Not having a good day today.

Discussion in 'Motorized Bicycle General Discussion' started by maniac57, Jun 4, 2014.

  1. maniac57

    maniac57 Old, Fat, and still faster than you

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    Pulled the Pig jug for routine inspection today after the first tank, and this is what I found.
    [​IMG]
    [​IMG]
    Notice the long crack in the center of the smaller hole? (Top pic is upside down) It looks like something was wedged between the wall and the slug, yet there are NO marks (other than normal wear) on the piston ON EITHER SIDE! The only sign of damage on the slug is the top which is is all dinged to hello from running the chunks through it, as is my new FredHead, which you KNOW is bunching my panties quite tight.
    Both transfers wasted with chunks run through the works, no sign of debris or ring damage. It would have messed up a ring if they had snagged BOTH of the lips. No shiny dust or bits remain. The only possible I can figure is a foreign object somehow getting past my briggs air filter (also leaving no sign)
    No strange noises?!?!?
    I find it baffling that this could happen with no odd symptoms or strange noises at all, especially considering how anal I am about every little noise or change when running in a newly assembled motor.
    The only thing I noticed at all was an inconsistent idle, which I figured was simply from the top end being so fresh.
    I'm beginning to think this motor is haunted or something.
    Maybe it's the re-incarnated soul of one of the thousands of helpless mechanical victims claimed by my younger days as a speed freak come back to make me pay for my engine sins.
    All I know is I'm getting real tired of this musical engine baloney.
    *trudges out to re-re-re-re-re-swap the Pig motor. Again.*
     
    #1 maniac57, Jun 4, 2014
    Last edited: Jun 4, 2014
  2. maniac57

    maniac57 Old, Fat, and still faster than you

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    I could understand had the damage been on the same side I touched up after the first top end failure, but this is both transfers, with the untouched side being the worse of the two!
    This, plus the untouched rings leads me to believe it had nothing to do with the previous problem. This was NOT another ring snag! (at least not unless this piston is made of diamond!)
    I can find no evidence to explain this except the cylinder wall collapsed over both transfers for some unknown reason, or I somehow sucked a chunk of something hard through my air cleaner.
    Maybe a chunk popped off the case under a stud. I'll have to check that when I get it out.
    Just blows my mind this could happen without my noticing or hearing anything at all.
     
  3. maniac57

    maniac57 Old, Fat, and still faster than you

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    Okay. I think it went like this:
    The original ring snag must have damaged the transfer lip more than I thought and started a small crack in the lip which broke off under power and caused enough debris to get sucked up into the other transfer, breaking off the big chunk, which then had carnal knowledge of my new FredHead.
    Once again it seems to boil down to MY error in not replacing the cylinder.
    In my defense, I DID inspect it and very carefully de-burred the small notch left from the first go-round. The only way I could have spotted this hidden defect would have been with dye and revealer. (magnaflux don't work on aluminum)
    Lesson learned. Never trust a china cylinder that has had ANY debris run through it, regardless of how it looks.
    *shakes head and slowly wanders off muttering*
     
  4. Davezilla

    Davezilla New Member

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    Wow... And let me guess... it was running ok until you found that?
    Did the engine ever overheat during break in? It could have been a small crack that went undetected and a piece broke off & bounced around in there doing the damage on both sides before spitting the pieces out the exhaust port?
    Hopefully if the bottom end shows no damage it'll just be a new jug and back on the road... I'm surprised the piston isn't all tore up, but I've seen some cylinders really bad still run just fine. It almost looks like what happens when one of the pin clips works it's way out of it's groove in the piston... Is there any signs of the pin clip coming out?
     
  5. allen standley

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    Never trust a china cylinder that has had ANY debris run through it, regardless of how it looks.

    When I lose a top end I take the motor off the bike and hose it out with the garden hose. dry it out, spray it with wd40 leave it upside down on the bench overnight-then reassemble with the new parts. I was haunted once with a loose piece, cost me 2 jugs.
     
    #5 allen standley, Jun 5, 2014
    Last edited: Jun 5, 2014
  6. Davezilla

    Davezilla New Member

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    Yeah... I'd definitely check the bottom end for any remaining debris because it will find it's way into the new jug too... I'd go ahead and disassemble the bottom end to check that nothing got lodged into the bearings as well since pieces can get pulverized into tiny bits that can find their way into the bearings ruining them as well... especially if I didn't know exactly when it happened.
     
  7. maniac57

    maniac57 Old, Fat, and still faster than you

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    I did rinse out the bottom end real well with nothing showing so I slapped another cylinder on it. Fired right up and doing fine so far. Aside from a few dings on the crown from the chunks, the piston is untouched. Rings were free and undamaged. Pure blind luck.
    It simply blows my mind that I heard and felt NOTHING when this happened. It might have been yesterday or last week for all I know.
     
  8. crassius

    crassius Well-Known Member

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    I've never trusted rinsing a closed bottom end, or even reusing bearings, as these things make a lot of aluminum debris that can hide behind the bearing cage & avoid magnets. Big-end bearing can hide a problem too.
     
  9. maniac57

    maniac57 Old, Fat, and still faster than you

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    I know. But I'm tired of working on it. If it blows again, then I'll do a complete teardown.
    The beauty of the china girl is that even catastrophic damage is really no big deal.
     
  10. xseler

    xseler Well-Known Member

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    Yep. Entire new engine less than $150. A bargain at half the price.


    Wait..........laff
     
  11. mapbike

    mapbike Active Member

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    Best wishes maniac57, hope this time is a charm and all goes well and the little gal has a long healthy life after her two minor surgeries... most of them seem to get happier after some work on the jugs....lol!

    Sorry fellas just had to say it...!

    Map
     
  12. crassius

    crassius Well-Known Member

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    yeah, I sell new motors for $100 exchange and will no longer sell a used or rebuilt one - just too iffy
     

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