Carb in Magician loose on engine seal

[Megadan]

Not a big deal with the wrong oil type. Maybe change the oil a bit sooner for the next go around just to ensure you got the rest of the "bad" stuff out, but it should be fine.

As far as the oil leak. Is it at the head gasket or the base of the cylinder where it meets the engine cases? This seems to pop up from time to time. You can check the head bolt torque to make sure one or two aren't loose. This will require taking the rocker assembly off, but it is pretty easy - 3 bolts. Then you will see the 4 head bolts. The torque spec is kind of generalized, but I have my head set to 28ft-lbs. Just go over them in a cross cross pattern like you would a 4 lug car wheel.

If that doesn't stop the leak then either the head gasket or base gasket may have been damaged during assembly. You can buy both as a pair for about 10-12 bucks on ebay.

As far as the bike starting, running, and sounding better. It's amazing what a proper valve adjustment can do ain't it?

The running issues you are experiencing aren't uncommon. To really get it to run properly it will require upping the main jet size to at least a 105, shimming the needle with at least 1 shim, and uncapping and turning the idle mixture screw out to around 1 1/2 turns from seated. This is a pretty good baseline carb setup for most stock Hawks and Magicians.