Breaking in an engine - TIPS!
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Thread: Breaking in an engine - TIPS!

  1. #1
    builder of bikes Array cosworth's Avatar
    Join Date
    Apr 2002
    The Island

    Breaking in an engine - TIPS!

    "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 that seal 3,000 + lbs. of combustion pressure on the way down ?? Of course it can't.

    How Do Rings Seal Against 3000+ lbs of Combustion Pressure ??

    From the actual gas pressure itself !! The pressure takes the path of least resistance, which means 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 (open that throttle man !!!), then the entire ring will make contact with the cylinder surface, and it will wear perfectly into the right shape.

    The Problem With "Easy Break In" ...
    The rough crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly "use up" the roughness, regardless of how hard the engine is run.

    There's a very small window of opportunity to get the rings to seal really well ... only about 20 miles !!

    If the rings aren't forced against the walls, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

    Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
    which is why more engines don't have this problem !!

    An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!"

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  3. #2
    '04 R1 - You are mine! Array FloMan's Avatar
    Join Date
    Apr 2002
    Yes please! Oh! That wasn't a question?
    Wow! This goes against everything I know on the subject...
    “Your failure to be informed does not make me a wacko.”
    -John Loeffler

    “The truth will set you free, but first it will make you sick.”

  4. #3
    Jason R
    Ya I have already seen that site and it seemed like it made sense. Wonder what Bowmax John will have to say about it.

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