S&S Cycle IST Ignition System for 1984-1999 Big Twin and Custom Applications User Manual

Page 3

All reference to Harley-Davidson® part numbers is for identification purposes only. We in no way are implying that any of S&S® Cycle’s products are original
equipment parts or that they are equivalent to the corresponding Harley-Davidson® part number shown.

NOTE: The electronics used in the S&S Ignition System require operation in single fire mode only. The S&S Ignition System cannot be used in dual fire
mode.

Ignition Coil Identification

Dual Fire Coil

In addition to the spark plug terminals, an aftermarket dual fire coil will have two wiring terminals: positive, negative.

Single Fire Coil

In addition to the spark plug terminals, an aftermarket single fire coil will typically have three wiring terminals: A negative terminal for the front
cylinder, a common 12v + terminal, and negative terminal for the rear cylinder This is the most common style of single fire coil.

All single fire coils are compatible with the S&S ignition if they have a resistance of 0.5 to 3 ohms. The standard rating for and aftermarket single
fire coil is 3 ohms. Coils with higher resistance will decrease ignition output.

The S&S® Ignition system will also support a variety of different ignition coil combinations as long as they are connected for single fire operation,
and yield a final resistance of 0.5 to 3 ohms. The ignition is also compatible with dual plug heads using the correct coil configuration.

Examples of custom coil/spark plug combinations supported by the S&S ignition:

• One coil single fire for single plug heads

• One coil single fire for dual plug heads.

• Two coil single fire for single plug heads.

• Two coil single fire for dual plug heads.

Spark Plugs and Plug Wires
Spark plugs must be resistor spark plugs (suppression type) of the correct style and heat range for the application. Do not use non-resistor

plugs

Spark plug wires must be suppression type. Do not use solid metal core plug wires.

B. Parts List
The S&S Ignition Installation Kit for 1984-1999 big twin and custom applications (S&S #55-1049 See Picture 1, below left) is intended only for

installation of S&S Intelligent Spark Technology (IST) Ignition Module (S&S #55-1013 See Picture 2, below right).

S&S Ignition System Installation Kit #55-1049 contains the following items (See Picture 1):

• 1984-1999 Wiring Harness Adapter (S&S #55-1021) Item (a)
• Cylinder Head Temperature Sensor (S&S #55-1039) Item (b)
• Camshaft Position Sensor Assembly (S&S #55-1024). Item (c)
• Camshaft Position Rotor Assembly (S&S # 55-1034) Item (d)

• MAP Sensor (S&S #55-1037, H-D® #32316-99) & Hardware.

Item (e)

• 1984-1999 Coil Harness (S&S #55-1038) Item (f)
• Knock Sensor Kit (Includes: Knock Sensor, Knock Sensor Mount,

& Hardware (S&S #55-1015) Item (g)

Picture 2

Picture 1

S&S® Intelligent Spark Technology ECU Module