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Douglas 1913 Model P motorcycle

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Douglas 1915 3 Spd-Gearbox and Clutch

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OC Douglas

Started by martin1, 17 Aug 2008 at 07:39

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Hi Douglas - Friends,

last friday I have finally bought the OC Douglas from a friend of mine in Austria.
He found it 35 years ago, and it was complete except the fuel tank and the gearbox.
He started restoring the engine but not more.
He found the fuel tank, but the gearbox is a YG which is I guess for a DT / SW model.

I have a couple of questions which I am not shure about on this bike:

- There is a cast-on generator housing on the engine, does someone have documentation or pictures about this ?

- The kickstarter gears inside the engine are missing, the kickstarter I have. Maybe someone has drawings or even parts.

- Which Oil-pump is on the bike, it is also missing, maybe someone has an Oil scematic ?

- Which is the correct carburator for this machine ?

So I will stop here with my questions not to bother you too much.

thanks for looking and making comments

Martin / Austria


Martin, welcome to OC ownership - you will not be disappointed with the machine - they are great. I can't give you definitive answers for many of your questions

1. I have never seen one with the generator - hopefully Doug can help out here !
2. I left the kickstarter off mine as I was also missing some of the gears - and its an ex race bike anyway which would not have had it - they are easy to start anyway
3. The oil pump is a single geared pump driven off the magneto pinion. We didn't have any of it when mine was done - made up a new one using later gears off a british single and machined up a housing.
4. Carburetors according to the books were "as available" - mine has an AMAC - I don't think they used specific Douglas design on these at all.

Sorry I can be of more help.



The generator drive is a part of the very rare option for electric lighting on the OC. I have seen pictures of the machined casting as fitted to your bike, and I think I have seen a blurb on it in a catalog spec about the electric option. Will have to do a bit of digging to find it, but not expecting a lot of detail. I do not recall having ever seen one fitted to a machine.

OC kick starters seem to be quite rare. Oddly I heard complaints that it is the kick start lever portion that is in short supply, particularly the reverse quadrant gear (teeth faced inward) attached to the lever. I gather it did not prove to be a very strong design. You might be able to do a trade in information/drawings if others need the quadrant and have the pinion. This engaged with a pinion which from illustrations looks much the same pinion with face ratchet as Douglas used in on their transmission mounted kick starters.

On carburetors, as Ian said, Douglas was vague on manufacturer. AMAC or B&B, but probably AMAC. Possibly even a carburetor of their own make when their credit with vendors was poor! I can only add they said it was a "two lever, semi-automatic type".

Gear cases and gearing are covered in this post-,1184.msg4130.html#msg4130

I can not help with the oiling circuit other than to say a line from the oil tank goes to the mechanical pump high in the timing chest and then to the one way non-return valve at the base of the front cylinder. Oiling is total loss. There seems to be some doubt as to how Douglas arranged the lines, as Ian can attest. Period photos show numerous arrangements as if Douglas could not make up their mind! There is also mention that if the sight glass became plugged, a tap could be turned 90 degrees and hand pump oiling substituted. With the single line from the oil tank to the engine, this suggests the mechanical pump pulled oil through the sight glass by creating a vacuum. Douglas had to abandon this system on the 350EW in 1926, which started out also with a small geared pump in the timing chest.



A bit more on the oiling circuit - beware of pictures - I set mine up exactly as per a picture I had of an OC at the Earls Court motor show - guess what - they had the oil lines connected the wrong way round !!

As Doug says you can either oil by mechanical or hand pump. Mine is set up with the two way tap under the tank to change between the two.

For hand oiling it goes from the hand pump, through the two way tap, through the drip feed and then to the front one way valve on the cylinder.

For mechanical oiling it goes from the oil tank, through the mechanical pump, through the two way tap, drip feed, front cylinder. I set it up with a pressure relief pipe in the mechanical circuit as well.

This all works very well - however I did try the "proper" routing first where the mechanical pump sucks through the sight feed and it was a failure - I can see why Douglas changed later on.


Fantastic to see another rare OHV Douglas come out of the woodwork! Particularly with the generator - this is so rare. I would think the carburettor fitted looks pretty correct - it certainly looks like an AMAC instrument to me.



Hi Doug, Ian and Graeme,

I am impressed. This forum is really amazing. Thanks for your help in finding information
about this bike and it´s setup. I have already found a BTH front headlamp. Is a BTH magneto
OK or was an EIC on this bike ?

thanks again for supporting and I will keep you updated on the progress if you like.

greetings from Austria



BTH magneto is what it should have

Please keep us updated - I did the same when I was doing mine



I could not find anything on the OC electrics, but I did find a little on the similar system fitted to the OB, immediate predecessor to the OC.

First, some pics of the castings, for those that like to see the insides. This should be quite similar to the OC, the most noticible difference being the OB lacked the mechanical oil pump.

Next the patent illustration from 1925/26. Full details can be found in British patent 254425

No mention of what make the electrics were, but on a similar system fitted to the 1924 2-3/4hp model, it was specified as P&H.

One wonders if there was any power left from the engine to propel the machine!  :wink:

Now, on to kick starts mechanisms. Again, all the illustrations shown are from the OB model, but should be very similar to that used a few years later on the OC.

First an illustration from 1925-

...and the patent illustration from 1924/25. Full details can be found in British patent 244559.




that is really phantastic. The dynamo case looks similar to what I have on my OC.
Very good that I have a picture of the cover for the dynamo and the gear, because
that is missing. Still the gear-side looks very complicated and I don´t know why they
where using so many parts just to close the dynamo gear drive.

Thanks also for the kickstarter pictures. It will not be easy to finish that part.

thanks again and I will keep you updated.

all the best



According to the patent claims the idler gear could be slid sideways to take the drive out of mesh, by turning the external knurled knob. I do not know if they retained this feature for the OC.




I have now started with the restoration. Everything looks good, the frame is in very good condition.
I have now sandblasted, ground painted everything. I am putting the bike together now, but on the
way I need your help. There are some parts that where missing which I need to make.

I will post pictures when I have done more on it

- The brakets between the fuel tank and the frame, can someone send me pictures or drawings so I can
  replicate them. I think they are casted alloy parts ?
- The fixture of the sattle with the frame ( flat steel ) is this fixed bolted to the sattle, can someone send me
  pictures of that, maybe also underneath the sattle.

thanks so much