WEIRD ENGINE BREAK IN?

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:

Here's another point of view:

www.steelthundercc.com/enginebreakin.html

Wow! It wasn´t my intention to start this controversial thread!:ohmy:

But it seems that there are several ways of "break in" or ring seating (thanks WG!), as an example I quote this from the link provided by Ibsen:

"The first 50 miles are the most critical for new rings and piston break-in. Most engine damage will initially occur during this period. Remember that if proper ring seating does not take place, the resultant blow-by will set the stage for possible future damage because there won't be sufficient oil on the cylinder walls for proper lubrication. So keep the heat down by not exceeding 2500 rpm. And vary the speed.
The next 500 miles should be spent running the engine no faster than 3500 rpm or about 50-55 mph. Do not lug the engine and continue to vary the speed.
Up to 1000 miles, the speed can be run up to 60 to 70. Continue to run the engine at different speeds including the lower 4~5 mph ranges. When the 1000 mile mark is reached, most Evolution engines should be broken in. Evolution engines tend to run slightly cooler; and therefore do not require as long a break-in period as earlier engines using iron cylinders.
From 1000 to 2000 miles basically use the same procedures as before, but you can be a little more liberal with the rpm range. Avoid overheating the engine and putting any hard strain on it (drag racing, trailer towing, sidecar operation).
2000 miles and up, have fun! Just remember, while our recommendations sound good and normally work, there is no cook book formula for proper engine break-in."

So, who owns the truth here? Probably no one and everyone at the same time...