You are going to hear 30 different ways to break it in, because there are different ways for different people.
That being said, here is my method I have used for all 7 smoker motors I've rebuilt.
*DO NOT use a synthetic blend oil for break in! A castor based oil is my weapon of choice. I use Castor 927 in two strokes.
*Remember, you WANT A LOAD on the piston the break it in! The "idling" theory does not put the proper load needed to seat the rings and seal it up. The "idling" method I can't undernstand.
My trick is the heat cycle break-in, 3 times.
*1st cycle: Ride the bike. Go NO MORE than 1/2 throttle, with NO hard accelaration. Ride the bike until it is to operating temperature like normal, then park it. Wait until it is cool to the touch (on the pipes/radiators). You want the motor 'ice cold', not warm.
*2nd cycle: Take the bike out again, this time go NO MORE than 3/4 throttle. Go through all the gears, NOT WINDING it out- short shift. Stay away from hard accelartation. Get it to running temp, and park it again. Wait for it to cool down a second time.
*3rd cycle: Take the bike out, this time go through ALL the gears, but don't bring it to redline. You can go as hard as you want in any gear, but don't hit the revv limiter. Get to operating temp, and park it. Let it cool down one last time.
After it is cooled down the 3rd and final time, take it out and tear it up. Like I said, you will hear X different ways for break in, but this is my choice. I have 7 rebuilds, ranging from rings, to piston and rings, to cranks, seals, etc. and not once ever had a problem.