I've had the DT 3.5hp which was the forerunner of the DT 4hp which I think you will find is the same as a 4hp in most other old 2-strokes... i.e. a size bigger than the very narrow 2hp-3.3hp models.
I'm going to take a guess that a 2hp-3.3hp will be around 12-13kg and the 4hp nearer 20kg.
Edit: Here's a Suzuki 4hp... 46lbs the guy says and you can see how much wider the hood is than the 3.3hp and 2hp.
And here's a narrow 3.3hp Mariner at 25lbs...
I've found this... very light weight and no starting issues...