Motor mount on a 24" bike

Discussion in 'Mounting Techniques for Bicycle Motors' started by Soylentbob, Apr 15, 2016.

  1. Soylentbob

    Soylentbob New Member

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    I wasn't sure where to post this so hopefully someone can help. I was looking at some of the Chinese made gas bike kits on ebay, but it appears they are for a 26"-28" bike. I have a 24" bike, partly because I'm for very tall and don't want to tip-toe my bike when I stop. I was wondering if there is a way to mount the kit onto a 24" bike and make it work properly?
     
  2. 2door

    2door Moderator
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    All depends on the frame. I've built two 24" bikes that required no modifications or special mounts. You need to check for clearance for the carburetor and spark plug. If space dictates there are off-set intake manifolds available as well as slant heads and shorty spark plugs.

    Spoke count is also a factor. You'll want 36 spoke rims as opposed to 32 if you plan to use the kit sprocket adapter of most aftermarket adapters.

    Tom
     
  3. allen standley

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    I've built 2 diamond frame 24s. Both needed the offset intake.
    easy item to find. They look like this.
    http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_2.html

    Also be sure the carb has the rubber O ring in place before inserting the new offset into the carb. Looks like this.
     

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    #3 allen standley, Apr 15, 2016
    Last edited: Apr 15, 2016
  4. crassius

    crassius Active Member

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    built one for customer once - worked OK, but he was disappointed in top speed & we had to redo for smaller sprocket

    for something low, I like to build cruisers that have 7 speeds & good brakes
     
  5. Soylentbob

    Soylentbob New Member

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    Thanks for all the helpful advice, hopefully this will work out for me with no major issues when I attach the motor.
     
  6. Soylentbob

    Soylentbob New Member

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  7. brown

    brown Member

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    If you cut the rear motor mount cross-ways you can make it thinner and drop the motor in the frame. It will help with head and spark plug clearance. However it will reduce the clearance for the carb. It will increase the likely-hood that you will need and offset intake.

    I almost always cut the rear motor mount saddle to lower the motor and the center of gravity. Sometimes if you go to far you will run into clearance issues with the pedal chain drive sprocket. Rarely a problem but worth looking at.

    How I cut my saddles is squaring them up iin a vice and then use a cutoff disc in a 4" hand grinder and cut it down to a least half the thickness. You could use a hack saw and a file and have the same results

    If you are interested I will post a picture of what I am talking about.
     
  8. Soylentbob

    Soylentbob New Member

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    Yes picture would be great thanks.
     
  9. 2door

    2door Moderator
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    Here is a little 24" bike I built that required no modifications. Stock intake and carburetor, straight plug cylinder head and it fit perfectly. The engine does look bigger in a 24" frame but that isn't a problem.

    Tom
     

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  10. allen standley

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  11. Soylentbob

    Soylentbob New Member

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    Turned out good, so mine should work too.
     
  12. brown

    brown Member

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    You can adjust cut saddle to however thick you want. The thinner you make it the closer the engine gets to seat post and increasing the need for the offset intake manifold for carburetor clearance.
    I still almost always cut a 1/4 inch off just so I can drop the motor some.

    0418161140.jpg

    You can fine tune the thickness of the saddle to eliminate any chain tension-er. I also use shims I get from one of the vendors on the site to also adjust the drive chain as needed.

    http://venicemotorbikes.com/shop/?product=chain-tensioning-shim-kit
     
  13. Soylentbob

    Soylentbob New Member

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    Looks like it should work then. I'll be getting a motor for it soon so I'll see how it goes.
     
  14. Soylentbob

    Soylentbob New Member

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    Hopefully these will not be too hard to cut to size.
     
  15. brown

    brown Member

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    You just want to make a straight cut. If you square it up in the vice you can let a hack saw follow the top of the vice jaws an then use a file to touch up the edges. If you don't have a vice find a friend who does. Only takes a few minutes to do.
     
  16. brown

    brown Member

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    When you get the motor you can try it without cutting the saddle. If you have clearance then just leave it stock.
     

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