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Douglas Motorcycles - General Discussion / Re: Four speed Aero gearbox
« Last post by FN on 26 Jan 2021 at 18:08  »
Doug,
I have LDMCC machine register, which shows the G/box No (U145) for one machine only.  That code fits into 1936-37 motorcycles system. Did they change anything for the new lubricant?
Gerd
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Hi I am after an uprated oil pump the same as the Dragonfly ,ie aluminium body not brass

Regards. Colin
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Douglas Motorcycles and Parts Wanted / Re: DRAGONFLY REAR WHEEL NUTS
« Last post by cbranni on 26 Jan 2021 at 12:50  »
I wonder why they used 24tpi when 26 was so popular, didn't check the form though. 24tpi was popular with Triumph in the 20's

Kind regards Colin
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Douglas Motorcycles and Parts Wanted / Re: DRAGONFLY REAR WHEEL NUTS
« Last post by eddie on 26 Jan 2021 at 12:40  »
British Hub Co. used BS Cycle threads.

  Eddie.
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Douglas Motorcycles and Parts Wanted / Re: DRAGONFLY REAR WHEEL NUTS
« Last post by cbranni on 26 Jan 2021 at 11:00  »
Hi Steve,

The nuts on my Dragonfly were 5/8 x 24tpi, what thread form they were I don't know (whit or cycle)

Regards Colin
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Before you go too much further, I think you'd better double-check the size.

It seems the 123-5 is the smallest of this pattern of B&B - only 0.71" bore. This might be fine on an 350cc EW, but it's very small for a 600? Some sort of 121 might be better - perhaps the 0.78" bore model?

Leon
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Looking further, I see from B&B List 26 (maybe 1927) that the 123-3 had a pilot jet.

Are we sure that the 123-5 is big enough for a 600?

Leon
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Hi Daren,

Very difficult to answer your questions, because the 123-5 doesn't appear in the usual B&B literature, which would have us believe that the 123 carburettor wasn't fitted with a pilot jet, and yet the 123-5 clearly is. Perhaps it was made specially for Douglas?

Also 1928-1929 crosses the boundary between the old firms (AMAC,B&B, Binks) and the new (AMAL). Technically a B&B wasn't available in 1929, yet I bet they were supplied. Were some sold with AMAL float bowl lids? I don't know, but yours it the early AMAL type. I'd guess they had B&B lids originally, even if supplied in 1929.

Parts? I've suggested asking seller b561 on ebay before: he makes lovely parts and reconditions carbs, though more AMAC than B&B. Here's an example: https://www.ebay.co.uk/itm/143927411703

Here are the relevant parts lists, even though the 123-5 is not mentioned specifically.

Cheers

Leon
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Douglas Motorcycles - General Discussion / Re: Four speed Aero gearbox
« Last post by Doug on 26 Jan 2021 at 04:40  »
Gred,

I found a picture of 6/Q146 on a gearbox in a 2011 eBay listing for a 1938 Aero. Engine stamped 6/Q146 (possibly 6/Q140). In 1938 Douglas started the practice of stamping the frame and engine number identical, and it would seem they extended this practice to gearboxes also. Unfortunately all the 1938 Aeros listed in the LDMCC machine registry do not have gearbox codes documented. But it is looking as if the 6/Q code extended to gearboxes also. My guess is your gearbox had been replaced with one from a 1938 model. If so, it was intended to use heavy oil for lubrication.

-Doug

[fix typo. 26Jan21 -Doug]


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