Scratch built

Discussion in 'Motorized Rat Rods' started by builder bob, Nov 22, 2015.

  1. builder bob

    builder bob New Member

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    Almost finished building my second bike! I still need to finish the jack shaft, bleed the back brake, get some bearing races for the head tube, and put on the blinkers.
     

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  2. wheelbender6

    wheelbender6 Active Member

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    Very cool and unique. Its very tough to pull off the cafe racer look with a motorized bike but you have done it.
     
  3. scratchbuilder

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    Like what you've done. I'm one for rear suspension. How does the shock location work? Do you need a real stiff spring to keep it from bottoming out? I just sold my rear suspension build ..so I could build another....lol
     
  4. builder bob

    builder bob New Member

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    Thanks! Hopefully it rides good

    Yeah it needs a really stiff shock in the back. I've got a 750 pound spring on it now but it's too soft. If I had more pipe I could have made the swing arm longer which would allow me to reduce the angle of the shock which would have made it stiffer.

    Does anybody know where I could buy bearing races? I don't really want to machine them.

    Edit: Oh also what's the gear ratio in one of these? http://www.amazon.com/4-Stroke-Transmission-Bicycle-Replacement-Motorized/dp/B00KWLLTXY I'm guessing 8 to 60
     
    #4 builder bob, Nov 22, 2015
    Last edited: Nov 22, 2015
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Fo'sho'!!!!!







    .
     
  6. builder bob

    builder bob New Member

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    Thanks!

    I was hoping I'd be able to ride this by now but I'm having trouble getting the jack shaft on at the right angle so it doesn't keep throwing my chain
     
  7. MEASURE TWICE

    MEASURE TWICE Active Member

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    You should check to see if there are some specifics to chain tension when the bike has a swing arm. See what others here might have done with similar.

    I was looking at a motorcycle and asked the owner if the chain was too loose. He said it was supposed to be that way. When the swing arm moved there was some Teflon nylon type material that was just underneath the bottom return slack chain that kept it from getting too much slack.

    If it is just alignment, it would be best to see picture of the sprockets and chain. On my bike I went for two jackshafts so I could have a very low ratio. I only have a very short chain between both jackshafts and the rest are pulleys and belts. The chain I did have to use washers to help when I removed and then replaced with various gears so I did not have to find the alignment by trial and error over and over each time. In addition the left and right side pillow bearings individually are adjustable which may be more of a problem, but I got it to work.

    I know a derailleur on a bicycle allows the chain to go at some angle, but I have enough adjustment to have the chain be centered. One belt to the rear wheel pulley has very tight clearance to the frame. I even had to cut and weld the frame tube when I opted for a (not home made but) manufactured replacement Whizzer clone sheave so it would not rub.

    Others should chime in an see what they may know.

    MT
     
  8. curtisfox

    curtisfox Active Member

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    If i remember right that trans is 5 to 1 ratio, But there was some,not sure if it was the CVT that were 7 to 1. I also think that trans reverses the direction. Best would be to email and see what you can find out. Another one.............................Curt

    http://www.gasbike.net/transmission-chain-drive.html

    Take that back, its the chain drive box and does not reverse the direction .............Curt
     
  9. builder bob

    builder bob New Member

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    It's just alignment that's giving me trouble because I don't have much room to work on the jack shaft. I also need to put a couple of rollers on to keep the chain from hitting the swing arm but that shouldn't be to hard.

    5:1 sounds good, I'll go with that. Does anyone make a CVT for these engines? If not I might talk to Comet about putting one together

    Do you guys know where I could buy bearing races? I don't really want to machine them
     

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