WEIRD ENGINE BREAK IN?

When you put load on your pistons and rings by throttling up the motor parts are being pushed in the direction the forces push. When force is increased loads shift direction and increase. Parts will try to cut new grooves in which to ride. When one path has already been cut and another presents itself, there are now to paths, which is more cut metal. This displacement and rearrangement of metal causes smoothing of surfaces and more total clearance, also less stable envirement for load displacement. ONe way or the highway. Break the motor in fast and sure that way its tighter. Just don't go too crazy the few times you gas it, so parts can slide into place and cut in smoothly.

I thought I might learn something which would revolutionize my engine rebuilding success over the last 25 or so years, so always in search of the hidden wisdom, I went to the website listed and found this little bit of arcane knowledge. . .

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure ?? Of course it can't.

Let's do the math and see, shall we?

Atmospheric pressure = @ 14.7 psi as example (sea level)

8.5 (14.7) to 1 = 124.95 psi

9.5 (14.7) to 1 = 139.65 psi

10.5 (14.7) to 1 = 154.35 psi

12.5 (14.7 to 1 = 183.75 psi

I wonder how far I have to take this table to get to "thousands of PSI"

I think diesal engines generate 22 to 1 . . .

22 (14.7) to 1 = 323.4 still not there. . .

so I think I have a little concern with what is being heralded as the "wring it out to maximize it" method.

Sure, gas pressure seals the rings, but I question the logic in taking a newly built/rebuilt heat generator to thermal limits immediately if parts like bearings, which are sometimes lead lined, are not given an opportunity to seat in under minimal loading. Aircraft engines might be a good analogy for an air-cooled engine like a motorcycle, but you don't get proper airflow around a six-cylinder air-cooled aircraft motor (or the oil cooler on any engine equipped) while it is sitting at low idle on the tarmac. So you have to run them up. There is also the issue that aircraft engines receive rebuilds based on hours, not mileage, so longevity is not really an issue for them, or for engines used in race applications for that matter. I wonder how many of the "wring it out" method get 300,000 miles or more of engine use? Off the record, I had a buddy with a vehicle who put over 157,000 miles on the original front brakes. The engine oil on that truck at 3000 mile intervals looked new.

Post edited by: KaZooCruiser, at: 2007/01/29 14:38

KaZooCruiser - We aren't talking about breaking in engines... these engines were broken in 30 years ago... we are talking about seating some NEW rings on freshly honed cylinder walls. I doubt taking the old bearings up to redline a couple times will do any damage if it didn't hurt them before the re-ring.

Hi George . . . maybe I missed something here. . .

kawadruida wrote:

Hey guys, I´m about to get my hands back on my ´84 GPz550 right after a top end rebuild . . .

www.mototuneusa.com/break_in_secrets.htm

Frankly, this goes against everything I´ve heard about a proper engine break-in. What do you you think about this, guys?

The title of the topic says it all: WEIRD ENGINE BREAK IN
It seems the question (and the responses) deal with BOTH a top-end rebuild and "a proper engine break-in."

If you go to the "secrets" page. . .you will see that the author is talking about new engine break-in, with statements about 300 engines and etc. Maybe the original post was limited to ring-seating, but the confusion and commentary following it deserves whatever input might assist clearing it up. I personally don't care if someone wants to rev to whatever extreme they choose. I've done wheelies to pull the strech out of a chain. It's just misstatements of "thousands of psi" that don't add truth or clarity to the mix which need to be corrected by fact.

Post edited by: KaZooCruiser, at: 2007/01/29 17:50

Post edited by: KaZooCruiser, at: 2007/01/29 17:53

OK, maybe I must have said: "a minor top end rebuild", but if you check the list, there are a bunch of things done: 4 intake valves, valve lapping, valve seals, new camchain, new rings, new pins, cylinder honing and new gaskets. To my wallet was a major drain, although...

It´s very interesting to see different approaches for the same purpose, every one with its own logic too. It makes sense when applied to what I´m intending to do: to seat some new rings in a freshly honed cylinder.

Now I remember when the mechanic delivered my freshly rebuilt Z550 some three yeas ago: before handing it to me, the guy took the bike for a "last test" spin around his shop. He warmed it up about 3 or 4 minutes, then took off just like hell. You could hear the 4 into 1 howling several blocks away. Then he came back, stopped right in front of the shop, yanked the throttle wide open a couple of times, shut the engine off and handed the keys to me. I got angry at the guy, blaming him for punishing my fresh engine right in front of my eyes. He said that everything was OK and I dindn´t need to worry. I can´t remember having any engine-related issue on that bike since I lended to my brother-in-law, who eventually bought it and rides it regularly.

