11hp Briggs and stratton synchro balanced gear placement?

I assume you are speaking of the horizontal crankshaft engine with the two weighted synchro balancers in the "bottom" half of the crankcase.

Assemble the camshaft and crankshaft into the engine ensuring you have left nothing out and then rotate the crankshaft so the piston and valves are at top dead centre.

On the outside of the lower crankcase half (housing the synchros) are two 3/8 inch self threading bolts. These are 1 each directly behind each synchro. Obtain a couple of new 3 or 4 inch nails (can't remember which) and pass one gently into the vacated hole behind the synchro. Applying gentle pressure to the nail, rotate the synchro until the nail travels into the timing hole in the synchro. Do this for each synchro and, with the piston still at top dead centre position, gently join the crankcase halves, moving the crankase back and forth slightly to mesh the gears.

Bingo! You've done it. Remove the two nails and replace the 3/8 bolts using a good quality thread sealant. Take care, these do strip quite easily.