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Douglas engine......again

The douglas engine is getting popular - here's mine

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Rob Manley11/09/2009 16:58:03
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71 forum posts
14 photos
Hey folks, I'm not sure if this is the right place to post this but here goes.  After all the help received by Malcolm in the past and recently on my latest project I decided to start a construction website along the same lines as his one on google pages.  His sad and sudden death only a week after I started it put a stop to it and it was only yesterday that i wanted to continue with it. 
It is under construction and will be for some time but i hope it inspires anyone to just get out and make something.  I am happy to answer questions or help anyone if I can as Malcolm did for me - its just a shame that the only official picture everyone's using is with him look miserable as sin, not the way he was at all.  
 
The idea is that I will make the complete bike and be able to ride it!
 
http://sites.google.com/site/halfsizedouglasmotorcycle
 
Now you've read the post - get out into your workshops!  
 
 Rob )

Edited By Rob Manley on 11/09/2009 16:58:33

JasonB11/09/2009 20:00:41
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25215 forum posts
3105 photos
1 articles
Nice work there
 
I have bookmarked your site for a more leasurely read.
 
Jason
Martin Cottrell17/09/2009 20:56:22
297 forum posts
18 photos
Hi Rob,
 
A fascinating project you have there and your "work in progress" looks to be of a very high standard. I shall look forward to popping in on your site as you progress to see how things are coming along!
 
Perhaps you could pin a note on this thread whenever you update your web site to remind us that you have some more bits to drool over!
 
Good luck, regards,
 
Martin.
Rob Manley20/09/2009 18:48:56
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71 forum posts
14 photos
Thanks for the interest Martin.  Sadly im back off to uni next week so progress might slow some what.  Although saying that, im hoping that i'll be able to use their lost wax casting facilities to cast the cylinders so im sure there will be more to report soon.  I tend to update in dribs and drabs but when i feel something major has happened i'll post it here for those of you who wish to have a nosey
 
Once this bike is built im thinking maybe a Rudge special in 1/2 scale or maybe even a black shadow if someone will lend me one
 
  Rob. 
Rob Manley26/09/2009 13:38:16
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71 forum posts
14 photos
Hey again folks, just to say that im back off to Uni now so there won't be many more updates for a wee while except filling in the descriptions.  But i have uploaded many of the photo's showing construction techniques used.  The magneto is the latest thing to appear. 
 
 Rob.
Windy10/10/2009 23:30:39
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910 forum posts
197 photos
Hello Rob,
                   A very good site as an old ex motorcycle enthusiast who had a Douglas many years ago it brought back some pleasant memories. It lookes first class keep up the good work. 
 
                    Windy.
ken heppener11/10/2009 07:06:10
24 forum posts
24 photos
Hi Rob....What an excelent job your doing.....Like Windy, I too am an old motorcycle enthusiast and even today I will drool over the old bikes when I see one....In my case I always went for the Triumphs of the late fifties.....Speedtwins and Thunderbirds.....Those where the days......Keep up the excelent work....Regards Ken.  
Paul Boscott11/10/2009 07:42:17
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99 forum posts
21 photos
Looking good

I am just starting a build on a model from photos your detailed record has shown me that the documentation of what I am doing will be worth the extra effort.
I will watch your progress with intrest.

Paul
Rob Manley18/01/2010 14:05:42
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71 forum posts
14 photos
Just to let those interested the site has been recently updated with extra parts filled in although it is still very much under construction.  I hope to see many of you at the Reading SME's 100 years exhibition in september 2010. 
Rob Manley11/07/2010 18:58:32
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71 forum posts
14 photos
Right - small update - I have been concentrating on the amal carb and have just finished the float.  Will be posting more pictures early this week.  I machined it from the solid in two pieces and soft soldered it together as per full size.  The wall thickness is 10 thou on all 3 faces.  It looks great but is still too heavy despite it's thin wall thickness so doesn't float in water (don't have any spare petrol anywhere at the moment). 
So, im now going to use cork with a small piece of 3/32 copper pipe pushed through the middle.  I have loads of synthetic corks which are the right diameter and just a bit too long which is easy to solve.  The problem is I am unsure if these corks (made by supremecorq) will react with petrol over a long period.  Just dipping in petrol isn't really a good enough test I dont think. 
 
Anyone know if these are suitable. 
chris stephens11/07/2010 20:35:06
1049 forum posts
1 photos
Hi Rob,
Why not use proper cork, after all it was good enough for half the original bikes of that era's petrol tap seals.
Now I come to think of it, I seem to recall that some foreign bikes had cork floats, but don't quote me, it has been many years since I played with bikes.
chriStephens 
John Olsen12/07/2010 10:37:13
1294 forum posts
108 photos
1 articles
Most of the older floats that I have seen were made from very thin brass pressed and soldered. Think in terms of shim stock, and not too much solder.  Petrol is less dense than water so if it won't float in water it is certainly no go in petrol.
 
Modern ones are often plastic, and not always very suitable plastic either. One of the Universities here looked into methanol fuels back in the seventies, and checked out the effect on carburators. Turned out some of the plastic bits would not stand up long term to petrol, let alone methanol. My memory of Amal carbs is from the seventies, when, shall we say, they were not what they had once been. The concentric had a float that was too small, so it would fail to close the needle valve properly, It is somewhat disconcerting to look down and see a little jet of petrol flowing out the overflow and onto ones boot. The cure was a viton tip needle valve, but even that was not 100% reliable.
 
There was someone, I think in ME a few years back, who said he was idly wondering about floats, and though of polystyrene foam, so dropped a chunk into some petrol. He said he had never seen anything disappear so fast....
Rob Manley05/08/2010 16:55:36
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71 forum posts
14 photos
Right, for anyone interested I have finished the half scale - fully working amal carb.  After some digging around the internet I found that cork painted with shellac is whats used.  Got some shellac but haven't done the painting yet.  
 
BUT, I couldn't resist.  A friend had a 60cc lawnmower engine sitting under a bench so with a little adapter plate we tried it.  IT WORKS. The choke works and it accelerates well, im really pleased (don't think I can use the word chuffed here). 
 
I still want to take some more pictures of the insides and will post them along with the descriptions to go with them asap.  You can see them here:

https://sites.google.com/site/halfsizedouglasmotorcycle/home/index/carburettor
 
Rob

Edited By Rob Manley on 05/08/2010 16:56:59

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