (galls.) |
3 |
2 |
2 |
3 |
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(13.6 Ltr) |
(9 Ltr) |
(9 Ltr) |
(13.6 Ltr) |
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Oil tank (pints) |
4 |
5 |
5 |
4 |
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(2 1/4 Ltr) |
(2.8 Ltr) |
(2.8 Ltr) |
(21/4 Ltr) |
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Gearbox (pints) |
2/5 (220cc.) |
2/5 (220cc.) |
2/5 (220cc.) |
7/16 (250cc.) |
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Front forks (pints) |
1/6 (100cc.) |
1/3 (190cc.) |
1/3 (190cc.) |
1/6 (100cc.) |
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Primary chain case (pints) |
1/4 (140cc.) |
1/4 (140cc.) |
1/4 (140cc.) |
1/4 (140cc.) |
| After engine C15-26792 & B40-2402 the gearbox capacity was increased to 1/2 pint (285cc) | ||||
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WHEELS: |
C15 |
C15T |
C15S |
C15 |
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Rim size Front |
WM2-17 |
WM1-20 |
WM1-20 |
WM2-17 |
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Rim size Rear |
WM2-17 |
WM3-18 |
WM3-18 |
WM2-17 |
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Tyre size Front |
3.25-17 |
3.00-20 |
3.00-20 |
3.25-17 |
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Tyre size Rear |
3.25-17 |
4.00-18 |
4.00-18 |
3.25-17 |
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Brakes, dia. x width: |
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Front (in.) |
6x7/8 |
7 x 1 1/8 |
7 x 1 1/8 |
6x7/8 |
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Rear (in.) |
6x7/8 |
6x7/8 |
6x7/8 |
6x7/8 |
| Rim Offset (Front & Rear) | 5/32 | 5/32 | ||
| Hub Outside Diameter | 7 | 7 | ||
| Hub Spoke Width | 2 1/4 | 2 1/4 | ||
| Spoke Length (below the head) | 5 7/16 | 5 7/16 | ||
| Spoke Dia | 10Gauge (1/8) | 10Gauge (1/8) | ||
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CARBURATION (AMAL): |
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Bore (in.) |
7/8 |
7/8 |
1.0625 |
1 |
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Main jet |
140 |
140 |
190 |
200 |
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Pilot jet |
25 |
25 |
25 |
25 |
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Throttle valve |
375/4 |
375/4 |
376/3.5 |
376/4 |
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Needle position |
3 |
3 |
2 |
2 |
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Needle jet |
0.1055 |
0.1055 |
0.106 |
0.106 |
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GENERAL DETAILS: |
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Front suspension movement (in.) |
5 |
5 |
5 |
5 |
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Rear suspension movement (in.) |
2.375 |
2.375 |
2.375 |
2.375 |
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Generator output |
60 watts |
60 watts |
60 watts |
60 watts |
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Contact breaker gap (in.) |
0.015 |
0.015 |
0.015 |
0.015 |
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Battery capacity |
13 amp/hr at 20 hr rate |
13 amp/hr at 20 hr rate |
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Overall length |
78 |
81 |
81.5 |
78 |
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Wheelbase (in.) |
51.25 |
51.75 |
51.75 |
51.25 |
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Ground clearance (in.) |
5 |
7.25 |
7 |
5 |
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Saddle height (in.) |
30 |
33 |
32 |
30 |
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Overall height (in.) |
37 |
42 |
41.5 |
36 |
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Handlebar width (in.) |
26 |
31.125 |
31.125 |
27 |
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Steering head angle |
65 deg |
63 deg |
63 deg |
65 deg |
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Steering lock angle |
50 deg |
60 deg |
60 deg |
50 deg |
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Weight (lbs.) |
275 |
265 |
265 |
275 |
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Tyre pressures Front (lbs.) |
16 |
19 |
19 |
17 |
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Tyre pressures Rear (lbs.) |
22 |
16 |
16 |
21 |
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The recommended inflation pressures are based on a riders weight of 140 lb. Increase the tyre pressures as follows, If the rider's weight exceeds 140 lb. |
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Front tyre: Add one lb. per square inch for every 28 lb. increase above 140 lb. |
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Rear tyre: Add one lb. per square inch for every 14 lb. increase above 140 lb. |
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If a pillion passenger or luggage is carried, the actual load bearing upon each tyre should be determined and the pressures increased in accordance with the Dunlop Load and Pressure Schedule. |
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There was a mistake on the Original BSA Service Sheets, which was replicated on my site as Paul Hughes noticed.
"You state, as does BSA Service Sheet No. 428, that the gearbox capacity for early C15's is 1/5 pint
or 220 cc. When I was at school 1 pint was approximately 560 cc which makes 1/5 pint approximately 110 cc. May I suggest 2/5 pint is the correct
capacity. From reading other factory service data I think either the proof readers or their metric conversion tables could be improved on."
Thanks to Paul for spotting it and letting me know.