Hey Ig, I ordered one of the ubiquitous Chinese bicycle engines that are being sold all over the web. It turns out that these engines are partial copies of a series of Russian bike engines that were first made around
1959. I thought you might be familiar with these engines. If not then maybe you will find this link interesting:
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Even if you are familiar with these engines you will probably enjoy looking at the pictures of the engines. The Russian engines were actually better looking engines than the Chinese copies. I'd love to have one. Eric