If you want to go a different route, ie, a small electronic tach + hour meter, look at Tiny Tach.
http://www.tinytach.com/tinytach/index.php
They can be bought for as low as $40 from eBay and Amazon and other places, are easy to hook up with an inductive coil wire wrapped around a spark plug wire, have an internal battery supposedly guaranteed for 5 years and are totally waterproof, small enough to be mounted anywhere. I saw them on a jetski forum and another bike forum and they seem to work just fine.