NB: These instructions are given for guidance only and cannot engage the author's liability in the event of misinterpretation, failure to assess the vehicle's actual condition and/or non-conformity, unsuitable mechanical practice or the use of inappropriate tools.
Installation manual for the DMC2 electronic ignition on the Laverda 750.
Prerequisites
- A battery with enough capacity not to drop below 5 V during fitting.
- A pair of plug caps with a built-in 5 kΩ resistor to limit interference.
- A general electrical system in good condition.
Mechanical installation (sensor and rotor)
The DMC replaces the original contact-breaker ignition with an optical sensor and rotor fitted on the advance-mechanism carrier, plus an electronic box. Precise sensor positioning and precise timing checking are essential.
- Remove the original ignition system in the left-hand cover.
- Fit the new rotor on the advance mechanism (see diagram).
- Fit the optical sensor on the back of the new stator with two M3 screws (remove the key).
- Gently fit the stator with its sensor onto the primary cover: the sensor must not touch the rotor (it would be damaged).
- Bring the screws up but do not tighten, so the stator can rotate for adjustment.
- Route the sensor wires through the primary-cover hole (where the original contact-breaker wires ran).
Electrical installation
The supplied harness already includes all connections. The +12 V is generally taken from the + terminal of the ignition coil (or, if interference is too great, from the + terminal of the key switch). Earth to a perfectly clean point on the frame, preferably the battery – terminal.
Function test
- Ignition Off. Remove the plugs, connect them to the caps and earth their bodies on the head.
- Set the box potentiometer to 0.
- Set the engine to 40° advance (sensor slot open).
- Switch On (never touch the HT leads — risk of electrocution).
- There should be uninterrupted sparks (only when the slot faces the sensor).
Adjustment and timing
Laverda 750s are sensitive to the timing point. The maximum value of 40° is already very high: never exceed it.
- Check the 40° mark on the starter freewheel.
- Remove the left camshaft cover; set the left piston to exact TDC.
- Measure the exact distance between the top of the plug well and the piston (as vertically as possible).
- Add 10.6 mm to this value → measurement X.
- Turn the engine by hand (normal direction) until the piston is at distance X: it is then 40° before TDC. Check that the freewheel mark is correct.
Pre-timing before starting:
- Potentiometer at 0 (test), plugs still earthed, pistons at TDC.
- Turn the stator fully clockwise, then switch on.
- Turn the stator very slowly anticlockwise to the exact point where the plugs spark continuously.
- Then turn slowly clockwise until the sparks stop: tighten the stator screws at this exact point.
- Switch off, set the potentiometer to 1 (curve no. 1, 40° advance), refit the plugs.
- Start, warm up, hold ~5000 rpm and check the 40° advance with a strobe light. Gently adjust the stator by hand if needed.
NB: this timing must always be done on position 1.
Potentiometer positions
0 = test program; 2 = switch pos. 2; 4 = pos. 4; 6 = pos. 6; 8 = pos. 8; 10 = pos. A; 12 = pos. C; 14 = pos. E. The odd positions (1, 3, 5, …, 15) are the intermediate "between" values. Curves 1–5: max 40°; curves 6–10: max 37°; curves 11–15: max 34° (see diagrams).