Author Topic: B29 Finished (Read 1977 times)

cycarmark · « **on:** 23 Jan 2023 at 12:32 »

I finally finished restoration of my B29 and wanted to thank all the folks on the forum who provided parts, drawings, help, information, and plenty of support and inspiration to see it through. It's a great riding bike, the smoothest running British twin I've ever ridden.

douglas1947 · « **Reply #1 on:** 24 Jan 2023 at 06:33 »

Congratulations to your very nice and good looking bike, well done.
I hope you enjoy it riding.
Michael

hoejmark · « **Reply #2 on:** 24 Jan 2023 at 08:36 »

Beautiful bike.
You can look foreward to riding it. I really like to ride mine.
It doesn't seem that the pancake dynamo is connected to the system?
hoejmark

cycarmark · « **Reply #3 on:** 24 Jan 2023 at 14:05 »

The pancake dynamo is connected, if you zoom in you can just see the blue wire coming out of it to the wiring harness. I'm not sure how well it works, but it does put out a little bit of power!

arturro · « **Reply #4 on:** 25 Jan 2023 at 08:28 »

Looks great . Congratulation
Best regards from Poland
Artur

cardan · « **Reply #5 on:** 25 Jan 2023 at 09:44 »

Well done Mark - that's a really super restoration. The finned valve covers, in particular, look fantastic. I've just re-read your old posts - from 2018-on - which really emphasize your efforts to get the details right, and also remind us of how useful the forum is! I hope you're pleased with the outcome.

Leon

cycarmark · « **Reply #6 on:** 25 Jan 2023 at 15:58 »

I really like the bike, it is an easy starter and is comfortable cruising around town. The low seat height is also nice.

The finned valve covers came out great, I drew plans for them and a local machine shop made them, amazing what 37 minutes of CNC machining will do!

The help from this forum was absolutely necessary on this bike, since there really is no repair manual (like for BSA and Triumph) all the forum folks who have worked on these and posted information was fantastic. Also, since my bike was missing things like the generator drive clutch, and the exhaust valve lifter mechanism, the drawings and parts provided by forum folks made the job doable.

douglas1947 · « **Reply #7 on:** 26 Jan 2023 at 06:48 »

Mark,

I have noticed you have made new valve covers.
I have only the rear cover and no front cover. So my bike runs without covers. Do you have the possibility to make a further pair or only the front cover for me?

Michael

hoejmark · « **Reply #8 on:** 26 Jan 2023 at 08:36 »

I made some magnet conversions to the BTH pancakes on my B29 and T6 so that they now produce some 3 to 4 amps. At the same time I also converted the cut out relays to diodes as I guess that the cut out itself consumes about 1 to 1.5 amp.
I can upload more informations if you like.
However LED bulps in the rear lamp and in pos. head lamp only consumes about 0,1 amp, that is a not so good dynamo may also be useable.
hoejmark

cycarmark · « **Reply #9 on:** 31 Jan 2023 at 00:21 »

The front tappet cover is a mirror image of the rear. The machine shop that made mine did the 3D model of them, and maybe they would let me have the model, I will ask. With that you could take it to a CNC shop and I'll bet they could make one or a pair. I do not have the machining skills or equipment to do such nice work. My 1935 Craftsman lathe is pretty good for spacers and shafts, but not much else.

The magneto rebuilder did exactly that, he converted the old magnets to more modern rare earth magnets and it works great. I had thought about having the same done on the generator. I would appreciate it if you could upload more information on this.

Chris · « **Reply #10 on:** 31 Jan 2023 at 10:17 »

Hi Hoejmark
I would very much like to know what modifications you made to the magnet in the pancake dynamo. I would be grateful if you could detail these.
Chris.

hoejmark · « **Reply #11 on:** 01 Feb 2023 at 12:54 »

