Adding a 2nd fuel tank outlet

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Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Adding a 2nd fuel tank outlet

Unread post by Darrell » Sun Dec 05, 2010 8:18 pm

I want to braze another 1/8"NPT union on the other side of my Bantam fuel tank. The reason (it seems to me) is because that being a 'saddle tank', there will always be a quantity of fuel opposite to the existing outlet that cannot be drained to the carburetta. The job would appear to be relatively straight forward with all of the precautions one must take when applying heat to a fuel tank that once held petrel - albeit 20 years ago. Does anyone have experience of this mod that could be of some value to me please?

My Starfire tank has 2 outlets which is just common sense to me and I cannot understand why all saddle type fuel tanks don't have 2 outlets - unless it's a compromise of economics.

The Mighty Gusset

Re: Adding a 2nd fuel tank outlet

Unread post by The Mighty Gusset » Sun Dec 05, 2010 8:31 pm

Petrel ?
Some bugger has put a dead sea-bird in your petrol tank ?
Bastards !
I hate it when they do that.
(Three times last week !)

The fact is, folk have been riding around on Mechanical Chickens since God was a baby, and haven't felt the need for a second fuel tap, so why worry about it ?
Just make sure you fill up before the fuel level drops to a level where it becomes an issue.

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Greenbat
Posts: 2748
Joined: Tue Feb 17, 2009 11:25 pm

Re: Adding a 2nd fuel tank outlet

Unread post by Greenbat » Sun Dec 05, 2010 8:34 pm

Darrell wrote:I want to braze another 1/8"NPT union on the other side of my Bantam fuel tank. The reason (it seems to me) is because that being a 'saddle tank', there will always be a quantity of fuel opposite to the existing outlet that cannot be drained to the carburetta. The job would appear to be relatively straight forward with all of the precautions one must take when applying heat to a fuel tank that once held petrel - albeit 20 years ago. Does anyone have experience of this mod that could be of some value to me please?

My Starfire tank has 2 outlets which is just common sense to me and I cannot understand why all saddle type fuel tanks don't have 2 outlets - unless it's a compromise of economics.


Thats your reserve tank. when you run out you tip the bike to the left as far as you can, some petrol sloshes over and off you can go. I imagine that in practice most of it gets sloshed over anyway, certainly on the roads round here.

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Hooli
Posts: 10183
Joined: Thu Feb 19, 2009 11:52 pm
Location: Doncaster

Re: Adding a 2nd fuel tank outlet

Unread post by Hooli » Sun Dec 05, 2010 8:37 pm

The Mighty Gusset wrote:Petrel ?
Some bugger has put a dead sea-bird in your petrol tank ?
Bastards !
I hate it when they do that.
(Three times last week !)


:lol: :lol:
Classics ain't built in Metric

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: Adding a 2nd fuel tank outlet

Unread post by Darrell » Sun Dec 05, 2010 8:42 pm

ok - Petroil then.

Stopping to refuel is not something I crave (read 'like') and when a simple mod can dilute the number of times I have to visit a service station - sounds good to me. Could be you have more time on your hands than I?

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Greenbat
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Joined: Tue Feb 17, 2009 11:25 pm

Re: Adding a 2nd fuel tank outlet

Unread post by Greenbat » Sun Dec 05, 2010 8:52 pm

Darrell wrote:ok - Petroil then.

Stopping to refuel is not something I crave (read 'like') and when a simple mod can dilute the number of times I have to visit a service station - sounds good to me. Could be you have more time on your hands than I?


A bantam should be good for over 60mpg, think the tanks about 8 litres so you should get well over 100 miles/tank. If you're riding it enough to find that a nuisance I am highly impressed! I usually faff about with jerry cans to get the oil mix spot on, if I'm going for a long ride I always top it up or carry a can. Which is irrelevant really.

Back on topic (ha!), You'll want something made up to screw the tap in as per the original-personally I'd go for brass or copper as its easily solderable, I reckon a good size flange to seat it should do the trick. As ever, send a drawing, the lathe hasn't been used in a while actually.
To join it, I'd solder it as lower temperatures are needed. I'd also have a spigot that is a tight fit in the tank, to give some additional sealing/security. Main problem is that even an old tank will have fuel traces that could turn to vapour and ignite. Dad successfully soldered the benly tank after rinsing with hot water then keeping a hairdryer blowing through the tank to dilute any vapours.

