| COMPRESSION RATIO
CALCULATOR |
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| 85mm x 88mm, DB34 Engine - Amount of Liquid
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| Engine Size |
62cc |
62cc |
62cc |
62cc |
62cc |
62cc |
70cc |
72cc |
73cc |
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| Std =
499cc |
9.0:1 |
8.9:1 |
8.8:1 |
8.6:1 |
8.5:1 |
8.3:1 |
8.1:1 |
7.9:1 |
7.8:1 |
C/Ratio |
| +20 =
505cc |
9.1:1 |
9.0:1 |
8.9:1 |
8.7:1 |
8.6:1 |
8.4:1 |
8.2:1 |
8.0:1 |
7.9:1 |
C/Ratio |
| +40 =
511cc |
9.2:1 |
9.1:1 |
8.9:1 |
8.8:1 |
8.7:1 |
8.5:1 |
8.3:1 |
8.1:1 |
8.0:1 |
C/Ratio |
| +60 =
517cc |
9.3:1 |
9.2:1 |
9.0:1 |
8.9:1 |
8.8:1 |
8.6:1 |
8.4:1 |
8.2:1 |
8.1:1 |
C/Ratio |
| 71mm x 88mm, B32 Engine - Amount of Liquid
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| Engine
Size |
43cc |
44cc |
45cc |
46cc |
47cc |
48cc |
49cc |
50cc |
51cc |
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| Std =
348cc |
9.1:1 |
8.9:1 |
8.7:1 |
8.5:1 |
8.4:1 |
8.2:1 |
8.1:1 |
7.9:1 |
7.8:1 |
C/Ratio |
| +20 =
353cc |
9.2:1 |
9.0:1 |
8.8:1 |
8.6:1 |
8.5:1 |
8.3:1 |
8.2:1 |
8.0:1 |
7.9:1 |
C/Ratio |
| +40 =
358cc |
9.3:1 |
9.1:1 |
8.9:1 |
8.8:1 |
8.6:1 |
8.4:1 |
8.3:1 |
8.1:1 |
8.0:1 |
C/Ratio |
| +60 =
363cc |
9.4:1 |
9.2:1 |
9.0:1 |
8.9:1 |
8.7:1 |
8.5:1 |
8.4:1 |
8.2:1 |
8.1:1 |
C/Ratio |
Position engine on
bench with spark plug hole vertical and uppermost with the piston at
TDC on compression stroke. Pour fluid from an accurate measuring jug until the fluid
level is half way up the plug hole. makea note of the amount of fluid
oil used
From the charts above,
you can work out your compression ratio, providing you know what
bore you are on (i.e. Std, +20", +40", etc ).
CAPACITY CHECK (CC )
STROKE =88 BORE =71 71 -: 2 =35.5 x35.5=1260 .25 x 88 =110902 x 3.142 =348454.084-: 1000 = 348.45 cc
ENGINE SPECIFICATIONS
| Engine Capacity |
348cc &
499cc |
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Con-rod
Centres |
6 15/32 in
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| Cylinder Bore (nominal) |
71mm &
85mm |
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Con-rod small
end |
Dia. 0.7505 in
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| Cylinder Bore (actual) |
2.794-2.793
3.345-3.34 |
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Rocker
Spindle |
Dia. 0.561
in |
| Stroke |
88mm = 3.462
in |
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Cam
Spindle |
Dia 0.6235
in |
| Rocker Spindle |
Dia 0.561
in |
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Cam Bush
size |
0.625
in |
| Valve stem Dia |
(inlet 0.309
in) |
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Gudgeon
Pin |
Dia 0.750
in |
| Valve stem Dia |
(exhaust 0.348
in) |
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| Valve Spring |
(outer free
length) |
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1.670
in |
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| Valve Spring |
(outer fitted
length) |
|
1.312
in |
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| Valve Spring |
(inner free
length) |
|
1.500
in |
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| Valve Spring |
(inner fitted
length) |
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1.218
in |
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| Inlet Valve Timing |
(with 0.018
valve clearance) |
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| Cam 65-2442 |
O.B.T.D.C
65º |
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C.A.B.D.C.
85º |
Lift 0.442 in
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| Cam 65-2446 |
O.B.T.D.C
63º |
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C.A.B.D.C.
72º |
Lift 0.404 in
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| Cam 65-2448 |
O.B.T.D.C
43º |
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C.A.B.D.C.
73º |
Lift 0.380 in
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| Cam
65-2420 |
O.B.T.D.C 25º |
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C.A.B.D.C. 65 º |
Lift
0.300 in |
| Cam 65-2444 |
O.B.T.D.C
60º |
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C.A.B.D.C.
85º |
Lift 0.422 in
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| Exhaust Valve Timing |
(with 0.018
valve clearance) |
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| Cam 65-2446 |
O.B.B.D.C
80º |
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C.A.T.D.C.
80º |
Lift 0.404
in |
| Cam 65-2450 | O.B.B.D.C
70º |
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C.A.T.D.C.
45º |
Lift 0.380 in
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| Cam 65-2452 |
O.B.B.D.C
64º |
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C.A.T.D.C.
34º |
Lift 0.370 in
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| Cam
65-2491 |
O.B.B.D.C 95º |
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C.A.T.D.C. 50º |
Lift
0.421 in |
| Cam 65-1891 |
O.B.B.D.C
85º |
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C.A.T.D.C.
60º |
Lift 0.423 in
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| Cam 65-2420 |
O.B.B.D.C
65º |
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C.A.T.D.C.
25º |
Lift 0.300 in
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| Magneto Points Gap |
0.010 in -
0.012 in |
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Valve stem
guide clearance |
0.001-0.003 |
| Ignition Timing Fully Advanced |
39º =
(15/32) |
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Valve
clearances |
0.006 |
| Spark Plug Gap |
0.018-0.020 |
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Flywheel
balance factor |
58% |
| Push Rod Standard Length |
9.0625
excluding spigot |
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Valve Seat
Angle |
45º |
| Flywheel run out maximum |
0.002
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