Britbike forum Forums British Motorcycle specific Brands Royal enfield forum Lucas MO1 Magneto Points Carrier

Hi all,

I am currently in the process of a complete restoration / rebuild of a Lucas MO1L Magdyno.

The unit I am working on is from my 1955 Royal Enfield 350 G2 Bullet, although the specific parts I am interested in are the same for many British motorcycle brands from the 1950's.

I have a problem with the fixed points carrier, as shown in the attached photographs. The threads that the fixed points contact stud screw into are stripped, so I am faced with the task of either making a repair with a helicoil (if I can find the necessary gear), or some other way.

Am I correct in thinking that the thread is 5BA? I have measured the diameter with a micrometer and put a thread gauge on it and it seems to be correct for 5BA but I would like someone who knows more about these magnetos to confirm this if possible please.

My preference would be a new carrier but so far I am struggling to find one. There are some on eBay from India, although I would prefer not to go down that route due to import duties and doubts about the quality.

Does anyone know where I could get a new carrier in the UK?

Thanks,

Kev Ev

Just a quick update.

I have made some further investigation with my parts and the thread on the fixed contact point stud is actually 4BA.

I have confirmed this with a brand new 4BA nut.

Kev,
I'd have to believe that finding a serviceable carrier would be the simplest path forward , especially given your UK location. I agree that the bronze replicas made in India are somewhat lacking, and often fit on the armature stub is quite loose.
If you're not able to find another carrier, in your shoes I would investigate replacing the threaded points "screw" with one having a larger diameter thread ... similar "screws" were used on various mags over the years.
I would start with the points "screw" used on the early K2F or BTH mags (both of these had a bronze points assembly) and that screw has with a larger diameter thread.
Good luck,
.. Gregg

Cheers Greg,

I am finding it very difficult to get hold of a new carrier but I think I have a fix now. I have managed to find a 4BA Helicoil kit.

All the best,

Kev Ev

Well done, Kev. I wouldn't have thought the carrier would be that difficult to source in the UK, but it sounds like you are now back in track.
.. Gregg

Hi all,

Update on the repair to my points carrier thread.

I had sent an email to Dave Lindsley Vintage Magneto & Dynamo Repairs to ask if he had any points carriers in stock.

He replied to me to tell me that decent quality carriers are not available but that the best option was a helicoil repair. He also told me that the thread for the fixed points contact stud is actually 3.5mm not 4BA.

I was really surprised to hear that it was 3.5mm. I didn't think that Lucas would have used metric thread way back then.

Anyway, I had a 3.5mm HSS tap set to hand so I grabbed a piece of aluminium bar and drilled and tapped a 3.5mm hole in it. The fixed points contact stud screwed in perfectly.

So I didn't need the 4BA helicoil and instead made the repair using a 3.5mm helicoil and now it's all done as you can see in the attached image.

Looks like its hanging in there - the details are well hidden !
3.5 mm sounds like a size you wouldn't come across by accident.
Although i came across a 7mm bolt the other day (but thats another story)

Can you report on how long the Brightspark condensor has been in service. ?
Straightforward install ?

Does anyone have any views on how is it that points carrier replacements are being made,
but that they are not satisfactory.
For something that is just a lump of metal, surely they can take the time to get them right ??
They are reasonably pricey ?

Hi Rohan,

Yes mate 3.5mm is an odd size and certainly one that I didn't expect to encounter on a magneto from this era? I have found, over more recent years, that it is general practice with most vehicle manufacturers nowadays to make fastenings with odd sized threads and even invent their own methods of driving nuts and bolts. I've always figured it's their way of preventing DIY and forcing customers to take it to the garage. Having peered into a few modern car engine bays I'm still trying to work out how on earth you can DIY these days?

Anyway I digress, so back to the thread: -

I can't comment on the performance of the EasyCap because I doubt the bike will be up and running for a while yet. The Magdyno rebuild is something I am undertaking while I still have access to the very well equipped machine shop where I work. I will be retiring soon and, although I have a very nice Myford Super 7 at home, some things are much easier with the machine tools available to me in my place of work. The one thing that appealed to me about it is the fact that, should the capacitor (condensor) fail, it is a very easy job to replace it. All you have to do is take off the moving contact assembly and swap it out. A ten minute job, as opposed to a complete magneto strip to change the original. Once I do retire I will then be able to concentrate on getting the bike fully restored and running again.

As far as the points carriers go, the only ones I have seen for sale have been from Indian sellers and what puts me off is the cost of shipping and import duties. I have no reason to think that just because they are Indian they will be poor quality but I would assume that people like Dave Lindsey, who made the comment to me about the pattern carrier quality, will know more about the subject than I do?

Cheers,

Kev Ev