The Mighty Gusset

Re: Adding a 2nd fuel tank outlet

Unread post by The Mighty Gusset » Sun Dec 05, 2010 8:57 pm

Sounds to me that it's you who has too much time, and money, on your hands.
How long is it going to take, and how much money, to modify a perfectly serviceable item, in order to make it ever so slightly more convenient ?
How much petrol do you think you are missing out on ?
It can't be more than about 1/2 a pint.
Also, seeing as it's a dodgy old pre-mix two-smoke, surely you've worked out roughly what sort of mileage you are getting, so that you can fill up with a fixed quantity of fuel (ie either 4 or 5 litres or a Gallon) so that the two-smoke oil calculation doesn't get too complimacated ?
How often do you actually do more than a complete tank full of petrol in one day's ride out ?

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: Adding a 2nd fuel tank outlet

Unread post by Darrell » Sun Dec 05, 2010 11:04 pm

Thank you Greenbat for your welcome comments. I had not thought about the hairdryer taking away any possible fumes during brazing/soldering. I shall definately employ that when fusing the union to the tank.

Thanks also for your offer of making said union on your lathe. I am already in possession of a lathe and will be fabricating the union at this end. I would like return your kind offer by offering you something in return. You mentioned "to send a drawing" in your reply - well I have been drawing electro/mechanical drawings all of my working life and if you would like, I could reproduce on AutoCAD an electrical drawing of your Bantam? Of course it would only be advantageous if you have modified the existing electrical circuitry - that way I could show all of the mods you have carried out on your machine. I have produced one for mine showing where I have departed from the standard wiring loom - 12V coil/Indicators/Non standard Ignition Switch/Main fuse/Indicator fuse/Ammeter/Handle bar heaters etc etc. To mark that up over the electrical diagram in the workshop manual would be a pain and it would look confusing. Far better to have a dedicated wiring diagram for my actual bike that I can modify and print out another copy - in fact I can print another copy when the other gets dirty in the workshop.

Just a thought.

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: Adding a 2nd fuel tank outlet

Unread post by Darrell » Sun Dec 05, 2010 11:34 pm

Negative Gus wrote:Sounds to me that it's you who has too much time, and money, on your hands.
How long is it going to take, and how much money, to modify a perfectly serviceable item, in order to make it ever so slightly more convenient ?
How much petrol do you think you are missing out on ?
It can't be more than about 1/2 a pint.
Also, seeing as it's a dodgy old pre-mix two-smoke, surely you've worked out roughly what sort of mileage you are getting, so that you can fill up with a fixed quantity of fuel (ie either 4 or 5 litres or a Gallon) so that the two-smoke oil calculation doesn't get too complimacated ?
How often do you actually do more than a complete tank full of petrol in one day's ride out ?

Compared to you yes, I probably do have more time and money but since when has your way been the only way ?

How long is it going to take ? It will take as long as it takes. Believe it or not, there are individuals out here that actually do like to work on our bikes in an effort to improve them albeit "ever so slightly more convenient ?"

Your thoughts of there being no more than 1/2 pint left when the engine goes silent are conservative to the extreme yet even that 1/2 pint will see me pass you at the roadside with a cheery wave while you are flaffing about leaning the bike over and all that tosh. I just wish I had your healthy 'back' to have the choice of doing it.

I never realised that husbandry of a 2T mix was such a coveted pastime.

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Greenbat
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Re: Adding a 2nd fuel tank outlet

Unread post by Greenbat » Sun Dec 05, 2010 11:44 pm

Thanks for the offer, I'm OK for wiring diagram but if I need owt else drawing I'll ask. I do carry a lot of diagrams in my head, though this one is written down...somewhere...
How did you do yours? Mine is 12v neg earth with a jap reg/rect and proper wired returns throughout-though sadly I couldn't avoid having the frame live, at least I'm not relying on it!

Regards the tank, steel does retain a small amount of petrol, even when dry and after many years. If you're doing hot things with it you need to be very careful. Ideally you'd want an electric soldering iron, or one you heat up. Naked flames are not a good idea! But as has been said, it does seem a lot of work for very little gain.

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