Thanks Leo, your engine is a model 92908 made on the 9th of June, 1986. It is 9 cubic inches displacement (148 cubic centimeters), a third generation design, with a PulsaJet carburetor, plain main bearings, and a recoil starter. The 92908 had a vertical pull geared starter, and an automatic choke.
The first thing you will need to check, is that your engine's flow of cooling air from the fan on the flywheel, is not being obstructed. To do that you need to remove the cooling air cowl (the black piece of sheet metal with the numbers on it). The cowl is retained by 3 small, horizontal, hex-head screws, one on the "front" (just above where the speed control cable attaches to a steel plate at the top of the carburetor) and two at the "back" (at the two bottom corners of the cowl, at the points most distant from the front screw). The three screws are all identical. However you cannot get access to one of the back screws until you remove the vertical pull starter. The starter is retained by two horizontal screws. The back screw is the same size as the three cowl screws, and the front screw (deeply recessed because it is just above the top of the fuel tank, in front of the fuel filler) is a size larger. Note that all Briggs and Stratton screws are inch sizes, not metric. When you remove the two starter screws the starter can be lifted off the engine. The cowl cannot be removed until you detach the speed control cable from it: it is retained by a single screw on the front of the cowl, right near the front cowl attaching screw. After freeing the cable, the cowl can be lifted off. Please post pictures of the areas under the cowl. There will be a lot of cooling fins, and we want to establish whether they are obstructed by things like dry grass and/or wasps' nests.
