Intake port piston location???

Discussion in 'Motorized Bicycle General Discussion' started by 577-Jersey, Jun 6, 2013.

  1. 577-Jersey

    577-Jersey New Member

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    Hi guys,,
    I have an engine here with low power and it pings a bit when warm,,running 32:1 dino,,I noticed when i took the intake off and turn over the motor,,the top of the piston does not come down low enough for the fuel to get into the chamber,,it comes down to the top of the first ring but that's it,,my question is,, shouldn't it come down a little lower or should I trim the port out with a grinder so the fuel can get into the chamber better,,or are all of them this way???

    Thanks Tom

    Good times.....
     
  2. maniac57

    maniac57 Old, Fat, and still faster than you

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    Be VERY careful changing the height of the ports, this controls timing on these engines and can lead to ruined motors. Most people simply grind a small "ramp" in the piston crown to improve flow. MUCH safer. I would counsel against messing with the port size unless you know exactly what you are doing. If you try the ramp. don't grind too far down into the ring lands. Leave a bit of untouched aluminum above the ring groove for strength.
    Search porting and high-performance engine mods. I've seen a thread here on this mod somewhere...
     
  3. crassius

    crassius Well-Known Member

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    2-strokes send fuel to the bottom end first
     
  4. 577-Jersey

    577-Jersey New Member

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    And up through the transfer port correct,,I need to pull the jug tomorrow and see whats going on,,sounds like its constricted somewhere..

    Thanks Guys!!
     
  5. 577-Jersey

    577-Jersey New Member

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    I may try that also!!

    Thanks Maniac!
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    I think the usual mod is to trim the piston skirt on the intake side and ramp the piston on the exhaust. (I'm heavily medicated tonight and cannot think straight)
     
  7. 577-Jersey

    577-Jersey New Member

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    I need to be medicated,,my sciatic nerve is so bad feels like a hot knife in my rear...
     
  8. maniac57

    maniac57 Old, Fat, and still faster than you

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    Knees here...thank goodness for modern pharmaceuticals!
     
  9. 577-Jersey

    577-Jersey New Member

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    That and beer!
     

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