Hi
Some years ago I converted my T6 pancake to a modern AC alternator, that should give 70 w. It produced plenty of power, but it had to work loose often due to vibrations. I feared that the vibrations should provoke damages to the timing mechanism so I skipped the system again, and had to search for another solution.
I learned from a friend how to replace a weak pancake magnets by more modern super magnets, that can be hidden behind the cover, and it works well. I have done this conversion to my B29 and the T6.
I use four Neodym block magnet, size 20x20x10 mm with the magnetic field perpendicular to flat areas, and when I place the North poles nearest to the two fastening screws, the dynamo produce negative earth (otherwise it produce positive earth). Due to the position of the fastening screws, the four magnets can not be placed at right angles to each others, but no matter it produces well anyway.
In various books i have seen, that the pancake typically produce 3 to 4 amps at app. 3000 RPM, and my hope was to reach that. As you can see from the test setup I had the pancake to give 4,15 amp at 6,21 V at a little below 3000 RPM. I also had it to produce 4,2 amps at 6,4 V and even more than that, but as I am not an expert on how heavy load the solderings, commutator and brushes can handle, I did place a piece of 1 mm alu sheet under each magnet to reduce magnetic flux. The figures I gave are with these alu underlayers. I have glued the magnets and underlayer to the steel areas in the pancake body with Araldite, but I have recently read that UHU MAX REPAIR glue should be the best. By the way, I used a handdrill that could run up to 3000 RPM in the test setup.
Be aware of that these magnets are very strong and you probably will end up with several carpenters louse (translated from danish) on your fingers, and when in position and the cover in place, it easily holds an 8 inch universal spanner.
In place of the cut-off relay, that itself steal 1 amp. or more, I use a diode. Those I have are well beyond what is needed (200 V / 25 A), but that was what the retired car electrian had in stock, an I got a handful very cheap
I also attach a copy of a wiring diagram from another thread in this forum, I have omitted the zener diode to regulate voltage to the battery, as I fear, that the dynamo then will produce max. power constantly to the frame when battery is full. Instead i have fittet a toggler switch in the power line from the daynamo so that I can switch of the load when I can hear when activating the horn, that the battery is full. But as I am no expert either in what happens inside the dynamo when running without load, I should be glad to hear comments on this.
I attach some photos
hoejmark

Screen snip of wiring diagram.

Original wiring diagram in Word (docx) format.

Screen snip of wiring diagram added. Images converted to linked files to correct distorted display. Please see Taking photos with mobile/cell phone. - Dave, 02Feb2023

hoejmark · « **Reply #12 on:** 01 Feb 2023 at 13:00 »

Hi again
The wiring diagram I refer to is the attached word DOCX document in the bottom of the photos.

I have it from this topic:
https://www.douglasmotorcycles.net/index.php?topic=5637.msg20431#msg20431

hoejmark

hoejmark · « **Reply #13 on:** 01 Feb 2023 at 13:07 »

cycarmark

"The magneto rebuilder did exactly that, he converted the old magnets to more modern rare earth magnets and it works great."

Have you more informations?

hoejmark

cycarmark · « **Reply #14 on:** 01 Feb 2023 at 15:48 »

Hoejmark,

I don't have any specifics on what was done to install new magnets into my BTH magneto, but the guy who did it is Gregg Kricorissian and his email is magneto@spyder-it.com If you ask him what he did to the Douglas magneto Mark Sawicki sent, I'll bet he will tell you. As with your generator modifications, if I get a wrench near the magneto now, it really sticks to it.

On my bike I've got the BTH cutout, what diode are you using in the place of the cutout?

cycarmark

hoejmark · « **Reply #15 on:** 01 Feb 2023 at 17:40 »

cycarmark
Are the new magnets placed inside or outside the original magnet and is it still there, the horseshoe magnet?

The diodes have the part number 130699 from this company:

https://hc-cargo.dk/catalog/g/generatordele/generator-reservedele/diodebroer/dele-til-diodebroer/dioder.

They are press fit diameter ø12,7 mm. The pin is to be connested to positive power and the housing to the negative earth. It was by coincidence that I found them at a retiered auto electrican and I know they can handle far more power ( can hande 25 amps at 200 volt) than needed, but they were cheap and they work.
I attach a photo from my B29 that I have owned and ridden for 30 years. A previous owner had made a not too little box to house the cutout, probably because the cutout cover was missing, and in the cover to the box he had placed an ammeter. The photo shows the box open and in the lower corner to the right I have placed a diode just so that can see how such a diode looks. I have not restored the bike except for the motor and the gearbox and therefore this weird box is still there.
I also attach a photo from the T6 of the cutout box without its cover so you migth see the diode instead of the removed relay.
Regards
hoejmark

Images converted to linked files to correct distorted display. Please see Taking photos with mobile/cell phone. - Dave, 03Feb2023

cycarmark · « **Reply #16 on:** 01 Feb 2023 at 20:28 »

The new magnets are inside the magneto. The old horseshoe is still there and the mag looks original. I have no idea how he did it, but it works great. Here's the best picture I could find of the exterior of the mag.

