Stop Botton Normally Closed?

Hi Guys, I picked up a Merc Mod 200 (20hp) in like new condition with very few hours on it. I got it for a song because it had no spark, but it turned over nicely and was tested for compression with the leak down method, and proved out at like 4% loss from new. When I removed the cowling, I was amazed at how clean the motor was under the hood. I was also amazed at the condition of the wiring, as the insulation literally crumbled to the touch. I also own a 1967 Merc 110 (9.8) and just replaced all the wiring on it, but its wiring was in much better condition than the wiring on this 72 model 200, in spite of being 5 years older.

The reason for this post is twofold:

To recommend that anyone owning a Merc of this vintage to change all their wiring, and to ask if the stop switch, which is located on the lower right front side of the motor is supposed to be normally closed, and opened (killing the motor) by pushing in. This is opposite to my 67 9.8 in that it is normally open, but it may be due to the type of ignition. I cannot tell from the Seloc Diagram, and find their manuals to be about as good as haynes, which really suck, IMHO. I could use the OEM WIring diagram for the "72" Model 200 Manual Start if anyone would be kind enough to send it to me at [email protected]

The ignition on this 1972 Model 200, 20hp is a Phasemaker Thunderbolt, Capacitor discharge ignition system. I am taking a lot of pictures on this rewire project and might post a story if anyone is interested.

I believe the stop button on the " phase maker " units is in fact closed for running and open to stop.

That is possible on a '72. What I remember is NOT to press the button when running on land on the muffs. Use the choke to stop it. Bad design that needs the exhaust pressure to stop the flywheel right away or it spikes the ign. unit from spinning with button pressed down for too long.