Try Sea Foam in your gas its cheaper and IMO better than Quickleen. If you have a horn motor I would assume you have a nicom coated engine sleeves, move to the 100% syn Pen. it has less ash content and is less likely to clog the elbow as quickly as the blend. There could bes something else going on, might try lapping your cages on a sheet of glass with sand paper then after flat go to a TDR reed ( .022" ) they seal,idle and live better for me than any other reed I've ran.

BTW: It is VERY common and almost a MUST for there to be some oil/fuel in the rear of the buterfly, after all the plenium takes a suction on the middle main bearings drafting oil/fuel/ and some exhaust from under the piston and routes it through the series of tygon tubing to recycle through the intake system, there will ALWAYS be some amount of oil/gas residue there if not your crank middle mains bearings will be toast shortly ! With this system that small hole IS going to be fowled every ones in a while, the nature of the beast..

Good luck,
Jay