I don't really have a favourite bike film, as such...
My favourite film does feature bikes, but they're not a main part.
You may have to be in the right mood, but these can be amusing if you switch off and expect cheesy comedic crap:
- Harley Davidson & The Marlboro Man
- Torque
- Freebird
I'm about to watch Fixing The Shadow (aka Beyond The Law/Made Of Steel), as recommended by a biker friend of mine.
Sons Of Anarchy is good, albeit somewhat dramatised.