S&S Cycle IST Ignition System for 1984–99 4 1/8 Bore Big Twin Engines - Manual (Page 5)

2. Existing Coil, VOES, and Cam Position Sensor
a. If so equipped, remove the existing dual fire ignition coil. This is usually located on the left side near the upper motor mount, above the
engine front rocker box, or to the left of the engine near the seat. Remove or insulate the “+” and module terminals in the existing harness
with heat shrink.
b. If so equipped, remove the existing vacuum operated electrical switch (VOES). This is located between the heads. Remove or insulate the
terminals and connector in the existing harness with heat shrink.
c. Normally, S&S® 41⁄8" bore engines equipped with the IST ignition system do not use Cam Position Sensors. If so equipped, remove the
two screws, gasket, and the plate covering the Sensor cavity. See Picture 5, above left. Remove the two ignition timing screws and the
sensor. See Picture 6, above right. Remove the screw and cup from the end of the camshaft. Reinstall the plate and two screws over the
sensor cavity. Remove or insulate the terminals and connector in the existing harness with heat shrink.
D. S&S System Installation
NOTE: On some models, it may be easier to access the cylinder head temperature sensor mounting point by removing the horn first.
1. Installation of the 41/8" Bore Engine Cylinder Head Temperature Sensor.
The Cylinder Head Temperature Sensor mounts in a boss found on the front head of all S&S 41⁄8" bore engine equipped motorcycles.
a. Install the Head Temperature Sensor.
b. Tighten the sensor to 10-12 ft-lbs using a deep well socket and a torque wrench. See Picture 7, below.
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Picture 5 Picture 6
Picture 7