The engine has BS stamped in the front cover, and by the looks of the head bolts, it's part of the 23, 230000, 240000, 300000, and 320000 engine families. It seems to have some form of two piece Flo-Jet. It also comes equiped with a small oil-bath air cleaner.

After pulling the head off, I measured the bore at 3in and stroke at 3.25in. which works out to 23cu/in.

The cylinder is cast iron and bolts to an aluminum base plate/oil sump. The head is also aluminum.

It has an internal magneto with points under an external cover next to the carburetor.

So...have any idea what model is it? If you know, please email me.

10/6/2002: I finally figured out that it's a Briggs & Stratton model 23 engine after another fellow showed that I had done the math wrong for the displacement (I figured 14cu/in instead of 23), and with that I was able to track down the engine model based on the displacement and ignition system. I have scanned a copy of the parts list for this engine in PDF form here.