I have fabricated a mount for my Ryobi 4 stroke 26cc from pieces of 2"x4" aluminum rectangular stock, obtained from the scrap yard for $1.00 #. First step is to turn the rectanular stock to a U stock, by cutting off one side. ( Or if you can find the right size U stock, you skip that step! It is all done with a band saw, drill press, and files. Took one evening and weighs 8 oz. Unlike the Jag Mounts which are attached to the oil pan, and a small mount for the stock muffler, mine mounts to the crankcase behind the flywheel, where the original fan housing was. That is after all where the engine was designed to be mounted. I will post a picture of the orginal flyweel mount(which was trimmed down and used for a pattern) and the face of the rectangular stock mount that I made. Another piece of rectangular stock then is trimmed, and attaches to the firewall to meet up with the mount on the engine, and done.

.My Ryobi is on Dynaflight Fly Baby ( about 80" wingspan) and weighs around 12#. The engine is not broke in yet, but turns an 18x8 at 6000rpm, and flys great! Stock carb and homemade muffler. My engine is the series with the plastic oil pan.