Big jugs

Discussion in 'Heads and Cylinders' started by Mouse, Jan 28, 2016.

  1. Mouse

    Mouse New Member

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    I have a 48cc grubee Skyhawk 2 stroke can I change the jug and piston to a 66/80cc?†
     
  2. ckangaroo70

    ckangaroo70 Member

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    Large jugs? Sorry...was expecting to see something different here. lol

    Really don't know why you couldn't go with the larger displacement jug. I think the lower ends are basicly the same on most all the china girls and I would assume the cranks the same, but perhaps more research is in order
     
  3. Greg58

    Greg58 Active Member

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    The stud spacing is not the same, I don't have the specs but I do know my 48cc's and the one 66cc are different.
     
  4. Mouse

    Mouse New Member

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    Is there any one who could help me with finding a faster reliable motor ? I'd like to go35-45mph without going wide open on the throttle. And can I modify the existing motor to do that?
     
  5. Greg58

    Greg58 Active Member

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    There are a lot of modifications that will increase speed, porting done right is one. Adding a expansion chamber is another, changing rear sprockets from a stock 44t to something with less teeth will increase top speed but cuts hill climbing ability. If you do upgrades do one thing at a time, that way you'll know if what you did helped or hurt performance.
     
  6. Mouse

    Mouse New Member

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    What about a jackshaft and hooking it into the existing bike gears?
     
  7. Greg58

    Greg58 Active Member

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    Yes a jackshaft kit will help, here in Georgia a multi-speed moped is not legal so you might want to check your state laws.
     
  8. Chaz

    Chaz Member

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    Mouse, getting a bike to do those speeds is not a problem. Doing those speeds safely is the real issue. You are asking for motorcycle performance from a bicycle, so that bike and all of it's components must be up to the task. I'm guessing that about 75% of your budget and efforts should go into building a solid bicycle foundation to bring it up to manufactured moped standards.
     
  9. Mouse

    Mouse New Member

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    Got a grinding feel in bike when motor is engaged. Bearing? Time to rebuild?
     
  10. sbest

    sbest New Member

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    6mm studs at 42mm for the 48cc.
    8mm studs at 45mm for the 66cc.

    Steve
     
  11. crassius

    crassius Active Member

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    grease the bucking bar & check chain run while there
     
  12. ajanessetrovy4712

    ajanessetrovy4712 New Member

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    Not trying to answer for Ben or Gary but last year all the Big Dawg races was on a .05 tree in 7.0
     
  13. Mouse

    Mouse New Member

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    Sometimes thinking is not enough. The remedy was rebuilding the clutch.trk
     

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