If I can make some additional suggestions on your carb issues D.S.
The needles. They are notorious for "walking" in thier threading on STS carbs.
I think what happens due to the fact that the o-rings and seals, have to survive the durration of a proper break-in. This excellerates the ware and drying out of rubber.
The engine, and it's componnents, get these conditions of heat cycling, and sleeve seating, to season with. This will reveal the symptoms, of a less than well built product, in general.
I'm talking about loose bolts, nuts, leaky & loose seals, walking needles, fowled plugs, ect, ect. This can occure while a normal break-in takes place.
Weather your using the best supplies or not, checking all metal the metal threading and using blue thread lock will help stop the loose bolt issues from disturbing your break-in.
Granted, It is best to be using the recommended fuels, plugs, and such. But, your still going to need some preparation for a reliable engine seal. With STS's, sealing the engine is top priority.(so I've been told).
They don't get shipped in a well sealed condition, ever.
Durring all the over-rich heat-cycling, crank vibrating needle tweaking, the engine that was tight, is now likely to become loose.
I say this again as a generality.
The point to all this is?.... Getting your engine properly sealed BEFORE you break it in is a good move on all engines. But STS, even more so.
NEEDLES: Teflon pipe tape on threads only.
Green Slime on O-rings. RTV hightemp-nitromethane compliant silicon seal for sealing the crankcase rear plate, heat sink Head, carb flute, carb lock assembly.
If you can do this in the beginning, you will be insuring a less troublesome break-in and will be very likely to have Zero issues with tunning. (in general)
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