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3.13 CHOICE OF THE BEST SPROCKET RATIO
The life of an engine depends on many factors but most of all, upon the speed at
which the engine is operated. If an engine is normally operated at speed higher than
what recommended by the manufacturer, the wears and stress of the various
components (con-rod, roller cages, bearings etc.) will be such as to drastically reduce
the life of the engine itself. It is therefore important that the user respect the operating
limits imposed by the manufacturer.
The operation limit for the "Reedster" is 14000 RPM for F3 and F4, 15000 RPM for F2
and 16000 RPM for F1 (the RPM limiter is calibrated at these values).
ATTENTION:
Never exceed the above limit. No obligation of IAME exists in case the above
limit is exceeded.
In case the user wishes to optimize, on the track, the sprocket ratio in order to achieve
the best possible performance without abusing the engine, follow the under shown
recommendations.
The engines are supplied with a 12 teeth sprocket (pitch 7.775 mm.), but 11 and 13
teeth sprockets are available as accessories. Table 1 shows the various ratios
between the sprocket on the axle and the engine sprocket given the different axle and
engine sprockets.
Tab.1
Sprocket
ratio
Teeth n°
axle
sprocket
72
73
74
75
76
77
78
79
80
81
82
To achieve the max RPM speed of 13500 RPM, the table N°2 has been prepared.
To achieve the max RPM speed of 14500 RPM, the table N°3 has been prepared.
To achieve the max RPM speed of 15500 RPM, the table N°4 has been prepared.
SUGGESTION:
During the track tests we recommend use of a tachometer recording the
max. obtained engine RPM.
Use spark plug caps or spark plugs with a min. resistance of 5KΩ to avoid
eventual interferences between the engine ignition and the tachometer
and/or telemetry.
Teeth n° - engine sprocket
11
12
6,55
6
6,64
6,08
6,73
6,17
6,82
6,25
6,91
6,33
7,00
6,42
7,09
6,5
7,18
6,58
7,27
6,67
7,36
6,75
7,45
6,83
Sprocket
ratio
Teeth n°
axle
13
sprocket
5,54
83
5,61
84
5,69
85
5,77
86
5,85
87
5,92
88
6
89
6,08
90
6,15
91
6,23
92
6,3
34
Teeth n° - engine sprocket
11
12
7,55
6,92
7,64
7
7,73
7,08
7,82
7,17
7,91
7,25
8,00
7,33
8,09
7,42
8,18
7,5
8,27
7,58
8,36
7,67
MAN-051 ING
13
6,38
6,46
6,54
6,61
6,69
6,77
6,85
6,92
7
7,08
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