Most electrical issues are Lucas related

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freefly103

freefly103

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The 70 Commando I put together from spare parts a couple of years ago started to develop an intermittent backfire that became progressively worse such that the bike became unrideable.


The bike is fitted with a Motogadget M.Unit Blue, Trispark EI and a single Mikuni VM34 carb.


The bike would start and run ok, and during a ride, backfire occasionally. The intermittent backfiring made me think that a wire was loose or that a hot wire was grounding somewhere.


Over the last 4 months, I started off by checking wiring connections, I sent the Trispark back to Oz for testing (all good), swapped out plugs, coils, re-wired parts of the wiring harness, etc etc.


Thinking that electrical issues are “carb related”, I stripped the carb and had it cleaned. The backfiring persisted.


As I contemplated starting the checks again last week, I sat down beside the side cover under which the M.Unit Blue is fitted. The cool thing about this fuse box is that there are lights showing which circuits are active which the ignition is switched on. I turned the key and saw the ignition circuit light glow, indicating that the ignition was active.


The M.Unit Blue isolates each of the 10 circuits on the bike, I had the thought that the problem might be on the input side i.e. the switch and/or power input connections.


I checked the connection from the battery to the M.Unit Blue. All good. Hmmm… what now?


For a laugh (I was far from laughing at this stage), I wiggled the wire connecting the ignition switch to the M.Unit Blue. The ignition light flickered on and off!


Since the ignition switch was new a couple of years ago, I hadn’t expected the switch to be the issue.


I replaced the switch with a temporary waterproof push button type that I found here at a Marine electrical shop on the island.


Problem solved.


Without the M.Unit Blue circuit indicator lights, I’m not sure I would have found the issue, especially since the switch worked when I started the bike.


The 4 months of checking a re-wiring is a good investment. Now I’m confident that the bike’s electrical system has been thoroughly checked and sorted.


Still, this saga was a very frustrating experience. New(ish) components shouldn’t fail this soon especially at 30 quid a throw.


Thanks Mr Lucas.
 
Wassell copy made in Asia, Lucas did make some rubbish as it was made to a price but that has been surpassed by the current crop of copyists. If you can get NOS then Lucas stands up to the Bosch of the same era and better than anything from Italy.
 
Lucas and Amal and the likes were always under pressure from the motor industry to supply their parts as cheap as possible.
Most of the Lucas stuff on my british bikes still works today. (Don't get me started on Italian electricks).
 
With over 43 years of owning old British twins I have never had a Lucas component fail and I have also owned a few old British cars in my time without any problem with Lucas components, but now running a JH maggie I now run very limit wiring and only lights, tail light, brake light and only a toggle switch for the maggie on/off switch.
But surprising how many new electrical components do fail, there is some rubbish around these days, so many things made in third world countries as well China, but people still buy them because they are cheap.
Opps just remembered I had a Lucas Rita EI fail after a year way back in the late 70s, replaced it with a Boya EI.

Ashley
 
I have had a genuine Lucas ignition switch fail before, but it was at least 40yrs old
Also I've had a Lucas coil fail but again it was approximately 40 years old
Also I have had 2 zenor diodes fail and one of those was only 3 yrs old
I have also had the usual switch gear problems but again not in the first few years and my bikes all stay outside and are used all year round so it's to be expected
 
"I wiggled the wire connecting the ignition switch to the M.Unit Blue. The ignition light flickered on and off!"

Could that have been a bad connection rather than a bad switch? I have no idea re the reliability of modern replacement switches; the original one is still in my '73 with no issues and all the original Lucas bar switches are working fine except for the kill button, which I disconnected in '06 while also disassembling/cleaning/lubricating the switches. They haven't been apart since then so despite my admiration for all the Lucas jokes, I have never had any real issues with either this Norton or my original '71 back in the day to confirm their accuracy.

I had read the adverts for the M unit blue some time ago but it struck me as a solution for which there was no problem - just adding another component between wiring connections! :) But it sounds like you are quite happy with it.
 
I replaced the connection between the M.Unit and the switch. It was the switch.

The M.Unit has a built in alarm, relays are also built in. It has lots of other features that, while probably not completely necessary for a Norton, make it easy to wire the bike. I'm happy with it.
 
