Choice Of Gear Ratio - Rotax Rm 1 Benutzerhandbuch

6.1.3. Choice of gear ratio

The engine 125 Max DD2 offers a broader performance range, inspite of its 2 gears offers a broad
performance band. Therefore the frequent change of gear ratios, as you are used to with 1-speed
engines, is no more necessary.
Note: It is not foreseen to exchange the 1
On most of the Kart circuits you will be well served with the standard gear ratio (35 : 62 is
equivalent to 12/90 at 1
If due to the special shape of the circuit (e.g. extremely sharp corners or long straights) it should
seem necessary, the gear ratio can be changed both to a shorter or a longer ratio.
The diagram (acceleration potential) depicts that the engine has its optimum acceleration potential
between 9.200 and 12.200 r.p.m. /min. It should therefore be operated in this range, overreving up
to 13.600 r.p.m. is possible.
When the engine speed exceeds 12.200 r.p.m. the torque drops and in consequence the
acceleration potential, therefore you should shift from 1
Motordrehmoment [Nm],
torque of engine [Nm]
26,00
24,00
22,00
20,00
18,00
16,00
14,00
12,00
10,00
8,00
6,00
4,00
2,00
0,00
Note: The maximum speed is limited at 13.800 r.p.m. by an electronic r.p.m. limiter.
If the r.p.m. range from 9.200 to 12.200 r.p.m. is not sufficient due to a particular track shape
(extremely long straight) the maximum engine speed of 13.600 r.p.m. should be aimed for.
Note: A basic requirement for the full use of the speed range between 12.200 to 13.600
r.p.m. is an optimized carburetor jetting (see chapter Carburetor Adjustment).
Seite/page 125/132
Operator`s Manual RM1
st
gear and 14/79 to 2
BESCHLEUNIGUNGSPOTENTIAL
ACCELERATION POTENTIAL
großes
Beschleunigungspotential
high acceleration potential
Motordrehzahl [1/min.], engine revolutions [rpm]
st nd
resp. the 2 gear individually.
nd
gear).
st nd
into 2 gear.
Kurve des Fahrwiderstandes
graph of driving resistance
ROTAX KART RM1 Ausgabe/Edition 05/2003