Intentionally causing harm to a dog pretty much guarantees that you're going to go to hell. I don't give a crap if he's pissing on your bike or eating your shoes. You're wrong if you try and hurt a dog that isn't trying to hurt you.
Here are my suggestions:
Buy some decorative fencing thats about a foot tall and links together. You can easily surround your bike with it when you're not ridding it. Should cost less than 20 bucks.
Set up a video camera and capture the dog in the act more than once. If you are able to determine the owner of the dog from the video take it to the owner and show them. Allow them to correct it. if they don't, sue them in small claims court. You will win.
Park in a different spot and see if the behavior moves.
Live with it. It's a dog. Dog's don't piss on peoples bikes to make them mad. They do it because they are either trained to or something is attracting them to that spot. Trying to "get even" with the dog is a rediculous mind game you're playing with yourself. Tyring to "get even" with the owner by hurting the dog isn't going to hurt the owner. It's going to hurt the dog.
PS: I'm a dog lover.