Author Topic: A7 plunger 1951, original air filtr box  (Read 416 times)

Online martinh

  • BSA A7 Plunger 1951
  • Moving Up
  • **
  • Join Date: Jan 2020
  • Posts: 10
  • Karma: 0
A7 plunger 1951, original air filtr box
« on: 26.01. 2020 18:31 »
Hi, I am just doing some inspection of my "new" A7. I am not an expert in BSA yet but obviously there is air box without air filter and also battery holder is rebuild by some handy man.
I have tried to search for some pictures, ebay spare parts, but most of the motorbikes do not have any air filter at all. Also mine was running long time without any air filter. Some spare parts are available, but especially battery holder there are plenty of different spars but nowhere complete holder.
Do anybody of have still the original air filter box/battery holder? If yes please could you send me some pictures?

Thank for any recommendation.
Martin

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #1 on: 26.01. 2020 19:35 »
The BSA A7-A10 Forum » Technical »Amal, Carburation »K&N Air filter on PLunger A10

This is for an A10; the A7 requires a slightly different air filter to carb hose, due to the lower carb height.

I bought a new battery carrier strap, (probably from Draganfly)

Online Nourish

  • A's Best Friend
  • ***
  • Join Date: Aug 2013
  • Posts: 117
  • Karma: 0
Re: A7 plunger 1951, original air filtr box
« Reply #2 on: 26.01. 2020 20:40 »
That looks like a cut down Triumph/BSA Triple air filter.

Online martinh

  • BSA A7 Plunger 1951
  • Moving Up
  • **
  • Join Date: Jan 2020
  • Posts: 10
  • Karma: 0
Re: A7 plunger 1951, original air filtr box
« Reply #3 on: 26.01. 2020 20:45 »
Now i see that i miss one part which is inside the air box where the filter is placed. I need to search for it or create something what can be used.

Online Nourish

  • A's Best Friend
  • ***
  • Join Date: Aug 2013
  • Posts: 117
  • Karma: 0
Re: A7 plunger 1951, original air filtr box
« Reply #4 on: 26.01. 2020 20:53 »

Offline Swarfcut

  • Resident Legend
  • *****
  • Join Date: Oct 2018
  • Posts: 878
  • Karma: 12
Re: A7 plunger 1951, original air filtr box
« Reply #5 on: 27.01. 2020 09:03 »
Martin. You are extremely lucky to have an airbox.  Most were discarded  or cut about as the fad for pancake filters took them out of use.

 The filter is basically a steel plate, with a corrugated filter medium bonded to it, as clearly seen in the link above. Esteemed member GB made a good substitute using a cut down modern filter. The air box is the same for A7 and A10, but as mentioned the rubber connector to the carb is different to take account of the heights of the differing cylinder barrels.

Swarfy.

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #6 on: 27.01. 2020 10:18 »
That looks like a cut down Triumph/BSA Triple air filter.
Yup. You can make two filters from that one. I bought a K&N filter which can be cleaned so I gave the other half away, (to someone here?).

I got this idea from someone on another forum.

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #7 on: 27.01. 2020 10:24 »
The filter is basically a steel plate, with a corrugated filter medium bonded to it
Not bonded. It comes off for washing. I had, (still have, I think) the original element. The metal plate has a spot welded perforated steel former to hold the filter element in position. You can see it in pic 3.

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #8 on: 27.01. 2020 10:32 »
Maybe someone will lend you a filter backplate for you to copy. It's mostly flat but needs flanges around the edges to seal the airbox.

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #9 on: 27.01. 2020 10:37 »
The rubber hoses are available online. Make sure to order the A7 version.

Offline spanersc

  • A's Best Friend
  • ***
  • Join Date: Dec 2008
  • Posts: 167
  • Karma: 1
  • Cambridgeshire. UK
Re: A7 plunger 1951, original air filtr box
« Reply #10 on: 27.01. 2020 10:42 »
Hi Martin.
I've studied the photos and I think that your casing is for a 'B' series bike with the aperture for the engine hose in the front face rather than the side face as per the 'A' series ones. What do others think?
Peter C    Cambridgeshire. UK    1950 A7 Rigid. 1952 A7ST 1953 A7ST 1953 A10S/Flash 1954 A7ST.  1955 A7SS.  1955 A10.  1956 A10RR.  1959 A10 Combination     1962 RGS  1954 CB34  1962 DBD34

Offline Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5849
  • Karma: 32
Re: A7 plunger 1951, original air filtr box
« Reply #11 on: 27.01. 2020 10:48 »
Hi Martin.
I've studied the photos and I think that your casing is for a 'B' series bike with the aperture for the engine hose in the front face rather than the side face as per the 'A' series ones. What do others think?
Martins filter case is certainly different to my one. I put that down to it being earlier and A7.

Martin, will you take pictures of the sides please.

Offline Swarfcut

  • Resident Legend
  • *****
  • Join Date: Oct 2018
  • Posts: 878
  • Karma: 12
Re: A7 plunger 1951, original air filtr box
« Reply #12 on: 27.01. 2020 17:48 »
   Yes GB, Martin's airbox , although being the correct shape (almost?) is not the right one.
 My filter is glued to the backplate and I have never risked taking it off in case the whole thing crumbles. Looks a good bit of 1950's glue, so thought it was standard. Haven't got an owners handbook, so don't know the recommended cleaning procedure. Contemporary vehicles had wire gauze filters which were usually washed in petrol and re-oiled, but washing the filter here in petrol seemed to me to be a bit risky in case the glue dissolved. So maybe the P.O. did the work with the glue.


Martin, 
      The rubber air hose connection to the carb needs to end up on the centre line, in front of the vertical frame tube. A closer look at the pictures tells me the airbox is not the  right one, and I reckon  spanerc is on the money. The correct air box has an oval aperture facing towards the oil tank, in front of the frame tube. The connector hose fits in here, then bends at  a right angle to join  to the carb.

 Yes, more pictures would help.

 Swarfy.

Online martinh

  • BSA A7 Plunger 1951
  • Moving Up
  • **
  • Join Date: Jan 2020
  • Posts: 10
  • Karma: 0
Re: A7 plunger 1951, original air filtr box
« Reply #13 on: 27.01. 2020 18:54 »
Here are some more pictures.

Online martinh

  • BSA A7 Plunger 1951
  • Moving Up
  • **
  • Join Date: Jan 2020
  • Posts: 10
  • Karma: 0
Re: A7 plunger 1951, original air filtr box
« Reply #14 on: 27.01. 2020 19:21 »
Maybe if it will only way i can rebuild it to a7 airbox. But it fit quite well to the oil tank
Thanks for your comments. Martin