Ignition Switch Problem

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jaydee75

jaydee75

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My MK3 has been trouble-free until today. I always start bike at the first key turn to the right. But today when I switched to position 2 (lights), the motor cut off and the lights are not on. There is a position just short of position 2 that the motor and lights work, but it's hard to jiggle and find the exact spot. What do you guys think is the problem and what can I do about it?
Thanks,
Jaydee
 
My MKII original Lucas had an issue like that....jiggling key needed to get lights on and enable starts. Took it apart, tried to clean it up but the bakelite insulator material cracked up upon reassembly. I bought the Emgo reproduction switch to replace it. I could swap the key tumbler to keep original key. Later I discovered the Emgo four position switch is not the same as Lucas...cannot have pilot light independent of other lights. It is circuit ed differently. No biggie...Pilot alone is not useful to me.
 
I'd rather take a beating than take that ignition switch apart, but I guess that's what I'll have to do.
The link above convinces me to do it. Thanks a lot, I may need help putting it back because the wiring is very confusing to me. What a jumble!
If anyone has a pictorial diagram for a Mk3 that would be helpful.
Thanks,
Jaydee
 
jaydee75 said:
I'd rather take a beating than take that ignition switch apart, but I guess that's what I'll have to do.
Click to expand...

It's extremely basic. Nothing to be afraid of.

jaydee75 said:
Thanks a lot, I may need help putting it back because the wiring is very confusing to me. What a jumble!
Click to expand...

There are only four wire connections and the (4) switch terminals are numbered.


jaydee75 said:
If anyone has a pictorial diagram for a Mk3 that would be helpful.
Click to expand...

Ignition Switch Problem
 
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My switches burned out regularly on my Mk2a until I fitted a relay between the switch and the headlight. Today you might be better finding a set of LED bulbs front and rear - the ones I have worked fine on a 1am ride from Dieppe to Calais on back roads. They were sourced from a classic car lighting supplier found on Google.
 
Back in 2011, when Mike Taglieri posted the fix in the link above, some of the parts may have been made of cardboard, but the newer Lucas switches are made with plastic or resin fiber, so they have improved somewhat...
 
I agree with drb and LAB, Mine packed up in the middle of a 3000 mile ride. When I got home I took it apart and found is was full of grey powdering gunge. I cleaned it and found the contacts inside were like new. A bit of electrolytic grease and its back on trouble free. I have always used relays for lighting circuits. It saves the voltage drop you get across all the wiring and gives you brighter lighting especially with halogen and the older style bulbs. I now use an LED headlamp, but still run through the relays. Still room in the headlamp shell for all that but no room for mice now. I haven't run my two horns through relays but who needs them anyway. Never had time to use them in frustration but they are good for acknowledging friends [ when they work ]

Dereck
 
I recently tore one down and discovered that some of my contacts were green. Apparently from something I had sprayed in there to lube it up while avoiding taking it apart. I was going to do the epoxy fix as per the link shared above but I decided I liked being able to get it apart.

I discovered that cleaning the ball and spring detention made a big difference in how it felt clicking between positions. I polished the contacts and slightly radiused the edge of each contact.

I used de-ox dielectric grease and my switch is very happy.

I have another one that needs cleaned. I’ve thought about posting a switch rebuild thread.
 
The epoxy fix does not prevent you from taking the switch apart. It just glues the two phenolic disks together making it less floppy inside.
 
drp said:
I had the same problem and using the repair scenarios described in the NOCNSW I rebuilt mine and it works better than it ever did. http://www.nocnsw.org.au/technical/rebuild-lucas-ignition-switchtobetterthannew
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I've fixed a lot of them, sometimes multiple times. I saw that link a few months ago and do it that way now. I expect them to never need to be redone now. Even a cracked insulator can be used. When sanding the contacts go to finer and finer paper until you get to at least 1000, 2000 better. Then use a tiny bit of dielectric grease or even Vaseline on the contacts. In any electronics, contacts need to be clean, smooth, and corrosion free to work well. Scratches give a place for corrosion to start and not be rubbed off.
 
batrider said:
The epoxy fix does not prevent you from taking the switch apart. It just glues the two phenolic disks together making it less floppy inside.
Click to expand...

Yes, I know that. But you don't unglue the phenolic disk, so I decided not to do it. You know how it goes, there has to be somebody who thinks the mod is overkill. This time its me.
 
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