erohslc wrote: Beware! Just poking an allen key in and twisting the adjustment screw is likely to rotate the piston and rupture the rubber diaphragm that seals the piston to the carb body, resulting in an internal air leak that prevents you from achieving mixture Nirvana. What you *need* is the proper ZS adjustment tool, which features an outer sleeve and an inner allen key. The sleeve fits into the piston holding it steady to prevent rotation, while the allen key is used on the adjustment screw. In fact, it's possible that such damage has already taken place, visual inspection of the diaphragm is one of the first steps to take. And if the high fuel pressure is leaking past the float bowl valve, no amount of screw fiddling will fix it.
I still have my Stromberg needle tool in my 'weird crap' tool drawer. It gets strange looks. 
