Service Bulletin: New Handlebar Ignition Cut-Out Button
Triumph Service Bulletin #13 1-29-1966
Dated January 29, 1966, this Triumph service bulletin #13 goes into detail regarding the new handlebar cut-button on ignition model twin cylinder motorcycles. This cut-out button was fitted on the right hand side of your handlebar near the throttle assembly. There where two different types of cut-out buttons used on 1966-1967 models but both look strikingly close. This service bulletin and this post will inform you on how to spot the two different cut-out buttons as they should not be interchanged.
Lucas "mammoth" kill button assembly
The new cut-out button that Triumph is referring to is pictured above. Many folks and restorers call this cut-out button the "mammoth" kill switch due to it's rather large unusual size. This specific cut-out button is correct for Triumph T120TT, T120C, TR6C and the T100SC models that featured A.C. ignition from 1964-1967. What makes it "correct" for A.C. models? The answer lies in the color of the plastic button, it's black - seriously.
Lucas black cut-out button
The kill switch that had a black color button is only correct for A.C. ignition models. Not just because the button color but because the buttons specific function. The black button has "normally open" contacts which should only be used with A.C. ignition models.
Lucas brown cut-out button
The kill switch with the brown plastic button is correct for models that where equipped with standard ignition from 1966-1967 which included the Triumph Bonneville T120R, Triumph Tiger TR6R, Triumph Daytona T100R, and others. Typically under Lucas part number 35601. The brown button has "normally closed" contacts.
Measure continuity between each terminal
If you are not sure exactly how to identify each kill button, you can measure continuity between each terminal using a meter. The black button (A.C. ignition) will not show continuity when grounded. The brown button (standard ignition) will show continuity to both terminals when grounded or when the button is pushed.
"Brown is for standard & black is for A.C..."
I hope this post was somewhat of an eye opener as I have seen many folks get the two buttons confused with each other. Remember the brown button is for standard ignition and the black colored button is for A.C. ignition. Thanks for reading today's post.