FWIW- I believe the "lightest" 4-stroke 15 hp, 15" short-shaft, manual start, outboard is the Suzuki 15 at 97 lbs (and same weight for the 20hp). It's EFI too.
In comparison, the comparable model Yamaha 15 & 20(carbed) are 111 lbs , which doesn't seem like all that much more until you start to carry it. Which, of course, is why a lot of us are keeping an eye out for even lighter good used 2-strokes.