Posted: Thu Sep 13, 2007 1:25 pm
Well there you go never to old to learn something new.jrdudas wrote:I know that there are two schools of thought on the break-in period. Some folks at the Ninja 250 forum stand by their opinion that you should ignore the maker's recommendation and ride it the way you normally plan to ride. For me I try to buy used and don't worry about break-in.
As for varying the RPM; that may be a valid practice for a number of reasons, but I don't think that the forming of a ridge in the cylinder wall is one of them. A ridge will always form in the cylinder wall and the placement of that ridge is determined by the point at which the piston stops its upward movement. The ridge will be found where the top-most piston ring reaches its maximum height. Theoretically the piston rises to the same point on every revolution without regard to the RPM. The physical distance from the crankshaft journal (where the push-rod attaches) to the top of the highest piston ring does not vary.
What does vary with RPM is the wear on crankshaft bearings, valve seats, camshaft lobes, valve lifters, timing chain, and piston rings.
For more detailed break-in information on the Ninja 250 specifically a lot of data can be found on the Ninja 250 forum.
JR