Ignition System

Ignition System xjcdadmin Wed, 06/10/2009 - 17:02

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IGNITION SYSTEM A. Circuit Diagram

Above circuit diagram shows only ignition circuit in wiring diagram.

B.  Description

This model is equipped with a battery operated, fully transistorized breakerless ignition system. By using magnetic pick-up coils the need for contact breaker points is eliminated. This adds to the dependability of the system by eliminating frequent cleaning and adjustment of points and ignition timing. This T.C.I. (Transistor Control Ignition) unit incorporates an automatic advance circuit controlled by signals generated by the pick-up coil. This adds to the dependability of the system by eliminating the mechanical advancer. This T.C.I, system consists of two main units; a pick-up unit and ignitor unit.

C.   Operation

The T.C.I, functions on the same principle as a conventional D.C. ignition system with the exception of using magnetic pick-up coils and a transistor control box (T.C.I.) in place of contact breaker points.

1. Pick-up unit

1. Pick-up coils

This unit consists of two pick-up coils and a magneto mounted on the crank-case (L.H.). When the reluctor (timing plate) projection passes the pick-up coil, the two signals are generated at the pickup coil and transmitted to the ignitor unit as a signal. The full ignition advance is determined by the width of the reluctor (timing plate) projection.

2- Ignitor unit

This unit has such functions of wave form, duty control, switching, electrical ignition advance, and etc. The ignition timing is advanced electrically using two signals from the pick-up coil. The duty control circuit is provided to control the on time period of the primary ignition current to reduce the electrical consumption. This unit also incorporates a protective circuit for the ignition coil. If the ignition switch is turned on and the crankshaft is not turned, the protective circuit stops current flow to the primary coil within a few seconds. When the crankshaft is turned over, the current is turned on again by the signals generated by the pick-up coils.


Do not run the engine without any spark plug cap(s) in place. Due to the high secondary voltage, it is possible to damage the internal insulation of the secondary coil.

D. Troubleshooting/Inspection

1. The entire ignition system can be checked for misfire and weak spark using the Electro Tester. If the ignition system will fire across a sufficient gap, the entire ignition system can be considered good. If not, proceed with individual component tests until the problem is found.

a. Warm up engine thoroughly so that all electrical components are at operating temperature.

b. Stop the engine and connect the tester as shown.

c. Start the engine and increase the spark gap until misfire occurs. (Test at various r/min between idle and red line.)

Minimum spark gap: 6 mm (0.24 in)


Do not run engine in neutral above 6,000 r/min for more than 1 or 2 seconds.

2. If the ignition system should become inoperative, the following troubleshooting aids will be useful.

Check entire ignition for connections


Poor connection



Check battery for voltage and specific gravity


Low voltage & specific gravity

Recharge battery


Check fuse and fuse connections --------------->
Weak connection or open circuit
Correct connection or replace fuse


Check resistance of ignition coil {primary and secondary) 
Primary: 2.5 Ω ± 10% at 20°C (68°F) 
Secondary: 11KΩ ± 20% at 20°C(68 F)


If other than specified

Replace ignition coil


Check pick-up coils for resistance Pick-up coil: 700 Ω ± 20% at 20°C (68°F)


If other than specified

Replace pick-up coil assembly


TCI unit is faulty, replace unit    


3. Ignition coil 

a. Coil spark gap test.

1)   Remove the fuel tank and disconnect the ignition coil from wire harness and spark plugs.

2)   Connect the Electro Tester as shown.

3)  Connect fully charged battery to tester.

4)  Turn on spark gap switch and the increase gap to maximum unless misfire occurs first.

Minimum spark gap: 6 mm (0.24 in)

b. Direct current resistance test. Use a pocket tester or equivalent ohmmeter to determine resistance and continuity of primary and secondary coil windings.

Standard value: Primary coil resistance:

2.5 ± 10% at 20°C (68°F) 

Secondary coil resistance:

11 KΩ  ± 20% at 20% (68°F)

Primary coil check

Secondary coil check

4. Spark plug

The life of a spark plug and its discoloring vary according to the habits of the rider. At each periodic inspection, replace burned or fouled plugs with new ones of the specified type. It is actually economical to install new plugs often since it will tend to keep the engine in good condition and prevent excessive fuel consumption.

a.    Inspection

1)   Inspect and clean the spark plug every 4,000 km (2,500 mi) and replace after initial 13,000 km (8,000 mi).

2)   Clean the electrodes of carbon and adjust the electrode gap to the specification.

b.   Installation

Be sure to use the proper reach, type and electrode gap plug(s) as a replacement to

avoid overheating, fouling or piston damage.


BP7ES (NGK) or W22EP (ND) Electrode gap:

0.7 - 0.8 mm (0.028 - 0.031 in) Tightening torque:

2.0 m-kg (14.5 ft-lb)