The Fleetwin model started in 1928 and rated at 6hp. In 29 they were bumped up to 7hp. Note sure if they made any mechanical changes or just upped the rating. The 29 models were 1F to 4F. The cylinders were initially copper plated. A nice look.
My Fleetwin is 1F044. It’s a strong running engine although a bit loud. They don’t have a water pump and rely on a pressure vacuum cooling system. Motor needs to be running on a boat to cool. I have found that they don’t cool well below 1/2 throttle.
I can post bore and stroke a bit later when I get to my books at home.
Congrats on finding an early motor.