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21
Douglas Motorcycles - General Discussion / Re: 80/90 Plus Gearing
« Last post by ccmman on 19 May 2019 at 11:06  »
This is the problem Clive, I'm not good at motorcycle gearing. I'm not clear where the gearing is measured.
To me, it makes most sense to refer to the engine revs/back wheel revs, because that gives you actual rea-life gearing.
In that case, my bike does just under 3 engine revs for every rear wheel rev in top. That means, say, 2.8:1.
Now take the figures I found on a factory spec sheet for the Plus 80:

1st  17.2:1, 2nd  10.6:1, 3rd  7.78:1, and top  6.17:1.

Clearly nothing like 2.8:1, so how are these figures arrived at? Is it engine revs to gearbox output sprocket maybe?
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Douglas Motorcycles - General Discussion / Re: 80/90 Plus Gearing
« Last post by Clive on 19 May 2019 at 09:13  »
Dont forget the bevel gears in the gearbox which must be at least 2to1 may be more
Regards Clive
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Douglas Motorcycles - General Discussion / 80/90 Plus Gearing
« Last post by ccmman on 19 May 2019 at 09:04  »
Have now got the engine running really well, though still running in, which is tricky on such a cammy engine!

But the gearing has me completely flummoxed. LJKS talks about a close ratio box on his 90, my box is the complete opposite. The first three gears seem ok, then top is crazily high.

At 2000rpm in top the bike is doing 55mph, which equates to 192mph at 7000 rpm!

My gearbox sprocket/rear wheel sprocket ratio is 17/53 or 3.12:1.

Any advice please, I am confused!

24
Douglas Motorcycles and Parts For Sale - Private / Re: post war front wheels
« Last post by tck on 17 May 2019 at 20:38  »
I also read that the later competition bikes sometimes had a ring shrunk round the outside of the drum to prevent 'belling' that is a possibility I suppose how effective was that I wonder?
25
Members' Gallery / Douglas advertisment.
« Last post by phil1 on 17 May 2019 at 15:59  »
An old magazine with a nice Douglas advertisement. from Phil.
26
Douglas Motorcycles - General Discussion / Mk4 sports
« Last post by tck on 17 May 2019 at 14:06  »
I have a 1950 Mk4 sports engine it has a rev counter housing on the front and two flange fitting carburetors
It was dispatched originally to Mcandless in NI (the feather bed guys)
I must admit I think I knew there must have been a MK4 before the Mk5 (and a 1-2-3?) but it is rarely mentioned anywhere and the designation 'sports' is new to me
What was different in the Mk4 sports engine from the T35 or the Mk5 and was there ever a MK4 non sports? or was the 'sports' a forerunner of the 80 or 90 plus?
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Douglas Motorcycles - General Discussion / Re: EW 350
« Last post by DMGOE on 17 May 2019 at 10:29  »
Hallo
Thanks for bring the picture in the post!

I want let the bike in this condition, but it stand long time in a collection and not runs. I had remove the sidecover from the in and exaust valves and i see that broken the valve spring..
In the moment i have two another projekts with german 500ccm ohv bikes... whenn i see the time than i want to look to the EW Engine .
I m so happy that i found my dream in a EW Modell! I want always a Douglas with „Contra“ engine in line.
They are so great Machines!!!

Manfred
28
Douglas Motorcycles - General Discussion / Re: engine rebuild
« Last post by Keith on 17 May 2019 at 07:14  »
Hi Ray, you might like to have a look at this post which covers how to make the new bronze shells etc.

https://www.douglasmotorcycles.net/index.php?topic=3376.msg12305#msg12305

Cheers, Keith...
29
Doug,
thankyou for taking the time to check yours.
I have seen 2 pics on this forum so far, one (Erics) had the visible oil slots up & the other (yours) had them facing down.
I can now see by witness marks where the old hold down clamps had been fitted on my engine that originally both the rear guides oil slots faced down, whereas both the front faced up! So, just like the generator drive, we have 3 variations!
30
Douglas Motorcycles and Parts For Sale - Private / Re: post war front wheels
« Last post by tck on 16 May 2019 at 13:42  »
Perhaps there is a cast iron 7" lace-able  drum in the old British auto jumbles? since I have to rebuild a wheel anyway. ....
Thanks Eddie for pointing out the basic problem and conformation by dawn  that all that glitters is not gold (gold paint perhaps!)
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