Author Topic: Douglas EW engine  (Read 14036 times)

0 Members and 1 Guest are viewing this topic.

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Douglas EW engine
« on: 26 Jul 2015 at 11:11 »
Just stripped this engine . The pistons both have "17" stamped on their crowns, plus an indecipherable mark like a K. Anyone tell me their significance, as the piston sizes do not appear anywhere? Is a source of oversize pistons known?
Also, is the thread on the flywheel nut left-hand or right-hand thread? Thanks

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #1 on: 03 Aug 2015 at 09:39 »
I've discovered that the thread on the flywheel is right hand. Can someone please describe the procedure for dismantling the crankcase (the cylinders are off), including removal of the flywheel and timing gears? Thanks

Offline graeme

  • Master Member
  • ****
  • Join Date: Oct 2004
  • Posts: 563
  • Location: Hobart, Australia
Re: Douglas EW engine
« Reply #2 on: 03 Aug 2015 at 11:15 »
Hi Patrick
Can I suggest you put this post in the general discussion part of the forum - that's where questions like this go

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #3 on: 04 Aug 2015 at 16:15 »
Thanks, but where is the general discussion part of the forum - can't see it on any of the main titles/ links?

Offline graeme

  • Master Member
  • ****
  • Join Date: Oct 2004
  • Posts: 563
  • Location: Hobart, Australia
Re: Douglas EW engine
« Reply #4 on: 05 Aug 2015 at 01:49 »
It's at the top of the list Patrick, but don't worry, your topic has been moved there now

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #5 on: 05 Aug 2015 at 09:01 »
Thanks, Graeme. Managed to get the flywheel off by making a special extractor, but am now stuck on how to undo the other end of the crankshaft, at the timing chest. Looks like a special tool is required, and is it left or right hand thread? What is the significance of the stamped arrows, obviously something to do with timing?
Can anyone give the serial number of the main bearing seal?

Offline shuswapkev

  • Senior Member
  • ***
  • Join Date: Mar 2014
  • Posts: 173
  • Location: gold coast
Re: Douglas EW engine
« Reply #6 on: 05 Aug 2015 at 13:27 »
main bearing seal...??
 I think oil seals,   rubber type weren't available until the late 1950,s
the company name on most oldies that I have broken down......Chicago rawhide might give you a clue as to what the original material was,....

your ew seal is 50-30 and 6...all I could fined is a number 8 width...aan 040 of trimming ...and bobs your uncle..

if you want to stick with .."correct"...it is a felt seal...

cylinders have to be real careful with boring out much...as on mine some cylinder areas were under .100 thou thick..i bored enough to sleeve and used 59mm pistons...chinese pit bike..just welded some ally on top..to get the height right..
JP in aus will make you a pair of pistons to any size you request...  I went with the cheap stuff because I don't have a motorcycle ...just a bin of parts...
but it is getting there...crank has new races, rollers..cylinders sleeved...new valves....new roller bearings...pistons fitted

my cylinders were about .030 taper..sorta like wine bottles..

good luck with it.

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3446
  • Location: Pennsylvania, USA
Re: Douglas EW engine
« Reply #7 on: 06 Aug 2015 at 02:44 »
Patrick,

You will need another special extractor to get behind the pinion, like the one shown in this post:

http://www.douglasmotorcycles.net/index.php?topic=240.msg609#msg609

The crankcase wall is very thin behind the pinion, so do not try to draw the crankshaft through and hope it will peel the pinion off. You should not have to remove the pinion Woodruff key, as I think it is flush with the main shaft journal. But check first to be safe.

I don't know about arrows, usually there are just lines to match up the gear teeth. But the EW handbook has the timing diagram.

The crankshaft timing pinion nut is a right-hand thread.

There is simply a felt washer behind the drive side ball race.

-Doug
« Last Edit: 08 Aug 2015 at 17:21 by Doug »

Offline carl denton

  • Full Member
  • **
  • Join Date: Aug 2011
  • Posts: 70
  • Location: bunbury australia
Re: Douglas EW engine
« Reply #8 on: 06 Aug 2015 at 05:46 »
hello Patrick

I have three EW engines that I will have to find the rest of the parts for , would you have any photos of your engine when it was broken down it might help me find the parts I am looking on line ?

yours carl.

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #9 on: 06 Aug 2015 at 08:31 »
Doug
Thanks that's most helpful. Just to be certain, do I understand that the crankshaft pinion simply pulls off, and is not threaded as I was wrongly guessing?
Carl
Will happily send photos when the engine is apart. Can you be more specific as to the bits you are missing? Patrick

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3446
  • Location: Pennsylvania, USA
Re: Douglas EW engine
« Reply #10 on: 06 Aug 2015 at 21:46 »
Patrick,

Yes, the pinion pulls straight off. Though it is not always simple!  :)

-Doug

Offline carl denton

  • Full Member
  • **
  • Join Date: Aug 2011
  • Posts: 70
  • Location: bunbury australia
Re: Douglas EW engine
« Reply #11 on: 07 Aug 2015 at 13:52 »
hello Patrick

this is what I have got in my motor , also looking for a sample of a piston from the same motor would now of any ?

