25 Hours before opening up
what actual happen when running a motor in is to polish and adapt all components to each other
it means it have to grind and form (molecular level) to each other to get the rough edges off
that is obvious more friction thus more heat generation
you don't want to load the engine to much as it could get in the danger zone
bearings are already pretty OK when they come from the factory and don't need that much time to really getting better performance.
When changing bearings in an electro motor the motor is started afterwards and normally on full work load (no running in period in this case)
when you measure the temp of the bearing you will find out that the new ones are doing way better then the old ones.
in a motor engine what does matter is the piston cylinder combination (axial movement) first you need to make sure that the clearance of the piston and cylinder is in the right specs (piston does expand more then the cylinder).
second you have to lubricate a bit more to take care of the increased friction.
heat cycles are done to give the parts time to contract and expand in several stages so they are getting more evenly used to each other.
also it controls the heat part better in the very early stages of the adapting process)
after an hour of riding (not loading the engine to much ) you should be fine of loading the engine.
still lubricate a bit more then normally for the first 2 a 3 tanks of petrol (and adjust your jetting a bit (to the rich side))
This is for a 2 stroke
A four stroke takes a bit longer as there are more friction points in the form of axial movement (so more heat generation for a longer time span).
there is also less lubrication in the piston cylinder process (one of the tricks you can do is increasing the cooling process of this specific part of the engine)
yet this is not practical in the most cases when it is a motorbike.
Robert-jan