1966 650 Mercury 4D magneto problem

[10jgoodman]

Replaced coil, and condenser, I get a shock when I spin the mag, but I have no spark. Thoughts?

 

[racerone]

Re: 1966 650 Mercury 4D magneto problem

Do you get spark from the coil itself ?---------Or no spark from plug wires ?---Tested / inspected the rotor ?

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

When I hold the copper lead off of the coil I get a shock, no spark at the spark plugs

 

[racerone]

Re: 1966 650 Mercury 4D magneto problem

The question was --" do you get spark from the coil " ----Not whether you get a shock.-------------Not sure why folks do not answer questions.

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

The question was --" do you get spark from the coil " ----Not whether you get a shock.-------------Not sure why folks do not answer questions.

I have the magneto in my hand,what is the best way racerone to check, to see if I get spark from the coil. What method do you suggest to test this? When I install on the motor and test I have no spark at the plugs. When uninstall the magneto from the engine, and I spin the shaft I get a welcoming jolt. Do you get spark from the coil itself ?--How do you test this-------Or no spark from plug wires ?--No spark from plug wires-Tested / inspected the rotor Rotor seems fine, not sure how to test?

 

[emckelvy]

Re: 1966 650 Mercury 4D magneto problem

Hold a screwdriver against the metal of the magneto case, with the tip of the screwdriver about 3/8" from the copper strap that connects to the coil.

Spin the magneto shaft smartly and you should get a very strong spark across the gap between screwdriver and copper strap. It should be purple-ish in color. The spark on a good "hot" mag will usually jump 1/2" or more.

If yours won't do that, it doesn't matter if it shocks you, it doesn't have enough spark energy.

Common problems with these are cracks/arc marks in the ign coil, dirty points, incorrect points gap, bad insulator where the grounding wire goes thru the magneto case.

The points must be cleaned to bare metal, then you polish with crocus cloth for a smooth surface. Gap to .008-.010".

For a thorough inspection of the ign coil you'd need to remove it; the allen-head screws sticking thru the mag case are what hold the coil in place. If there are any cracks, or signs of arcing between the coil and the inside of the mag case, the coil is shot.

HTH.......ed

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

Thanks I will test

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

I tested the mag and the spark that I have is only a small spark about 1/8", I only spun the mag with my fingers. So I'm thinking if I used my electric drill it would be more. I will clean my points tonight and re gap again. I coil I'm using is brand new, at least that is what I'm told. I also took the entire mag apart and cleaned it with a dremel drill(wire brush), emery cloth.

 

[racerone]

Re: 1966 650 Mercury 4D magneto problem

Spinning the mag by hand should get you a small electrical storm.----Try a drill and see what happens.--Spin it in the right direction.

 

[Chinewalker]

Re: 1966 650 Mercury 4D magneto problem

Spinning it over by hand should be plenty fast. It doesn't spin over that quickly when you're roping the motor over, either, and it should still spark nice and hot. 1/8" arc is simply weak spark. Cleaning the points should help.

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

So I disconnected the condenser and all but the coil wire to the points, the spark was less than 1/8 of an inch. I connected the condenser and it was the same. So I took the points apart and filed out the pits on the points, utilizing some sticky sandpaper that I placed on a flat head screwdriver, to make sure the points where square. Tested again and still the same amount of spark. So then for the heck of it I put the old condenser back on and tested. Holy Smokes I have Spark, at least 1/2 inch, that is turning with just my fingers. So much for the Mercury Dealer getting me the right condenser, it appears the condenser I have is not for this mag! Thanks all I'm a rookie at this but I'm very confident that I will get this machine running now!

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

Hooked Magneto up to motor and I have spark at the plugs! The wiring is a complete mess. Can someone confirm that the terminal on the magneto needs to be switched to the battery ground. So basically, when the circuit is complete to the ground, it will then kill the engine. So the switch needs to be open, except when I need to turn off the motor, then it will be closed.

 

[emckelvy]

Re: 1966 650 Mercury 4D magneto problem

Yes, the white wire which connects to the side terminal on the magneto is grounded (via the ign switch) to kill spark with the key in the "OFF" position.

Here's a typical wiring diagram for mag-equipped 4-cyl, maybe that'll help you get your wiring cleaned-up:

http://www.maxrules.com/oldmercs/Wiring/0_1965a/4.pdf

HTH........ed

 

[10jgoodman]

Re: 1966 650 Mercury 4D magneto problem

Ed thank you! This is awesome!