The BSA A7-A10 Forum

Technical => Frame => Topic started by: terryk on 29.08. 2007 13:32

Title: A10 plunger fuel tank
Post by: terryk on 29.08. 2007 13:32
Hi all, I have noticed there are two sorts of plunger A10 fuel tanks. One has slots at the back where tank attaches to bolts on the frame and the other tank has rings that the bolt goes through. I'm under the impression at this point that the slot ones are for 1950- 52 and the rings are 53 on is this correct does anyone know for sure. My bike is 51.
thanks
Title: Re: A10 plunger fuel tank
Post by: Beezageezauk on 29.08. 2007 20:24
Hi Terry, 

You are quite correct to realise that there are two basic types of A7/A10 fuel tanks.  The ones with the slots fit the rigid and plunger frame models and the ones with the single bolt top mounting are for the swinging arm models.  The one you need for a 1951 model is the type with the slots.

Beezageezauk.
Title: Re: A10 plunger fuel tank
Post by: G/F DAVE on 29.08. 2007 20:47
Hi, Terry I have a 1952 Goldflash the tank that is fitted has the rings at rear  these are for rubber mounts it has slots at the front, I also have a 1953 frame this has same rear mount as 1952  frame but front mounting has sleeved rubber inserts, I think either tank will fit both types of plunger frame . I,m sure my tank is the later type to suit frames the with rubber mountings front & back ie; 1953 onwards, hope this is of help to you. ?? all the best Dave
Title: Re: A10 plunger fuel tank
Post by: a10gf on 30.08. 2007 00:02
Never tought about it before, there seems to be two different a10 plunger tanks, one for the cowlheadlamp model and one for the no-cowl. See page 179 and 187 in bacon's bsa twin restoration. On the no-cowl there are cut-outs for the rear bolts, and bolts are slightly visible both rear and front, with visible mounting flanges in front.

Hope this helps.
E
Title: Re: A10 plunger fuel tank
Post by: terryk on 01.09. 2007 12:24
Hi again, Hey all you a10 plunger 1950 - 53 owners who has rings at the back to attach tank and who has slots. What year is you bike.
I have two different tanks both need repairing. One has rings and the other has slots at back. I want to know which tanks to use so I can spent the time fixing it, my bike is 51.
I think at this stage 50-52 has slots and 53 on has rings when headlight cowl was introduced. I know there is a later tank with a hole thru tank top but I want to know about earlier ones.
thanks in advance. Terry
Title: Re: A10 plunger fuel tank
Post by: G/F DAVE on 01.09. 2007 14:39
Hi, Terry the one for your 1952 frame is the one with slots front & rear, I have the later rubber mounted type fitted to my 1952 flash so  you could use either of your tanks. I,d go for the one in the best condition. All the best Dave...
Title: Re: A10 plunger fuel tank
Post by: a10gf on 01.09. 2007 19:16
Some pictures

rear non-slot tank
http://www.a7a10.net/BSA/bsapics/BSA11.08.04.jpg

rear slot tank
http://www.a7a10.net/BSA/bsapics/i-6_B_L.jpg

+ on page 13 in "BSA Twin Restoration", there is a picture of a 1951 w smaller chrome tank with apparently no slot for the seat, looks like an earlier A7 tank size.

Then, in Bacon's "twins and triples" I find the pic of a non-slot tank on a 50' plunger, so now I am confused! Anybody know the exact story and dates?



Title: Re: A10 plunger fuel tank
Post by: Brian on 07.09. 2007 22:59
Thought I would see if I can confuse the issue even further ! My 53' plunger has rubber mounts back and front. Where it gets a bit harder is with the smaller A7 tank, the early ridgid and plunger ones have holes at rear to mount and the mounts are closer together. My 51' A7 has slots and the mounts are wider apart so you have to use spacers the same as the A10. The good news is that they are all interchangeable, I tried them, the only thing is you need the two spacers at the rear if using the wider mount tank. Does anyone know for certain if any A10's had the smaller A7 style tank fitted at the factory. I have seen plenty of them on bikes but have yet to see a original photo of one on a bike.
Title: Re: A10 plunger fuel tank
Post by: Simon59 on 18.01. 2018 12:35
Hi All. Just to add to the mix, my 1954 plunger A10 fuel tank has rings at the rear that a bolt goes through to fix it to the frame. The rubber inserts in the rings were rotten but I will replace them with something suitable if I can't get the OEM items.

On the subject of tanks, can anyone recommend a company (or DIY process) to de-rust and seal the inside of my tank? The bike hasn't been used for 46 years, so nothing has been done to it. I believe the rust can be removed with drain cleaner acids, but these are hard to buy now and I would probably prefer someone else to do it if the cost is reasonable. Is Petseal the best sealant?

