USEFUL DATA - ALL MODELS
Model
|
A7 Up to Engine No. |
A7 S.T. Twin |
A7 On and after Engine No. |
A7S/T&S/S On and after Engine No. |
A10
|
R/R and S/R |
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Engine bore |
62mm. |
62mm. |
66mm |
68mm. |
70mm |
70mm |
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Engine stroke |
82mm. |
82mm. |
72.6mm. |
72.6mm. |
84mm |
84mm |
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Engine capacity |
495 c.c. |
495 c.c. |
497 c.c. |
497 c.c. |
646 c.c. |
646 c.c. |
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Petrol tank capacity |
3 gal |
3.5 gal |
3.5 gal |
3.5 gal |
4.25 gal |
2 or 4 gal |
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Oil tank capacity |
4 pints |
4 pints |
4 pints |
4 pints |
4 pints |
5.5 pints |
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Gearbox capacity |
1 pint |
1 pint |
1 pint |
1 pint |
1 pint |
14 fl ozs |
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Compression ratio |
6.6 - 1 |
7 - 1 |
6.6 - 1 |
7.25 - 1 |
8.5 - 1 |
S/R |
R/R |
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8.26-1 |
8-1 |
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Clearances: |
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Inlet tappet(cold) |
.015" |
.015" |
010" |
008" |
010" |
008" |
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Exhaust tappet(cold) |
.015" |
.015" |
.016” |
.012” |
.016" |
.006” |
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Piston ring gap(plain) |
.013" |
.013" |
.013" |
.013" |
.013" |
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Piston ring gap (oil control) |
.011" |
.011" |
.011" |
.011" |
.011” |
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Piston ring side clearance |
.002”/.004” |
.002”/.004” |
.002”/.004” |
.002”/.004” |
.002”/.004” |
.002”/.004” |
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Piston clearance — |
.003”/.005" |
.003”/.005" |
.003”/.005" |
.003”/.005" |
.003”/.005" |
.003”/.005" |
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Gear ratios: |
S/T |
S/S |
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Top |
5.1 |
5 1 |
5 1 |
5.0 |
5.28 |
4.42 |
4.53 |
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3rd. |
6.2 |
6.2 |
6.2 |
6.05 |
6.38 |
5.36 |
5.48 |
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2nd. |
9.0 |
9.0 |
9.0 |
8.8 |
9.28 |
7.77 |
7.96 |
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1st. |
13.2 |
13.2 |
13.2 |
12.9 |
I3.2 |
11.41 |
1168 |
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Carburetter: |
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Jet size |
- |
110 |
- |
- |
- |
250 |
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With air cleaner |
140 |
- |
140 |
160 |
170 |
240 |
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Sparking plugs: |
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Cast Iron head |
L.10S |
L.10S |
L.10S |
L10S |
L.10S |
NA 10 |
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Alloy head |
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Plug points gap |
.015” to .018” |
.015” to .018” |
.015” to .018” |
.015” to .018” |
.015” to .018” |
.018” to .020” |
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Timing: |
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Inlet valve: |
Opens before T.D C. |
24 |
24 |
30 |
42 |
30 |
42 |
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Opens after B.D.C. |
65 |
65 |
70 |
62 |
70 |
62 |
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Exhaust valve: |
Opens before B.D.C. |
60 |
60 |
65 |
67 |
65 |
67 |
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Opens after T.D.C. |
21.5 |
21.5 |
25 |
37 |
25 |
37 |
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Ignition setting |
3/8” |
3/8” |
5/16" |
3/8” |
11/32" |
3/8” |
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Magneto points gap |
.012" |
.012” |
.012” |
.012" |
.012" |
.012" |
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Tyres: |
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Size (front) |
3.25x19 |
3.25x19 |
3.25x19 |
3.25x19 |
3.25x19 |
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Size (rear) |
3.50x19 |
3.50x19 |
3.50x 19 |
3.50x19 |
3.50x19 |
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Pressure front (PSI) |
17lb |
17lb |
17lb |
17lb |
17lb |
17lb |
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Pressure rear (PSI) |
18lb |
18lb |
18lb |
18lb |
18lb |
18lb |
NOTE. Standard A7's after Engine No. CA7 5282 and Standard A10’s After Engine No. DA10 1647 have the same camshaft as the S/S and R/R machines and valve timing is therefore the same.
PISTON CLEARANCES
To avoid the possibility of seizure or piston tap, pistons must be fitted with adequate but not excessive clearance.
The following are the recommended total clearances between the bottom of the piston and the cylinder wall.
A7. |
|
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A7. |
(Star twin) |
.002"/.004" |
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A7. |
(Split skirt) |
Star twin & Shooting star |
.0011"/.0031" |
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A10. |
|
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A10. |
(Super flash & Road Rocket) |
8 : 1 |
.003"/.0045" |
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A7. |
(Shooting star) |
8 : 1 |
.0035".005" |
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A10. |
(Golden Flash) |
7.5 : 1 |
.0035"/.005" |
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A10. |
(Super rocket) |
8.5 : 1 |
.004"/.0055" |