Stumper, Your description on the progression of the PP sounds right on.
The one I had from Thechnic had a Mac commercial engine, it came from a Mac dealer, that was a good little engine suprisingly enough from Mac, never gave me a lick of trouble, clutch shoes broke in it though and just couldn't find parts, searched high and low for it too.
Got a news flash update on this PP thing we got going here.
My HT-75 didn't finish the season liked I hoped it would.
The HT- 75 is now history, been replaced by the HT-101, with a 2 cycle, 4cycle engine with adjustable valves. Engine is a little bigger, though not much, suppose to have more torque. Oil system to chain and bar the same as 75, (needs improving IMO), chip discharge has been changed, still has that same crappy grip though, it's also gained a pound in weight.
This is going to be my first experience with a 2 cycle 4 cycle engine . They put the choke in a good spot, of course we have to have those limiter caps. It doesn't seem to be cold blooded, but it is still new. The engine has a different sound to it, not like a normal 2 stroke, but it is queiter though doesn't have that 2 cycle scream. The acceleration is mediocre, almost poor, but it is not a true 2 stroke. At idle you would swear it is going to load up and quit, but it hasn't so far.
As of this post it is still cherry and untried ( it's raining here today)so I really can't say how it performs doing trees. Everything works good when it is new, we'll see how it does in a couple of months.
Almost forgot to add this, the bigger engine and exra weight does seem to help in balancing the thing a little better, it is still a little tip heavy for my taste when it is fully extended.