BRAND NEW YD100

Discussion in '2 Stroke Bicycle Engines & Kits' started by MTBNewf, Jan 19, 2020.

  1. MTBNewf

    MTBNewf New Member

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    As the title says.

    I've done considerable research so I have a clue.

    Advice on how to proceed?

    Thanx in advance

    Jim
     
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  2. Greg58

    Greg58 Well-Known Member

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  3. MTBNewf

    MTBNewf New Member

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  4. Greg58

    Greg58 Well-Known Member

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    You'll hear a lot of opinions on the engine and the frame, I have had good luck with my aluminum frame and 48cc engines. My first bike which I still have is almost 9 years old with no frame problems. Cannonball rides along the coast where it gets very hot, he hasn't posted anything about his giving problems.
     
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  5. MTBNewf

    MTBNewf New Member

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    Yeah.

    I understand the rational but bein an old mtber, something inside me screams "NO STEEL FRAME". lol.
     
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  6. MTBNewf

    MTBNewf New Member

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    So the motor has arrived.
    All lookin good out the gate.
     

    Attached Files:

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  7. Greg58

    Greg58 Well-Known Member

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    Was the piston installed correctly? With the larger bore I was wondering if the ring end might be outside of the ports if installed either way.
     
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  8. MTBNewf

    MTBNewf New Member

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    piston was installed correctly.

    there is nothing to stop the rings from spinning in their slots.
    is that normal?
     
  9. Greg58

    Greg58 Well-Known Member

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    The 40mm ad 47mm pistons have pins in the ring grooves to keep the rings in place, the pins are located on each side of the intake port.
     
  10. Greg58

    Greg58 Well-Known Member

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    Look at the ends of each ring if they are designed for locator pins they will have a half Moon cut on the bottom half. If the ends are flat they aren't.
     
  11. MTBNewf

    MTBNewf New Member

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    CM200202-140454001.jpg
    no spot for locator pins that I can see.

    So these rings just "spin" in their grooves?
     
  12. FOG

    FOG Well-Known Member

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    That's too scary too contemplate.

    Years ago. Holed a piston in a Zundapp. Couldn't find no Zundapp piston but a Yamaha had the same dimensions. Except for the locating pins. It fired up for about half a second when a ring snagged a port and chunked the cylinder.

    End of Zundapp.
     
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  13. MTBNewf

    MTBNewf New Member

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    there are spossed to be pins in 2 stoke pistons, yes?

    So what now?
    new piston? modify this one?
     
  14. Greg58

    Greg58 Well-Known Member

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    Looks like the ring ends do have a taper so spin the rings all the way around and look for the pin. There’s no way for the engine to last if the ends are not stationary.
     
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  15. Greg58

    Greg58 Well-Known Member

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    Look at the picture below you can see the pin in the top of the ring grove.

    upload_2020-2-4_10-49-2.jpeg
     
  16. MTBNewf

    MTBNewf New Member

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    ok.

    So I found the pins. small victory.
    thanks for u guys or I'd be truely lost here. lol
     
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  17. MTBNewf

    MTBNewf New Member

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    So, I got the flash cleaned up, transfers smoothed and matched a bit, matched up and textured the intake track/polished the exhaust port and got the gaskets trimmed up.

    Gonna figger the mounts next.
    once she's on the frame to my satisfaction, won't be long for first run.
     
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  18. MTBNewf

    MTBNewf New Member

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    SO.....gonna hold off on firing her up for the first time.

    Just read some stuff on break in and there are some of the opinion that you should put the motor under a load as soon as you start it up, (to seat the rings), the first time.

    Thoughts?
     
  19. Greg58

    Greg58 Well-Known Member

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    I like to put the engine through a couple of short heat cycles at first, the road I live on is half a mile long so I make two to three runs up and down varying engine speed. I then let it cool and repeat, I've had good luck doing this. After that I don't make super long runs but I do increase ride time. After 4 to 5 trips if the engine temperature seems good I'll ride it as much as I want.
     
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