I always keep a 10-pound fire extinguisher nearby to my bikes.
Agreed, its always useful to have a couple of working fire extinguishers nearby, especially for old bikes that are stored in the garage, which essentially are like potential Molotov cocktails waiting to go off.
When I store my bikes in the garage I always disconnect the
battery and ensure the petcocks are closed (and in working order).
Worthwhile checking your household insurance as well, if the worst were to happen and one of your bikes goes up in flames whilst in the garage, taking the house with it, you may find you aren't covered.....