Anyone's good experiences or advice appreciated!  *smiley4*   
Title: Re: A10 plunger fuel tank
Post by: Peter Gee on 18.01. 2018 14:46
Do NOT use Petseal, ethanol turns it to gum in a few years IMO. I use POR from USA and there are others.
Title: Re: A10 plunger fuel tank
Post by: BSA_54A10 on 18.01. 2018 23:00
Hi All. Just to add to the mix, my 1954 plunger A10 fuel tank has rings at the rear that a bolt goes through to fix it to the frame. The rubber inserts in the rings were rotten but I will replace them with something suitable if I can't get the OEM items.

On the subject of tanks, can anyone recommend a company (or DIY process) to de-rust and seal the inside of my tank? The bike hasn't been used for 46 years, so nothing has been done to it. I believe the rust can be removed with drain cleaner acids, but these are hard to buy now and I would probably prefer someone else to do it if the cost is reasonable. Is Petseal the best sealant?

Anyone's good experiences or advice appreciated!  *smiley4*
Best thing to do is clean the tank then unless there is a hole, don't touch it just remember to keep it full most of the time and occasionally drain it totally to remove condensed water.
Hydrochloric acid will remove rust from the inside of a tank and you can get it from any swimming pool shop in 5 gallon tubs.
Title: Re: A10 plunger fuel tank
Post by: BSA_54A10 on 18.01. 2018 23:02
Some pictures

rear non-slot tank
http://www.a7a10.net/BSA/bsapics/BSA11.08.04.jpg

rear slot tank
http://www.a7a10.net/BSA/bsapics/i-6_B_L.jpg

+ on page 13 in "BSA Twin Restoration", there is a picture of a 1951 w smaller chrome tank with apparently no slot for the seat, looks like an earlier A7 tank size.

Then, in Bacon's "twins and triples" I find the pic of a non-slot tank on a 50' plunger, so now I am confused! Anybody know the exact story and dates?

Most likely one of the 1000 errors in every Bacon book.
You should treat them as coffee table books not reference material.
The only worthwhile parts of them are the apendicies at the back.

All he did was add a bit of text to link BSA factory press releases together.
Most of the photos are from the same source so they are what the advertising department said the factory was going to make FOR THE UK MARKET next season and not necessarily what the factory actually made.
OTOH the tables in the back of the Restoration Guide which were compiled from the parts books would be a lot more use to you.
Again it is UK SPECIFIC but it does clearly show when a new tank was introduced and how long it got used.

You also have to remember that BSA's production time preceeded computer controlled inventory and BSA regularly ran out of parts
So the fitting of substitute parts was not uncommon, be they parts from a different model that would or could be made to fit or parts bought in from an external supplier.
BSA made their own tanks, but if the presses were set up to make Bantam tanks when they ran out of A 10 tanks, the last 10 tanks needed to fill the order currently being made would be sourced externally , if they could not be pinched from the spares warehouse.
Considering just how easy it is to damage a tank and A 10's are now old enough to draw a pension there is no reason to believe that any bike is still wearing the same tank it left the factory with.
Title: Re: A10 plunger fuel tank
Post by: Simon59 on 19.01. 2018 09:20
Thanks Trevor. So you would de-rust the tank but not seal it? Sounds sensible if keeping the tank mostly full and draining it for the winter reduces the effects of the dreaded ethanol.

I've read a very interesting article online (from RealClassic.co.uk) that suggests using sodium hydroxide (caustic soda) to remove any gunge, then hydrochloric acid (spirits of salt) to remove the rust followed by a rinse of phosphoric acid to protect the newly cleaned surface.

Whilst all these chemicals are relatively cheap, a recent spate of acid attacks (really!) in the UK has made them difficult to buy.

Sounds like a bit of a faff but I'm desperate to hang on to my original tank rather than buy an Indian after-market replacement, but after 46 years in the back of a damp garage, my tank is pretty badly corroded inside.

Title: Re: A10 plunger fuel tank
Post by: Greybeard on 19.01. 2018 09:38
My tank came back from the platers rusty inside. I lined it with POR15. We don't have as much ethanol here in the UK.
Title: Re: A10 plunger fuel tank
Post by: Rex on 19.01. 2018 10:16
Yep, POR15 for me too. Did a Scott tank with leaky seams and it's really effective. Make sure you put a blanking plug or old duff taps in the outlets though!
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 19.01. 2018 13:46
Make sure you put a blanking plug or old duff taps in the outlets though!
I bought some blanking plugs for the tap spigots but still needed to buy a thread tap to clean the threads further in.