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #12 on: 07 Aug 2015 at 14:43 »
Doug
Thanks for the confirmation. Anyone in the UK got the crankshaft pinion removal tool they could lend me? I would of course pay postage and guarantee its return.
Carl
In your first picture, the crankshaft pinion is missing, but it appears in the other two, so not quite sure what your problem is, other than a piston, which I will look out for. Meantime, I attach a photo of my timing chest.

Offline carl denton

  • Full Member
  • **
  • Join Date: Aug 2011
  • Posts: 70
  • Location: bunbury australia
Re: Douglas EW engine
« Reply #13 on: 08 Aug 2015 at 13:16 »
hi Patrick

your picture help lots , was not sure if I had got all I need for that engine . it looks like I need a spring and the oil pump , have got to find the complete set again for another two engines now then . the piston is for a sample so I can get some made by JP pistons . anything you can find will help lots .

yours carl . 

Offline oily bloke

  • Senior Member
  • ***
  • Join Date: Mar 2009
  • Posts: 211
  • Location: Surrey. UK
Re: Douglas EW engine
« Reply #14 on: 09 Aug 2015 at 09:36 »
You can use Honda CB750 pistons. (SOHC). the only mods are small end bush in rods and a few thou off the crown plus top edge radius. Simple, readily available and so much cheaper. The material used in the Honda pistons is suitable for the extremes of temperature in the EW.
Hope that helps.
Andy

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #15 on: 09 Aug 2015 at 09:42 »
Andy
Presumably the Honda pistons are of aluminium, while those in the Douglas are cast iron. Does the weight difference affect the flywheel balance?

Offline Alan Cun

  • Master Member
  • ****
  • Join Date: Feb 2007
  • Posts: 430
  • Location: Qld Central Burnett District
Re: Douglas EW engine
« Reply #16 on: 09 Aug 2015 at 09:43 »
Hello Carl, Be aware while looking for bits for your EWs that the motor shown has the quick release Magneto. The gear is fixed into the timing case by a plate with 3 screws on the mag side and the gear runs on roller bearings. This mag set up was replaced on later model with the gear fixed to the taper of the mag and fits through a larger hole to the timing gears.
You will also notice the gearbox sits on slots on the frame. On later models the gear box slides on round frame section with an underneath 4 hole plate. As previously mentioned these two boxes are different internally (spring and ball gear locaters).

regards Alan

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3446
  • Location: Pennsylvania, USA
Re: Douglas EW engine
« Reply #17 on: 09 Aug 2015 at 13:27 »
Patrick.

Aluminum pistons were available on the 'Sport' 350EW, with no change to the engine. There are counter weights on the crankshaft to take some of the reciprocation loads off the main bearings, but there is no balance factor such as you would have with a single. Being an opposed twin, changes in the counterweights or piston mass will effect the rocking couple due to the slight offset of the two cylinders. Otherwise the pistons would cancel each other out perfectly.

-Doug

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #18 on: 10 Aug 2015 at 12:37 »
I have only just twigged it, from Carl's photo - the crankshaft pinion is in two pieces! Am I right in thinking that the outermost section is the oil pump drive, which is threaded (right-hand?); and that the innermost is the drive pinion, which pulls off, hence two separate extractors required?

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3446
  • Location: Pennsylvania, USA
Re: Douglas EW engine
« Reply #19 on: 10 Aug 2015 at 14:25 »
Patrick,

Correct. On the EW the oil pump worm serves double duty as the nut.

There are two styles of worm; fine and course. There was a problem with the initial oil pump worm gear stripping its teeth, so they switched to a coarser tooth profile. Something to keep in mind if you look for replacement parts.

-Doug

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #20 on: 17 Aug 2015 at 11:19 »
Andy
At 61mm, the Honda CB750 pistons are only just above the standard Douglas bore of 60.8mm, so look likely. Can you please give a model number, as I believe there were several CB750 variations? Also the gudgeon pin diameter, the height from in centre to top of crown, and overall height?  I believe the Honda parts number starts 13101, and then two serial numbers follow, depending on the variation. Thanks

Offline oily bloke

  • Senior Member
  • ***
  • Join Date: Mar 2009
  • Posts: 211
  • Location: Surrey. UK
Re: Douglas EW engine
« Reply #21 on: 17 Aug 2015 at 17:44 »
All the single overhead cam CB750's (Except HRC but you wont find them anymore) used the same piston. I cannot recall the data you ask for. The earlier Honda part numbers are first five are part type, second three are model group and last three are supersession or factory numbers.
Look up CB750F SOHC.
When I fitted mine I used all three rings. Some said do and some said don't fit the oil rings. I did and all is well.
Hope that helps

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #22 on: 19 Aug 2015 at 13:18 »
Andy
The Douglas gudgeon pins are 12.7 mm, while I am told those on the Honda 750CB are 15mm, about the same diameter as the Douglas  conrod top end hole. Presumably you bored out the conrod to accept the Honda gudgeon pin? Thanks

Offline oily bloke

  • Senior Member
  • ***
  • Join Date: Mar 2009
  • Posts: 211
  • Location: Surrey. UK
Re: Douglas EW engine
« Reply #23 on: 19 Aug 2015 at 21:57 »
Hi,
The existing bushes are just over the pin diameter leaving a thin wall bush. Bored slightly undersize refitted and reamed to sliding fit.
The other option would be to bush the piston pin hole.
Andy

Offline graeme

  • Master Member
  • ****
  • Join Date: Oct 2004
  • Posts: 563
  • Location: Hobart, Australia
Re: Douglas EW engine
« Reply #24 on: 20 Aug 2015 at 00:57 »
When my father restored the 1914 3 1/2hp outfit in the mid-70s, he fitted Hillman Imp pistons that have a gudgeon pin diameter the same size as the little end hole in the rod minus the bush. A highly regarded engineering friend assured him that this would be fine considering the use and loads put on a machine of this age. Over nearly 40 years now, this bike has done a huge number of rally miles, and being an outfit it works very hard indeed - there have been no issues whatsoever with the pistons, save that they are now a bit worn and need renewing. Just a thought!

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #25 on: 21 Aug 2015 at 13:35 »
Graeme
I'm a bit puzzled there, as the standard EW bore is 60.8mm, whereas FW Thornton, the piston people in the UK, are giving the Hillman Imp bore as the inch equivalent of 68mm.

Offline ian scott

  • Full Member
  • **
  • Join Date: Mar 2008
  • Posts: 64
  • Location: Sydney. Australia.
Re: Douglas EW engine
« Reply #26 on: 22 Aug 2015 at 01:27 »
Patrick. Graeme is not making a piston suggestion for you. His point is that you could safely run the gudgeon directly in the small end of the rod with no bush - steel to steel. Thus avoiding having to reduce the gudgeon hole in the Honda Pistons and so use the Honda gudgeon pins.

Offline carl denton

  • Full Member
  • **
  • Join Date: Aug 2011
  • Posts: 70
  • Location: bunbury australia
Re: Douglas EW engine
« Reply #27 on: 22 Aug 2015 at 11:21 »
hello Patrick

I have had a look in to getting some pistons made in Perth , and it looks like the cost is going to be ok but have got to get at least 8 from them . al depends on me getting my hands on one original Douglas piston for the 350 EW.


yours carl .

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #28 on: 22 Aug 2015 at 13:16 »
Carl
I think I have found a couple of pistons from a Honda 750 to fit my EW, the suppliers have standard size 71mm and +0.5mm oversize if you are interested. If not, I may be able to lend you my original as a pattern, once I am sure I am suited, which should be within the next week or so.
I now understand the point about the Hillman gudgeon pins, but must admit to a bit of surprise about the idea of steel bearing upon steel, but I suppose that's what happens when a cast iron piston goes up and down in a cast-iron cylinder.

Offline Chris

  • Master Member
  • ****
  • Join Date: Jun 2004
  • Posts: 498
  • Location: Kent, UK.
Re: Douglas EW engine
« Reply #29 on: 22 Aug 2015 at 15:50 »
Hi all
My 1910 model D like the later 2.3/4hp machines used a 3/8" diameter gudgeon pin. Mine has been running for many years with pistons from a 1930s Douglas with a 1/2" gudgeon pin which is running in the standard conrods with the small end bush removed so steel to steel does work. Chris.

Offline carl denton

  • Full Member
  • **
  • Join Date: Aug 2011
  • Posts: 70
  • Location: bunbury australia
Re: Douglas EW engine
« Reply #30 on: 23 Aug 2015 at 01:44 »
hello Patrick

I am the sort of bloke that will only build a motor the way it was designed , it makes things hard some times but they spent years designing a bike and I am not going to try and re designee it . it would be good if I could lone your old piston the person at JP I have got to talk to is on holidays for three weeks .

Yours carl.

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #31 on: 23 Aug 2015 at 07:47 »
Carl
Let me have your full name and address, phone number, and email address, and I will see what I can do. Patrick

Offline shuswapkev

  • Senior Member
  • ***
  • Join Date: Mar 2014
  • Posts: 173
  • Location: gold coast
Re: Douglas EW engine
« Reply #32 on: 25 Aug 2015 at 10:13 »

 JP pistons...
when I asked them for a set...they seemed to have a pattern on hand... I think $200.00 each..??
 but check your cylinders for taper...mine were factory size at the spigot and about .040-.050 bigger at the other end...cylinders were quite thin.. not much room for a rebore...I measured less than .100 in some areas...  luckily the fins go the direction they do...help to hold all together
mine also had some large rust pits that couldn't be bored out

so I have sleeved  and now have 59mm pistons fitted in... went on ebay and keyed in...59mm pistons...

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #33 on: 12 Sep 2015 at 08:05 »
Andy
Re your post on 9 August, I have now obtained some Honda pistons, but am puzzled as to why one needs to skim a few thou off the piston crown and radius the top edge? Thanks, Patrick

Offline oily bloke

  • Senior Member
  • ***
  • Join Date: Mar 2009
  • Posts: 211
  • Location: Surrey. UK
Re: Douglas EW engine
« Reply #34 on: 12 Sep 2015 at 09:19 »
If you over rev the crank will flex. I was advised that the crank will flex under normal conditions. Radiusing the piston edge conforms with the combustion chamber design and aids flow and reduces the possibility of a hot spot as the top of the piston rises just above the edge of the inlet port area.
Build the motor and measure the height in the chamber. They will be slightly different to each other due to the rods never being quite the same length and the barrels having slightly differing bore length where they have been machined. Simply match the two by taking the few though off of the top.
You will be bringing the compression ratio up a wee bit but not enough to be of concern, however, you may need to alter your carburation and ign timing to suit the improved performance.
Hope that helps.
Andy

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #35 on: 22 Sep 2015 at 16:03 »
Thanks, Andy. Can you advise what running clearance there should be between the Honda pistons and the Douglas cylinders? My cylinder man is thinking 5 thou.
BTW, Alpha bearings are saying that the concept of running an oversize gudgeon pin - 15mm- in the EW engine is not viable, as the conrod is not robust enough. They say it works with the later engines which have a stronger conrod. It looks as if I shall have to use the original 0.5" pin, and bush out the piston trunnions.
Patrick

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3446
  • Location: Pennsylvania, USA
Re: Douglas EW engine
« Reply #36 on: 22 Sep 2015 at 16:07 »
Patrick,

See this post about early and late connecting rods.

http://www.douglasmotorcycles.net/index.php?topic=109.msg259#msg259

-Doug


[22Sep15] Oops, sorry, I see you were asking about gudgeon pins, not the big end. 
« Last Edit: 22 Sep 2015 at 17:51 by Doug »

Offline oily bloke

  • Senior Member
  • ***
  • Join Date: Mar 2009
  • Posts: 211
  • Location: Surrey. UK
Re: Douglas EW engine
« Reply #37 on: 22 Sep 2015 at 16:29 »
Hi Patrick,
I simply removed, bored , replaced and reamed the standard bush that was in the rods that were in the bike which left a thin wall bush and did not cut into the eye of the rod at all. It is possible there is more than one type of rod. My engine dates to 1926 and apart from the timing cover conversion I had assumed the rods were original. There may be more than one type of rod fitted to the EW and yours has a smaller eye than mine. I don't know.
The piston to bore clearance of 4 - 5thou should be fine. 3.5 thou would be appropriate for the Honda engine but the SV EW runs much hotter so allowing for the additional expansion would be wise although I doubt the superb quality of the Honda pistons require it. Better safe than sorry. I doubt your bike will be a daily driver so that additional clearance will make little, if any difference. I run all three rings and put a little 2 stroke oil in the petrol (I mean a little probably several hundred to one).
Hope that helps
Andy

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #38 on: 23 Sep 2015 at 19:31 »
Regrettably, the saga continues. Today, my engine specialists advised me that they had started on the rebore, but had not been able to complete it, as the stroke on their boring machine was too short, hence I can go neither forwards nor backwards, with a part-finished rebore. One must have come across Douglas rebores before, can anybody advise from experience a specialist with the right machine, preferably in the Midlands?

Offline patrickhowell

  • Full Member
  • **
  • Join Date: May 2015
  • Posts: 72
  • Location: Broom, Warwickshire
Re: Douglas EW engine
« Reply #39 on: 26 Oct 2015 at 13:49 »
Am coming to the end of the engine overhaul for my 1928 EW. I used 61.5 mm Honda 4 pistons, which have a 15mm gudgeon pin, as opposed to the original 12.7mm one. Alpha Bearings advised that the small end rod eye was not substantial enough to bore out to 15mm, hence I am having to sleeve the Honda pistons to take a 12.7mm pin. Question is, what material should I use for the piston sleeves? Phosphor bronze has a different expansion rate to aluminium, will that cause a problem?

 

motorcycle