Hurricane Mathew Build

Discussion in 'Motorized Bicycle General Discussion' started by wrenching4fun, Oct 8, 2016.

  1. wrenching4fun

    wrenching4fun Member

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    Didn't have anything to do while waiting out this storm, so I camped out in the garage for a while. Pulled the 66cc HT out of my Stiletto and threw in a 79 cc Predator I bought with a gift card my son gave me to Harbor Freight. Removed all of the extras including the governor and cowling. The engine went in quickly, and the Hilliard clutch was easy to fit, but it took 3 days to find a short in my tach light that was keeping my stator from driving my LED headlight and tail light. (shorting amperage straight to ground) All is good now and will be testing my gearing as soon as the streets dry off. The Hilliard has 10 teeth and my primary drive is an old moped sprocket with 40 teeth. The secondary on my jackshaft is a 10 and the sprocket on my wheel is a 36. Hoping for 45 or 50 MPH out of the gate. Could only get 40 with the Chinagirl. Can see why people like these Predator engines. They start on the first pull and they are easy to modify.
     
  2. TheNecromancer13

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    No way you're going to hit 45 or 50 running a 14.4:1 gear ratio. I have a heavily modded 79cc predator and it only hits 40 with a 13.1:1 ratio.
     
  3. wrenching4fun

    wrenching4fun Member

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    Thanks for the encouragement, Necromancer. It was very helpful. Since you seem to know everything, maybe you can tell me what size capacitor I need to keep my LEDs from blinking at low rpm.
     
  4. mat_man

    mat_man New Member

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    Welcome W4F

    Giant Stiletto looks great. Tons of space. Built in jackshaft.

    I am only getting 30 MPH using your gearing with this:

    Rawge's Mini Chopper jackshaft calc:
    http://rawge.bravepages.com/minichoppers/jack.htm

    (6000 RPM with 24" wheel)

    With 45 MPH gearing you are going have pedal more to have a decent clutch life.

    Wind resistance goes up with cubed root of speed.
    But with such a long bike you could lay down to cheat the wind.

    Best of luck.
     
  5. TheNecromancer13

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    Unfortunately not, I'm pretty clueless when it comes to electrical stuff. I haven't even experimented with engine powered lighting at all.
     
  6. mat_man

    mat_man New Member

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    Your bike has a 7 speed freewheel I overlooked. Gearing looks perfect
     
  7. wrenching4fun

    wrenching4fun Member

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    Actually, Mat Man, I removed the freewheel to install the fatty on rear. Would like to figure out how to re-install. Here are some bad photos of the work so far.
     

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  8. wrenching4fun

    wrenching4fun Member

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    Last photo.
     

    Attached Files:

  9. mat_man

    mat_man New Member

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    Wow! Great build on a bike made to be motorized.
    I think you have room for a 212cc in that frame.

    With your bike returned to the stock freewheel,
    You will have the same function as a $150 Sick Bike Parts Shift Kit.

    This is the great option for top speed for the 79cc.

    This guys 79cc is getting 40mph with a SBP shift kit:
    https://youtu.be/DZQxBofT_Mk?
    4 stoke motorized bicycle 40MPH

    You may have problems with the new NC registration and insurance laws.

    Thanks for the great hi-res Pics.
     
    #9 mat_man, Oct 13, 2016
    Last edited: Oct 13, 2016
  10. wrenching4fun

    wrenching4fun Member

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    I had to add an adapter to the OCC hub for a bolt-on sprocket, so will have to figure out how to re-adapt it for a freewheel. The threaded side of the hub holds another adapter for a brake disc. Might have to reverse and improvise. Does anyone know if they make four or five speed freewheels?
     
  11. mat_man

    mat_man New Member

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    New Suntour 8.8.8. Multiple Free Wheel 5 Speed 14.18.22.28.34. for 1/2 x 3/32
    http://www.ebay.com/itm/New-Suntour...d-14-18-22-28-34-for-1-2-x-3-32-/400622986470

    This is what I would use. High Quality.
    You may be able to rebuild this freewheel and get larger than 34 teeth.
    You may need to space the frame wider and add spacers. This has been done before on OCC's and may be documented.

