I don't have a '79 Special schematic handy but the wiring harness will work with the 1981 4R0 TCI.
The '81 schematic shows that the ballast resistor start-up bypass wiring was deleted when Yamaha added the 3 Ohm ignition coils.
1978 to 1980 2H7 TCI
![](http://i953.photobucket.com/albums/ae18/3Phase_2009/Misc/XS11/Electrical/Ignition/1980_TCI_zpsqpv1gjqj.jpg)
1981 4R0 TCI
The '81 schematic shows that the ballast resistor start-up bypass wiring was deleted when Yamaha added the 3 Ohm ignition coils.
1978 to 1980 2H7 TCI
![](http://i953.photobucket.com/albums/ae18/3Phase_2009/Misc/XS11/Electrical/Ignition/1980_TCI_zpsqpv1gjqj.jpg)
1981 4R0 TCI
![](http://i953.photobucket.com/albums/ae18/3Phase_2009/Misc/XS11/Electrical/Ignition/1981_TCI_zpsupohinaw.jpg)
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