Here are a couple of four-stroke twins that are a complete mystery! My friend and colleague Ian Russell of Rustler fame was given them by a good friend of his who sadly is no longer with us. All that Ian can say is that his late friend was a car boot sale addict who found these two engines in that manner. He knew nothing whatsever about them.
As far as I can tell, these have to be products of the early pioneering era. Although now in somewhat deteriorated condition, they show signs of having been quite well made originally. They may well be home-made one-offs, in which case we'll probably never know what they really are or who made them. However, if anyone out there recognizes either of them, please get in touch using the appropriate email address!