Custom Aluminum Cylinder Tank Build Input

Discussion in 'Motorized Bicycle General Discussion' started by Wheeled Relics, Mar 18, 2014.

  1. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    I am currently working with a manf of go-kart fuel tanks to produce a small run of motorized bicycle cylinder tanks that will fit double-bar design bicycle frames.

    My initial design is for a cylinder tank that will fit between a range of straight moto-bike style doublebar and bent-bar frames.

    Round Aluminum Tank Tapered Ends
    2.75" Dia x 11" Long (fitting between most doublebars)
    1.5" Offset Filler
    Bottom rear offset down-spout/petcock

    I would like some input from the motorized bicycle community on desired specs of tanks of this simple cylinder design to fit in double bar frames. Thank you.
     
  2. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
  3. FFV8

    FFV8 New Member

    Joined:
    Oct 29, 2013
    Messages:
    552
    Likes Received:
    1
    Does not seem terribly practical.

    With the filler 1/3 of the way down one side, you will be lucky to get 500 cc's of gasoline in it.

    Even with creative fueling the tank holds less than a Liter.

    The basic China Girl tank is 2 Liters.
     
  4. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    The diagram is my first brainstorm to get the ideas across to the head of the shop. I'll draw some more precise drawings up tonight. This is the exact reason I'm posting in the forum asking for ideas so thank you.

    The filler will be positioned high enough and tall enough to be able to fill the tank to capacity. This is the kind of feedback I need though... I'm looking for options that fit between the double-bars like the motor kids of the 20's and 30's (ie:evans) instead of the top tanks of the china doll kits.

    An idea I have to increase capacity that would fit in with a tubular tank while keeping cost down is tapering the back end like the old school motorbike tanks, except tapering it like a cone, to use the angled part of the frame geometry. The downspout would still be located at the lowest point in the bottom rear.

    The design idea is based around existing tooling for producing cylinder tanks for these go-karts, being able to use an orbital welder will keep cost down for me.
     
    #4 Wheeled Relics, Mar 18, 2014
    Last edited: Mar 18, 2014
  5. wret

    wret Active Member

    Joined:
    Feb 24, 2014
    Messages:
    352
    Likes Received:
    30
    You can split it and stretch it out.

    [​IMG]
     

    Attached Files:

  6. bairdco

    bairdco a guy who makes cool bikes

    Joined:
    Aug 18, 2009
    Messages:
    6,403
    Likes Received:
    50
    i had the same idea a few years back. the reasons i abandoned it where; a tank tha small hold roughly 24oz of fuel, about 1/5 of a gallon.

    that would give you about 20-30 miles on a china 2-stroke. i used to ride 30+ miles daily to work and back and needed more gas.

    there are many different double bar frames made over the years with different spacing between the bars. on a wide spaced frame like a worksman, the tank would look small and goofy. on some older bike's there's 2.5" spacing, plus many different tapers, from angles to sweeping bends. fitting these frames would be tough for a universal tank.

    cost is another factor. getting a welded cylinder is cheap but adding in a quality petcock, bung and cap brings your cost up. too make it up a tank would end up retailing for 150 to 200 bucks.

    not to offend anyone, but the majority of bike owners are, uh, lets say "thrifty," and think that since they're motor costs under $200, tanks and expansion chambers should be a lot less than that, even though the same amount of work as building custom motorcycle parts go into it.

    the double bar frame isn't as popular as a box store cruiser, so your customer base is limited. also, many builders of vintage bikes have the skill to make their own tank.

    if you're serious about making tanks, a universal behind the seat tank may be more profitable.
     
  7. FFV8

    FFV8 New Member

    Joined:
    Oct 29, 2013
    Messages:
    552
    Likes Received:
    1
    Baird covered all of it well.

    "Thrifty" was kind indeed.

    I think the idea of a behind the seat tank is a very good one.

    I admit I am spoiled by having 2 gallons in the tank on the sidehack.

