Article and write up by Dennis Mears / Flotek Performance.
In this article I'm going to discuss engine break-in .what it is why it's needed and the proper way of doing it . There are several methods people have used, this is only one and my preference that I prefer to use. Engine break-in is basically a procedure to allow for the thermal expansion of the rings and cylinder wall to wear in the moving parts to themselves to obtain a good bore seal. This is critical to the performance and longevity of the engine . Assuming all the Assembly is complete and all the proper testing has been done, you can begin the break-in process. It is a good idea to start with fat jetting (specifically a larger than Normal main jet ) and work your way down. The main jet is the real circuit to be concerned with. Be sure to use the same oil premix ratio you would've typically always use. I'd recommend 32-1 and good castor based oils such as Klotz or Maxima .Its important to be sure all nuts are torqued down to spec. Basically this is a process of repeated heat cycles followed by running the machine on a light load for short periods of time to promote the thermal expansion were looking for . Keep the bike in neutral after a short run at Idle to a quarter throttle for several minutes, now it's time to shut it down .I like to do this three or four times over the course of a day, allow 15 minutes or so to cool all the way so the pipe is near room temperature. I like to put a fan aimed at the cylinder especially for a air cooled engine during the cool down process. Once that is complete you can take the bike for a leisurely rides but never holding the Throttle wide-open or doing extended high RPM runs for too long you want to gradually increase the load and rpms as you do this. Its now a good idea to check what the plug or plugs look like as far as jetting. You want to look for a cardboard color on the porcelain with a 2mm tall ring inside. Also it's a good idea to re-torque the head and base nuts just in case they worked loose .Many people baby their bikes during this time and their bikes don't last as long and never really run right to their potential in my opinion. It really doesn't take a long time to do this and its unnecessary to burn several gallons of gas through. In my experience one tank of leisurely riding should be more than enough gradually getting higher rpm's and running it at higher speeds for longer times it's better to just ride it hard as you always do and don't baby it .You want heat and wear to occur not a glazing effect on the bore. At this point you can ride it as you always do and continue to monitor engine temperature jetting for good measure and peace of mind. Do a plug chop to confirm jetting and that everything looks OK. Dennis Mears