Selection Of The Transmission Ratio - Rotax Fr 125 Max Betriebsanleitung

Attention: The fuel filter (30) must be inspected periodically and cleaned as required.
Remove the hex. screw (32) and gasket ring (31).
Pull out the fuel filter (30) and clean the filter and fuel inlet.
Refit the fuel filter (30), the gasket ring (31) and hex. screw (32).
Install the carburetor into a vertical position and tighten the two clamps on carburetor flange
and carburetor socket.
Connect the fuel hose to the inlet nipple of the carburetor.
Note: When trying to start the engine it will take a few seconds for the fuel pump to fill the
float chamber and for the engine to start.
Note: With the adjustment screw (34), the idle speed of the engine can be adjusted. By
turning in the adjustment screw (34) the idle speed increases and by turning out
this screw (34) the idle speed will be reduced.
Note: With the adjustment screw (29), the fuel mixture formation can be adjusted. By
turning in the adjustment screw (29), the air-fuel mixture will become richer at idling
and by turning out this screw (29), the air-fuel mixture will become leaner at idling.

4.2. Selection of the transmission ratio

Because of the special tuning used, the engine performance is very good in the speed range
from 6000 to 12000 r.p.m.
Peak performance will be achieved at 11500 r.p.m. but over-revving of up to 14000 r.p.m. is
permitted.
Note: The maximum engine speed in kart operation will be controlled by the ignition unit.
At engine speed above 13800 r.p.m. the ignition timing will be controlled such that
the engine performance will drop significantly (see diagram 1).
performance drop will result in the intersection of performance graph 1 and drive
resistance graph (see diagram 1, in this particular case at approx. 14100 r.p.m.)
Attention: Never run the engine without load. By revving the engine without load, speeds of
above 14000 r.p.m. can be reached and this excessive engine speed will
drastically shorten the life span of some components (conrod, conrod bearings
etc).
If the speed range of 6000 r.p.m. to 12000 r.p.m. should prove inadequate due to a particular
track routing, target 13500 r.p.m. as the maximum speed.
Note: A basic requirement for use of the speed range from 12000 to 14000 r.p.m. is that
the carburetor has optimal jetting (refer to Section 4.1 Carburetor calibration
diagram 1).
For approximation and optimizing consult Tables 2 and 3.
Note: The values in the tables refer to a maximum speed of 13500 r.p.m. This engine
speed may not be reached because of too high a drive resistance, therefore use
the stated values for approximation only.
Seite/page 67/80
Operating Instructions FR 125 MAX
FR 125 MAX
This targeted
Ausgabe/edition 07/99