    Bicycle Scooter Sprocket Metal Wheel 3 Speed Freewheel
    http://www.ebay.com/itm/Bicycle-Sco...db532ef&pid=100005&rk=4&rkt=6&sd=381730185526

    Made in China. I would replace balls with grade 25 and pack with grease.
    You may not have spacing issues. You may be able to rebuild this freewheel and get more teeth.


    This might work:

    Home built disc brake on motorized Schwinn Stingray
    https://www.youtube.com/watch?v=BDpS0yzpWus
     
    #11 mat_man, Oct 13, 2016
    Last edited: Oct 13, 2016
  12. wrenching4fun

    wrenching4fun Member

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    Thanks for the tips, Mat Man. The bike came with Shimano hardware (except for shifter which was a Sram MRX-7), but am open to Sun products if they're better. Took it out for a spin and broke the master link on the 415 main drive chain. Might have miss-installed due to excitement over getting finished. Replaced it and took another test drive. I think I'll ride as a single speed for a while and tweak everything. The frame has already been widened quite a bit to accommodate the OCC wheel. Don't know if I can squeeze any more space for freewheel without throwing everything out of whack or compromising the frame. Took a section of exhaust out to shorten pipe. Looks much better. The bike has plenty of power with the 79, a 212 would be overkill at this point unless I wanted to race( been there, done that, over it). After all, it is a motorized bicycle. .shft.
     
  13. mat_man

    mat_man New Member

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    The Suntour freewheel is 30 years old, not going to do 7 speed SIS index shifting.
    (Cogs and spacers too wide). But quality is as good as Shimano.

    LBS trash many 7 speed wheels. Cheaper to replace than labor to fix.
    Chop off outer 3 cogs and weld it up. Free wheeling function not required.
    Freewheel must safety wired to prevent it being unscrewed.

    Exploded 7 speed freewheel:
    http://forums.mtbr.com/singlespeed/...step-step-photo-guide-373319.html#post7289205
    Homemade SS Freewheels - step-by-step photo guide


    Specialized Fatboy 20" has 4" tires, disk brake and 9 speed on 170mm spacing,
    (same spacing as OCC ?) :
    https://www.specialized.com/us/en/bikes/mountain/fat-bike/fatboy/fatboy20/106643
    Specialized Hub 170, Hi Hi disc, alloy, QR, 32h

    Sub $200 Mongoose Fatboys might be the same.
     
    #13 mat_man, Oct 17, 2016
    Last edited: Oct 18, 2016
  14. Tony01

    Tony01 Member

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    The 79cc will only take you to 40. You'll need to do some major mods to it of you wanna go faster. If you wanna do 50 better to go with a 212cc as it will do 55 easy as stock with governor removed. And you'll need a gear ratio of approx 8:1 on a 26" tire to do it. I dunno the size of that rear but if it's a 24 or 22ish an 6:1 will do. Your current gearing of around 14 will top out at maybe 25-30mph.

    I have my 212cc setup with a 6.4:1 top gear on 26".
     
  15. langolier

    langolier New Member

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    Good looking build. You may hit 45 or 50 but with that kind of gearing you may have a hard time with hilly terrain. Like previously stated perhaps a 212 would be a better fit. I recognize that gas tank, I used to own a 1976 Harley SX-250 dirt bike.
     
  16. wrenching4fun

    wrenching4fun Member

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    Thanks, Langolier. I think these tanks came on 250 and 350 Sprints. Got mine on Ebay for $25 already cleaned, lined with a petcock and new cap. It fit the frame, so I threw it on. No worry with hills here on the coast. My house is only 14 feet above sea level. I thought about a 212 but I'm afraid it would attract the wrong kind of attention. It would fit and would be an easy swap. I think I'll try a multi-speed cassette first. Need to spec out the clearance. My other MB has a Huasheng hooked up to a Shimano 3-speed. It's a blast to ride, but the Phantom pipe makes it sound like a Cushman scooter!
     
  17. wrenching4fun

    wrenching4fun Member

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    Swapped out my plain jackshaft for a threaded one with double nuts on both ends. No more problems with chain. Will be experimenting with freewheel and derailer next. Not much room to play with. Thanks for input on choices.
     

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