iKarus C42 Series Pilot Operating Handbook page 21

Pilot Operating Handbook for the C42 Series
If the engine has been flooded, close main fuel valve, open the throttle to
a half and start the engine. When the engine starts, quickly reduce the
throttle to idle.
A four-stroke engine requires a long warm up period. Run the engine at
2000 rpm for at least 2 minutes then increase to 2500 rpm – 3000 rpm
until the oil temperature is at least 50°C (122°F).
The cylinder heads of the ROTAX 912 engine are liquid-cooled whereas
the cylinder barrels are air-cooled.
In the case of the C42 (C42A), there are separate cooling systems for the
coolant and the oil.
In the case of the C42B, C42C and C42CS only the coolant is cooled by
a cooler. The coolant and oil systems are connected to one heat
exchanger; thus, the temperatures of both fluids adapt to each other. The
temperatures of the coolant, oil and cylinder head is therefore, almost
identical. Due to heat exchange the oil also warms up faster during the
run-up phase. It is, however, still necessary to mask the water cooler if
optimum engine temperature (>90°C) is to be achieved during cold
weather operation (max. one third of the surface may be covered with
tape or self-adhesive neoprene).
Perform the MAG check at 4000 rpm. Rpm drop should not exceed 300
rpm with a maximum difference between MAGs of 115 rpm.
In case your aircraft is equipped with a cowl flap, please refer
to the instructions in the paragraph 4.9 : Equipped with
Optional Cowl Flap
POH C42 SERIES ISSUE1 (B) REV7 25/04/2020 Page 21 of 73