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brand new engine siezed on run in

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  • #1

    brand new engine siezed on run in

    Hi everyone. Looking for a bit of help and info here.
    I recently bought a gp1200 99 non pv model in bits. I rebuilt it using all new sbt liners pistons etc.
    Had a local machine shop machine the liners once fitted to suit the standard pistons. I did a first tank of fuel, premixed at 32:1 going nice and slowly working it upto 1/3 to 1/2 throttle. Had done about 5-6 runs letting it cool each time. 2nd tank of gas about 20mins into a run I started working it upto 2/3 to 3/4 throttle and it nipped up on no1. Was all alone and had to ride it to shore. Messed up my brand new liner and piston really badly. At all times the cooling system was running perfect and I had done plug checks after each run and they were all a lovely tan colour showing perfect tune. Engine machinists have said since the liner is so bad they cant prove its there fault...typical but im after as much help as possible incase ive missed something as this has just cost me a fortune!
    The machinists were pretty sketchy on what the clearance was, but ive demanded that the fixed cylinder and the remaining 2 all run 4 thou clearance now as even the other two cylinders showed rub marks around the skirt at gudgeon pin height. Was this simply a clearance issue??? Let me know your thoughts please.
    regards gareth
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  • #2
    Re: brand new engine siezed on run in

    Did you replace the crank seals in the crank case?, Did you rebuild the carbs too?
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

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    • #3
      Re: brand new engine siezed on run in

      Originally posted by Technical Support View Post
      Did you replace the crank seals in the crank case?, Did you rebuild the carbs too?
      Yes. Everything was replaced.
      The only thing ive changed is ive gone to 150 main jets now for running in to add some cooling. Plugs are slightly darker but not wet looking. Changed to penrites new mc2st oil. Its an ester based oil for high performance seadoos and gokarts. 2 tanks done and everything is still fine.i did have to gap one set of rings on the original engine. But I checked them in the other cylinders and they were the same.

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      • #4
        Re: brand new engine siezed on run in

        Maybe the clearance was a little too tight, I personally would have gone 5 to 5.5 thou.
        SBT Tech Support is here to help with your problems.
        We try to answer each question quickly and accurately.
        Please do not use Private Messaging for Tech Support, use the forums.

        Comment

        • #5
          Re: brand new engine siezed on run in

          Originally posted by Technical Support View Post
          Maybe the clearance was a little too tight, I personally would have gone 5 to 5.5 thou.
          Do you know what the required clearance is? There standard sbt pistons and liners. They first started saying they had machined to 3thou then about 4 calls in said that they had given it 4thou. If the required clearance is 5 to 5.5 please let me know as they can reimburse for the damage and strip it down and remachine to 5thou.

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          • #6
            Re: brand new engine siezed on run in

            From O.E they are set to 4 but the cylinders on O.E are nicasil. SBT will set the clearance up on steel sleeves around the 5.5 to 6 thou area.
            SBT Tech Support is here to help with your problems.
            We try to answer each question quickly and accurately.
            Please do not use Private Messaging for Tech Support, use the forums.

            Comment

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