As far as I can make out, the term "Diamond Edge" was only applied to the 60 series (i.e. 190 cc Intek) engines. There is some suggestion that "Edge" related to the 190 series specifically, and "Diamond" indicated a cast iron cylinder liner. Note that in the Inteks with model numbers beginning with 8, there are both cast iron and aluminium bores, depending on model. The advertising people, in their usual fashion, call the aluminium bore models "Kool-Bore".
If you open the crankcase Mark, I would be very interested in the camshaft, especially the decompressor mechanism. As far as I can tell from the manual, it uses the same decompressor as the bigger Inteks and the Vanguards - a mechanism which seems to lack long term durability. Some detailed pictures would be useful to us all.
