OK, good find on the throttle cam…Sometimes those stamped cams get bent bacwards/out of the way if the carb butterfly linkage is stiff or jammed. That throttle linkage must be “syncronized” properly. In other words, the carb butterfly should be completely closed (cam not touching the throttle lever) at dead idle, and it must start to open the butterfly at just the right time…I can’t remember where the throttle lever needs to be set on this engine when the butterfly starts to open, I’m sure someone will post the instructions. The engine will not idle properly if the butterfly is cracked open slightly at idle speeds, or will will run rough at mid range speeds if the the butterfly is set to start opening too late.
So, the first step is to check and adjust the syncronization, once someone kindly posts the instructions.
Once syncronization is set properly, I would put the engine on the boat, then try to adjust the needle. Warm the engine up at WOT, then slow it down to the lowest speed it will continue to run on its own…Set here, I would make very fine adjustments, try closing the needle 1/8 turn and let the engine run a bit…If quality improves slightly, then close the needle another 1/8 of a turn and continue this process until the engine starts to falter.
If the engine runs worse when you first close the needle 1/8 turn, I would try opening it 1/8 turn and repeat the process described above. Make sure that packing nut is fairly snug so the needle is a little tough to turn…Not too tight, but snug. You don’t want the needle packing to be too loose or the needle witll turn on its own and could suck air through the packing nut.
Finally, you need a higher water level in that tank….The water level should be above the gearcase/exhaust housing joint. Running the engine with the low water level in your video could destroy the rubber water pump impeller…
