Ignition/starting problem
The starting problem exists whether the start button is connected up or not. No wiring is changed to use the start button - it's just an accessory like you'd use for cranking the engine when you're under the hood that hooks to 12v and the starter solenoid wire.
Using a start button DOES change how the system works see below
When using the ignition switch, the coil is powered by the brown wire coming off the switch which bypasses the ballast resistor. .
This guy is starting to sound like ME
OP: You need to get a voltmeter and see what you have right at the coil + during cranking WHEN USING THE KEY in a normal factory manner. This engages the "brown wire" IGN2 bypass circuit. It's a simple one..........goes from the IGN2 terminal on the swtich, through the bulkhead and to the coil + side of the resistor.
The other thing you must understand that during cranking, using the key, the normal "ignition run" IGN1 is disabled. The IGN2 terminal is the only ignition source
It's VERY possible you have more than one problem...........
Points deteriorating or a bad condenser or coil, meaning a weaker spark.
Something broken in the brown wire circuit.
Or maybe it's not electrial..........at all
Check the spark with a grounded probe right at the coil tower. Do this AFTER checking out and repairing -if necessary- the IGN2 circuit.
