Small Engines (Lawn Mowers, etc.): Older Sears Roto Spader, libertymutual com, briggs stratton

Question
Hi -
I'm also a volunteer on All Experts, in the category of insurance, hope you can help. Saw your instruction note- by tag wire you mean very fine wire, like on a twist tie or a little thicker?  I'm a pretty handy gal,  
Got this for $40- old Sears Roto Spader, not of the same model that chews your legs off, but reverse gear was removed. It's got a 4hp 4 cycle Briggs & Stratton in it. Runs good not under power after I fixed the crack in the gas line connection, but when you put it in the dirt it's like it's not getting enough gas and quickly boggs down and dies.  Is slightly better since I fixed the gas line connection.  One suggestion I've had it to use a bit of STP Gas treatment in it to degunk the carb. Do you have any other suggestions (besides the above)  diagrams of how a briggs engine like this work, or anything that will help a gal with a rototiller out in the stix get it running proper? Appreciate your time. If you're responding during daytime hours, my work email is denise.krueger@libertymutual.com. Thanks for your help! Denise  

Answer
Yes, I mean a fine wire like the one inside a garbage bag twist tie.  Anything that will go inside the internal passages and will be stiff enough to dislodge any debris or varnish.  Carb cleaner will only really work as a maintenance procedure...if the carb is plugged, only mechanical removal (tag wire) will ensure it is clean inside.  First, if the carb is equipped with a high speed mixture screw (it likely has one), start with the screw at 1 1/2 turns out from lightly seated then turn it until the engine starts to surge, then open it 1/4 of a turn.  If the screw has little or no effect, this indicates there is a blockage inside the carb that needs to be cleaned.  Hope this helps.