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Hi Buzzie and Leon,

Here is a summary from John Holmes in Loose Fillings No. 2A, Summer 1999, from their website that covers the early air cooled cars in Queensland. Appears that the Dougie IoM engine was not used for very long in the Chatterton - Warburton special.

Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 08 Jan 2019 at 20:34  »
Some photos
Douglas Motorcycles - General Discussion / Re: DT/SW5 Engines
« Last post by Buzzie on 08 Jan 2019 at 20:30  »
Hi Doug

There was a fair bit to digest in your last post! I've looked at my bits and pieces and have used those points as a check list so to speak. The remarks below refer to the first engine. As I've mentioned before I'm starting with that engine and leaving the second one til later.

Starting with the valve gear etc. Amazingly it all looks in really decent condition. The rocker inner tubes are a clearance fit between the perches, and the perches are virtually wear free. The rocker shafts are in good condition and are a clearance fit inside the inner tubes, although there is some wear where the rockers have obviously been moving on their inners. I have found four rocker shafts which have the little copper cones and the wrap around asbestos pieces. I will attach a photo. The ball ends of the rockers are in reasonable condition, but the pads that bear on the valves are worn. They probably would dress flat with a stone, but I would worry about how deep the surface hardening goes.

I notice one of the rockers has some holes drilled in the arms. See photo below. I wondered if these might be to do with the exhaust valve lifter. This system is a complete mystery to me. I've looked carefully at the bikes in the National Motorcycle Museum, some dont appear to have it fitted, and what I could see on the others left me none the wiser.

I read the info about the lubrication system with great interest. A lot of tips there for me to follow when I get to that stage. Particularly about the types of lubricants to use and the wicking material. I think a heavy oil would probably be my route forward. The engine is unlikely to run for more than about 20 minutes at a time before I would get the chance to top up the rocker shaft reservoirs.

I just read your link in an earlier post to your 2004 crankshaft post. I am in a bit of a quandary. The bottom end of the engine including the cylinders and pistons were all assembled by the company I mentioned at the outset, so at the moment I am unable to inspect these. My instructions were to get the engine in decent working condition and get it running, replacing worn parts as they thought necessary. My dilemma is I chose the company because they have a good reputation and I felt I could entrust them to rebuild the whole engine. They quickly did the work they have and were confident in it. Unfortunately the job stalled (for getting on for 10 years!!) when they couldn't find some of the parts and were defeated by the head gaskets.

So my dilemma is whether to take it all to pieces to check it all for wear and reassemble it myself or to trust the quality of their work. I certainly trust their experience in reassembling etc over my lack of experience. I will have to separate the two crank case parts to fit the missing gasket, and oil up the parts that have dried up and I cant reach from the outside. I can see from the outside that the crank end float of the crankshaft isnt excessive. The crank taper doesnt show excessive wear and but does have some localised damage. I will attach a few photos. The cylinder bores have no visible wear and have been nicely honed and the standard pistons and run well in them, the rings scraping oil as they rise and fall in the cylinders

I have measured the combustion chamber etc volumes to calculate the compression ratios. I estimate the CR is 9.8 to 1 for the fitted dome top pistons and a 0.188" spacer fitted under the cylinders. The flat top pistons would provide a CR of 6.75 to 1 if fitted. Seems about right for Methanol and pure petrol respectively.

You mention that you have some Douglas nuts. Can you supply these? I have searched on the Forum and have found mention of your conrods, and rocker arms etc, but no mention of fixings etc. Is there a website or a list anywhere? I will probably need a lot of new or reworked components for the second engine, but I definitely need a supply of nuts and studs to put the first engine together. I had a quick look at the valve gear on the second engine, and it will need a lot of attention.....

Best wishes

Douglas Motorcycles - General Discussion / Re: S5 Axle & Bearings
« Last post by Doug on 08 Jan 2019 at 17:45  »
The original bearings were 1/2 x 1-7/16 x 11/16 inch. Those have been obsolete for a very long time. When old stock does turn up on the market, the cone itself often goes for over $200! SKF W5700 and Timken 00080x cone and 00152 cup are part numbers seen.

I have heard of the substitution of Timken 00050-00152x, which is 1/2 x 1-7/16 x 17/32, which is currently in the Timken catalog. However, a few things to keep in mind. First, it has a shorter hub, so spacers would be needed under the bearing nuts, or longer bearing nuts made to suit. The second difference is the cone sticks through the cup by 0.022 inch, whereas the original had the face of the cup and cone flush. The third difference is the new bearing does not have a generous radius on the bore of the cone at the small or inboard end. They have the big radius at the other end, expecting a diagonal load path across the bearing and races. They dont seem to have envisioned a situation the way Kingswood uses the bearing, nipped up hard against a shoulder on the axle on the one side. Not anything that can easily be done about that, it just means a regrettably sharper radii on the axle, and a higher stress concentration. The usual way around this is to make a false shoulder on the axle with a spacer or a groove behind the shoulder to redirect the stress path. Alternatly you can grind or turn (with a CBN tipped tool) a larger internal radius on the bearing race, depending on how keen you are. A potential fourth issue is the cage of the Timken 00050 cones might foul the sheet metal cup (#8325-1) that keeps the felt out of the bearing. This based on the 3D model that Timken provides; I do not know if the real bearings have such a long cage. The cage could be trimmed or cups with more offset made.

