Hey Spinach,
Yeah, mine did have a mechanical governor... disconnected now. The motor will over-rev if you let it. I will be the first to admit that I dont know a whole lot about carbs, and Bean is most likely a whole lot better to ask about this than me. I'm just going on what the mechanic who actually did the work told me. He was a heavy truck mechanic for 20+ years. Maybe he was just tryin to jack up the bill by talking me into a rebuild on my 750, I dont know. He did try to re-jet the 570 a couple of times and couldnt get it to work. There was a nasty whistle in the carb when you first cracked the throttle, and absolutely no torque. I came down to the shop and checked that out myself. The rebuilt 750 is really doing an impressive job.. 70mph with no issues, and good pick-up off the line. As I am not a mechanic, and the motor is running great for the first time in 2 years, I dont think I'll do any experiments!! Yknow, let sleeping dogs lie and all that. I have no idea how to incorporate the old governor system with a new carb. I just keep an eye on the tach!!