RPM Limits on new bike

I've read several articles telling its better to trash a new engine when warmed up. The piston rings should seal better afterwards. The gradual approach is supposed to be a legacy from the 2-stroke era.

I did it the old way though

[embee]

Originally Posted by Stef

I've read several articles telling its better to trash a new engine when warmed up. The piston rings should seal better afterwards. The gradual approach is supposed to be a legacy from the 2-stroke era.

I did it the old way though

I'll not comment on those articles, I can only justify why the engine industry (after all, what would the people who design, develop, and manufacture engines and components know anyway ) uses basically similar break-in procedures.

The process is about getting controlled wear during break-in so that surfaces eventually conform. The surface finishes on components (mainly rings and bores) as machined are specifically produced to provide an appropriate wear regime.
In the early stages the high spots are in contact, and will wear away nicely. The oil will prevent the metal molecules bonding providing the oil can withstand the contact conditions. However, because the contact pressures locally are very high, if the sliding speed is too high it generates too much heat, the oil can't survive, and you get micro-welding and tearing of the surfaces instead of simple wear.

Therefore you start off for a short time with low speeds and loads to let the wear surfaces get a bit larger to reduce the contact pressure, then gradually increase speeds and loads to maintain the wear process until the true contact area is big enough to then continue with normal wear rates. This ensures the optimum performance, oil control, blowby control and lifetime of the engine.

That's why it's important to use higher loads and speeds towards the end of the break-in, otherwise the surfaces can polish before there's an optimum contact area developed.




.........but hey, it's your engine.

Very well written embee, a good clear understanding of what is going on during those 1st. 1000 miles or so.
I'll bear this in mind when my running in is due.

Another good point I'd say from friends who work with greasy bits n a suzuki dealer who gave me a decent explantation was that the oil first in, that is the oil you ride away with new is much thinner than the regular normal oil you'll have after 1st (500mi) service. So don't cane it with the thin oil. Make any sense? logic? I think there's something in there