Seriously.

I've ridden motorcycles in North America for 15 years, logging more miles on the bike than the car most years and commuting by motorcycle more often than not. 6 of those years were spent in California, so I'm used to splitting lanes and shooting small gaps.

Riding on Bali was still challenging. So many other bikes, moving in all manner of different directions, so many drunk riders after dark in Kuta...

Take a riding class at home. If you're American, the price ranges from free to $250. At least you'll have a general idea of how motorcycles handle before you have to ride one in left hand traffic with 5000 of your closest motorcycling friends.

Also, I know the locals don't do it, but there's nothing stopping you from wearing some f@#ing gear. I own plenty and just brought some, but a halfway decent jacket and cheap full-face helmet aren't that expensive.

That said, if you really want to get out and see stuff, the bike is the way to do it. Much like motorcycling anywhere else in the world, not being an idiot goes a long way to preserving your ass.