IAME MINI SWIFT 60CC - USA - Sprocket Ratio Adjustment; Adjusting Sprocket Ratio for Max RPM

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MAN-85 – USA
Assume to use the engine with Z=11 teeth sprocket and that during the preliminary
tests a Z=72 teeth axle sprocket has been used.
 From Table 1 with Z=11 as engine sprocket and Z=72 on the axle sprocket, a
ratio of 6.55 is found.
 Make a few laps on the track and, record the max RPMs achieved by the engine.
Assume that we read 12.000 RPMs.
 From the Table 2 to achieve a max. RPM 14.500 (operating limit for the MINI
SWIFT engine) a sprocket ratio of 7.85 should be used (having used, during the
tests, a sprocket ratio of 6.55 and having achieved 12.000 RPMs).
 From Table 1, to achieve a sprocket ratio of 7.85, a Z=86 teeth axle sprocket
should be used.
Sprocket ratio to achieve max. 14.500 RPM
Sprocket ratio
Engine max.
RPM during
tests