S&S Cycle IST Ignition System for 1984–99 4 1/8 Bore Big Twin Engines - Manual (Page 6)

2. Installation of the Knock Sensor Kit
• Knock Sensor must be mounted to the rear cylinder for correct operation.
• Mounting the Knock Sensor on the front cylinder will provide an incorrect signal.
NOTE: There are two mounting locations possible for the knock sensor. Read the description of each location, and then examine your motorcycle for which
one to use. The first location has better clearance than the second location, the knock sensor will work well in either one.
Location 1: Rear cylinder head, across from the temperature sensor on the front head. Some S&S® heads have an unused threaded hole in the
rear head near the intake port. If the extra threaded hole is present, install the Knock Sensor there. See Step a below. If the threaded hole is not
present, use Location 2.
Location 2: Top motor mount at the rear cylinder head attachment point. All stock heads and some early S&S heads do not have the unused,
threaded hole across from the temperature sensor, and must use the top motor mount location. See Step b below.
a. Knock sensor mounting at Location 1:
Rear cylinder head
1. Remove the plug from the rear head.
2. Insert the 5⁄16" x 11/2" coarse thread bolt (l) through the Knock Sensor and 1/4" thick spacer (h).
3. Attach this assembly to the rear head and torque to 11 ft. lb. See Picture 8, below left.
b. Knock sensor mounting at Location 2:
Top motor mount location.
1. Remove rear motor mount bolt from rear cylinder head.
2. Test fit Knock Sensor Mounting block to rear motor mount location using 3⁄8" x 2" coarse thread bolt (k) and 3⁄8" lockwasher (n). Test fit
Knock Sensor to mounting block (i) using bolt (j) and lockwasher (m). See Picture 9, below right.
Carefully place fuel tank back into position to check Knock Sensor and mounting block clearance. Position the mounting block so that
the Knock Sensor or mounting block does not contact the fuel petcock or any other part of the motorcycle. If the wiring harness or outer
body of the Knock Sensor (black plastic portion) contacts the engine or any other part of the motorcycle, it could damage the Knock
Sensor, or interfere with its ability to detect knock. Special care for rubber mounted motors must be given to accommodate engine
movement in the chassis. View Knock Sensor while motor runs to make sure it has proper clearence.
3. After determining final position for Knock Sensor, remove mounting bolts and lockwashers, then re-install them on mounting block
bolt (k), torque to 33 ft- lbs., and Loctite® 243 on knock sensor bolt (j), torque to 11 ft-lbs.
6
CAUTION
Picture 8 Picture 9
CAUTION