I'd be happy to lend out the plugs and tap if anyone here needs them.
Title: Re: A10 plunger fuel tank
Post by: cyclobutch on 19.01. 2018 16:00
I've got a melty liner in one of my tanks.

If you do go with one it needs to be able to cope with at least 10% ethanol in petrol.
Title: Re: A10 plunger fuel tank
Post by: Minto on 01.07. 2020 02:19
Make sure you put a blanking plug or old duff taps in the outlets though!
I bought some blanking plugs for the tap spigots but still needed to buy a thread tap to clean the threads further in.


I'd be happy to lend out the plugs and tap if anyone here needs them.

Hey GB
Having just got a new replica tank, I'll need to to run a tap through the fuel tap threads before I fit them. Very generous offer on the loan but I'd prefer to buy the necessary tap but could you tell me what size I'll need to order please.
Cheers
Jase
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 01.07. 2020 09:13
Make sure you put a blanking plug or old duff taps in the outlets though!
I bought some blanking plugs for the tap spigots but still needed to buy a thread tap to clean the threads further in.


I'd be happy to lend out the plugs and tap if anyone here needs them.

Hey GB
Having just got a new replica tank, I'll need to to run a tap through the fuel tap threads before I fit them. Very generous offer on the loan but I'd prefer to buy the necessary tap but could you tell me what size I'll need to order please.
Cheers
Jase
I think it's a BSP thread. I'll need to find the tap before I can tell you the size. If no one gets back to you, I'll tell you later.
Title: Re: A10 plunger fuel tank
Post by: BigJim on 01.07. 2020 09:38
If that's an Indian tank then it may be nothing like GB's original. Am pleased with my tank but the taps took some fettling. Can't remember what the thread was sorry to say but i did fit an off the shelf adaptor and forced it in with lots of tank sealer and it's been good for years and lots of miles now. A more patient or sympathetic owner would probably/definitely baulk at this.
Title: Re: A10 plunger fuel tank
Post by: Minto on 01.07. 2020 11:04
Cheers GB and Jim, I can definitely see some fettling occurring over the weekend!
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 01.07. 2020 18:59
Sorry for the delay getting back to you. I've only just remembered to look for that tap.
It says BSP 3/8 - 19 on the side.

The offer of a loan of the tap is still open.
Title: Re: A10 plunger fuel tank
Post by: Minto on 01.07. 2020 19:05
Thanks GB, that's very generous of you. If I message you my address how do you want paying for postage? I'll post it back the same day it arrives.
Cheers
Jase
Title: Re: A10 plunger fuel tank
Post by: trevinoz on 01.07. 2020 23:00
Really needs to be BSPP, BSP is tapered whereas BSPP is parallel.
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 01.07. 2020 23:03
Really needs to be BSPP, BSP is tapered whereas BSPP is parallel.

Are you thinking of the tap spigot maybe?
Title: Re: A10 plunger fuel tank
Post by: trevinoz on 01.07. 2020 23:11
I am thinking about the thread in the tank.
I am not in the shed at the moment and I am thinking about swinging arm tanks which have a reducing bush which screws into the tank and if my memory serves me well the bush is 3/8 BSPP to 1/4 BSPP.
Title: Re: A10 plunger fuel tank
Post by: Rex on 02.07. 2020 08:32
Really needs to be BSPP, BSP is tapered whereas BSPP is parallel.

No it's not. BSPT is the tapered thread fittings (of which there are none on a BSA) but the tank spigots are BSP (which is a parallel thread) not BSPP.
BSP and BSPP are not the same.
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 02.07. 2020 14:05
Thanks GB, that's very generous of you. If I message you my address how do you want paying for postage? I'll post it back the same day it arrives.
Cheers
Jase
The tap is in the post, First Class.

I don't want you to pay me anything. If you would like to donate an amount to this forum of at least your return postage charge, I will be happy.

No need to rush it back; I'm not planning to use it for the foreseeable future!
Title: Re: A10 plunger fuel tank
Post by: Minto on 02.07. 2020 15:21
Thanks GB.
Ill look into how to make a donation
Cheers
Jase
Title: Re: A10 plunger fuel tank
Post by: trevinoz on 02.07. 2020 23:36
Rex, According to my thread chart, you are wrong.
I will grant you that I should have called the tapered form BSPT but the parallel form is BSPP, unless my thread book is wrong.
Title: Re: A10 plunger fuel tank
Post by: ellis on 03.07. 2020 11:33
Hi everybody
I hope you are keeping well?  Just to answer the question about Ethanol in our fuel. I have resurched this for the last tweve months about the quantity of Ethanol manufactures put in their fuel. I have only found one company that does not ad it to their fuel. Esso Super Synergy 97 octain does not contain any Ethanol apart from some stations in Devon and Cornwall also some stations in the North East of England. They tell me they do not have any plans to put Ethanol in the 97 octain fuel. You will notice that the pump does display a 5% Ethanol lable as they have to have that on the pump by law.

