The first time I saw that frame I had to have one.
Got in touch with my good friend Denis Curtis, of CMR fame, to build me one.
So as it turns out: they couldn't keep rings in the thing. The frame set up a sympathetic vibration in the motor that made the rings flutter. If the rings lasted the whole race, the bike probably won, but the bike dropped out of a lot of races with ring/piston failure.
... and that's why they only made a couple of them. Coolest LOOKING TZ frame out there
i'm very dubious on that explanation of ring failure. If true, its one of the most bizarre explanations i've heard, and how did they prove it?
I reached out to Tony F, he calls bullshit on that explanation (wherever it came from). I was just curious to the validity of that story. He may reply here. 0.02
Reminds me of a certain engine on the dyno that broke the top coil on some valve springs.
They blamed it on the dyno vibration.
Beehive type spring and the top coil is coil bound at assembly, with zero lift.
So essentially zero added stress while running 6400RPM.