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1973 20HP Evinrude Fastwin magneto problems

U

uk_vintage

Contributing Member
"Hello,

I was wondering if

"Hello,

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.

Cheers"
 
73 evinrude is listed as 18HP

73 evinrude is listed as 18HP and the 73 johnson is 20HP---they show in the book to have IDENTICAL systems.The coil under the flywheel is the driver coil and the external coils are the ignition coils.What is the model # of your engine and what is the OHMS readinon the driver coil.
 
"Hello,

Thanks for the repl

"Hello,

Thanks for the reply, I think my friends Johnson is a later model than mine (although I'd still say 70's) but they're still identical. My model number is 203b02 (the equivalent of the U.S 18hp 18304a so I'm told) and it is a european model manufactured in Belgium I believe and true they are identical, except the coils and the way that they are wired to the points and ht leads. I know that there was a change to the magneto at some point, they upgraded the coils and armature plate so I think I have the older style one, despite my coils reading more than the newer ones. As far as I can see there are no external coils, only the two under the flywheel fixed to the armature plate and they both read 1.2 Ohms.

Edit: Have just looked a diagram of the magneto and it does show an ignition but it only shows one driver coil, now I'm really confused because both of the armature plates in question have two coils on them and no external coils (unless they are hidden or very small). I feel I should add at this point that my engine works fine (a little rough maybe) with my friends magneto but not with mine. Follow this link, that is what my friends magneto looks like and is wired like. Mine looks like that but is wired differently.

http://www.duckworksmagazine.com/06/columns/max/index9.htm

Cheers"
 
Update: I have noticed that my

Update: I have noticed that my flywheel has two magnets on it and my friends only has one so I'm starting to think my magneto might be right. Does anyone know anything about this engine as regards to external coils because I'm starting to think that I might be missing something here. Is it worth emailing Bombardier or it that a stupid question?
 
Go to -----shop.evinrude.com -

Go to -----shop.evinrude.com ----- for the pictures/parts of your motor.
 
"I already did that, I need an

"I already did that, I need an actual picture of the engine block with the magneto attached, schematics just won't do. I have made some progress anyway in another forum. So for anyone that cares here goes:

My magneto has one low tension coil which feeds both sets of points, these in turn feed 2 external coils (that I dont have) which then feed the spark plugs. The remaining coil on the armature plate feeds an AC lighting system not a remote kill switch as I thought. So potentially problem solved, need to get some of those external coils though and they are pricey! I would rather get two new coils the same as my friends Johnson and wire it up like his, however, would this be possible because Ihave two magnets on my flywheel instead of one so would this mess the timing up?"
 
You have two magnets that swee

You have two magnets that sweep by the one driver coil and I believe you have two cylinders that need to fire-----Get it??
 
"Erm, will the points not dete

"Erm, will the points not determine the correct timing though? Surely it doesn't matter how many magnets there are as long as there is a charge there?

Cheers"
 
The two magnets are needed on

The two magnets are needed on your system since you have only ONE COIL that produces a charge.The points determine which coil fires. When you have two ignition coils under the flywheel you only need one magnet.----Try to reason through it and you will see that it is really elegantly simple.
 
"OK there's no need to pat

"OK there's no need to patronise me but point taken. Thanks for your help, now I know what's going on I can plan accordingly!"
 
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