Compression Issue??? Please help!

Discussion in 'General Questions' started by ihotch, Aug 25, 2015.

  1. ihotch

    ihotch New Member

    Hey so This 80cc motor kit has been complete hell for me. I ended up taking it to this guy 2 hours away where he told me why my bike wouldn't even turn over, which was because the piston came installed backwards and the top end didn't come with top or bottom gaskets. After installing everything, the bike ran great for probably only 10 miles before I felt oil on my leg which was coming from the bottom gasket. While replacing it I noticed that the top gaskets were crushed and caused the piston to hit the top of the cylinder. After replacing those, The bike will now start but only stay running while pedaling, once you pull in the clutch or give it gas it'll bog down and die. I cleaned the carb, played with the settings, and still does the same thing. I even bought the upgraded carb off ebay and tried seeing if that works (which it didn't). This bikes been nothing but a money pit so it would help me greatly if someone could tell me what they think is the issue.
     

  2. crassius

    crassius Well-Known Member

    there are many cylinder/piston combinations for these motors and none of them have identifying marks - sounds like you ended up with wrong replacement parts which may now be damaged

    best move might have been to report problem to seller of kit, but sometimes that doesn't help either

    a simple, but frustrating, fix would be to get a new motor and save the old for parts
     
  3. jaguar

    jaguar Well-Known Member

    can you give more details about the gaskets being "crushed"?
    the stock bottom gasket is OK but you need to make your own head gasket out of gasket material from the auto parts store. Do that after you plane the head and the cylinder top because they aren't truly flat which is why they leak so much. Use sandpaper and glass. details are on my site.
     
  4. ihotch

    ihotch New Member

    Thanks for the help! Well it just looks the head of the cylinder was tightened down too much and pushed the inner part of the gasket in. Hard to explain it.
     
  5. jaguar

    jaguar Well-Known Member

    over tightening is only necessary when the surfaces are not truly flat
     
  6. crassius

    crassius Well-Known Member

    you are aware that there is a compression ring built into bottom surface of head that is supposed to bite into the gasket a bit to seal better aren't you?
     
  7. jaguar

    jaguar Well-Known Member

    a pathetic attempt to make up for their lack of ability to plane the surfaces correctly
     
  8. ihotch

    ihotch New Member

    got some rubber gasket material from the auto parts store and made all new gaskets. still the same problem. The guy on ebay who I bought it from refuses to refund my money or replace the parts.
     
  9. jaguar

    jaguar Well-Known Member

    could be that the crank seals are shot
     
  10. jaguar

    jaguar Well-Known Member

    but even if those seals are shot there should be some decent compression. Maybe the rings are broke. take it apart and inspect it.
     
  11. ihotch

    ihotch New Member

    They Look fine. Probably gonna have to buy a whole new motor for it.
     
  12. jaguar

    jaguar Well-Known Member

    can't tell by looking at them. spray soapy water on them while turning the engine over (with the spark plug out and the kill witch on). if bubbles come out then they are bad.
     
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