I think the only 'ass' round here is the person who keeps asking the same question over and over again, and ignoring all the replies!. And if you 'say it is critical', why are you asking questions on here?, when you already know all about it?.
If it'll make you happier though?, I'll make it simpler for you:
1) You MUST include capacitors - I presume you understand this?.
2) It must not be too small.
3) It must not be too big.
Personally I wouldn't go smaller than 0.1uF, or larger than 10uF - although if all I'd got was 22uF, I wouldn't be concerned about it.
You've also misunderstood Audioguru's point about spikes, it wasn't what you think it is. Your requirement is VERY, VERY simple, if you want to use a 7809? (and there's no reason not to, it's a perfectly reasonable choice), any smallish caps (as above) would do perfectly. I would also suggest the comments about not connecting it with the bike running, or while starting it, are completely unfounded. You're making your project far more difficult than it is!.
BTW, I would suggest you don't attack or harrass moderators, as you WILL be banned - consider this your ONLY warning!.