Mercury doesn't have a high altitude / alternate jetting selection in their parts diagrams. I already removed the plugs covering the idle air screw to try and get the mixture dialed in better, but it has negligible change, which tells me the jetting definitely is off (seen this before with re-jetting dirt bikes for the same altitude many times). I did a little more digging and this a Teikei carburetor, which makes sense as the power head for this motor was made by Tohatsu. The Tohatsu parts diagram for their outboards shows a different carburetor than Mercury, so it's unclear if these jets would be compatible with my carb. Does Tohatsu offer alternate main and pilot jets?
