stuck sprocket on a old kids bike that is held on at the crank?

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by TheSignGuy, Aug 19, 2016.

  1. TheSignGuy

    TheSignGuy New Member

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    Found a nice 35 tooth sprocket off a junk kids bicycle but the screw ring is stuck that holds the peddle to the crank tried a mallet a hammer and a screw driver won't come off rehearing to 35-24, (Front to rear).


    Any solutions will have to be custom punched to fit my front assemblies or atleast to weld on.
     
  2. maniac57

    maniac57 Old, Fat, and still faster than you

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    cut the nut with a dremel or other thin cut off wheel.
    It will release once you get close to parting it.

    Usually works.
     
  3. TheSignGuy

    TheSignGuy New Member

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    True but in specifics I'm having an issue with gearing I know not to go to big on gearing.

    For what I want to gear in would seem like it would lack power uphill


    So here is the break down for my current gearing I have 3 options


    current gearing: 13 tooth front sprocket x 24 tooth rear sprocket = 15.5mph top speed. (Top end screamer)


    first gearing option: 13 tooth front sprocket x 35 tooth rear sprocket = 18.8mph

    second gearing option: 13 tooth front sprocket x 40 tooth rear sprocket 20.6 mph

    third gearing option 13 tooth front sprocket x 50 tooth rear sprocket = 25.8mph


    Basically the issue here is unless I got up to 60 tooth in the rear which I have limited space for a sprocket that big, plus I feel I would slugg on hills from that gear size 50 is as high as I can get at the time and these ratios the current is accurate with my weight on it.

    But the downfall is its a 49cc so a big bore kit can conquer the differance in the speed with a lower tooth ratio.
     
    #3 TheSignGuy, Aug 22, 2016
    Last edited: Aug 22, 2016
  4. kevyleven007

    kevyleven007 Active Member

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    Dang. Too bad a 60 tooth wont fit. maybe you could try a 40?
     
  5. TheSignGuy

    TheSignGuy New Member

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    Either way if I threw in a 60 would have to be welded on a 40 would work problem is I wish I could find a axle hub bolt for schwinn with the sprocket built in at 40-60
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    Your math is wrong.
    A smaller rear sprocket will RAISE top speed if front stays same.
    Not like you have it
     
  7. TheSignGuy

    TheSignGuy New Member

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    Was thinking more long the lines of this speed ratio 18- 22 set up 18 being in the front for longer flat level for the gear ratio,


    18x 20÷20 = 1
    9.8mph

    Right now it's 24 to 13 baby teether pretty much 15.5mph

    This is ambrionic to what it could do.
     
  8. Saddletramp1200

    Saddletramp1200 Custom MB Buiilder

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    With a 66cc & a 38 T sprocket I get about 18 mph. In the bed of a pickup It gets 75 or so.
     
  9. TheSignGuy

    TheSignGuy New Member

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    FS FRONT SPROCKER X RS= FRONT SPROCKET ÷ TD = TIRE DIAMETER= SPEED


    SO CURRENT IS WRITTEN LIKE THIS

    FS 13 X RS 24÷ TD 20 = 15.6 MPH actual speed is 15.5mph which is a .1 losage in mechanical conversion theory.

    There are two chains one in the cvt cover and one for to drive the rear tire.

    The goal is to not exceed moped laws of 30 mph so I want to be slightly underneath that law.

    Initial thought is FS18 X 24÷20 = 21.6MPH - .1 = 21.5 MPH


    MY ACTUAL TIRE HEIGHT IS 20 X 1 1/4 GIVEN THEORY IN ADDITION TO LOSSAGE..

    upping teeth in the front only would still provide a better gear ratio


    Removes that screaming engine feeling, but still provides full power load without to much loss of torque.

    19 tooth is as big as the front sprocket can get without customization. So an 18 should do very well toward top speed.


    I may also need to rejett as past 3/4 throttle it boggs out. The pikot circuit is fine as it fires the engine first kick everytime have not changed plugs yet but I have cleaned mine and verified it stays a nice coffee brown but runs lean after 3/4 turn meaning main jets to small also plan on removing the redneck gy6 China exhaust and welding on my extra moped muffler which should be a lot quieter on roads without roaring uo the block like a teenager when I have to hit the sidewalks. In town traffic hour.
     
    #9 TheSignGuy, Aug 26, 2016
    Last edited: Aug 26, 2016

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