Break in period

was92v · 10-11-2009, 11:13 AM

Do you guys think there is a difference between a new engine /gearbox and rebuilding an engine that all the other hundreds of parts are already run in?
There are hundreds of friction points in a new engine/gearbox that are lapping in besides the cylinder walls, piston skirts and rings in a new motorcycle engine/gearbox that are not at all a concern when rebuilding a used unit. I worry more about gear tooth faces, dog surface and bearing run in, than the ring to wall seal. With the rings and the cylinder finish used these days, unless something was screwed up when it was built, the ring/wall seal in a done deal almost as soon as you start the engine. After rebuilding an engine, a couple of heat cycles to shape the piston is about it. All the rest is already done.

10-11-2009, 11:13 AM	#16
was92v Nowhere Man Join Date: Nov 2008 Posts: 558	Do you guys think there is a difference between a new engine /gearbox and rebuilding an engine that all the other hundreds of parts are already run in? There are hundreds of friction points in a new engine/gearbox that are lapping in besides the cylinder walls, piston skirts and rings in a new motorcycle engine/gearbox that are not at all a concern when rebuilding a used unit. I worry more about gear tooth faces, dog surface and bearing run in, than the ring to wall seal. With the rings and the cylinder finish used these days, unless something was screwed up when it was built, the ring/wall seal in a done deal almost as soon as you start the engine. After rebuilding an engine, a couple of heat cycles to shape the piston is about it. All the rest is already done.