Electrical Modifications


A factory modification to the early cam chain tensionerContrary to the beliefs of many one-make enthusiasts no manufacturer ever made a bike which was devoid of  design errors. Likewise the suppliers of ancillary equipment had their own problems which often compounded the manufacturers errors. Add 50 years of damp & deterioration, the benefit of hindsight, improved materials & technology & we have the opportunity to improve on the product of  Mr Parrilla. The Hicam Parilla engine was an innovative design for its day with many unique solutions to problems which other marques handled in a more conventional (& some may say heavyhanded) way.

Here we will consider the improvements we can make to the engine & ancillary equipment. If your bike is for show & light (or no) road usage then these modifications will be of no, or little, interest. The OE (original equipment), if in good condition, will be perfectly adequate. If you are considering track use, regular road usage or entering an event such as the Motogiro D'Italia then they will be worthy of consideration.


Where do we start?


Original CEV 110mm 2 wire 6v generator The biggest improvement to the reliability of the machine as a whole is to both improve the charging system (including a change to 12v) & remove the need for a fully charged battery to power the ignition system. The OE CEV or CESA 6v dynamo & mechanical voltage regulator can be made to work ( I completed my first Giro D'Italia with just such a setup) but its complication, lack of spares availability & at best marginal charging capacity (40w) make it a weak point.

Vape 12v alternator & self generating CDI.


Vape 12v alternator & self generating CDI An answer to the problem of providing a reliable & improved charging & ignition system can be solved by the fitting of a Vape 12v CDI combined ignition & charging system. A 12v charging only system is also available should you prefer to continue with a points & coil arrangement. See the suppliers website:




The fitting process - remove CEV rotor & fit Vape baseplate.


CEV stator removed Spacing ring & stator backplate in place

Fit stator & prepare to time the rotor


Set the crank to the appropriate fully advanced ignition timing for your model

Stator in place with wiring threaded through slot in mounting ring

Piston stopped at 50 deg btdc prior to fitting rotor to crank with timing marks on base lined up to groove on rotor




Continued on Electrics 2