It all comes down to how carefully a motor was put together and tuned I think. Back at the factory and now.
I've spent enough time with the Halls to conclude that these are all over the map. Their dyno gets used a lot and they are always willing to test a new tuning strategy, whether theirs or anyone's. 650's with single carbs from mid 20's HP to high 30's and low 40's. Twin carbs from the 20's to around 50.
How fresh is the motor? How are the cams timed? What size carb? Exhaust? Gearing? Even from the factory, I bet no 2 bikes were identical. I've never found any evidence that they dialed in camshafts. How many combinations could that result in?
Bottom line IMO is a careful build and the small details matter.
So, Tony, I have a pretty fair running 650 with 2 carbs. How bout it?

Last edited by Mike Baker; 07/18/19 10:39 am.