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91
Douglas Motorcycles - General Discussion / Main shaft felt seal
« Last post by Bynorthsea on 03 Mar 2019 at 18:38  »
Just stripped my Dragonfly engine to get my crankshaft refurbed, I did so not worrying about draining the gearbox. As a result when I upended the assembly oil poured out into the clutch housing, now when I got the bike there was oil in the case but I was advised not to worry as the gearbox oil level was below the shaft height. Now I have sometime waiting for my new crankshaft I thought it would be good to check the seal. I hoped I was going to be able to pull off the cover plate without entirely stripping the box, not so it seems. Before I do strip the box I'm wondering if I can insert a felt seal through the end of the cover plate and then refit the coupling. In the plate there appears to be a space for a seal and on the splined coupling there is a bearing surface, if that is the case then as it is the currently seal is entirely missing. Comments and advice would be much appreciated.
92
Hi yoshimasa,

I think your engine with EN number should have the smaller flywheel.
Please have a look in the center:
may be there is an "extractor ring" (small ring srewed into the flywheel above the center fixing nut) already fitted in the flywheel.

When you have this ring, you have to unsrew the center nut, after some revolutions the center nut will touch the extractor ring and with further turns you will extract the flywheel from the cone.

If there is no ring inside the thread of the flywheel, you can also use an separte extractor.

I have both parts for my bikes.
My bikes have the bigger dia flywheel (235mm), outside thread is 38,2mm x 20G) on extractor.

I can not manage to send a photo on the forum, may be to many pixels?
If you want, you can send me a private email to send you photos.

Michael
93
Douglas Racers and Racing History / Still looking for 1914 OHV Heads?
« Last post by pvn06 on 03 Mar 2019 at 13:05  »
Hi All,
I haven't had chance to post many updates recently, but am now back working on my Douglas 2 3/4hp project bike, which I am hoping I might have back on its (now restored) wheels later in 2019.

However, as a future project, I still have in the back of my mind it would be nice to build a recreation of the first OHV racing bike - of the type used by Douglas in the 1914 TT.  With this in mind I have been slowly acquiring possible donor parts - a very rough 1917 2 3/4hp frame and forks (would really appreciate if anyone has a gaff 4 hp frame for sale though - with duplex front tubes) or reasonable fork blades as mine will need retubing) or any other period parts.

Particularly though .. . I would love to hear if any of the original OHV engine parts have survived, particularly cylinder heads (which I would really like to acquire).  As far as I can tell from the few photographs of these engines available - they look to use the 2 3/4hp crankcases, but special barrels and heads made only for this model.  As far as I can tell there was a second hand oil pump fitted (built into the oil/petrol tank behind the normal one) - which looks to be feeding oil directly to the bigend. 
I have seen one photograph of what I assume was a prototype engine with barrel/head combined (as per SV 2 3/4hp models), but all other photos look to show seperate head/barrels.


I thought that if I was to make a recreation of this engine I would need to have patterns made for both barrels and heads - but fortunately, I recently acquired a set of early 350 barrels which with some machining look like they will be suitable.  I am assuming these are from the first production OHV models of 1920/21, but luckily these are correct 350 bore (others I have seen have been 500), and have correct '2 stud' type mounting points to the crankcases.  They are actually '3 point', but from the look of it the 3rd casting mount can be removed without issue.  They will also need the base flange machining as it is much 'beefier' than the original SV barrel flange on 2 3/4hp models.  However, very close and looks like it will save me having to have these cast.

It would be great if a set of heads were to turn up in the same fashion - and save a lot of grief.  This is a (very) long term project bike anyway, but any parts or information anyone has about this model would be greatly appreciated - and obvioiusly if you have any old head parts propping open a shed door, then please let me know!

Best wishes
Paul
www.RacingVincent.co.uk
94
Hi All,
I recently purchased this NOS Ferodo brake block off Ebay for my Douglas 2 3/4hp.  Old brake blocks are still occasionally available - I had previously picked a couple of similar (but not quite right) old stock items from Founders Day rally. 
However, what is wonderful about this item is the lovely (although very faint) label which was still on the brake block - which reads 'Douglas 2 3/4hp' in what looks like a very old font style!  It gives a wonderful glimpse into what the labelling of after market parts would have looked like in (Edwardian?) times.

This block will go on to the rear brake of my own 2 3/4hp project bike (which I am now in the process of re-assembling) . . . but it seems almost a shame that the sticker will need removing - unfortunately too far gone to stay on in use

best wishes
Paul
95
Thank you for the update Eddie, it does not totally surprise me - and I appreciate someone far more experienced than I am with these engines in practice, coming back with useful updates.
That said, I am still not sure the original collar I was working from had not been modified itself, the indent/slot for the pin looks very pronounced, with no other noticeable marks around the recess. 

However, I only have a couple of manky other originals (hence why I wanted to manufacture new ones) - one of these looks like the slot is less pronounced (or just worn!), and the other still in situ on a barrel, but looks like it is badly worn.

With your advice, I have manufactured another set of collars, but to the original pattern you describe - i.e. just a recess for the full circumference - this is now Item 0730 on my catalog.

From an engineering perspective though - I still think the type with a milled slot to be a better design, in that it holds the pin properly captive - but most importantly stops the valve collar from spinning around the valve.  Since starting to acquire old Douglas 2 3/4hp engine parts I have seen a few examples of old worn valves where the top of valve (where the collar sits) is also worn in the same way as a valve stem wears at the line of the valve guide.  This does not seem like a good thing, and on most later design of engines (particularly where taper cotters are used) it is more normal the valve spring top plate is locked to the valve stem. 
I would be interested to take feedback from other owners with knowledge in practice - but until I hear anything contrary, will offer both types so anyone wanting to can try for themselves.  For my own part, I am still going to give the modified type a try in my own engine first, and will report back once I have done so.

Thanks for feedback Eddie, and see attached couple of photos of type without slot below

best wishes
Paul
www.RacingNorton.co.uk
96
Douglas Motorcycles - General Discussion / Re: HONDA PISTONS FOR DRAGONFLY
« Last post by BIKEMAN on 03 Mar 2019 at 10:26  »
Thanks Doug for that very usful piece of imformation i can proceed with confidence - bikeman
97
Douglas Motorcycles - General Discussion / Re: HONDA PISTONS FOR DRAGONFLY
« Last post by Doug on 02 Mar 2019 at 23:00  »
Typical instruction sheet with Wiseco rings. Radiused ring shown as the top ring (second sheet), with the second ring as a scraper.





-Doug
98
Douglas Motorcycles - General Discussion / HONDA PISTONS FOR DRAGONFLY
« Last post by BIKEMAN on 02 Mar 2019 at 16:23  »
I have purchased a set of forseti 250n pistons from austrailia. The problem i have is there are two plain rings one is black in colour with sharp edges,the other silver in colour with small radius ,what order do i fit them on the pistons? I have no instructions with the pistons and have e mailed austrailia as yet with no reply. Can anyone help?
99
Hello Michael

Sorry for my late reply.

I do not know the type of the flywheel.
The outside diameter is approximately 21.5 cm.

I would like to produce an extractor in Japan.
Do you know the size of the extractor?
100
Douglas Motorcycles - General Discussion / Re: Magneto
« Last post by Buzzie on 01 Mar 2019 at 22:18  »
Tony Cooper just did a BTH for me. He was excellent and very good price.

He doesnt do the internet, but you can call 0121 559 2405 Mon to Thursday. He did mine all by post
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