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331- SERIES: BOYER ELECTRONIC IGNITION KITS



FOR CLASSIC TRIUMPH, BSA & NORTON: REPLACES POINTS, POINTS PLATE,
AUTO ADVANCE UNIT AND CONDENSERS

The Boyer-Bransden MK4 is a contactless ignition system utilising an advanced and patented trigger switching system and featuring electronic advance and retard. The kit replaces the auto advance unit, points, points plate and condensers. Engines function best with a retarded spark for starting and low revs, but need ignition advance to run at high speed. The MK4's analogue system simply advances the spark at a set rate from fully retarded to maximum advance, as engine speed rises from zero to 4,000 revs. Thus eliminating the inaccuracy of mechanical advance/retard units. The Boyer-Bransden Mark 4 Contactless Transistor Ignition provides absolutely accurate timing for motorcycles. Once set it cannot vary its precision. It incorporates an advance and retard circuit which has no moving parts and is fully sealed for life in a material which is water, petrol and oil proof. It simply cannot wear out. There are no "rubbing parts" - no friction. There is a much better spark - at all engine r.p.m. figures. For improved economy, starting, smooth running, and all round performance, you can't beat the MK4! See the 331-Series in the Price Guide for price and availability. Replacement parts are also available. Warrantied!

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NOTES: Coil Requirements - Boyer Electronic Ignition Kits work best with less than six ohms total resistance on the primary side of the coils. Since the coils are wired in series, the resistance is the total of all the resistance in all the ignition coils in the system. Stock 12 Volt coils have 3.5 ohms of resistance each, so a twin cylinder bike with two coils has a total resistance of seven ohms, and a three cylinder bike has a total resistance of 10.5 ohms; both more then the limit of the Boyer kits. The modification is to install 6 Volt ignition coils, which have a resistance of approximately 1.7 ohms each, so that the total resistance in a twin is 3.4 ohms, and in a triple is 5.1 ohms, both within the allowed impedence range. Only the the ignition system is involved, nothing else needs to be changed. Since single cylinder bikes have one coil (3.5 ohms) they do not require a new coil. Later Norton Commandos have six volt coils with a ballast resistor so the coils are kept and the ballast resistor removed. Every kit is supplied with complete instructions and a troubleshooting guide.

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GENUINE BOYER BRANSDEN ELECTRONICS
ALTERNATOR POWERED
RACING IGNITION SYSTEMS
Ignition Box combines the Boyer Amplifier with the Power Box that
replaces the rectifier, zener diode and capacitor.
(For no lights operation only)

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For instructions please see the Tech Help Page

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