First like any of these engines we take out the spark plugs, and with a finger in plug hole number one
we slowly turn the hand crank until air is felt pushing out around the finger. Then from a hole in the
top of the clutch housing the Fire mark can be seen prior to reaching TDC.
When this is straight up spark should fire for number 1 at running speed.
The crankshaft showing the front pulley set screw hole is factory drilled in line with the rod journals
Watching this set screw you can find TDC without opening any other compartments, or in case you can't find
the markings
The outside surface of the flywheel is stamped for Fire and TDC but only the F is labeled on the back face
Pistons 1 and 4 are at TDC with the mark, 2 and 3 are BDC. The pulley set screw is pointing straight down.
The F in the right place happens on the exhaust stroke too so you still need to verify being on
compression stroke.
The cap is cast with the order the wires receive spark.
Since the WC firing order is 1-2-4-3 the wires attach as labeled on the picture here
The bottom side of the cap
The points just beginning to open
These pointers line up when wire 1 gets spark
Wire 1 gets spark with rotor in this position
One half turn and Wire 2 gets spark with rotor in this position
Another half turn and Wire 3 gets spark with rotor in this position
another half turn and Wire 4 gets spark with rotor in this position
Then the cycle starts over again
The impulse coupler looks the same in all positions since a slot looks the same every half turn,
so looking from the outside only, there are 4 positions the mag can be in and only one of them is correct.
The impulse coupler needs to snap at TDC, any earlier and hand cranking can be dangerous.
There is a piston ready to fire every half turn so watching the crankshaft pulley set screw, the
impulse snap should happen when it points straight up and straight down on every revolution.
At running speed the coupler no longer delays the spark advancing spark by 30 degrees.
With these things lined up the mag is mounted and timing should be close enough to run.
Then with a timing light the fine adjustment can be made on the coupler.
It is still very rough to look at but a couple things are getting there.
