I was wondering if you could help me. I have a 1973 20 hp Evinrude fastwin and I am having trouble getting a spark from it. A friend of mine has the equivalent Johnson engine. I am having trouble working out the magneto on the Evinrude out because it looks as if one coil feeds both sets of points and the other has only an output which I assume is used for a remote kill switch (it doesn't go to an ht lead but a set of wires which are then connected to another set of wires coming from a switch on the side of the engine, this is in addition to the kill switch on the front of the engine).
My friends magneto differs from this in that each coil has an output for it's respective ht lead and an output for the points, in addition to this it also has a ground which connects to the top of the pickup. I'm very confused because the coils on mine (evinrude) read 1.2 ohms and on the Johnson they read 0.9 ohms so I should be getting a spark. The thing that bothers me is that my magneto seems to run two ht leads (and two sets of points) from one coil and pickup, is this right, surely that would invoke timing issues? I assume that it must be possible that it is right because the two armature plates differ in their design, the Johnson one has a hole in each of the recesses under the coils which takes the output from the coil to the ht lead, the Evinrude only has a hole under one of the coils, the one which feeds the mystery kill switch.
I need to know about these differing types because all of the spare coils i have seen look the same as the ones on my friends Johnson and will not fit on mine because of the lack of a hole on the armature plate.
So I wondered if anyone could tell me what on earth is going on here because I'm at my wits end, my dad is a mechanic and he can't work it out either. I can send pics of both magnetos if you need them too. Any help would be gratefully received.
That is actually two, independent magnetos, UKV. They should share only the points cam and the flywheel. Each has its own points, condenser and coil.
Sounds like someone tried to work on it without either a manual or understanding of how it works.
You really need a manual, but try reconfiguring it to match your mate's Johnny.
In addition, we need to wonder why someone messed with it before. Coils from that era are notorious for not lasting more than about 30 years. Look for swelling or cracking. You may have a bad coil (or two) as well as the misconfiguration of the mags.
Thanks for the reply, this is surely a weird one. I'm pretty sure someone has been under there before as the coils have no casing (and still produce a better reading than my friends Johnny). The problem is I can't understand what is going on because one of the coils outputs is wired to a remote kill switch instead of an ht lead, but this kill switch looks as though it is meant to be there because the engine lower cover has a hole and moulding in it for this. I think I will have to buy two new coils and rewire them to match the Johnny . The other thing I don't understand is on Bombardiers site the diagram of the magneto shows one of the coils that I have, with no ht lead coming from it, and one larger coil with an ht lead coming from it, which doesn't look like it will fit on the armature plate and I can only see one ht lead, check it out:
Does UK Vintage mean you are in UK and have an European motor? I ask because US Evinrude motors in 1973 were 18 or 25hp, not 20 as the Johnsons were. So, I'm not sure what we are working on here.
Anyway, the 1973 18-25 hp Evinrudes had what is called a "low tension magneto". It had one driver coil under the flywheel connected to two sets of points. The two spark coils were mounted externally, and also connected to the points, as was the kill switch. There might be a second coil mounted on the armature plate, and if there is, it is an AC lighting coil and has nothing to do with the ignition.
Yes I have a European motor but I'm told it is the equivalent of the U.S 18 or 25 hp. What you have just described makes a little bit of sense because on the engine block is a plastic junction box type thing which I now think might be for that external coil.
I also noticed that my flywheel has two magnets on it and my friends Johnson only has one. So clearly we have two different systems here, but which is better, I prefer the idea of feeding the ht leads straight from each coil but will that work with a flywheel with two magnets instead of one? The other problem is the schematic on Bombardiers site only shows one external coil and I can't see that there's room for two to be honest (I trust what you're saying though). So when you say one of the coils on my armature plate is for AC lighting, did OMC design it like that or has someone done it their self?
I am hopefully going to be getting a manual for the engine within the next few days, it's for the 18 hp version so I'm hoping that will help, unfortunately I'm impatient and want to know everything so please carry on with the knowledge! A picture would be good if anyone knows of any.