I replaced Lucas points with Japanese Daichi points because the Lucas points had done about 20,000 miles, which was the most I ever managed to get from US made auto points in the 70s.
The Daichi points failed in 300 miles so the old Lucas points went back in and worked fine for at least another 10k.
Finally I managed to locate some NOS Lucas points and installed those, although it wasn't necessary.
I kept the old Lucas points as they are still working fine. I've now put away 4 sets of NOS Lucas points for that bike, so that'll more than see me out.
The Lucas points are the highest quality ignition points I've ever encountered and we used to install lots of different ignition points, made in the US , Germany and Japan.

I have also had a couple of Lucas copy ignition switches fail.
 
I'm just in the process of re configuring the switch positions on my Lucas 169SA switches, and I have to say for things that are 45 years old they are in great condition, and look as though they will easily go on for another 45. The internal design is a very clever modular concept.

I'm not sure which ignition switch I have, but will carry out the mods other folks have done over the winter in order to keep it reliable.

http://www.nocnsw.org.au/technical/rebuild-lucas-ignition-switchtobetterthannew

The only thing I don't like about Lucas wiring is trying to separate the bullets. They are a pain.

Cheers,

cliffa.
 
cliffa said:
The only thing I don't like about Lucas wiring is trying to separate the bullets. They are a pain.

Cheers,

cliffa.
Click to expand...

Try putting anti-oxidation grease on the bullets (also spade type connectors). The stuff is available in most electrical supply outlets (for electrical contractors). Keeps oxidation at bay, and makes separation much easier.

Slick
 
Replace ALL the female bullet connectors. Don’t wait.
Most electrical issues are Lucas related
Most electrical issues are Lucas related
 
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When I installed the new (OEM-type) harness a few years back I used di-electric grease on all the connections, and, as pointed out, it does make subsequent disconnecting much easier and prevents corrosion. When I first worked on the bike after purchase in '06, many of the bullet connectors would not come apart at all. Trying to pull them apart broke the wires and left the bullets inside the connector! Of course, they were probably original and untouched since 1973 so it's hard to be TOO upset about that. ;)

Sometimes I think we can be a bit harsh when we criticize components that are no longer working properly but are 40 years old... :)
 
True.
A friend who loves all Japanese and German bikes recently went through my shop with his BMW rider friend.
Most of the bikes are remarkably oil tight but the 650ss with a sump full is an exception.
On viewing the puddle under it they both had a laugh then made derogatory comments about British bikes leaking oil.
( Some friends!)
Never mind the other 10 bikes with dry concrete under!
I pointed out that the SS is 51 years old and asked if they had ever looked under at the floor under a collection of 50-70 year old ( in use) Japanese or German bikes?
I know of one running early Honda Goldwing that has done a lot of miles, but it has also been apart for a couple of rebuilds . It now leaks oil profusely, much moreso than my old SS
Same with bullet connectors, Japanese bikes used them by the bucketload and at forty or fifty years of age, guess what, they are also often corroded and in need of replacement.

Glen
 
With Japanese bikes, you throw them away and get a new one, before you have trouble with the electrics. My friend has an immaculate Yamaha RZ350. He is currently trying to install a timer to get the turn indicators to turn off after use - so he won't have to remember to turn them off. There are two parts to the indicators' circuit, half is in the speedo which counts how far you have ridden. The other half is timed through a bimetal strip. Which ever way he goes the clicker shuts off his timer. Lucas was never so complex - all you ever did was replace the whole lot with something sensible. I used two three-way switches under the seat of my bike, to control the power regulation from the alternator and everything else.
 
Magnet Marelli is better than Prince of Darkness ? - The Japanese and German mentality is 'do it right first time', - NOT 'if it ain't broke don't fix it'. When Lucas was supplying to the British car and motorcycle industries, they could all supply any kind of shit and still make a profit - they had a captive audience . These days we have free trade - no tariff protection, so if quality is poor, manufacturers cannot compete. Reputation and repeat business are about product and service quality. Even the Chinese are about to find that out. The problem the British have is that a Royal Enfield from India is probably better than any which ever came from England. I used to work in a large engineering factory which had every part of the old British manufacturing system. - 'When they were good, they were very very good and when they were bad they were horrid'.
 
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