Interestesting topic, but now I am concerned.

I am doing a lot of concurrent work on different systems of my KZ1000 (Carbs cleaned and rejetted, new valves, valve seats ground, re-shim'd, new piston rings, gaskets, Dyna S ignition). I'm afraid I won't be able to just put it all back together, fire it up and 'ride it like I stole it'.

I'm hoping I can, but what if I can't? What if I need to do carb or ignition adjustments before it will run well enough to take to the freeway? Will I be blowing my opportunity to get the rings well-seated by letting the engine idle while I get things 'dialed in'?

What would you guys suggest?

Post edited by: Skyman, at: 2007/01/31 15:20

I have never had a problem getting an engine started after lapping valves, replacing a few valves, honing/new rings, etc. Once started, tune the bike by setting the timing and sync the carbs, etc... THE BIKE WAS BROKEN IN YEARS AGO! The bearings, transmission, lower end, etc etc received whatever break-in they were going to get at that time. HONING CYLINDERS, LAPPING VALVES, SEATING RINGS isn't breaking things in... what has to wear to make it fit? Nothing? Well, the rings need to bite into the new cylinder wall hone but that is seating rings and not a BREAK IN. Look at the owners manual of any car or truck. The break in procedure should be carefully followed because all the parts in the engine are new. This isn't the case with what we are talking about here... the term "Break In" shouldn't really be used unless you found a crate motor somewhere in a, well a crate.

Actually, the #1 issue in engine breakin is lifters/cam followers. If you don't change camshaft or lifters, don't sweat too much. The #2 issue is rings. A certain amount of care has to be taken here, but George is right, they will eventually break in fairly well, no matter how you do it. For everything else, the breakin isn't the concern, it's how much care you put in to putting it back together. So, Skyman, you're not worried about breakin. You're just worried about breakin'.

I feel relieved. Reading this thread had me worried that I had to follow this procedure, otherwise my rings wouldn't set right and I'd have poor compression.

Thanks guys.

All the hard work is done. Now if I can just find the time to put it all back together!

KaZooCruiser wrote:

I thought I might learn something which would revolutionize my engine rebuilding success over the last 25 or so years, so always in search of the hidden wisdom, I went to the website listed and found this little bit of arcane knowledge. . .

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure ?? Of course it can't.

Let's do the math and see, shall we?

Atmospheric pressure = @ 14.7 psi as example (sea level)

8.5 (14.7) to 1 = 124.95 psi

9.5 (14.7) to 1 = 139.65 psi

10.5 (14.7) to 1 = 154.35 psi

12.5 (14.7 to 1 = 183.75 psi

I wonder how far I have to take this table to get to "thousands of PSI"

I think diesal engines generate 22 to 1 . . .

22 (14.7) to 1 = 323.4 still not there. . .

so I think I have a little concern with what is being heralded as the "wring it out to maximize it" method.

Your mistake is in comparing apples to oranges

Note in the original statement that he says "Combustion Pressure"? Then you calculate static compression pressures. No comparison is possible.

I have toured automobile assembly plants, and every completed vehicle coming off the line was rolled straight onto a dyno, and the motor was started and run at WOT. Full throttle, full load, how's that for breaking in a brand spanking new motor?

I have not toured any motorcycle assembly plants, but I have seen pictures of Honda's coming straight off the line onto a dyno for a full throttle/full load run.

It's all kawadruida's fault for starting a thread like this!!! :laugh:

I'll be doing new ring seating when the 615 goes in(still waiting for the head to come back from Canada for some friendly port cleaning).

:evil: Just to be the devil's advocate in the car world...

Not all, but many of the high-perf engines built in the auto industry are first run in a test machine, first without fuel and negative forces (90 second intervals) and secondly with propane so that there is no visible evidence from the combustion.

Big motors are run in stages 200, 500 then 1500 RPM then about 1/2 throttle with propane to check everything out including NVH, balance and a whole pile of other crap that could fill a library :woohoo: The motors have to run full temperature then they are shut down. With really high-perf factory engines they even run externals for water while the lesser engines run air cooled for the first 5 minutes of their life

Sorry way off topic but it just sounded like fun to throw this in cause... well let's say it's not common knowledge but all the UAW involved can debate it for the next hundred years.

Bikes are way better and the technology is way higher IMHO.:blush: