Author Topic: New French Douglas Owner  (Read 3259 times)

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Offline Thomas59

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New French Douglas Owner
« on: 06 May 2014 at 12:32 »
Hi to all,
This Topic, just to present me and my Dougie
I just buy a Douglas 4HP 1920 a few months ago in UK. It was my 40 years old gift  :D
I was looking for a good runner to use it as much as possible in rallyes : I don't want just to have it but to ride it. In France, there are not a lot of Douglas but I always find this bikes beautiful when I came in UK for the Pionneer run or other events.

My 4HP is not completely original but I hope, I will ride it on many kms ...

I began with a problem with the oil pump gear wich had a broken teeth for 2/3. I buy a new one rebuilt not so far from my home. Now with my new gear, I just ride with this beautiful bike but I have a lot of smoke near the magneto, does it is normal, please ? When the bike is in the garage, it loses oil on the floor. It's not only several drops but quite a lot of oil ... The bike runs at approximately 40mph max, I was hping a bit more, does it is normal ?

I don't have experience with duggies, any help will be appreciate.

Sorry for my english, it's not good as I want ...

Regards

Thomas

Offline arturro

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Re: New French Douglas Owner
« Reply #1 on: 06 May 2014 at 13:12 »
Dear Thomas
Welcome on Dougi team  :) I think it will be better if you send some photos with place where oil is loses.
We have many experts in our forum so soon I think you will find answers for your problem.
Best regards Artur

Offline graeme

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Re: New French Douglas Owner
« Reply #2 on: 06 May 2014 at 13:41 »
Hello Thomas

A 4hp Douglas should do over 40mph easily. I think the lack of performance with your machine, plus the smoke around the magneto, suggests to me that there is a lot of "blow by" past the piston rings that is breathing out behind the magneto. In other words, the engine could be a bit tired. I think it might be worth taking off the barrels and measuring the cylinder bores and the pistons and rings to see if they need renewing - rings at the least I would think.

Cheers,
Graeme

Offline Thomas59

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Re: New French Douglas Owner
« Reply #3 on: 06 May 2014 at 15:11 »
Thank you for your very quick answers Artur and Graeme  :D. It's good to see I'm not alone  :lol:
Tomorrow, I will take off the barrels to look at and measuring. I will let you know !!! Do you know, where to find parts ? At least, rings ? I have other barels and pistons but I don't measure them yet ...

Cheers

Thomas

Offline Thomas59

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Re: New French Douglas Owner
« Reply #4 on: 06 May 2014 at 17:10 »
I can't wait, I measure my barels and pistons (not those on the bike, the others ones).

My two pistons doesn't have the same size, I have a piston standard size and the other 0.005 inch more ...

At 10mm from the bottom, I have 74.2mm for the first piston, 74.38mm for the second.

For the first barel, with a 74.2mm piston size, the clearance is 0.29mm and 0.277mm in the bottom, 0.467mm and 0.483mm at the top

For the second barel, with a 74.2mm piston size, the clearance is 0.297mm and 0.310mm in the bottom, 0.410mm and 0.484mm at the top

I don't really know what are the good clearance on that kind of engine. What do you think about this, please ?

Regards

Thomas

Offline Thomas59

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Re: New French Douglas Owner
« Reply #5 on: 07 May 2014 at 17:22 »
Hello,
I just look at my pistons and bores : one ring was broken, the first one of the rear cylinder : well done Graeme !!!

I measure barels and pistons :

At 10mm from the bottom, I have 74.38mm for the rear piston, 74.45mm for the front.

For the rear barel, with a 74.2mm piston size, the clearance is 0.273mm and 0.302mm in the bottom, 0.287mm and 0.406mm at the top

For the front barel, with a 74.2mm piston size, the clearance is 0.299mm and 0.316mm in the bottom, 0.389mm and 0.555mm at the top

The pistons are better, I think reuse them with new rings. I found 10 * 74.5X2.5mm rings, I will use 4 for each piston, I hope it will be ok.

What do you think about that, please ?

I also saw a valve guide which move ... I had to verify the others ...

Regards

Thomas

Offline Thomas59

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Re: New French Douglas Owner
« Reply #6 on: 08 May 2014 at 15:43 »
Hello,
Finally, two valve guides was moving, I replace them...

For the oil leaks, I start to understand, there was no seal behind the bores and at other places ...

I have more and more surprises with this bike ...

For the conrod, there are two hole at the piston place, much I put them upwards ? For now, only the rear is upwards. Any idea ???

Regards

Thomas

 

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