i got mine to dive underwater once. its a combination of things.. you pretty much jjump it out of the water and nose dive in real hard, but you have to be able to push the front end down.. its hard. they are a blast though. and yeah my modified 440 has an automatic bilge, my 550 has a manual.. the 550 will fill up if you wreck alot, jsut gotta bilge it every once and a while.
you can get them brand new for $5900 the kawaski 800cc standup, but im cheap and wouldnt pay that much for one.
but i found one on ebay if your interested.. dude lives in grove city.. looks like a good deal. id definately take a look at it, see whats up. if you need someone to go wiht ya and chekc it out hollar at me. he said it needs a battery and the carb cleaned. ill bring a batter of mine, and some starter fluid and carb cleaner. anyway heres the link
http://cgi.ebay.com/ebaymotors/1990-Kawasaki-550-SX-jet-ski-jetski-stand-up_W0QQcmdZViewItemQQcategoryZ56422QQihZ008QQitemZ180002026820QQrdZ1QQsspagenameZWDVW