The break-in period comes down to the piston rings and how well they settle within the cylinders. To get a good fit, the rule of thumb goes something like:
- Avoid full-throttle starts and rapid acceleration
- Avoid engine speed to exceed 4000 rpm
- Avoid hard braking for first 300 km (200 miles)
- Avoid driving at constant engine or vehicle speed for extended time
- Avoid towing anything
- Follow manufacturer's recommended oil change interval
If you're not a rule of thumb kind of person, check out this site for something different:
http://www.mototuneusa.com/break_in_secrets.htm