'Fat axle' conversion:

The bearing is pulled up tight against the shoulder on the brake drum side, so some dimensional correction will need to be made in light of the several above differences to retain the correct alignment between the brake drum and the backing plate. On the other end the bearing floats and is where you set the bearing clearance, so things are not so critical.

However you are still stuck with a 1/2 axle. The originals were made of a 5% nickel alloy steel. Even so, as you found they are typical bent and that quickly ruins the (expensive) taper roller bearings. Source of NOS axles, are you joking? The first improvement would be to make the center portion larger than the original 9/16 forged diameter. Still, it has to be reduced to a 1/2 where it passes through the axle and it is a long way to the frame lugs. Nor does it provide a shoulder for the bearing to seat against. It sort of nips up and sticks on the radius.

Original axle layout (cage and rollers not shown):

If making new axles you might as well convert to 17 x 35mm x 10mm sealed ball bearings. You can use the original hubs by making a sleeve for the outer diameter, split to ease installation (and removal!) This allows for a significantly larger diameter through the bearing and the bearing nut for a stiffer axle. Outboard of that it can be reduced to 1/2 so the frame and forks need not be altered. If it bends a little out there, it will not harm the bearings. When using original hubs (vs. making new) you will need to take a shoulder to shoulder measurement between the bearings of the hubs as I am sure they vary. With the ball bearing design there is no adjustment, the clearance is machined into the corresponding shoulder distance of the axles. Of course you can skim a little more off or add shims if the machining is a little off. While the link below is an article primarily aimed at replacement axles for the 1936-38 Aero, the same idea would apply to the S5/S6/T6 family. So use the axial dimensions from you original axles. For example on the S5/S6/T6, #9384 (rear axle) is 7-15/16 inch overall and #9382 (front axle) is 8-9/32. The bearing nuts are Americanized threads to suit my conditions, but they could just as well be metric.


Douglas Motorcycles - General Discussion / Dragonfly carburation II
« Last post by Bynorthsea on 08 Jan 2019 at 17:09  »
After few more session working on the carb I have finally reached the conclusion that it has been 'attacked' sometime in the past and there is nothing more I can do to sort it out. With everything clean, the right jets and set up it still was over rich and unaffected by the air screw. It appeared that the pilot jet was being bypassed, on checking the depth the jet seat the jet was not mating but binding on the thread. Pleased to find a fault a possible solution was to ease the thread and screw the jet further in. This done and after checking I still had fuel to the jet, the bike started but now would only run on full  choke, very disappointing. More checking and scrutiny particularly of the air screw appeared to show the fuel passage in the body Being closed off by the screw as soon as it was screwed in. Conclusion when it was running rich it was being fed through the bypass in the jet block from the unseated jet, seating the jet meant that fuel could not take that route and was now unable to enter because of the peculiar positioning of the air screw. Can't think of anything else I can do other than replace the carb.
So even if I could get hold of a new 375/7 I'm not inclined to afford the 200. So some questions.
1. Has anyone a useable 375/7 for sale?
2. There are more 375 carbs with a 7/8 bore than 375/7s, would stepping up 1/16 make much difference?
Finally and not worrying about the authenticity debate has anyone any experience of fitting a Dellorto, Mikuni, Beijing etc
Thanks in advance for any help
Douglas Motorcycles - General Discussion / Re: B29 Finally Rolling
« Last post by douglas1947 on 08 Jan 2019 at 16:33  »
Your bike looks great in that "as used" condition.
May be the new paint on the rim will lost the gloss a bit whenyou use the B29?

I hope I will finish my 1930 H3 also until spring!?

Do you have new clamps on your footrest rubbers?

Members' Gallery / Re: Douglas frame numbers
« Last post by Oldbiker on 08 Jan 2019 at 15:03  »
                     I now have the registration document for the bike it shows that it was registered on 03/11/1936 and that the frame number is recorded as FZ228DEXP12894. There is no model type recorded.  It has a 5/L engine with larger cylinders to make it 600cc and is fitted with Webb heavy girder forks. So I think it must have had an interesting journey so far, we will see what the future brings.

                                                                                                     Many thanks for your help
Douglas Motorcycles and Parts For Sale - Private / Re: Veteran Forks
« Last post by Steveza on 08 Jan 2019 at 13:53  »
Hi I would be interested in purchasing for my 1913, to South Africa?
Douglas Motorcycles - General Discussion / B29 Finally Rolling
« Last post by cycarmark on 08 Jan 2019 at 13:16  »
Finally got the wheels done and tires mounted, the 19" modern rims and Mitas tires work great.  I am amazed at how low the seat height is on the bike.  Thanks all who helped me figure out the way to go with the lack of 25x3 tire sizes.
Douglas Motorcycles - General Discussion / Re: 1931 t6 carb
« Last post by derek morgan on 08 Jan 2019 at 12:31  »
thanks very much for advice paul, have the carb out as I was going to take it down the shepton show beginning of feb. will try your advice at weekend and let you know results regards derek
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