Before breaking in your engine, we recommend draining the factory shipping oil, and filling your new motor with a mineral 10w/40 oil.
During this run-in period, the cross hatching left in the bore by the factory honing process, will act to shape the new piston rings into perfect conformity with the bore, therefore creating a good ring seal. This ring seal is crucial not only to the performance of your engine but also it's reliability and longevity. If the rings allow 'blow-by' gases to enter the crankcase area, an almost endless list of problems begin for that engine. Most of this piston ring 'bed-in' process will happen relatively quickly in many plain cast bores and once the cross hatching is gone, or diminished to a great extent, your chance to create a good seal will be gone.
This brings me to a slightly controversial topic...the hard break in. In order to achieve good pressure against the hatching in the bore, your rings need gas pressure behind them. That is how rings work. They do not hold back the combustion gases under their own 'springiness' as may be thought. The grooves in your piston where the rings sit are actually engineered to be wider and deeper than the piston rings themselves. This is to allow the expanding gases to get behind the ring and force, with great pressure, the ring against the bore. As the power increases, so does this action. You may begin now to see where we are going with this.
Now we do not advocate starting your engine for the first time and revving the pi$$ out of it. But we do recomend you well and truly load the engine up. Warm the engine for only a minute or two, then begin to ride in second gear and accelerate to about half revs, but accelerate hard, then get on the brake hard, back on the throttle and so on. Just don't overrev yet. You can see you will be putting good 'gas load' behind those rings every time you accelerate hard. After 15mins of this you should start revving through second gear to at least three quarters, and powering into third. Then hard on your brake, downshift to second again, then go through the process of revving through both gears again. Now be sure not to excessively overrev it yet.
After the first hour of running, dump the oil for fresh stuff ( it will be grey with bore and ring shavings) and give the bike a good half days ride. After a period like this, dump that oil again and switch to a good quality 10w/40 oil of your preference. Many guys like to switch to semi or full synthetic.
Till next time,
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