I can't get my DA-100 to perform well in the air AND not be lean at start-up, at least not when it's below 80 degrees outside.
For the best in-air performance, I manage the lean cold running via a choke servo. I start the motor with the choke 3/4 of the
way closed. I slowly open the choke as I taxi out. By the time I'm ready for takeoff the engine is warm and the choke is
fully open.

I used to have a Brison 6.4 and it was the same way. I had to start it at half choke below 80 degrees if I wanted the mixture
to be just right in the air.