Engine break-in and seating of rings...

I like to fully understand things or it bugs the crap out of me. This might be a question for the pros out there like Paul and Kirby.
I know that honing cylinders helps the rings seat but I don't think I fully understand what is happening when the rings "seat".
I think the honing roughs up the outer surface of the steel inside the cylinder walls and then the new rings wear in together with the roughed up steel of the cylinder walls to make a new perfectly air tight seal.
Am I correct? Or am I missing something?
Do the rings rotate at all when working in the cylinders or do they stay exactly where they are placed when installing them?
And why are you supposed to vary engine RPM's during break-in? Is it because that puts force on the pistons/rings at different locations within the cylinders to help the rings perfectly seat?
Why is it so important to break-in a new engine? What is it exactly that causes problems if you don't break-in properly. Thanks guys!

Here you go...

New Engine Break-in Procedure

Excellent article, thank you!

well there is alot going on in a cylinder . and yes piston ringgs will rotate to a point but not constantly thats why we stagerthem as well but also to create a seal . rings wear in to a point but its the cylinder that is softer than the ring. when we vary rpm we vary cylinder pressure ! rings expand and contract ! when cylinder pressure changes ! also in an air cooled motor temps change in drastic messures. cause there is no cooling system to keep cylinders at constant temp. in reality pistons dont wear as much as the bore does due to how hard the rings . but the rings take the brunt of the abuse at break in it real easy to ruin and micro weld the rings at break in . the best thing to do when breaking in a air cooled motor . if your jetted correct is to ride it very mellow than to sit and let it idle with a fan on it and then shut it down and repeat . your better off riding it down the block and back have a beer and repeat . you and your motor will be much happier and have a good buzz going.

Thanks Paul. I have been running my rebuilt motor varying the RPM's with a fan blowing on it for about 5 mins at a time. I've done this about 5 times already. I'm trying to get the oil warm but not too hot. I have not been riding the bike yet. Is this ok or should I be riding it during break-in? Does it matter?

well brother i would be riding it in short burst with a load on the motor its much better than free reving it both methods work i get on the bike and ride it less ability to load the cylinders with fuel . ride up and down the block and then let it cool and repeat

I agree. I think riding the bike will put more pressure in the clyinders, more force on the rings, expanding them and therefore producing a better/deeper seat and mating of the two surfaces.
Thanks guys.

Last year when I went from 88 to 95 it was broken in on the Dyno...Just make sure the person is a well known respected pro or serious damage could happen...I literally burn no oil between oil changes...Never have...

The break in on my shovel was very similar to what was said above in that excellent article. I idled mine a couple times in the shop long enough to get the oil up to near operating temps. Then went for short rides at varying speeds, letting the motor cool down completely between rides. I think it's very important to never lug the motor, EVER. Better to drop to a lower gear and rev it up briefly.

I did check the head bolt torque sooner than 500 miles - more like 250. Changed oil twice, at 50 miles and then at 500.

Marc55 - I would have thought break in on the dyno would be a no no. I wouldn't subject my motor to dyno abuse (that's what I call it) LOL. But that's just me.

paul pretty much sumed it up,stay away from the "ride it like you stole it" guys,thats a crap shoot at best

Why "let it sit and idle" with a fan on it then shut down? What does the idling do?

The idling just takes it thru heat cycles and begins the wear in without stressing out the motor. Head gaskets are most vulnerable during the first few start ups. The break-in instructions that came with my motor said to watch for oil leaks during that time.

Sure enough, I had one at the front head gasket, which was already blown.

Its not good . You load the cylinder with unburnt fuel and the temp is not as good as riding the bike . Air fuel ratio is to rich at an idle for break in and oil preesure tends to be low. Also the oil that is circulating. Is at a higher temp due to the fact that there is a very low speed of air running across the jugs . Not quite as nice as 30 mph air pushing across the fins . It can be done with a fan but I don't like it at all . A quick fire and let the oil get to the lifters and rockers . And even then I don't let it idle set it up around 1200 rpm works for me . Jmho

Ken would have never done that with a new bike...My bike had 38,000 miles on it so there was minimal expansion and contraction of metal and we used the same jugs...Many heat/cooling cycles...He did not do it in one sitting either which I failed to mention...He had the bike for a week and did a little each day...He knew I was in no rush...Wnen I picked it up it was tuned and ready to go...Changed the oil to synthetic the following week...Hope to do my heads in early 2013...Should end up with a very reliable build that will give me 90/100...What I like now is that the 26G's give me a real flat torque curve from about 2,500 to 4,000 which works for me...I spend most of my time between 2,500 and 3,500...I also have a 6 speed OD and the package works really well...Just want more power and more torque in that range...

Thanks Paul!