S&S Cycle IST Ignition System for 1984–99 4 1/8 Bore Big Twin Engines - Manual (Page 9)

7. Motorcycles with a 7-pin ignition connector instead of an 8-pin connector
Some Harley-Davidson® motorcycles manufactured between the years 1991 and 1994 had a 7 pin connector in place of the 8-pin connector.
A 7 to 8 pin adapter is available through aftermarket sources such as Drag Specialties (part #: DS-243068). It is a universal adapter that allows
many different ignition systems (including the S&S IST ignition) to work on motorcycles with a 7-pin connector. If the IST installation is on a
motorcycle with a 7-pin connector, an adapter can be purchased separately.
NOTE: If using an 7 to 8 pin adapter plug or if your motorcycle is already equipped with an 8-pin ignition connector, the IST power harness adapter is not
used.
8 IST power harness adapter
The power harness adapter (#55-1540) Is used when installing the IST ignition on an S&S 41⁄8" bore engine used in a custom application. It
has an 8-pin connector that plugs into the matching connector of the Main IST harness. The power harness 8-pin connector has three wires
coming out of it: chassis ground, switched ignition power (battery +), and tachometer signal. Only two connections to the motorcycle are
required for the ignition system to operate: chassis ground, and switched ignition power (battery +). The tachometer trigger wire is optional.
See Picture 14 and Table 2, below
a. Connect the power harness into IST ignition system main harness. Make corrections in wiring lengths by cutting and splicing using
supplied connectors.
9
Picture 12 Picture 13
Picture 14
Table 2
Wire Color Wire
Designation
Main Stripe
White Black Battery “+” (Switched Ignition Power)
Black N/A Chassis Ground
Pink N/A Tachometer Signal