Auxiliary Fuel Tank for Diaphragm Carburetors

G

gone_fishin

Guest
this isn't exactly "wild" but it does fall into the "when good isn't good enough" category :)

i've gotten a few requests for details of my extra tank, & i apologise for slacking off :oops:

this is being done with a GEBE/tanaka32 setup.

so, here goes...i'm posting my pics for now, and will be composing the rest thru the afternoon. this is way easy for the layman, and i'll keep it simple. that's what this topic will be, a simple presentation using "drinking straw" terminology, not the place to discuss rocket-science :cool:
Mvc-811f.jpgMvc-816f.jpg
__________________
"....Get a bicycle. You will not regret it. If you live." - Mark Twain - May 10, 1884
 


G

gone_fishin

Guest
let's start by looking at the fuel system.

the diaphragm carby simply draws fuel by means of vacuum, so we're just looking at a drinking-straw in a glass of cola.

tip: when you "prime" the system, forget about "how many times" you're supposed to push the bulb, it's about filling the system before starting. pump the bulb until you see the bypass/overflow full of fuel, no bubbles. give it another one to be sure. set your choke if needed. if your engine's a good starter, you've probably just learned how to get a "1st-pull" almost every time :)

so, the "draw" comes thru the vent on the gascap, then thru the filter/pickup inside the main tank. there is always a draw on the fuel & the overflow is constantly going back into the main tank, that's how the carby always has fuel to use. we can use that constant draw :)

now, all we're going to do is change the direction and length of the drinking straw.
 
G

gone_fishin

Guest
changing directions is simple. i used a small 1/4" long sheet metal screw to plug the vent in the gascap. then i put a 3/8" hole in the side of the main tank, positioned as near the top as practical.

on the add-on tank, i put a 3/8" hole at the top. the new vent, in my case, was a breeze to locate, some folks may just use another venting gascap.

after that, it's two rubber grommets & some 1/8" ID fuel line. i chose clear line because i like to watch.

i put about 1 1/2" of line into the top grommet and placed the grommet in the main tank aux. inlet.

i put enough fuel line thru the other grommet to let the end dangle about 1" off the bottom of the tank. then i "screwed" a 1 1/2" piece of brass tubing on the end as a weight. i put the grommet in place. done :)

for the best first run, top off the main tank, cap it tightly with the plugged cap. fill the aux. tank...start the engine...

if everything's tight, you'll see an immediate draw on the new line :cool:
 

azbill

Active Member
Joined
Dec 15, 2006
Messages
3,697
nice neat approach ! :)
you could probably use spray paint for vinyl/plastic on the jerry can to blend in with the bike a little
cool idea none the less dude :D
 
G

gone_fishin

Guest
;)
MVC-818F.JPG
as soon as i have a warm day :)
__________________
"....Get a bicycle. You will not regret it. If you live." - Mark Twain - May 10, 1884
 
R

recumbentbill

Guest
Aux tank

Thanx Augi. Your explination and pics with captions cleared things up.
Bill:D
 
G

gone_fishin

Guest
i'm glad it helped...i hope i didn't put anyone off with the simple-talk :???:

i should mention: my system draws fuel thru a 3' line and lifts it 14" without a problem :)
__________________
"....Get a bicycle. You will not regret it. If you live." - Mark Twain - May 10, 1884
 
O

OldPete

Guest
2 strokes will lift a higher head than the 4 strokes, just the nature of the beasts. Two pulses vs one per engine rotation of 720 degrees. (as per Denis at GEBE.)
 
Top