After doing the engine assembly and engine installation on the bike, the next step is to "Break-in" the engine which is also known as run-in or running in, is the procedure of conditioning the engine by giving it an initial period of running, usually under light load, but sometimes under heavy load or normal load. It is generally a process of moving parts wearing against each other to produce the last small bit of size and shape adjustment that will settle them into a stable relationship for the rest of their working life.
Before doing the break-in, it is as important to do a pre-engine start check and fine-tuning, this means you will check the necessary bike and engine parts by riding the bike with the engine turned off and making the necessary adjustments on the brakes, chain, clutch, etc. to make sure that everything is properly tuned before the engine is started for the first time.
For more details about this, click on the link below:
Pre-Engine Start Break-In | Fine-Tuning The Mechanics Of Your Motorized Bike