I know, I'm a glutton for punishment but I decided to be a guinea pig again and bought one of those cheap Dyna DS1-1 clones for my 400F. I had to finish the machining to the rotor that came with the Tytronic and guess what? The rotor that came with the cheap dyna clone didn't fit either but it wasn't because it wasn't finished, but rather it's bore was too big to fit properly on the 400's mech adv. Thinking that maybe they sent me a rotor for the advance on a 550/750, I went through my spare parts and found the advance mech for a 750 ....... but the rotor was too small for it so on the lathe it went to open it up. Once I got it fitted and installed on the bike, it runs great. Longevity remains in question but so far it's lasted twice as long as the Tytronics did. Right now I'm sorting out carb tuning issues but I'll make a separate post for that.