I couldn't manage toy helicopter droping bombs in a buildnig mission so I know how You feel but finally I did it. I don't remember that motorcycle mission, Driving motorcycle is hard I admit, Maybe it's later on
When is it ?
I'm currently after "Shakedown" mission and buying various busineses around town.
Also here's a tip for making money : When You have bought "Sunshine autos" it's relatively easy to make cash with the "endurance" race - 40k $ per ~/+ 5min. race, It is easier than shorter races because the AI makes a lot of mistakes (crashes) in a long run
edit: maybe if it's before my current game I can send You a savegame so You can play on ?