After break in (actually a couple hundred miles should be more than sufficient) you can run at 40/1.
Any good name brand two stroke oil for AIR COOLED ENGINES is good.
Don't use the stuff for outbaord motors.
Synthetic you can run at 50/1 after break in.
Running too much oil in a two stroke is as bad as too little, but for different reasons. You WILL make a massive carbon build up, which will ruin plugs first, but eventually it will clog the exhaust, make the ring(s) stick (really bad) and more.