The RUNTRONIC CDI spark ignition system with a flux sensor can give an automatic spark advance in a step-less range of 15 to 50 degrees. The speed dependent advance curve is affected by a magnetic flux plate, mounted on the sensor - and by changing the position of this plate, the spark advance curve can be modified. The optimum ignition point can be found by varying the position of the flux plate while the engine is running. Technical data for the unit as such, are the same as for the standard units.
The sensor shall be mounted according to the instructions included with the unit. Arrange it so, that the flux plate angle can be varied. A non-magnetic arm can be fixed to the plate, or the plate fixed to a rotatable shaft through the core of the sensor. The magnet must be mounted in a non-magnetic material and it can point either in the axial direction (arr. “A”), or in the radial direction (“arr. “B”), according to the figures below. When the magnet is mounted on the crankshaft, the distance between the magnet and the sensor (the air gap) should be 1 to 2 mm (.04 to .08”). In case the magnet is mounted on the camshaft, it is advantageous to use a somewhat smaller air gap, and/or an increased radius (R) to the magnet. The standard arrangement is that the sensor and the magnet line up when the piston is in its top dead center (TDC), but in this case it can be practical to start with a setting of 10 to 15 degrees after TDC - due to the large advance angle that can be obtained with this unit. The full advance is reached at an engine speed of around 5,000 RPM with the basic settings given here.
The magnet is mounted in an axial position, with an axial air gap, according to Figure A. The radius to the center of the magnet should be around 25mm (1.0”). When the flux plate is pointing towards the center of the shaft, 15 degrees of spark advance is obtained. When the flux plate is turned towards the approaching magnet, the advance angle increases.
NOTE: If the angle “V” is increased beyond about 50 degrees, the function of the speed-related spark advance is lost and the ignition point will jump suddenly from low to high.