S&S Cycle Ignition System For All 1999–03 Carbureted Harley-Davidson Twin Cam 88 Engines - Manual (Page 5)

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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 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. Stock Harley-Davidson® Twin Cam 88® heads and some S&S heads do not have the unused threaded hole. 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 Twin Cam 88® 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 lock washer (m), knock sensor (g), and 1/4" thick spacer (h).
3. Attach this assembly to the rear head and torque to 11 ft-lb. See Picture 6, 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" lock washer (n). Test fit
knock sensor to mounting block (i) using bolt (j) and lock washer (m) See Picture 7, below right.
Picture 5
Picture 7 Picture 6
CAUTION