Replace distributor with magneto 99 dommie

Hi Hugh.  The mag can be one of 2 types.  and require different drive arrangements. The auto advance type has a tapered shaft to accept a combined sprocket / centrifugal advance unit. (which ideally needs to be from a Dommy and have the correct adv curve and no of sprocket teeth.) The other type of mag has a manual advance ,cable operated which works on the points cam ring..This needs a different taper fit sprocket (with the right no of teeth). Neither mags can utilize your existing internal Adv/retard mechanism.The mag also needs to be an anti-clockwise type. Thats about the total sum of my knowlege on mags!.

Do you intend to use the bike? 

If it is for 'original' or 'show', then it needs either the dissy or a mag on it If you just want to get on and ride it, consider using a Mercury model 'mushroom' with your choice of electronic ignition inside. This will cost less than/about the same price new as will having a mag reconditioned and once installed it is a fit and forget item. 

Regarding the ebay mag, you really need to know who reconditioned it. There are so many stories of badly done mags you need to know, otherwise it will possibly need redoing  and cost you loads more. 

Me? The only bikes (or cars, come to that) I have owned with points were a Honda 125 and an MZ. My 650 came with a non-working mag but as I had no knowledge  of how to fix them I fitted a 'mushroom' with a Boyer in it as I wanted a reliable 'everyday ' bike when I built it. It was cheaper to buy the whole lot new than having the mag reconditioned. Sold the non working mag and got half the cost back. No regrets whatsoever. 

I do have a 'modern' (well, 1981 is modern for my bike) reg-rec from a Kawasaki 1100 and a 3-phase alternator too. No ammeter, no charge light, It just works.

Regards, George. 

My magneto powered singles are no more difficult to start than my electronic ignition Dommie. So in my limited experience the difference is not enough to make the change worthwhile if that is the only reason.

Hi Hugh,  I also have a dodgy right leg .but have developed the technique of left leg starting.Having had Italian machines its now easy. I also had severe tennis elbow and was forced to use my left hand for everything.I am now ambidextrous.The human body has an amazing ability to adapt. I can also use all my fingers independently ,like a piano player. Toes can be trained to work like fingers.On a Norton wet sumping,thick oil and highish compression are the main culprits in difficult starting  for us oldies. I mostly bump start from cold with my handy hill.Regular use,multigrade oil and a compression plate also help.My 99 needs full choke and light flooding to first kick start from cold.

As with many changes / conversions / upgrades the Norton ignition system can be a balance of gain against loss.

The magneto gains independence from the battery which leaves more power for lights and accessories. The one fitted to my 1960 Model 99 did 85,000 with very little servicing. My current 650 has had two rebuilt magnetos and both have given hassle over 10,000 miles of riding. Points wearing, cam heel wearing, pick-ups failing and end cap disintegrating. The other big disadvantage being that to adjust the ignition timing requires disturbing the exhaust system, foot rest, gear lever and timing cover.

The distributor and electronic systems both need a battery (or power box) and reliable charging system to operate. Get this sorted out and the advantages make a long list. Especially going electronic which  offers easy starting, smoother idling, smoother acceleration, better fuel economy and very easy adjustment of the ignition timing.