mcgreggor57.
You should be ok with either a brush-paint job or rattle-cans, no real need for an AB
on 1/12 scale Bikes.
Unless of course you want to add your own custom paint scheme and get a flawless clean metallic look on some parts.
If you use a brush might I suggest adding a retarder to the thinner, many airbrush
thinners got that already in. Also sold under the name of "levelling thinner".
The Retarder delays the drying time and also helps smooth out brushstrokes, hit it afterwards with a good polishing compound, add your decals and polish with a modelling wax and you should be ok.