    [​IMG]
     
  8. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    I'm calculating an 11"x2.75" cylinder with a 5" cone to hold 80 cubic inches or 1/3 of a gallon.

    I ride 8 miles to work (4 miles each way) so my fuel need is minimal for. 48cc china doll. I've never ran the china doll bubble tank dry on a leisure ride however I've taken msr fuel canisters full of mix if I have thought I might. I guess you'd call me a low risk user.

    The short answer to 1/3 gal not being enough is that 1/3gal may not be enough for some, but its just enough for others. The trade off for the smooth ergonomics of a torpedo tank is its capacity, however maximized. Speaking for myself personally, its worth the trade off, but my risk of running out of fuel is very low for the applications I use my bike for (short commutes & leisure rides)

    The tooling of the manufacturing company I'm working with is set up to handle tubing in increments of sizes. If a short production run is successful, increments of 1/4" or 1/2" dia could be setup to fit common straight double bar frames. 2" 2.25" 2.75" 3" I have the variety of frame sizes you are referencing, and have been measuring and projecting a tank fit for each one.

    This isn't the appropriate thread to discuss end cost (per mods msg to me) but I can say this is not necessarily an accurate estimate given the existing tooling setups and the an orbital welder. It's my intention to keep this number as low as possible.

    There is currently a couple different suppliers for small fuel barrels that fit behind the seat. I'm not one to compete with what's already a tiny niche in the motorbike community, that isn't to say it won't happen, just that it already has.

    I think its accurate to say i'm aiming at a specialized customer base with a specific need that doesn't commercially exist. Specifically china doll replica builders. The double bar frame may not be as popular to the average motor bicyclist, but its popular with enough people that are building antique and board track replicas that a commercially available torpedo tank similar to what was produced with bicycle engine kits of the twenties and thirties may be desirable, esp for those who do not have the fabrication equipment or skills available to them to make their own tanks. I am seeing more and more china doll kits going on board track, antique style and double bar bicycles, with plenty of people spending time and energy making their own versions of tube tanks.

    Personally I've been hunting for commercially available in frame torpedo tank options for a couple years now with no real luck other then what I would consider less then aesthetically pleasing commercial grade sheet metsl tanks that never quite fit my application needs.

    The opening i'm seeing here is an inexpensive, aesthetically "correct" torpedo tanks, for all the double bar owners out there, including myself. If anyone is aware of small commerciallu available in frame tanks that fit double bars please share them with me! I love to spend money wisely, and I have an idea of what I want to spend it on.

    .
     
    #8 Wheeled Relics, Mar 19, 2014
    Last edited: Mar 19, 2014
  9. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    Researching chassis brackets for attaching tank to frame.

    Ideas and references welcome:

    [​IMG]
     
    #9 Wheeled Relics, Mar 19, 2014
    Last edited: Mar 19, 2014
  10. LabRat

    LabRat New Member

    Joined:
    Dec 24, 2011
    Messages:
    597
    Likes Received:
    0
    That tank built like that would not hold much less than half a gallon
     
  11. LabRat

    LabRat New Member

    Joined:
    Dec 24, 2011
    Messages:
    597
    Likes Received:
    0

    Nice tank!
     
  12. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    yes about a third of a gallon


    (pre-war speed chief improvising with a small engine tank):
    [​IMG]
     
    #12 Wheeled Relics, Mar 19, 2014
    Last edited: Mar 20, 2014
  13. wret

    wret Active Member

    Joined:
    Feb 24, 2014
    Messages:
    352
    Likes Received:
    30
    It would add some cost but if you could extend the filler neck with a 45° tube, you would get to fill the whole tank.
     
  14. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0
    Absolutely. The filler will be high enough to fill the tank completely. The fill hole will be 1.5" extend high enough to top off.

    The capcity difference with the conical addition to the end of the cylinder increases volume from 1/4 gallon to 1/3 gallon.

    Dave
     
  15. Wheeled Relics

    Wheeled Relics New Member

    Joined:
    Aug 18, 2013
    Messages:
    23
    Likes Received:
    0

Share This Page