Recent Posts

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71
Hi Everybody. 'm fitting a miller switch new to the bike.
It has the park/emergency/off/Ign & charge/head/Pilot positions
I've removed the Miller Switch front and need to confirm the orientation before re-fitting.
What moulded switch text faces forward on the bike?
What moulded contact number aligns with this?
The wiring diagram shows the contact numbers from the underside.
Many thanks

72
Hi Ian

Thanks for posting that really interesting about the  Australian Rowe and Warburton Specials. They are mentioned on the 500 OA website, but the information is very scarce! Those articles you have found tell us all there is to know!

Im sure that the 500OA will be really interested to read about these cars, so I will send the articles to them when I get a mo.
 
73
Douglas Motorcycles - General Discussion / 1931 t6 carb
« Last post by derek morgan on 07 Jan 2019 at 13:56  »
good afternoon, would be very grateful if any members could give me any info on my t6 carb. the prpblem I am having is the float chamber does not shut off and petrol keeps running out of bottom of carb, this happens when fuel tap is switched on without using tickler. have taken carb off and needle appears to shut off when blowing air into reservoir and turning it upside down while blowing, grateful for any advice Derek morgan
74
Hello,

For my Douglas 4HP 600ccm from 1918 I am still urgently looking for the two fenders.
I would also take other similar ones for the restoration on the original fenders for the 4HP

Thanks and best regards,
Ditmar


75
Douglas Motorcycles and Parts Wanted / [Search]Break lever for 2 3/4HP
« Last post by Domas on 07 Jan 2019 at 07:26  »
Search Brake lever! Original, no replica?
76
Douglas Motorcycles and Parts Wanted / CW carby
« Last post by Alan on 07 Jan 2019 at 03:17  »
Looking for the correct carb for my 1924 CW and pics of this as shown in the Book of the Douglas 1924 manual attached.  Happy to purchase or p/x for the carb as currently on the bike (pic also attached) and will also throw in the parts included in my advert request for a brake block ( 27 Oct 2018). Thank you Alan
77
Douglas Motorcycles - General Discussion / Re: improving brakes?????
« Last post by Bob M on 06 Jan 2019 at 22:27  »
The friction qualities of various types wood has been well documented by engineers and published in Machinery's Handbook many years ago. To quote my 1919 edition, page 521 on,

"For brakes where wooden brake blocks are used on iron drums, poplar has proved the best brake-block material. The best material for the brake drum is wrought iron. poplar gives a high coefficient of friction, and is little affected by oil. The average coefficient of friction for poplar brake blocks and wrought iron drums is 0.6; for poplar on cast iron, 0.35; for oak on wrought iron, 0.5; for beech on wrought iron, 0.5; for elm on wrought iron, 0.6 and for elm on cast iron, 0.35. The objection to elm is that the friction decreases rapidly if the friction surfaces are oily. The coefficient of friction for elm and wrought iron, if oily, is less than 0.4."

All Northern Hemisphere woods unfortunately, native Australian hardwoods don't get a guernsey but there is enough info there for you to get the grey matter bubbling over.

As an aside I find having an early edition of Machinery's Handbook helpful in understanding how the factories of the day went about their business, what materials and info was available to them and how they used them. It can be surprisingly useful.
Cheers, Bob 
78
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 06 Jan 2019 at 21:43  »
Today I went to a huge Classic Car open day held in Bicester today at a business park dedicated to Classic and Veteran Car businesses of all sorts. One of the businesses was Classic Oils who specialise in supplying oils to classic and veteran cars, and their technical expert was there. So I lost no time in discussing the lubrication of my Douglas engines!

Following our discussions on here about oils I asked him if he could supply monograde fully synthetic oil. He told me that none was available in the UK, but that he knew it was available in the US where it was used by sprinters and Drag Racers. He asked me why I wanted a monograde oil, because he couldn't think of any circumstances in which a monograde would be a better solution than a multigrade oil. I outlined our discussions and he told me his opinion was that any lubrication requirement would have an optimum viscosity which would be more precisely met by a multigrade oil. He felt it was inevitable that in operation the oil would be at at a range of temperatures in the engine, and the optimum viscosity would only be available at all of these temperatures if it were a multigrade.

