I'm trying to find out where I can get the proper size aluminum spinner for my US Engine 41cc. I wanted to buy another 3in spinner I got off Amazon that is installed on my DLE 35. It fits perfectly around the prop on the 35, however, on the US 41 the prop bolt shaft is smaller, 5/16 so the spinner mounting plate hole is too big. Every site that has spinners does not specify the back plate hole dimensions. Is there an insert ring that can be purchased separately?

Its normal to use a bushing in the spinner backplate to reduce the hole diameter. Smaller spinners often have 1/4” holes and larger spinners have 3/8” or 10mm holes. Many times these bushings are provided with the spinner but if not they are usually sold as an accessory. If you can’t find one, many of us have spares and would probably just send you one in the mail if you make a request with size needed.