[Tim Hancock]

I am not sure how the boat carbs are set up, but standard motorcycle type carbs will not run completely dry unless you drain them from the float bowl screw. While running them till they quit "may" prevent the tiny pilot jet orifice from clogging, it will leave a small quantity of fuel in the float bowl which can then develop chunks of crap as the the fuel deteriorates. When the vehicle is re-fueled and started in the next season, there is a very real chance that the chunks of congealed crap can get suck into the main jet causing the engine to go severly lean. This exact scenario happened to me two years ago resulting in a seizure in one cylinder of my old snowmobile. When I tore it down to rebuild, I found little lumps of congealed crap gas in the float bowls.

Similar thing happened in my ultralight last spring.... The d@mn thing quit while climbing out nd luckily I got it down safely in a farm field just south of my house. I found congealed lumps in my float bowl... luckily I did not damage my engine.

The best surefire way to deal with the problem IMO is to drain the tank then dump in a gallon or so of AV gas. Then run the machine long enough to insure that the whole fuel system including the float bowls have cycled through to the point that the whole system only contains the AV gas.