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Seal selection

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IanH18/10/2021 17:12:18
106 forum posts
61 photos

Hi Noel,

I converted my own 1933 coil ignition Morgan to electronic ignition something like 20 years ago. The set up I used was from Luminition and was based on a kit provided for Moto Guzzi motorcycles. The through beam infra red units fit neatly to the contact breaker housing, I made one IR unit fixed and arranged for a bit of adjustment on the other to fine tune the timing on No 2.

The magneto contact breaker housing is smaller and I suspect you would struggle to get the hard wired Luminition through beam units in. If there was a PC board mounted equivalent through beam unit it would be a nice solution. Do you know of a suitable component?


IanH19/10/2021 09:08:26
106 forum posts
61 photos

4e33493d-6163-4959-8e44-dddb45aa370e.jpegHere is the contact breaker housing with the Luminition through beam units installed. The 4 core cable heads off to the control unit under the bonnet and the coils.

Nigel McBurney 119/10/2021 12:20:59
944 forum posts
3 photos

When I rode in trials on uk two strokes 60 years ago,the sealed wheel bearings did not last very long,some of current riders in pre 65 trials have added an extra neopriene seal out board of the bearing with some success, and if memory serves me correctly I believe that my 69 Bultaco had seals between hub and a bush on the spindle to help keep the water out,a mag does not get that much mud but will get a lot of rainwater and 3000rpm is an awful lot faster than a motor cycle wheel. If the ht leads are "live" then there should be a rubber cap which is a tight fit on the lead and the pick up to keep out of the mag,I found some of these rubber caps on a web site selling BTH mag spares,I required one to keep any rain water from the mag of a restored stationary engine. In those days it was difficult to keep water out of Villiers engine electrics and carbs with cut up inner tubes and plastacine,lot easier nowadays with modern sealants.

noel shelley19/10/2021 18:41:21
847 forum posts
19 photos

Hi Ian,That's a neat adaption. The chopper arm seems very wide ? I was not involved in the electronic side of things but I would think it would be possible to use an infra red source and receiver to make a sensing head to suit almost any applications. Many units only used a single sensing head and a chopper arm of the required number of arms for the cylinders, ie 4,6,8. One of this systems benefits was the very precise relationship of the arms and therefore the accuracy of timing between cylinders, I seem to recall that .25 of 1 degree was claimed. The accuracy of the contact breaker cam was never very good and wear in the distributer bushes would result in timing scattered all over the show. A good coil and a damp night would result in a spectacular light show under the bonnet, and a warning that if you had any heart condition to keep well clear of a running engine ! There are some on here who may be able to help in the design of the electronics of a sensing head. Noel

IanH19/10/2021 19:15:22
106 forum posts
61 photos

Hi Noel,

i remember at the time a discussion with the folk at Luminition about the size of the chopper. I recall that the leading edge puts power on the coil and it is the training adage that triggers the spark. The width of the chopper then determines the dwell angle and the duration that the coil is powered up. Too long a dwell angle could lead to the coil overheating. The Morgan engine is pretty slow revving by comparison with modern stuff so a small dwell angle would be fine. We decided to start with the chopper shown in the photo and then reduce it if we hit problems. It never got changed!

the electronic magneto has a 180 degree dwell angle, even more extreme. The reason for trying 180 degrees was that if it worked, we could reverse the direction of rotation of the magneto with the same 180 degree ring magnet. Reducing the dwell (bringing the N and S poles of the ring magnet close together) would mean that the ring magnet would have to be turned upside down if the mag was to run backwards. I ran the mag on the lathe at low revs for half a day in the warm workshop to see if it did overheat - it seemed fine so we are road testing with the 180 degree dwell.


larry phelan 120/10/2021 09:08:49
1113 forum posts
14 photos

"Progress", my friend, "Progress"

Or is it ???

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