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Villiers Dynastart Operating Instructions

The Single Cylinder Unit consists of an external bell type armature, a stator and a contact breaker and a cam. The stator is constructed from twelve pole pieces of which six carry the starter windings and six the shunt windings. An ignition coil, condenser, voltage regulator, cut-out and starter solenoid complete the assembly.
When starting the engine, the Dynastart operates as a series motor and is controlled by a starter switch which operates a solenoid and thus does not control the main current but_only an auxiliary circuit. When the Dynastart is driven by the engine, the shunt windings are excited and the current generated is utilised both for the ignition system and for lighting and battery charging.
Initially the generated voltage increases with engine speed and as soon as the rated level of twelve volts has been reached, the cut-out switch closes and charging of the battery begins. When running, this voltage is maintained by automatic voltage control and is kept nearly constant independent of speed, the normal no-load voltage being approximately fifteen volts. As current is consumed, the voltage drops in conformity with the output. The prescribed charging rate is reached at speeds varying between 1200 and 1500 r.p.m., and will meet a continuous load of 90 watts thereafter.

The BELL TYPE ARMATURE is keyed to the crankshaft and fits on a taper.
The TIMING CAM is secured to the armature flange by two screws.
The CONTACT BREAKER is located in the outer cover of starter housing. Provision is made for rotation to allow for timing adjustment.
The aluminium SWITCH ASSEMBLY BOX houses the VOLTAGE REGULATOR, CUT-OUT, and STARTER SOLENOID on a common support.
The IGNITION COIL is a 12-volt heavy duty type and is mounted on the casing of the engine of the chassis.
The CONDENSER is attached to the Switch Assembly box.
In the twin installation there are two ignition coils, two condensers, and a dual contact breaker assembly.

The contact breaker assembly is housed in the right-hand cover and access is obtained by removing the two screws securing the small plate. The contact breaker point gap should be maintained at 0.020” to 0.022", measured with the piston set at top dead centre. Provided that the contact breaker points are kept clean and in adjustment, replacements will not be necessary until a considerable mileage has been covered. It should not be necessary to remove the complete assembly from the right-hand cover unless major replacements are required but it should be noted that if the assembly base plate has been disturbed from its original position, the ignition must be re- timed. Turning the assembly clockwise will retard the ignition and vice—versa. The heel of the rocker arm should be fully bedded to the cam before timing the ignition, especially on the twin cylinder installation.

Access to the armature is obtained by first removing the right-hand engine cover, followed by the timing cam and centre hexagon nut. The special extractor can then be screwed into the hub of the armature. When removing the armature from the driveshaft, take care not to damage the exposed armature windings. It is recommended that the armature is removed every 5,000 miles so that the carbon dust may be removed, particularly from the brush holders. Brushes should also be examined for wear (see 4 below).

To remove the inner housing and stator, disconnect the battery, and cables A, D+ and DF from the switch assembly box. Remove the three socket headed screws securing the stator to the crankcase spigot and the four screws holding the inner housing to the crankcase. After removal ofthe screws the stator and the inner housing can be lifted away from the crankcase spigot. Care should be taken to prevent damage to the oil seal which is located in the stator.

In case of defect or failure this unit must be returned for repair and adjustment. Removal of cover will automatically invalidate maker's guarantee.

Generally, re-fitting is the reverse of the operations outlined above, but the following points should be noted:--
1. The mating faces of the stator crankcase spigot must be clean and coated with “Wellseal" or a similar proprietary jointing compound, strictly to maker's instructions.
2. The crankcase oil seal must be in position and the stator inner housing and cables must be in their correct relative positions before fitting the stator and housing to the crankcase spigot.
3. The four screws securing the stator inner housing to the crankcase should be locked by punching metal into the slot ofthe screws, and the shakeproof washers replaced on the three fixing screws. All screws should be tightened down in rotation to avoid distortion of components.
4. Brush pigtail connections must lie against the stator windings with the brushes correctly positioned in the holders. Brushes should be free to move in the holders and be replaced if worn to the shoulder of the brush. Replace insulating material correctly.
5. The drive shaft key must be of the correct size and correctly positioned before the armature is fitted to the shaft. The centre nut must be securely tightened, taking care not to damage the armature during this operation. Crankshaft and armature tapers must be clean and undamaged, and the armature should be rotated by hand, after tightening, to ensure that it is not fouling the stator.
6. Replace ignition cam, checking that it is correctly located, and secure with the two fixing screws.
7. Ensure that all cables are re-connected in accordance with the Wiring Diagram.