ELLIS
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 03.07. 2020 13:37
... They tell me they do not have any plans to put Ethanol in the 97 octain fuel....

... You will notice that the pump does display a 5% Ethanol lable as they have to have that on the pump by law.
Just to clarify. Are you saying that although that fuel does not have any Ethanol, by law, they have to have a lable that say it does?  *pull hair out*
Title: Re: A10 plunger fuel tank
Post by: Minto on 03.07. 2020 15:58
Presumably it's like the warning on the bag of potatoes I bought a while ago that stated "may contain nuts".
Jase
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 03.07. 2020 17:11
Presumably it's like the warning on the bag of potatoes I bought a while ago that stated "may contain nuts".
Jase
Or more crazy, on a bag of nuts, it says the same thing!!
Title: Re: A10 plunger fuel tank
Post by: morris on 03.07. 2020 19:11
E5 or E10 just means that the fuel sold at that pump contains anything between 0 and a maximum of 5 or 10% ethanol
Title: Re: A10 plunger fuel tank
Post by: ellis on 03.07. 2020 21:34
Absolutly right morris. Sounds stupid but thats British goverments for you.   *dunno* *dunno*

ELLIS
Title: Re: A10 plunger fuel tank
Post by: Rex on 03.07. 2020 22:02
Sounds logical enough to me... *whistle*
Title: Re: A10 plunger fuel tank
Post by: BigJim on 03.07. 2020 22:42
Just to throw two pints of black and tan on this observation wise. I once bought a bag of charcoal with a " may contain nuts" warning on it. This caused immense hilarity in the family, mostly very mature years wise, and general disdain at PC gone mad. How could a bbq fuel cause any sort of danger? Fast forward a few years and i meet a father who lost his daughter to a nut allergy. Now my observation is this (please don't respond as it should have it's own topic). Were people dying before of allergies and being recorded as something else? Is this a new thing brought on by modern diets/pollution/record keeping/other ? Obs over, back to the garage, need to fit panniers for scrumpy delivery to Devon for birthday party!
Title: Re: A10 plunger fuel tank
Post by: BSA_54A10 on 04.07. 2020 02:18
Most allergies & auto immune problems are genetic in origin.
Decades ago those with poorer genes died early and did not reproduce so pass down defective genes.
Now days every pair of people as expected to be gentically compatiable ( they are not ) and to have the capacity to produce genetically perfect children.
This is a total fallacy as any live stock farmer , or animal breeder will attest.
However for some strange reason people seem to think we are not animals and the laws of animal reproduction do not apply to humans.

Title: Re: A10 plunger fuel tank
Post by: Greybeard on 04.07. 2020 10:49
Although the discussion of allergies is interesting, it should have its own topic.
Title: Re: A10 plunger fuel tank
Post by: Minto on 08.07. 2020 09:16
Greybeards
Thanks very much for the tap, perfect! Beer tokens awarded.
Its now on it's way back to you.
Cheers
Jase
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 08.07. 2020 10:16
Greybeards
Thanks very much for the tap, perfect! Beer tokens awarded.
Its now on it's way back to you.
Cheers
Jase
I'm really pleased that it did the job for you.  *good3*
Title: Re: A10 plunger fuel tank
Post by: Greybeard on 14.07. 2020 10:22
Greybeards
Thanks very much for the tap, perfect! Beer tokens awarded.
Its now on it's way back to you.
Cheers
Jase
The tap arrived this morning. Cheers!
Title: Re: A10 plunger fuel tank
Post by: Minto on 18.07. 2020 03:02
Glad it found its way home ok. Thanks again.
Well, went to fit the taps, and the spigot on the RHS tap fouls the top of the float chamber and no amount of fiddling with the float bowl gives any clearance. So now waiting for a couple of angled spigots to arrive to try out. Never ending innit! I'm assuming that the tap threads in the tank are a bit out, as well as the rear mounting slots. I dare say I'll need to customise the new knee rubbers to fit too! Still, it looks a million times better than the tank which it's replaced (no idea what that came off but it wasn't an A10).
Cheers
Jase