Design Of The Rotax Engine Fr 125 Max, Fr 125 Junior Max And Fr 125 Mini Max; Technical Description Of The Rotax Engine, Type Fr 125 Max, Fr 125 Junior Max And Fr 125 Mini Max; Type Of Engine; Cooling Circuit - Bombardier-Rotax FR 125 MAX FR 125 Junior MAX Installation And Operator's Manual

OPERATING INSTRUCTIONS FOR ROTAX ENGINE TYPE
FR 125 MAX, FR 125 JUNIOR MAX, FR 125 MINI MAX
1. Design of the ROTAX engine FR 125 MAX, FR 125 Junior MAX and FR 125 Mini
MAX
Single cylinder two cycle engine, reed valve controlled, 125 cm
Liquid cooled, forced flow by integrated water pump

Balance shaft

Integrated thermostat
Digital battery ignition
Integrated electric starter
Pneumatic controlled exhaust timing
Crankcase impulse operated fuel pump
Piston carburetor Dell'orto VHSB 34
Intake silencer with integrated air filter
Tuned exhaust with after-muffler
2. Technical description of the ROTAX engine, Type FR 125 MAX, FR 125 Junior
MAX and FR 125 Mini MAX

2.1. Type of engine

Single cylinder two cycle engine with reed valve controlled inlet. Mixture lubrication is achieved by
adding oil to the gasoline in a specified mixing ratio.

2.2. Cooling circuit

The coolant is routed from the radiator through the crankcase to the water pump. The water pump
is driven by the crankshaft via a reduction gear. The water pump transmits the coolant through
cylinder and cylinder head back to the radiator.
The cooling circuit is equipped with an integrated thermostat which is regulating the coolant
temperature.
2.3. Balance shaft
The balance shaft rotates counter-wise to the crankshaft to reduce engine vibration.

2.4. Ignition unit

Ignition timing is controlled by the digital battery ignition unit consisting of the trigger coil on the
crankcase and an ignition coil with the integrated electronics. Manual ignition adjustment is neither
required nor possible.
The power circuit for the ignition unit is protected against current draw by an ON/OFF circuit
breaker switch. At a forced engine stop the ignition unit still consumes current. To stop the engine
and to avoid discharge of the battery on a non-running engine, the ignition circuit must be opened
by releasing the ON/OFF circuit breaker.
If the white marking is visible on the button of the circuit breaker, the ignition circuit is open and the
engine cannot be started. If the button is pressed firmly and released, only the black end of the
button remains visible and the ignition circuit is closed and the engine can be started.
Seite/page 75/108
Operating Instructions FR 125 MAX and FR 125 Junior MAX
3
displacement
Ausgabe/edition 09.2003