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Old 03-19-2014, 12:53 PM
Wheeled Relics Wheeled Relics is offline
Motorized Bicycle Member
Join Date: Aug 2013
Location: Portland, Or
Posts: 23
Default Re: Custom Aluminum Cylinder Tank Build Input

Originally Posted by bairdco View Post
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.
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)

Originally Posted by bairdco View Post
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.
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.

Originally Posted by bairdco View Post
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.
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.

Originally Posted by bairdco View Post
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.
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.


Last edited by Wheeled Relics; 03-19-2014 at 02:17 PM.
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