A cold gas engine needs to be choked and flipped several times to get the fuel to the combustion chamber. After flipping it several times the engine will try to start with the choke on but will only pop ( run for one to three seconds and die) at this point you open the choke and it should start in one or two flips. When you land and want to kill the engine flip the choke switch on and the engine will die.

My DL50 needs to be primed with ignition off and the choke on. Usually 10 or more revolutions of the prop, then I turn the ignition on and flip it 2 to 3 times more with choke on, until it pops, then choke off, flip one more time and away it goes. In my case this is how my DL50 wants to start, it's very consistent.

Geppino