He also told me that if the engine was running on Methanol, only a high quality synthetic oil would be a suitable multigrade solution. The methanol could adversely contaminate mineral oils, even if only went through the engine just once due to the total loss system. He said that the only other solution that could survive this environment would be a monograde vegetable or fully synthetic oil.

He suggested the following fully synthetic multigrades available in the UK. Penrite Racing 15w50 or Racing 20w60, or Millers CFS 15w60.

What he had to say seemed to me to make sense, wonder what you guys think?
79
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Doug on 06 Jan 2019 at 21:09  »
Douglas,

I got the impression that Bert Dixon and the "Red Devils" were not factory, but a outside tuner that happened to specialized in the DT engine.

The cylinder head nuts are a a very slim hex; even so, you usually need a thin wall tube socket or offset ring spanner to tighten them. 5/16-25 thread, #z385; they are also used on the bottom two crankcase half bolts.  I have them in nickel plated alloy steel and eventually will have them available in heat treated stainless steel like much of the other DT hardware I do. You don't need a lot of torque, usually just what you can apply with a six inch long wrench handle. 

The 8-spline camshaft is the more common one. It is the same spline as used on the road going models servo band brake levers. Late in the game (c1932?) and for reasons unknown they switched to a 6-spline for some of the racing/dirt track and aeronautical engines. However the 1932-35 ohv road models continued with the 8-spline. I have not noticed a master spline key to control orientation before. Certainly not on the 8-spline.  I only have one example of the 6-spline, and I cannot say I have looked at it that closely.

Make sure that the inner sleeve of the rocker arms is a snug fit between the perches. It is that which the perch clamps down upon, and since cast iron is not very flexible you don't want to make it have to deflect too much! They should be a snug fit. The rockers should have some end float, but often they have cut into the perches and worn grooves and have too much. I have seen some nasty shim jobs with spring washers that just made the problem worse, but the ultimate solution is to weld up the grooves with silicon bronze and mill flush. Often the ends of the rocker arms need building up to restore the length. The bore of the rocker tends to wear on a diagonal because of the off center thrust of the pushrod and valve. If not worn too badly, they can be honed to 12mm and new sleeves made from pre-hard 12mm Thompson shafting (the original size is 15/32). Often the sleeve seize and spin on the rocker shaft bolt, wearing it instead of the sleeve. New rocker arm bolts are available.

The only special washer for the oil/grease reservoir is the one underneath. This is a conical shape and originally was copper sheet wrapped around an asbestos core. Not available. I figured on mine I would just make them out of some temperature resistant polymer or solid copper. At the top, under the cap nut is a steel washer and then a fiber washer. There is some misconception as to what to put in the reservoir because of the grease fitting. If you do use grease, make sure is is a LOW temperature melting grease. The idea is once the engine warms up, capillary action starts and lubrication is fed to the rocker arm sleeve. One or more wicks are stuffed down the hole in the center of the rocker arm bolt to the bottom. The tails exit the slot, and lie in the bottom of the reservoir. The lubricant travels up to the slot in the rocker arm bolt by capillary action and down into the drilling and thence the rocker arm sleeve by siphon action. The bottom of the hole and exit to the sleeve is lower than the floor of the reservoir. When the engine cools down this stops, preventing the lube from just siphoning through and leaking out; an automatic shut off valve. Obviously you don't want to use a light oil that would wick at room temperature. But if you are only going to run the engine for short periods, something that starts to wick sooner rather than later is preferred. So a heavy oil is probably best. Originally the wick was probably cotton cord or string, but now machinery oiling felt is probably the best choice. Pipe cleaners can be used, just make sure they are not the synthetic type as they do not wick oil worth a damn! If you are only going to do demo runs, probably just taking the grease fittings out and applying a few drops of oil to the center of the rocker arm bolt would probably be best.

-Doug
80
Douglas Motorcycles - General Discussion / Re: improving brakes?????
« Last post by andertheke on 06 Jan 2019 at 19:14  »
Hi Michael,

thank you very much, I will first do some experiments with rubber.

Best regards
Peter
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