Which Break In Method For You?

[Steve 0080]

Climb on, sink steel, ride off.....

[BIGLRY]

I know I made a smart ass post above about breaking in a new bike engine or any engine for that matter, but I though I'd expand on it a bit with a link to an article that explains why I said "Ride it like you stole it" for guys & gals who don't know all about the intricacies of an internal combustion engine and would rather ride their scoot than work on them.
I have been a firm believer for many years in what the article's writer, Pat McGivern exposés as how to do and why his method works. The author has built many engines with empirical evidence that this method produces long life engines with superior performance. I to over the years have build many engines...stock and some not so stock. I use and recommend his methods, my VTX1800s, Runes, F6B were broke in this way and not only does my F6B runs flawlessly, IMHO I feel it is a cut above some other F6B I've run against in the power dept. Yea... I do have an open custom exhaust & Torq Loopz).
Even if you disagree it is still a good read with logical explanations to the science behind this engine break in procedure.
Example: "The piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.
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.

How Do Rings Seal Against Tremendous Combustion Pressure?
From the actual gas pressure itself! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into the cylinder surface, to seal the combustion pressure as well as possible."

http://www.mototuneusa.com/break_in_secrets.htm

[Dave Ritsema]

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.

I had read that article before, the author lost all credibility with me with the "Thousands of PSI " of combustion chamber pressure statement. More like 160 - 180 PSI?

[stroguy]

How much pressure is generated on the piston head upon detonation?

[willtill]

How much pressure is generated on the piston head upon detonation?

If you have detonation; you have bigger problems.

[BIGLRY]

If you have detonation; you have bigger problems.

Very true and why normal combustion is sometimes referred to as a 'controlled explosion' while "detonation" is an 'uncontrolled explosion' and pre detonation is an 'uncontrolled explosion' igniting the air/fuel mix before it is suppose to!

[stroguy]

Larry said contraire.

[BIGLRY]

How much pressure is generated on the piston head upon detonation?

See post above

[BIGLRY]

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.

I had read that article before, the author lost all credibility with me with the "Thousands of PSI " of combustion chamber pressure statement. More like 160 - 180 PSI?

Ah contraire my friend, while it is true the compression of the cylinder may be 160 to 180 PSI when turning over an engine not running like when doing a compression check, but when an engine is running and the air & fuel mix are being detonated in a controlled explosion to make power to push the piston down the combustion pressures do rise much higher that the "160 to 180 PSI" found in a non-running engine's compression.

"Combustion / Expansion Stroke
This stroke is where the spark plug ignites the air/fuel mixture, creating very high cylinder pressure which rise very quickly. Peak cylinder pressures near TDC (where spark occurs) will be in the range of 300 psi for engine's at light loads, to 1000 psi for production engines at full power to 1500 psi or greater for race engines."
http://performancetrends.com/Definit...r-Pressure.htm

Here is a quote from http://mb-soft.com/public2/engine.html about the compression pressures on a 4" aluminum piston, the article is a long read so I only put in info pertaining to our thread.
"Since the piston is 4" in diameter, the top surface of it is just PI * (4/2)2 or around 12.6 square inches. Each of those square inches experiences the 500 PSI(G) pressure (Pascal's Law), so the total force then instantaneously applied to the top of the piston is 12.6 * 500 or around 6300 pounds. (OK. It is ACTUALLY the 515 PSIA, but there is natural air pressure pressing against the UNDERSIDE of the piston as well, so the NET effect we are interested in is due to the GAUGE pressure. Not too different, but slightly!) But those aluminum alloy pistons in your engine are pretty amazing in being subject the 6300-pound force of hundreds of explosions pounding down on them every minute!

[MotoMike]

Well, there you have it. My next ride is going to be a WHOLE lot different!!