Not on a motorbike, but in a spa bath from the water jets yes.
I've never had an ****** riding on a motorcycle but I have gotten very aroused from the vibrations. The vibrations make me feel like I want to pee my pants. I haven't done that yet, but I've thought about it.
yes to the jets, but you have to be positioned right up against it. and the motorbike, no, but it can get you really turned on. at least in my case.
The water jets can give me an awesome O. :)