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Welcome to the British Motorcycle Wiring Helper


Most Vintage British Motorcycles used wiring harnesses and components from Lucas. Therefore, the wire colors are more or less consistent across brands. The table below covers most wire colors used and attempts to say how they were used. Where there are known differences from the standards, those differences are mentioned in the notes column. You can sort by any of the columns - just click on the header. If you'd like to see how I wire a Norton Commando, look here.

Wire Color Stripe Color Color Code Where Used Notes Examples
Black B Ground on Negative Ground Machines Most machines are positive ground and have no black wires. However, some harnesses use black instead of red! Color Code: B
Black Red BR Contact Breaker to Center Cylinder's Coil, Triples Color Code: BR
Black White BW Contact Breaker to Timing Side Cylinder's Coil, Twins/Triples On singles, this is the Contact Breaker to Coil wire. Color Code: BW
Black Yellow BY Contact Breaker to Drive Side Cylinder's Coil, Twins/Triples Color Code: BY
Green G Dynamo Field Only on Magneto machines Color Code: G
Green Black GB Stator Low Output (RM19), One Leg (RM24) Color Code: GB
Green Red GR Lefthand Turn Signal Color Code: GR
Green While GW Righthand Turn Signal Color Code: GW
Green Yellow GY Stator High Output (RM19), One Side (RM21), One Leg (RM24) On Norton, also goes to Warning Light Assimlator Color Code: GY
Light Green Brown LGN Turn Signal (Direction) Switch (Handlebar) common to Flasher Unit Color Code: LGN
Brown N Stop Light Color Code: N
Brown Black NB Horn button to horn (See PB Below) Color Code: NB
Brown Green NG Taillight, Pilot Light, Speedo & Tach Illumination Color Code: NG
Brown Blue NU Battery to Ignition Switch if no Ammeter or Battery to Ammeter and see NW Color Code: NU
Brown White NW Ammeter to Ignition Switch I use 14 gauge wire for this and NU Color Code: NW
Purple Black PB Horn button to horn (See NB Above) Color Code: PB
Red R Ground on Positive Ground Machines Some harnesses replaced this with black, but that is not common. Color Code: R
Blue U Light Switch (Headlight) to Dip Switch (Handlebar) Color Code: U
Blue Red UR Dip Switch (Handlebar) to Dip (Low) Beam Color Code: UR
Blue White UW Dip Switch (Handlebar) to Main (High) Beam Color Code: UW
Blue Yellow UY Ignition Switch to Headlight Switch Color Code: UY
White W Ignition Switch to Coils and other circuits on when key in run position or run+lighting position. Color Code: W
White Black WB Contact Breaker (Distributor) to Ignition Coil Only on Magneto machines Color Code: WB
While Green WG Stator Common (RM19 & RM24), One Side (RM21) Color Code: WG
White Brown WN Oil Pressure Switch to Oil Pressure Indicator Triumph when installed. Norton to Warning Light Assimlator, and when my Voltage Monitor/Oil Pressure module is installed. Color Code: WN
White Purple WP Ballast Resistor to Ignition Coils Norton Color Code: WP
White Red WR Starter Switch (Handlebar) to Starter Selenoid Norton MKIII, Triumph T160 Color Code: WR
White Blue WU Under tank junction to ballast resistor Norton, See WY Color Code: WU
White Yellow WY Engine Kill (Handlebar) Triumph Twins/Triples when no balast resistor is used: To coils.

Norton Commando, Pre-MKIII: To junction under tank where it connects to the White/Blue which connects to the balast resistor.

Norton Commando MKIII: To the balast resistor.
Color Code: WY
Yellow Y Dynamo Output Only on Magneto machines Color Code: Y

Burlen, the parent of the AMAL Carb Company    The AMAL Carb Company     Tri-Spark, inovative electrical products for the Vintage British Motorcycle    Wassell, the 70 year old suppliers of British Motorcycle parts
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