Motorcycle Engine "Break-in"
The "Motorcycle Extremist" Way!
The question of proper engine break-in procedure is raised on a regular basis on many forums. People needlessly create new threads in an attempt to gain information on this topic, and without even thinking to use the forum search function and a general internet search tool first. Because of this, and to assist anyone that may need this information, I'm making this document in the hopes to create a place where people can gain a good general understanding for this subject. I have been studying about and working with engines for over 30 years, and I have paid especially close attention to the area of engine break-in. I've taken this experience and created this article and break-in procedure to assist anyone that my need this information. I have deliberately left out any extraneous technical details in order to keep this article concise and to the point. If you'd like to study this topic more in-depth just to quench your curiosity, a simple search on the net should get you what you need. I will include a rather well defined set of instructions in this article for what I consider to be proper break-in procedure for the modern motorcycle engine.
You may be wondering why proper break-in is so important, and why you should be interested in doing it correctly. In order to answer these questions and to help you gain a better understanding of the what, why, and how of engine break-in, I'll provide a little background information to give you a basic and fundamental understanding on the topic.
Breaking-In is the name given to the process that occurs during the first miles of a new vehicle's operation. In particular, internal friction in the engine will be higher when components are new. Later on, when continued operation of the engine has ensured that the components have 'bedded in', this internal friction will be greatly reduced. A period of careful breaking-in will ensure lower exhaust emissions, and will optimize performance, fuel economy and longevity of the engine and other motorcycle components. During the first 500 miles (800kilometers):
Every new engine has internal components that must be "worn-in". This "wearing-in" of components is what's known as "break-in". The main components that need to be broken-in/worn-in are the valves, the cylinder bore, and the piston rings. These components must be worn-in so that they mate properly with the surfaces they will interact with over the life of the engine.
The Valves -
If the valves are not worn-in correctly, they will not seat correctly against the combustion chamber of the cylinder head, which will lead to a loss of compression and proper combustion, allowing blow-by of gases, which causes a loss of power, efficiency, reliability, and longevity.
The Cylinder Bore and Piston Rings -
The cylinder bore of a new engine is somewhat rough, and the piston rings are not properly mated to the cylinder bore. Some of the cylinder bore roughness must be worn down and smoothed out in order to create just the right amount of seal between the bore and the piston rings. Also the rings must be worn in correctly to mate with the cylinder bores. This process must happen properly in order to create the right kind of seal that will keep the combustion gases separated from the engine oil, and vice versa. Furthermore, if this wearing-in process does not happen correctly, the cylinder bore walls can glaze over, which will cause a lack of lubrication between the cylinder bore and piston rings, leading to overheating, a loss of performance, premature wear, and a loss of reliability. If this glazing does occur, the only way this problem can be corrected is for the engine to be torn down, the cylinder bores re-honed, and new piston rings installed, after which they must of course be broken in correctly, or it must be done all over again until it is. So you see how crucial proper break-in of these components actually is.
Quite simply, these engine components must be properly "worn-in" to ensure good performance, reliability, and longevity; it's really just that simple. If these parts are not worn-in correctly there will be a loss of performance in every way. There will be a loss of power, poor fuel efficiency, increased oil consumption (burning oil), among other problems.
Read the above article carefully and next time, before starting any threads, kindly do a little bit research....