Another email from Viktor: "I´m working on two Norton projects that I have found in the Czech Republic - the earlier one is a side valve Norton with a plain bearing conrod (engine no 6581), the other a flat tank Model 18. Unfortunately, both projects have incomplete frames as they have been crudely modifed to take saddle tanks or rear suspension. I've now invested into patterns of the headstock and I can offer machined castings for around 240 euro. The castings are beautifully made and are cored castings in SG (spheroidal graphite) iron, which whilst not exactly as per Norton (who used so called black heart malleable iron) will be easily strong enough for the job. In more detail, the castings were made from 42CrMo4, based on chemical analysis on parts of the original frame"