Here is a rare one for you. This is a vintage 1961 A. Stihl model 6507 go-kart motor/engine in good complete condition. This is pretty much the same motor as the they used on the Stihl 090 from what little information I can find on it.
This turns over freely with with the pug out and has good spark. The compression is very strong. I can pull it over well once and the compression builds so strong in the cylinder it becomes nearly impossible to pull over well.Really needs a compression release. I did not get it running but sure it won't take much. It is going to be a long time before you ever see another one offered. The item "Very Rare Vintage 1961 Model 6507 A. Stihl Go Kart Motor Based On Stihl 090" is in sale since Saturday, May 23, 2020.
This item is in the category "eBay Motors\Parts & Accessories\Other Vehicle Parts\Go Kart Parts". The seller is "glennerdog" and is located in Newport, Oregon. This item can be shipped to United States, Canada, Bahamas, Uruguay.