Which magneto?

Hi Christian, There are several previous posts regarding magnetos. The general opinion seems to be try "Brightspark", for the best, and cheapest, solution. They will overhaul your mag, or supply a D.I.Y. kit. I have a '54 88, which has been fitted with "Thorspark" electronic ignition. This uses the original magneto, with the points replaced by a trigger unit. The coils fit in the tool tray, and the old H.T. leads taped up under the seat. At a casual glance, it appears to be the original system. A magneto with manual advance would probably cause a lot of hassle, you would have to lock up the existing auto advance unit. I have been more than happy with the "Thorspark" conversion, but, had I been living in the U.K. would probably gone to "Brightspark" Returning the mag., from Spain, would been too costly, and time consuming. The "Thorspark" kit was delivered within a week, and fitted in less than a day. Hope this helps, John.

Christian, it seems as if your magneto armature needs to be re-wound. I had the same trouble with the K2FC mag on my Manxman, the bike would start and run well when cold, but would not start when hot. I had the armature re-wound by Independent Ignition Supplies in Devon, and everything worked again. I sent the armature by post from the U.S.A.

There is not much difference between auto advance and manual advance from a practical point of view, as long as either is set up properly. Stick with what you have and get it working. If you have the mag serviced now, it should be done by the time it is warm enough to ride in comfort.

Hi again Christian, the auto advance is a separate device from the magneto (inside the timing cover). You could possibly remove it, and fit a fixed sprocket (or even get it tack welded) but why bother? The trouble with your magneto is most probably the condenser breaking down when hot. Check out "Brightspark", on the internet, before spending money on another mag., which may develop the same fault. A lot depends on how quickly you want to get the bike running. I went for "Thorspark", mainly, because I wanted to use the bike within days, not weeks. John.

I would stick to the auto-advance on your 88 even though I would recommend manual advance on a BSA A7 for better low-down pull...an off-topic conversation if ever there was one! A decently overhauled magneto (the capacitor is so often the problem) will give you years and years of reliable service and of course you are not reliant on your charging system to keep the engine running, a fact I greatly appreciated when my 99 stopped charging passing Shrewsbury on my way to Norwich some time ago. Try Dave Fisher in Dorset, 01929 421255. Highly thought of in vintage motorcycle circles. Gordon.

Hi Christain,

I assume you are in the UK? I am in the USA & work on Lucas magnetos. I was so impressed with the guys at Brightspark I now sell their replacement capacitors at my shop. In addition to the capacitor being a much better quality than the original capacitor, it is relocated. Instead of being inside the end of the armature, it is now re-located to just under the points (contact breaker) !! How great is that. I would stronglyrecommendthat you give a look the their site & if you want to give it a go yourself, the website is great with step by step instructions & pictures, if youdon'twant to attempt it, Brightspark will do the whole project for you. I know they did several for Anthony Curzon & others on this site & I think they have sold well over 1,000 units without a single in use failure. I have no financial gain here, as I am sure you would be dealing with a UK supplier, not me in the USA.

They are listed on this very site in the services section under electrical (type in brightspark) or go right to their website here:

http://www.brightsparkmagnetos.com

I normally like electronic conversions on coil ignition bikes, but for bikes with a magneto I much prefer a properly rebuilt mag over the electronic conversions. A properly set up mag will give years of trouble free service if maintained correctly & when age sets in it will start to fail slowly, & will usually get you home. When theelectronicmodels decide to fail, it fails 100 % , no spark at all & you get to start pushing it home. Just my opinion & experience.

As to your bike cutting out when warm, by bet is the capacitor. There are a couple of simple test to know if the armature is bad once it is apart that can be done with a simple volt meter with an Ohms range. The other armature test is the "squish" test, it the coils are squishy, time for a rewindregardlessof how the meter reads. Of couse I am trying to diagnose over the internet & that is not the best way. If you do need a rewound armature, I don't thinkIndependentdoes them anymore, I use them for Mag parts, but I thought I read that he sold his armature rewinding machines.

All the best to you, please dont hesitate to PM me on this site if you wish, advice is still free (& worth every penny!).

Skip Brolund

Hi Christian, If your bike is a slimline its also posible that your bike was orriginaly fitted with a distributor, so thats another way to go. In the day coil ignition was not thought to be "proper" and lots of bikes got fitted with a mag from the breakers.My Atlas was built with a twin points unit and coils,converted to a Mag,then swapped back to a points unit and Boyer(by me) .In hindsight i wish i had stuck with the mag!. The electronic options give better starting (very helpfull on a HC 750) but are disadvantaged by the need for a charged battery and often a different advance which spoils the midrange pull.A manual Mag has the advance gear at the points end, An auto advance mag has the advance inside the timing cover. Both are good in there own way.