If your motorcycle uses an electric starter (as opposed to a kick starter), the starter will draw far & away more current than the ignition system - like perhaps fifty times as much. A bike with only a kick starter only needs a tiny battery, while one with only an electric starter requires a big one.
When battery capacity is too low, generally both the starting system and the ignition suffer... and GENERALLY they both fail at about the same level of low capacity - as long as the starter is capable of cranking the engine, typically the ignition system is also capable of delivering a spark sufficient to start the engine.
One very quick check, if you think your battery capacity is dropping off, is to hang a meter ON THE BATTERY POSTS (not the fuses), then try to start the bike. If, while cranking, the battery voltage drops below about 75% of nominal (9V for a nominal 12V battery), then the battery's capacity is too low and it requires charging or replacement.