There are a number of these bikes in the country now thanks to eBay and the crook US dollar. It's a pity they aren't very good on our dirt tracks tracks. They've got a class for them on the Long Track circuit that is getting stronger all the time. Quite a few XR750 Harleys are turning out as well as the Triumph and 750 Yamaha stuff.
I've got a similar Trackmaster roller to that. It's way down the pecking order on my projects but I'm going to use a 650 Benelli engine when I eventually get to it.
My mate Jonsey has a genuine Trackmaster serial # B1 which was verified by Ken Hemsley himself to be the very first frame he built for an A65 BSA engine in 1968. Alan got it from NZ with the ESO engine in it that's now in Black Betty. He plans on restoring in with an A65 engine once he's completed the 15 projects he currently has on the go. His Trackmaster Nourish 850 is nearly ready and he would have taken it to CD5 if there would have been a DT part of the program.
