The only issue when washing any vehicle is making sure not to get water in the cylinder. With motorcycles this is much easier than a car (open exhaust and possibly airbox). On the ninja, with it's factory airbox and snorkel, you only have to worry about not getting water in the exhaust....
I would love to take like an hour, wash the bike with the garden hose, dry an wax it all, but I rarely have time for this. So I usually roll a "chain lube", and wash into one. I take her home, clean of the chain with de-greaser, ride to the self-wash, take 2 minutes to power wash, ride back (the long way) to heat up the chain, spray on the chain lube (if the chain is the right temp, my lithium grease bubbles into the crevasses), and polish up the muffler. Total time: 30 min