Is this an AMF roadmaster? it's got the star chain ring. but I think I've seen hiawatha with the star chain ring too.
The only serial number I can find is on the bottom bracket.
J00001
I saw a hiawatha seneca with the star chain ring and the same guard, so I've been kinda confused if it's even a roadmaster. the guard looks exactly like that, but there was never any paint on it. it's chomed...
The late 50's and later AMF made bikes don't have a sequence to the serial number that IDs the year. If on the bottom bracket, check to see if there's numbers and a Cw to the right.
But there are a few characteristics that can get pretty close to the year it was made.
RustySprockets is right on, the chain guards and sprockets help narrow it down. Late 50's was the spiral sprocket, then came the star sprocket, mid 60's came the sprocket with squares in it. The exact years they switched is not known.
Your seat post is also a late 50's early 60's style. It tightens like a handlebar stem, no collar on the seat tube to tighten. In the 60's they began using the collar like other bikes.
Many Western Flyers were made by AMF too. They were the same bikes but had different head badges and model names, usually on the chain guard