Author Topic: B31 Fuel Tank  (Read 6048 times)

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Offline tommy

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B31 Fuel Tank
« on: 28 Nov 2004 at 21:23 »
I have just purchased a Douglas B31 complete, but in rough condition.
I believe the basics are the same as the 1926 EW, but the fuel tank is saddle rather than in between the top frame tubes.
Anyone got any info on them?
The fuel tank is shot and I am looking for a good one if anyone has one for sale.

Hope someone can help.

Thanks

Tom




Offline Doug

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B31 Fuel Tank
« Reply #1 on: 05 Dec 2004 at 05:28 »
Tommy,

The B31 is the 'Touring and Overseas' version of the A31, which itself is an updated in detail EW.  According to catalog specifications, the petrol tank holds 2.5 gallon with 0.5 gallon of oil in the aluminum sump under the engine.  The A31 tank hold only 2.25 gallon, but it also contains a compartment for the oil, as it has no sump under the engine.  This compartment may account for the 0.25 gallon, as it is not very large.  

But from catalog appearances, the B31 petrol tank looks taller and slightly larger than the A31.  More akin to the other larger capacity models offered in 1931.  But these all have petrol tank capacities given as 3 gallons.  So it looks as the B31 petrol tank is particular to that model.  It may have used the same pressings as the A31, and the difference in the catalog is just down to artistic license.  Besides the lack of an oil compartment, it has a gate screwed to the side of the tank for the hand change, where the A31 has the gate built into the right-hand knee grip.  The A31 was build down to the 224 lb weight class for a special road tax savings.  

You will probably find that the L3 and H3, the 1930 versions of the B31, use the same petrol tank.  Pictures of L3 and H3 indicate this is so, and they are the same size and shape as the A31 (except they do not hold oil.)  The B32 (for 1932) shows a shift gate built into the knee grip and may not have the tapped holes for a separate gate.  Again the tank looks bigger, but still lists at 2.5 gallon verses the A32 at 2.25 gallons and all the other bigger machines at 3 gallon.  

I can send you a catalog scan of the A31/B31 if you would like, send and email address via the Private Message function.  

-Doug

Offline tommy

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B31
« Reply #2 on: 05 Dec 2004 at 19:50 »
Dear Doug,
Thank you for the information.
The tank on my B31 has a single filler cap, 2 x fuel taps (single carb?) and does indeed have the gear change gate bolted on the right hand side of the tank.
The engine has a sump for oil and the fuel tank has a pipe coupled up on the underside joining the left and right hand sides of the saddle tank together.

This is presumably to ensure the fuel is = in both halves of the tank.
The machine was last used for hillclimbing and I think grass track racing in the Oxfordshire area around 1965.
I do not know if the balance pipe has been added for competition use or if there has been an oil tank in the back of the tank at some stage or if it was standard fitment.

I am trying to get some pictures of the bike up on the site at the moment so you all can look and see it.

I will mail you for the catalog scan.

Thanks for your help.

Tom

Offline alwyn

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Re: B31
« Reply #3 on: 05 Dec 2004 at 23:50 »
Quote from: "tommy"
....cut....
I am trying to get some pictures of the bike up on the site at the moment so you all can look and see it....cut....Tom


Hi Tom,
Please send your photos to < photos@douglasmotorcycles.net > and we will attach them to your posting and possibly add them to the Members' Gallery also. Large original photos are preferred.
Alwyn
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Quotable Quote - "640 k should be enough for anybody"! - Bill Gates - 1981.

Offline Doug

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B31 Fuel Tank
« Reply #4 on: 06 Dec 2004 at 02:25 »
Tom,

The petrol balance tube at the rear of the tank was a typical fitting for all saddle tank Dougies.  In most cases a banjo fitting and bolt rather than a conical set gland fitting.  Sent scan, but am getting delayed delivery notices.  It will keep trying automatically for half a day.  Let me know if it does not arrive.

-Doug