Ignitions 1000/1200 LAVERDA:

* BOSCH HKZ (1973 - 1978):

The original Bosch ignition of the 1000 Laverda is a source of various problems, above all the first serie HKZ. If you have not yet replaced it by a good one like the IIS (see page "improving"), here are the main points to check on a Bosch HKZ system.
But keep in mind that this ignition is the first thing to change on a 1000 Laverda... See the "improving" page

- Checking an original Bosch HKZ ignition (1000)

- Check the ignition coils: Disconnect the black wire (bikes before the end of 1973) or the red wire (bikes after 1973) from the junction box under the tank. Connect an ohmmeter to
this wire and to earth. Resistance should be of 250 to 400 ohms. If not, change the coil.

- Check the pick-ups: For bikes before the end of 1973, disconnect one of the violet wires from the junction box under the tank. Connect an ohmmeter to this wire and to earth.
Resistance should be less of 100 ohms. Check the other violet wire. If resistance is higher than 100 ohms, change the stator. For bikes after 1973, disconnect the two wires coming
from each pick-up. Connect an ohmmeter to these wires. Resistance should be less than 100 ohms. If not, change the stator.

- Checking an original charging system (1000)

- Disconnect the yellow/black and the yellow wires from the junction box under the tank (two yellow/black wires for bikes before the end of 1973). Connect an ohmeter, resistance
should be very low. If there is no resistance or, at the contrary, a very high resistance, change both charging and lighting coils.

- Checking a Bosch rectifier

- Disconnect the two red wires and the earth wire on the rectifier. Connect an ohmmeter (+ and -) successiveley to the two positive and to the negative, resistance should be very low. Reversing the ohmmeter connections, resistance should be infinite. If not, replace the rectifier.

- If ignition problem

1- Ignition switch on "ON"? If yes:
2- Check ignition coils. If OK:
3- Check pick-ups. If OK:
4- Check stop engine relay.

* BOSCH BTZ (1978 ->):

The BTZ has a better reliability, even if the spark power is yet unsufficient. One again, replace is soon with a modern ignition, IIS or DMC2
(see the "improving" page)

Some starting problems, often followed by a detonation into the exhausts often mean a failure of the ballast resistors. A good way to solve the problem is to shunt the resistors. In
this case, the module looses its protection against the HT current, but I know several bikes which run ok without these resistors. Your own choice though...
Another common problem is that the ignition modules are not perfectly grounded. Check the connexion and, if necessary, connect the earth wires directly to the battery negative.

- Checking starter motor (1000)

Static test
Brush pressure
750 à 1600 gr.
Minimum lenght of brush
11,5 mm

Dynamic test
35 à 55
9000 à 11000
On engine
340 à 430

- How to replace Nippon Denso High Tension ( HT ) connector wires:
Nippon Denso Ignition Coil High tension lead replacement ( Pinky, biege colour ) stamped 028700
There is an epoxy resin around the HT cable entry point on the body of the ND coil which can be carefully removed by use of small side cutters. Take care not to damage
the ignition coil body plastic case.
There are two parts to the HT lead, the inner HT lead/copper wire with insulation cover and an outside thin plastic sleeve o
r sheath.
Pull hard on the HT lead until it comes out of the coil body tube, this will leave the outer sheath still inside the coil tube. By carefully pushing a screw driver down between the
sleeve and inner bore of the tube until you feel the remaining epoxy break its bond, continue working around the sleeve until it frees from the bore. There is a standard spike
termination at the end of the bore, be careful not to damage it.
A good quality copper core HT lead of 7m/m diameter ( 8 m/m will not fit in the bore ) can then be inserted into the bore ( tube) until is stops and then a good quality silicon
sealent or Epoxy can be used to secure the new HT lead to the ignition coil body, try not to use building grade silicon as it cures by liberation of acetic acid which attacks copper components. Use 738RTV if you can find it at the local electrical wholsalers, or at least neutral cure silicon which is becoming more available from hardware stores.
Once done use NGK spark plug covers with 5.0K ohm supression resistance to terminate the HT leads for clean firing of the spark plugs.

- How to find Nippon Denso HT coils for Bosch BTZ?:

No problem to find them new or used (brokers), the twin coil was fitted to any Suzuki 4 cylinders of the Eighties and the single one was fitted to Suzuki 380, 550 GT and others
2 strokes of that time.

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