Thanks for the info on the diode, it may reduce the loss of power through the old cutout and the feeble generator may charge a little more.

cardan · « **Reply #17 on:** 01 Feb 2023 at 23:31 »

Call me old fashioned, but for our purposes I don't think there's any need to update the magnets in any magneto. The magnet steel is pretty good stuff (it's a tungsten alloy steel in the vintage BTH horseshoe magnetos) and if the magnetism has been diminished with time, it should be possible to remagnetise it back to original with the proper equipment. In original form, the magneto should allow the bike to start easily and run slow and fast, which should be enough?

That said, BTH was never satisfied with their magnets, and updated them as new technologies became available. In all BTH magnetos after the horseshoe magnet type - M1,M2,K1,K2, etc. - the magnet was small and sat at the top of the magneto and the pole pieces, clamped against the magnet, were just soft iron. BTH certainly would be using rare earth magnets if magnetos were still a thing.

Leon

hoejmark · « **Reply #18 on:** 06 Feb 2023 at 08:18 »

Leon
I fully agree on your comments, and I have rebuild more prewar BTH magnets incl. rewinding of coil, new modern condenser and remagnetisating with good result. However I am also keen to keep my bikes running rather than perfect originality, hence I am also interested in new ways to solve problems.
regards hoejmark

cycarmark · « **Reply #19 on:** 06 Feb 2023 at 23:59 »

The magneto rebuilder I used was not satisfied with the level of magnetism in the original magnets, after re-magnetizing them. I was happy to defer to his expertise and the magneto has worked very well. He did the work without changing the outer appearance which is great. I too am old fashioned and the old bikes are of more interest to me than modern ones (which I consider more of an appliance) and there is more than enough antiquity in the B29 to satsify my tastes!

Now all I have to do is get a little more power from the pancake dynamo to power more than the wattage of the LED lights currently fitted. I think it just keeps up with the load, but the ammeter on the back of the headlight does not show much activity, charging wise. The diode Hoejmark mentioned looks like it may help compared to the original BTH cutout.

eddie · « **Reply #20 on:** 07 Feb 2023 at 07:57 »

One of our local members in the LDMCC had a similar problem with the pancake dynamo on a 500 Aero - no matter what he did, it stubbornly gave almost zero output. Then one of our older members threw in the thought "Have you tried changing the magnet? - I've got one hanging on the workshop wall that I stick small items to, so that I don't lose them - I'll bring it in!" With the 'new' magnet fitted, the dynamo gave a good charge. Further investigation (using the old schoolboy method of a sheet of paper and iron filings) showed that the original magnet had a flaw that was producing a negative, out of phase charge that partly cancelled the main charge.
Needless to say, the 'new' magnet stayed in place and the original (flawed) one now hangs on the workshop wall, being still capable of looking after the safe storage of those small items!

Regards,
Eddie.

cycarmark · « **Reply #21 on:** 07 Feb 2023 at 13:11 »

I had the mine re-magnetized and it gives a better output but still not that great. The guy who did it said the circular construction of the magnet made it difficult to re-magnetize. I take breaks from working on getting more output from the pancake but have not given up just yet!

Doug · « **Reply #22 on:** 07 Feb 2023 at 19:37 »

There were two types of magnet, a full ring with one gap and four alternating poles; and a (presumed?) later type with two crescent shaped poles of conventional N-S arrangement. I assume you already looked at this post here showing the different types:

https://www.douglasmotorcycles.net/index.php?topic=2461.msg8898#msg8898

I suppose it is a matter of working with what you got. I would not have thought it would have been too difficult to recharge the ring magnet as per the following illustration. It might not be a perfect setup, but ought to increase the magnetism from dismal to mediocre!

-Doug

cycarmark · « **Reply #23 on:** 07 Feb 2023 at 21:18 »

Yes Doug, I have seen that post and it was very helpful at the time. Mine is the form A with the ring magnet, and I think after the attempt at re-magnetizing it is indeed mediocre!