Re: 1965 mercury 650 wiring problems
Your 1965 Merc should have a magneto, which is self-generating (makes sparks on its own without any need to apply +12V to it).
You should have a connection point sticking out the side of the mag body, with a wire connected to it. This is the kill wire (thru the external harness from the ign switch). To be sure there's nothing shorting out your ignition, disconnect this wire and then see if you get spark.
If not, you'll need to pull the magneto and clean/gap the points. There are (4) 1/4-20 bolts with 3/8" heads holding the magneto to the belt drive unit.
The mag drive has a "flat" tooth, so you can't get it out of line when you reassemble. You'll need to pull (2) 1/4-20 bolts and remove the metal bracket for the spark stop, carb stop, & idle stop screws. Then you'll be able to get at the mag mounting bolts.
Once the mag is down, turn it on its side & remove the (2) screws holding the distributor cap to the mag cover. As I recall there should also be a ground strap to undo on the mag, then you can pull the mag out and lay it on your workbench.
Use care pulling the rotor, so you don't break it; next comes the screws for the mag cover.
At that point the mag is open for servicing. I'd recommend removing the points & cleaning the contacts with medium-grit wet 'n dry sandpaper, then polishing with crocus cloth or very fine wet 'n dry. If the points are "hazed" over, you won' t get any spark. They must be cleaned to bare metal.
Points gap is .008"-.010".
You can check for spark after servicing the mag, by taking a screwdriver & grounding it on the metal body of the mag, holding the tip about 3/8"-1/2" away from the wide copper strap attached to the coil. Smartly spin the mag shaft and you should get a nice, fat spark jumping from the copper strap to the tip of the screwdriver. Don't get zapped, it'll make you jump!!!
Most of the time a no-spark problem in a mag is caused by dirty points. If you get no spark after servicing the points, you could have a bad coil, condenser, or an internal short.
Note that the above is just an overview for servicing the mag; recommend you buy a service manual for your motor, which will go into the job in great detail, with lots of pictures. A Merc factory service manual will give you the best info. One of the manuals put out by Seloc has enough detail in their mag servicing section to do the job, too.
Here's a good source of info online for Old Mercs:
Old Mercury Outboard Timing, Adjusting, and Testing 1966 & Earlier -- Mastertech Marine Outboard Motor Parts
I've attached a typical wiring diagram for a 4-cyl magneto-powered ignition, maybe that'll help.
HTH & let us know how it goes..........ed
