6v Electronic Ignition.

SNAP! I have a 1959 99 - all original which I bought from Pride & Clarke in 1965.  Not as complete as yours as it's still in 6 million pieces - although I talk about it a lot and am always buying bits!  I will definitely have quite a lot of bits left over, even some new parts, but won't know until I finish

I intend to stick with a 6_volt system - I bought a new battery and a lovely NOS pair of 6V Fiamm wind-tone horns to mount on my Britax crash bars.  I will replace the old selenium rectifier with a much cheaper and more reliable solid state one.  Change the coil because they are relatively cheap.  Change the bulbs for LEDs - although, probably like you I will mostly be a fair-weather daytime, occasional rider.  (I'm 75 and haven't ridden since about 1970!).  My eyesight's still good and 6 volt lights were fine in my day!  I might just change the headlamp bulb for a QH type and LEDs for the other bulbs. 

I will still use a new PRS8 switch, but am mindful of the charging rate change when using all LEDs.  You can buy electronic points substitutes for about £45, but reviews are variable - as they are on just about everything.  (With almost anything you look at, reviews seem to vary from "Best thing since sliced bread" to "A total pile of poo"!)  Changing the troublesome distributor condenser for a more meaty external one sounds like a good idea too.  Obviously you need good spark plugs and leads.

These are all relatively cheap and easy mods to try as you put it all back together and if they work, you will have saved yourself some grief and money.  It's the "suck-it-and-see" principle.

When people ask me "Why didn't you go for a 12V system?"  my answer is "Because"!

12V has the following advantages-more choice of battery, more choice of bulbs/LED/headlights.     Electronic ignition is easier with 12V more choice, you can run decent wasted spark so that the two sparks are timed precisely as opposed to relying on wear or not in the 18D2 advance/retard. You get rid of the Distributor function in the 18D2.

6V wiring and connections need to be cared for more to reduce losses. If you retain points then 18D2 points can be scarce, condensers can be scarce.

Reliability is down to the builder bearing in mind- You are installing a 50 year old dizzy in the 18D2 The original alternator can go 12V without an issue. 6V with the original PRS8 switching of the alternator means a lot of relying on electrical connections and switching and understanding. There is no maintenance of Electronic ignition-fit and forget. One timing point. Kick starting is NOT an issue with 12V or 6V it is getting electrics right, carburation right, and starting procedure right.

I used to recommend 12V over 6V as the lighting was much better, but LED's are just as good 6V vs 12V as the native voltage internally is 5V. My last main LED headlamp bulb states it works with 6v to 24V with the same output. So that's a dead argument leaving you with the lack of proper voltage regulation which has again been overcome by the current 6V scooters now using 6v Zener's.

There is a 6V positive or negative earth regulator/rectifier part way down this page which is better again.

http://www.norbsa02.freeuk.com/goffyelectrex.htm

If you go EI a voltage regulator is a must. Do not rely on the Lucas switching in and out alternator coils.

Since re-building my 99 some 25+ years ago  the distributor ,PSR8 and horn have needed  no attention. other than normal servicing  of points. and cleaning connections,  

Pazon produce the 'Altair 18D2-6' 6v electronic ignition system for use with the 18D2 distributor. They say it's for Triumph Twins but can be used on Nortons, BDSAs etc. It might be worth contacting them to check - cost is circa £235.00. Boyer supply a 6v system but for dynamo only (it's quite an old system in any case).

If you do decide to stay with the 6v system I've got a Pazon 6v electronic ignition kit that I don't intend using. PM me if it's of any interest to you.

Boyer do a points triggered electronic unit. It lets you keep to 6 Volt and you take out the condensor. The current load on the points is reduced as they only act as a switch. It also keeps the standard advance mechanism. 

Paul

My 99 has the Boyer 12v + earth  points triggered system.  Cheap and cheerfull, works well but in hindsight I would have liked to get rid of points  if  only to reduce the possibility of different timing points on each cylinder that you can get with cam runout.

My  88  with all std 6 v electrics  went all over Europe  and England for years  with negligable maintenance , No reason that a lightly used and well maintained bike would not be practical . A modern rectifier and a full sized battery would be my consesions  to  progress. Thanks to years of experience we now know  where all the weakness points  are  and can give the attention  to where its needed.

Yes indeed we are on holiday...........