Aircraft can use a starter generator.
Some old Cushmans' ran them ,so did old small Kawasaki's.
The "general" idea you really need to first study is the difference between DC and AC motors (like this Electric Motor - body, used, water, life, law, plants, energy, system, air, cause, primary, waves, basic, change, part, principle
Then you need to look at how complicated
a starter generators can be for small MB's >>> Dan's Motorcycle Generator/Electric Starter (Dynamo)
That will tell you that it may be better just to find on old starter/generator to adapt to your motorized bicycle for your experiment.
(they do rob a bit of engine power as they do drag on your performance)
A battery drill does not like spinning at high rpms for a long sustained
periods of time, it will wear out the mechanical parts pretty quick (gears, bearings, etc). The starting rpms required for your motorized bicycle motor to be spun by the electric drill are pretty low and the hi-torque applied is only for a brief time. The "generation" of electricity (AC or DC) will take some circuitry to use the higher Motorbike RPMs (to charge a battery, or run a light) AND some "switching" to get the juice to flow in the direction you want.
Can an electric motor be used as both a starter and generator? Sure, have been used for 100+ years. BUT when used as such a hermaphrodite they are a bit half-arsed in both functions; cause you don't get something for nothing.
Short answer: If you get a used electric drill, a simple manual hand tachometer like this cheapie electronic one like >>> Digital Contact Tachometer
OR this deluxe one Digital Photo Sensor Tachometer
and a Volt/Ohm/Meter you can play with the drills rpms and the volts/amps/ohms output that you get and see for yourself. That simple test will broaden your understanding tremendously. Well worth the effort.