Sportsman Flyer sprocket hubs are, arguably, the best on the market. They are designed to be used with Worksman wheels, again, arguably the best on the market.Tonight I took my brother's Sportsman Flyer 'broken' hub sprocket adapter and tested it on my rear hub. It definitely does not fit the 1.50" hub. I know they say 1.52", but I just wanted to make sure. Looks like the bolts bottom out before they completely tighten onto the hub. I can spin it with ease.
Darn...because I was going to chase the threads on the sprocket studs and fix it for myself!
Now I have to decide if I want to go with the gasbike 1.50" hub adapter http://www.gasbike.net/36-tooth-cnc-sprocket-adapter-4102-prd1.html (Does anybody know if it's actually 1.50 vs the 1.52 which is more common with the other brands of adapters?) or go straight for a new rear wheel (26" of course, which means a new tire and tube as well) with a 'proper' coaster hub and spring for the SF adapter since it bolts onto the hub more uniformly with 3 bolts vs 2.
Would this be worth my time? http://www.gasbike.net/CNC-Pineapple-Sprocket-Bushing-Kit-4153-prd1.html
Be that as it may, if you are fitting a SF sprocket hub to something other than a Worksman wheel and, as you claim, it doesn't quite fit (I'll asume by a few thousandths of an inch) then go to a nearby hobby store and buy some brass shim stock. It comes in varying thicknesses from a couple thousands to about twenty thousands, and typically they offer a multi-pack with some of each thickness size. You can cut it with sicissors to fit the inside diameter of the sprocket hub flange to wheel hub to take up the space.
P.S. Spend the money on Worksman wheels. You won't regret it... and Worksman wheels come with excellent bearings and are properly trued wheels with heavy 11 gauge spokes.