| Villiers Handbook | |
Authors
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Introduction
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History
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Crankcases
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Crankshafts
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Pistons
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Primary Drive
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Gearbox
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Ignition
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Induction
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Exhaust
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Silencing
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Ignition
The Villiers ignition system has come in for more abuse over the past three decades than any other part of the engine. This abuse is not unfounded, as the sparks department is notorious for its failures. In standard form it is heavy and unreliable, and is best forgotten.
There are many courses of action that can be taken
- remain standard, if you must
- modify the standard system
- use coil ignition
- go electronic.
Villiers got it wrong, in that they placed the components that suffer under extremes of temperature, next to the major source of heat, ie the HT coil and the condenser. These items if of modern manufacture and materials (beware of rewound coils that are reconditioned in the old fashioned way) should not suffer in the same way, as they use modern resins and are oven baked on completion of the rewind.
Use of external ignition coil
As the high tension side of the system gives most problems, why not replace it with an external HT coil, wiring diagram schematic Fig 28 . To do this strip off the fine HT windings of the flywheel coil and find a Japanese single wire energy transfer coil (FS1E or C50) and mount it under the tank. If a wire is taken from the contact breaker/LT coil connection, out via the redundant HT pick up hole, encased in a 1/4" black plastic tube, and connected to the new HT coil, no one will be the wiser. Should the LT current prove to be insufficient then the original coil can be rewound to provide more power, or one of the lighting coils can be wired in parallel to provide the necessary extra urge. A commercial alternative from Competition Classics is called "Little Demon" and is mounted on the standard castings. As the flywheel is going to be some 30 years old, it might be a wise idea to have it re-magnetised, which will in turn restore the power output of the LT coil.As an alternative a LUCAS 6V two wire battery operated coil can be used to provide the spark, if the negative terminal is wired to earth and the + terminal to the contact breaker. This system will work from the standard LT coil with no extra power needed. Competition Classics intend to market an external flywheel electronic ignition unit with a programmable advance/retard capability. It will fit straight onto a Villiers crank, and additional weights may be added to the flywheel for trials work. A variant of this will be available to replace the Greeves Mk2 Stefa unit.
As many racers use a foolproof total loss battery system, why not opt for a battery coil system, using the existing contact breaker. This can even be a rechargeable 6 or 12 volt system if required, running off the internal lighting coils (see Fig 29 ), or with the flywheel removed, a total loss 12 volt system. To further improve the now reliable spark of the battery/coil system a Boyer Inductive Discharge Unit should be fitted. This unit which runs on 6 to 12 volts, involves no changes to the wiring as it plugs into the coil connections, and takes away all the destructive power from the contacts using them only as a trigger switch. Large and ungainly 12 volt coils can be dispensed with and a change made to a Japanese single wire (CDI type) coil, but be careful of the primary coil resistance as this is critical to the spark strength. An added bonus to this type of system is that the contact breaker gap no longer becomes critical, as only a small amount of dwell is required to signal the discharge unit. Gaps of between 5 and 25 thou can be used, allowing a finite setting of the ignition timing to be carried out.