AMF Roadmaster

Discussion in 'Motorized Bicycle General Discussion' started by dracothered, Jul 18, 2013.

  1. dracothered

    dracothered New Member

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    Here it is on the frame now, still need to do a little more to them.

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  2. mapbike

    mapbike Active Member

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    wow.... Looks awesome draco........ nice work!

    That is gonna be a very cool and unique ride when you're done, I'm very excited for you and for me to get to see it when it's finished, gonna be something to really be proud of no doubt....

    Map
    reddd
     
  3. curtisfox

    curtisfox Well-Known Member

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  4. dracothered

    dracothered New Member

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    Yea I have it.

    So if I put in:
    Gearbox: Transmission Ratio: Primary :3.722 1th:2.615(34:13) 2th:1.611(29:18)
    then use 13T and 38T with a 22" tall tire at 7000 rpm's it comes out to 42.1mph.

    36T = 44mph @ 7000 rpm and 54 mph at 8500 rpm
     
  5. dracothered

    dracothered New Member

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    It looks more like a motor bike now, but the engine needs to be moved back some. So off come the BB, but leave as much of the tube that come down to the BB for welding the engine mount to it.

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  6. curtisfox

    curtisfox Well-Known Member

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    Sounds about right. I do it the old fashion way by multaplcation..........Curt
     
  7. maniac57

    maniac57 Old, Fat, and still faster than you

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    Looking good!
    I'm still a bit concerned about strength.
    I urge you to err on the side of caution. That engine is fast enough to hurt you.
     
  8. dracothered

    dracothered New Member

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    In what areas do you think it need more beefing up?
     
  9. maniac57

    maniac57 Old, Fat, and still faster than you

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    That's a lot of engine to hang off that single downtube...I'd be worried about fatigue cracking at the steering tube and/or the bottom bracket. Even with thicker than normal tubing, I'd seriously consider bracing it better with some triangulation or heavy gusseting. It looks to me like it will act as a sort of spring and you're putting a lot of faith in one tube.
    Just my opinion from 30 years of welding and fabrication.
    You should be able to figure something to keep the look you like without compromising strength. Maybe a flat strip welded the length of the tube to add vertical load strength?
    You have the skills, think about it.
     
  10. dracothered

    dracothered New Member

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    I can see your points and here is a virtual mock up...

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    I was already planning on beefing up the area where the engine will mount. I do thank you for your concerns on this.
     
  11. dracothered

    dracothered New Member

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    Well the frame brace is for real now.

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    Still need to add some gusset to the head tube.
     
  12. mapbike

    mapbike Active Member

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    Looks excellent.....

    I also was concerned about needinging a bit more beefing up in those areas but figured you would probably come to that conclusion, obviously you have very good fab skills so you'll make it right and it will be a very enjoyable build when you're done, it dont get no more custom than that.

    Again......great job
    Map
    reddd
     
  13. dracothered

    dracothered New Member

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    They are getting better with each thing I do, but no where as good as others on here. My welding still sucks, but that is partly due to the welder I have.
     
  14. mapbike

    mapbike Active Member

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    As long as the weld holds and has good penetration thats all that matters, a grinder and some paint will take pretty much care of the rest, I've seen some very pretty welds that arent strong, just burn them ingood and grind off the ugly stuff.......lol!

    Many times Ill pick the most unique over the fanciest.... I think what you're doing is unique and its gonna look great also.......many people out there would love to have your skill, you're doing a great job draco.

    Map
     
  15. maniac57

    maniac57 Old, Fat, and still faster than you

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    This looks much stronger and safer! Still looks good too!
    You are doing a great job building and I look forward to the completed bike!
    Very unique!
     
  16. maniac57

    maniac57 Old, Fat, and still faster than you

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    I also agree with Mapbike. I have a crappy buzz box 110 welder and it's impossible to get pretty welds even with my experience. The important thing is to get good penetration. Like Map said, a grinder will make it look good. Concentrate on strong rather than pretty.
    Your skills are obvious. Just don't get hurt.
     
  17. curtisfox

    curtisfox Well-Known Member

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    maniac the welder you have just a stick welder if so try some 7014 its a contact rod,just turn the heat up a little and hold it right on the metal. Make a pro out of you............Curt
     
  18. mapbike

    mapbike Active Member

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    Yep 7014 is one of the easiest rods to weld with on a cracker box welder, its a strong weld and an easy flux rod, can make some pretty welds with it as long as metal is good and clean.

    Map
     
  19. dracothered

    dracothered New Member

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    Added the bottom Head tube gusset brace. I used a section of a bent chain ring to give it some flair.

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  20. dracothered

    dracothered New Member

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    Welded the top gusset in place with my new welder (OH MAN IT WELDS SO MUCH BETTER)

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