On the stinger a pull start maybe tight I start mine from the clutch side with a allen hex bolt and a kart starter like a modern kart The stock US 820 has real smooth power (no need for the copper head model ) always starts and runs..... If you get it with the Mac tapered shaft you can use a nice Horstman or Burco dry or oil clutch or use the clutch from the mac 49 sell the mac 49 on ebay .. for the older WB crankshaft the only new clutch is the Noram but get the billet drum...... but they brake clutch springs you can get those from Comet karts ..... .If you can get the new US 820 with the tapered shaft from dave Bonbrite not a used one I think they are around $500 a deal cause you can get parts when you figure the cost of a used engine and a rebuild ....the only part thats hard to find is a header to run a pipe but they make a nice repop muffler the motor mount comes from Comet karts you may have to buy the kit or just machine up the botton to the engine plate....You can see the engines on usmotorpower.com but order it from Dave ...These engines stock are VKA vintage ok ...I stopped running my macs way to fragile and tempermental
If you get an 820 with the stepped pto, 5/8 to 9/16 you can get a new Max Torque clutch from Jim Donovan at Max Torque, do not use the Noram, they break the hub after a while, especially if you modify the engine. Try and find an engine with the tapered pto, its a much better setup, the stepped crank also likes to break out the keyway. A stock kart version (Industrial) 820 puts out about 10 HP, the Vintage 820 (Copperhead style) puts out aprox 18 - 20 HP. I think the Industrial type is around $650.00, the Vintage 820 is $1300.00.
The Industrial type can be modified into a Vintage 820 with port work, piston change, head change, reed and carburetor change. You can get a header kit from Terry Ives.