quote FrankR:
If adjusting the high speed needle has no effect, the gasket may be missing on the main nozzle. But more likely is it is just open way too far. It will run rich till you get it somewhere close to optimal setting, then it will make a difference as you fine tune it. It closed down too far, it will cut the gas off and it won’t run. You obviously haven’t gotten it that far leaned out yet.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.