Early 1980's Honda CB series ignition notes by lou Dudzik 12/18/06


Coils:
TEC AW82-TR1
Primary DC resistance: 2.3 to 2.4 ohms
Primary Inductance: Initially 7mH
The core seems to magnetically saturate quickly.
Inductance is 7mH until about 3.5 amps.
After 3.5 amps, the current increases at a rate closer to 5mH.
If the final current will be above 3.5 amps, use 5mH.
The coils need 1.6 msec of dwell to arc across a 3/8" gap using the stock ignitor.
The coils need 2.1 msec of dwell to arc across a 3/8" gap using an HEI ignitor.
According to Clymer diagram:
1/4 coil has a Blue wire to the ignitor
2/3 coil has a Yellow wire to the ignitor

Pickups:
Tec brand.
530 ohm +/- 50 ohm
357mH
rotor tip clearance .4 to .7 mm.
1/4 pickup Blue wire + 
1/4 pickup Blue wire with white band -
2/3 pickup Yellow wire +
2/3 pickup Yellow wire with white band -
Main signal goes positive then negative with the above polarity.
Stock ignitor uses the white-band wire as the input and thus triggers on a negative going voltage to start the dwell.
The stock ignitor requires a main signal that goes negative then positive.

Rotor:
The rotor and pickup plate are on the left side of the engine.
The rotor is mounted on the mechanical advance unit which is mounted to the end of the crankshaft.
Turns counter-clockwise.
The rotor is an iron slug with an leading, increasing-radius ramp up to a protruding tooth followed by a trailing, decreasing-radius ramp after the tooth.
The leading ramp is about 85 degrees long before the center of the tooth.  The trailing ramp is about 95 degrees after the center of the tooth.  The remainder of the rotor is a constant radius.  The radius is constant on the opposite side of the rotor from the tooth. Because of this, there is no signal generated opposite of the tooth.  This allows the opposing pickup's "crosstalk" to become clearly visible.  Since the "crosstalk" occurs during a point where there is no main signal, the crosstalk becomes a significant secondary signal (even though it's amplitude is magnitudes lower than the main signal).  The entire signal only crosses zero-volts twice.  Once in the center of the main signal, and once at the center of the secondary signal.
The rotor's tooth clearance to the pickup's center is .4 to .7mm.  (.6mm was used for testing.)
See the diagram for details on the reluctor's output signal.

Ignitor:
Each ignitor controls one ignition coil.
BLK/WHT wire is positive power supply.
GRN wire is ground.
YEL wire is to the ignition coil.
BLU wire is to the blue or yellow pickup wire.
WHT wire is to the white-banded pickup wire.
The BLU wire provides a bias voltage to the pickup.
The ignitor initiates dwell to the ignition coil when the WHT wire's negative-going voltage (from the pickup) drops below a threshold voltage.  When the WHT wire's voltage changes polarity and crosses a second (higher) threshold, the dwell ends and a spark occurs.
In a static DC situation, the first threshold is about .64v, and the second threshold is about .85v, and the bias to the pickup is about .7 volts.  However, during normal operation, the first threshold is about .3v, and the bias is about .9v. ( The second threshold could not be determined since the voltage was increasing too rapidly.)

Performance:
During performance tests, an open-air gap of 3/8" was used at the spark leads.  A 1/2" gap would have been preferred, but was not attainable consistently.
At 1300 RPM dwell was 6msec (47 degrees). 
At 9000 RPM dwell was 1.6msec (86 degrees).  
Sparks became intermittent by 10,000 RPM.

Spark Delay:
Due to the nature of inductive pickups, there is a small delay from the time the rotor's tip passes the center of the pickup and when the spark fires. This delay can be seen with a timing light on the pickup. At 1300 RPM, the delay is about 3 degrees.  At 8000 RPM, the delay has increased to about 8 degrees.  At idle, this delay is compensated for by rotating the timing plate.  This is a static compensation of 3 degrees. Therefore, at 8000 RPM there is a net delay of about 5 degrees.  This reduces the amount of advance provided by the mechanical advancer, and is normal.  Similar behavior can be found on most reluctor-triggered ignitions.