the K4 starts and runs but it runs at 2/3 power and does not have any top speed. It also does not idle well and wants to stop when trying to get down to idle speed.
You might want to get in touch with Lincoln Davis of Pine Tree Boat Club for some operating hints. If you can find it he posted an account of running a K4 on a boat
some time back. The two part carburetion set up would see to require just the right touch for best results.
Louis