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81
Douglas Motorcycles - General Discussion / Re: improving brakes?????
« Last post by douglas1947 on 06 Jan 2019 at 16:28  »
Hi Peter,

I have also restored horse carriages in the past and these had originally wooden blocks braking direct on the steel tyre of the rearwheels.
Best results have blocks out of soft wood. I used best blocks of Poplar  (german: Pappel).
Harder wood has less friction and tendency to sream.

If you like I will have a look at my workshop for some wood.

Michael
82
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 05 Jan 2019 at 19:28  »
Sorry, pics wont load. Ill try again later
83
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 05 Jan 2019 at 19:22  »
I suppose the engine isn't going to get running by me typing on the internet!

So today I thought I should go out into the garage and start investigating the hardware in the light of what I've learnt. I need to measure the engine up to estimate the compression ratio. The first thing I discovered is that with the cylinder head nuts I've got are so big I cant see how to get a socket or even a spanner on them to tighten up them up. I ground down the outsides of the jaws on an old 14mm open ender which allowed me to get them just starting to nip, but I'm lost for a way to tighten them properly let alone torque them down. I need some Douglas threaded K nuts lol. There must be a solution but I cant see it!

Next up I tried test fitting the camshaft gear, and noticed that the camshaft in one engine had 6 splines on the shaft where the drive gear sits, but that the other engine has a drive gear with 8 splines. Also it appeared to me that the splines are cut to different widths to control the orientation of the drive gear on the spline. I haven't yet tried to time the cam, as it all has to come apart for final inspection before final assembly.

The first engine came with a plethora of rocker shafts, and 5 rockers. I have managed to pair rocker shafts, rockers and inner mounting bolts to get four sets with not too much play. However I don't have any of the washers that go on either side of the oil/grease reservoirs. I get the imprecision that these are fibre washers, is that correct? Also I have read that the shafts which run through the rocker mountings and hold the lubricant reservoirs should have little wicks running through them. I wonder what these are made of, and how thick they are?

best wishes

Douglas

pics attached :-
8 spine cam and wheel
6 spine cam and wheel installed
Rocker sub assemblies


84
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 05 Jan 2019 at 17:29  »
Doug

Thanks for the info on the plug holes and the little chambers. I did wonder if they were to protect the plug in some way, but I hadn't thought about fouling issues. I'll probably leave them as they are in on one of the pairs of heads for the first engine, with a view to doing Eddies mod and using modern 14mm plugs on the tuned engine when I build it.

It looks like all the bits of info of power outputs are pointing towards the same answers! I'd not heard about the Red Devils engines, I suppose that they were for factory riders bikes?

best wishes

Douglas
85
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 05 Jan 2019 at 17:11  »
Hi Eddie

Thanks for the info about the head gasket, the plugs and magneto. Of all the issues that have come up the head gasket is the one that is concerning me the most. I will have to look around for someone who can tig weld the rings following the procedure you and Doug describe. What sort of torque do you tighten the head down to?'

I hadn't thought of looking round for any rings because I didn't realised they were re usable. However I will advertise for some, more in hope than anticipation. Also I wondered if anyone had tried using a conventional modern head gasket, the copper/aluminium asbestos copper/aluminium sandwich type? I thought it might expand into the ring when tightened down to provide an additional seal to the flat surface to surface seal.

I have two magnetos, one is a rather sorry looking EIC affair which is incomplete and I dont think is the right one for the engine. However the other one is a Bosch MD2 x4 model, which fits the engine and looks to be in good condition and complete. So I'll follow your advice and send it to Paul Lydford  for an overhaul and ask them to fit the second capacitor. I don't want to be worrying about a decent spark whilst I've got so many unknowns to deal with elsewhere.

Best wishes
Douglas
86
Douglas Motorcycles - General Discussion / Re: improving brakes?????
« Last post by eddie on 05 Jan 2019 at 17:02  »
Peter,
           You may find that a rubber based material is too effective - that was the case with the VMCC's 'retarding material'. When used on veteran Douglases, the rear wheel often instantly locked up. Wood seems to be a good alternative to a 'Ferodo' type material.

  Regards,
                 Eddie.
87
Douglas Motorcycles - General Discussion / Re: improving brakes?????
« Last post by andertheke on 05 Jan 2019 at 16:52  »
Graeme,

thank you very much for your answer. I'm astonished that wood possibly seems to be better than rubber.
Usually Wood becomes hard by heating it (as the stone age people did) due to friction,
so I better will try your "wheelie bins" idea  :lol:


Best regards
Peter


88
Douglas Motorcycles - General Discussion / Re: Dragonfly oil leak.
« Last post by chid on 05 Jan 2019 at 14:39  »
Thanks Eddie, will have to get some shrink wrap and try.

Chid
89
Douglas Motorcycles - General Discussion / Re: Dragonfly oil leak.
« Last post by eddie on 05 Jan 2019 at 11:21  »
Hi Chid,
             As there is no blockage, the breather should cope with the normal amount of crankcase fumes. Unfortunately, Dragonflies that still have the original split skirt pistons can suffer from excess crankcase pressure. When worked hard, the original pistons tended to collapse, resulting in the ring grooves taking on a wavy form, causing the rings to jam and not seal correctly. When this happens, it is usually accompanied by smoke from the exhaust. The easiest remedy is to fit pistons from the earlier Mark series engines, or the repro pistons available from the LDMCC.
  At this stage, my advice would be to cure the leaks at the grommet and cylinder heads (these are known common faults), and run the bike again to check whether there is any other leakage.

  Regards,
                 Eddie.
90
Douglas Motorcycles - General Discussion / Re: Dragonfly oil leak.
« Last post by chid on 05 Jan 2019 at 09:59  »
Hi Eddie
I have started her up and there is pressure coming out the breather hole. Before I take it apart do you or does anybody else have any other ideas.

Chid
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