Wow Patrick, great insights. I have to say that I find most everything they did for the 1977 engine redesign was a mistake. Now that was AMF money allowing the change, but the same Harley engineers, who must have had their brains taken over by space aliens in 1970. Another fiasco was the late adoption and crazy disk brake program 1973 on. I don't think they had a decent front brake until the late model setup in 1984. And I note the -75 part numbers on the 1977 case parts that showed they wanted to release the engine in 1975, not 1977. So that gave us the kludge monstrosity brake and shift setups in 1975 and 1976.
There were also some warning signs. The 1970-71 wet clutch and cone ignition were a bad idea as well. I guess your observations explains why so many young guys are snapping up mid-sixties Sportsters, they sure run and ride nice. It always seemed to me a 900cc engine was happier than the 1000cc. Oh yeah, that reminds me of another festival of incompetence, the 1972 one-year-only 1000cc heads and barrels.
Those Pohlman Studios pictures of yours are a treasure trove when it comes to figuring out what they built. No wonder Harley cried when you would not give them back. Does anyone know if Harley has one Sportster saved brand new for every year of production? That would be great to see.
I know about auto factories "stuffing the channel" as they called it. They would pressure the dealers to order as much as they could in the slow time, with the promise of giving them the hot product when things went on allocation. For GMC, that was 4x4s in the spring. If the dealer took a lot of the dog stuff the year before, they made sure he would plenty of 4x4s come spring.
The production Sportster numbers
on this very site surprised me, how sales dropped off in 1954, 1955 and 1963. Harley may have been in the black every year, but I am sure they were losing money on K-Models and Sportsters many years. Since 1969, Honda CB750s sold about 50k a year. And they had a disk brake and a 5-speed transmission. Its sure hard to finance design work when you only sell a thousand bikes. The way Harley stayed in the black every year was by starving the engineering department. Another example of the finance Whiz Kids from WWII ruining everything they touched.