02-03-2020, 01:01 AM
My 1976 CB750F was dual fire, dual points, dual coil.
Dual points were replaced by a Martek 440 electronic ignition, as maintaining proper dwell with points was a nuisance.
The below link should provide a succinct pictorial explanation.
https://www.crypton.co.za/Tto%20know/Ign...%20sp.html
Prior to EFI (2007 up) Sportster's were primarily dual fire:
Coil Testing
Dual fire coil testing for Ironheads and Rigid EVO, (except for Spοrtster Spοrt 1998-2003)
Coil 31614-83A has two primary screw terminals (+ & -) with twin coil towers.
Primary resistance is measured from + to - terminals, at 2.5 to 3.1 ohms.
Secondary (high voltage) winding resistance is tested from coil tower to coil tower at 10,000 ohms to 12,500 ohms.
Single fire coil testing for Spοrtster Spοrt (1998-2003)
Coil 31646-99 has three connectorized primary terminals (- + -), referenced A (front) B (12 VDC) C (rear) and twin coil towers.
Primary resistance is from + to -, both B to A and B to C at 0.4 to 0.6 ohms. For the 1200S (dual plug heads), measure secondary resistance between both front coil towers and then between both rear coil towers at 11,700 to 12,700 ohms.
Single fire coil testing for carbed (ICM) rubsters, 2004-2006
Coil 31655-99 has three connectorized primary terminals (- + -), referenced 1 (rear) 2 (12 VDC) 3 (front) and twin coil towers.
Primary resistance is from + to -, both 2 to 1 and 2 to 3 at 0.5 to 0.7 ohms.
Secondary (high voltage) winding resistance is tested from coil tower to coil tower at 11,000 ohms to 15,000 ohms.
Single fire coil testing for EFI (ECM) rubsters, 2007 and up: Coil 31656-07 has 4 primary terminals, referenced, left to right, as A (+), B (+), C (rear) & D (front). A or B to D should measure 0.3 to 0.7 ohm and A or B to C should measure 0.3 to 0.7 ohm.
Secondary resistance: 3,000 to 4,800 ohms, tower to tower
Note: If resistance is lower than specified, that winding has partially shorted, bypassing part of the coil.
If resistance is higher, then corrosion or failing internal connections may be adding to the resistance.
Dual points were replaced by a Martek 440 electronic ignition, as maintaining proper dwell with points was a nuisance.
The below link should provide a succinct pictorial explanation.
https://www.crypton.co.za/Tto%20know/Ign...%20sp.html
Prior to EFI (2007 up) Sportster's were primarily dual fire:
Coil Testing
Dual fire coil testing for Ironheads and Rigid EVO, (except for Spοrtster Spοrt 1998-2003)
Coil 31614-83A has two primary screw terminals (+ & -) with twin coil towers.
Primary resistance is measured from + to - terminals, at 2.5 to 3.1 ohms.
Secondary (high voltage) winding resistance is tested from coil tower to coil tower at 10,000 ohms to 12,500 ohms.
Single fire coil testing for Spοrtster Spοrt (1998-2003)
Coil 31646-99 has three connectorized primary terminals (- + -), referenced A (front) B (12 VDC) C (rear) and twin coil towers.
Primary resistance is from + to -, both B to A and B to C at 0.4 to 0.6 ohms. For the 1200S (dual plug heads), measure secondary resistance between both front coil towers and then between both rear coil towers at 11,700 to 12,700 ohms.
Single fire coil testing for carbed (ICM) rubsters, 2004-2006
Coil 31655-99 has three connectorized primary terminals (- + -), referenced 1 (rear) 2 (12 VDC) 3 (front) and twin coil towers.
Primary resistance is from + to -, both 2 to 1 and 2 to 3 at 0.5 to 0.7 ohms.
Secondary (high voltage) winding resistance is tested from coil tower to coil tower at 11,000 ohms to 15,000 ohms.
Single fire coil testing for EFI (ECM) rubsters, 2007 and up: Coil 31656-07 has 4 primary terminals, referenced, left to right, as A (+), B (+), C (rear) & D (front). A or B to D should measure 0.3 to 0.7 ohm and A or B to C should measure 0.3 to 0.7 ohm.
Secondary resistance: 3,000 to 4,800 ohms, tower to tower
Note: If resistance is lower than specified, that winding has partially shorted, bypassing part of the coil.
If resistance is higher, then corrosion or failing internal connections may be adding to the resistance.