Rotax mixture control
I've been looking for an ultralight aircraft to buy, and I found a very odd (for me) feature in the Rotax 912 engines: they have no mixture control lever!
My question is: when ruducing power from takeoff to cruise, is there an automatic leaning? But, how agressive is that leaning? What is the "cruise" mixture automatically set by the carburator equivalent to? Best power, Best economy, or none of those?
In a regular carburated engine, like Archer's O-360, after setting cruise RPM, I had to lean the mixture to the point I wanted. I know that the carburator enriches the mixture automatically at takeoff, so that in other regimes, the rich mixture is not as rich as on takeoff power.
My conclusion is that this regular non-full power rich mixture is still much richer than the best power mixture in a regular carburated engine.
If the Rotax carburator's does just the same, and with the lack of the mixture lever, I will have no choice but to fly at a richer than necessary mixture in all situations but takeoff.
As in Brazil the Rotax 912 is not compatible with autogas (because of the 25% of ethanol added in it), I will have to burn only avgas. I think this would be very bad for the engine.
I also found the CHT's limits of the Rotax too low (300 F), compared to the 400F I'm used to use in my IO-520. Are the materials used in the Rotax somewhat inferior to those used in the regular general aviation engines?