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Boyer Bransden

Over 40 Years' Proven Performance

In 1969 Ernie Bransden designed and patented a miniature electronic ignition that was a fraction of the size and far more efficient than any of its competitors. Since that time various electronic ignitions and manufacturers have come and gone, but Boyer Bransden have been in constant production.

Today, Boyer Bransden produce one of the most efficient ignition systems in the world. The company's ignitions are used by many motor cycle racers and a Boyer-Bransden system has been taken up by a major Formula Three car race team with impressive results.

The Advantages of Electronic Ignition

Electronic ignition is now standard for the majority of new vehicles. It offers better starting, smoother running, improved fuel economy and lower emissions when compared with more traditional systems.

On certain types of older or high mileage vehicles, wear in the distributor may affect the timing and cause a falling away of performance, whilst sparking at the points burns the contacts and wastes energy.

Some classic vehicles suffer from "fragile" electrics which may be affected by vibration or dampness, often an electronic ignition system will eliminate these problems allowing the machine to be used with greater confidence and to its full potential.

Legislation against pollution is set to become even tougher. Electronic ignition systems allow most of the available energy to reach the spark and offer more complete combustion. As such, they are an important and simple weapon in the war on pollutants, helping to keep classic machines where they belong - out on the road, not in museums!


Micro Digital & Micro Power Ignition

The Micro Digital ignition provides almost total control over ignition functions. In common with the MKIII, it offers electronic control of advance and retard functions. However, because the Micro Digital features a built in computer, the size of a postage stamp, it can make more than a million ignition decisions per second, to constantly monitor engine speed and time the spark precisely to suit. The programming of this micro processor also gives control over ignition coil energy, starting speed, tickover stabilisation and rev limits!

In common with the MKIII these systems are manufactured using the finest semiconductors and are fully encapsulated to protect against moisture intrusion. All units are guaranteed for five years.

The Micro-Digital system is designed to use the original coils where possible, the time these coils are switched during the ignition cycle is programmed into the microchip. With older machines, the coils have a high primary resistance and require a long switch on time. If the coils are replaced, it is important that coils of a similar resistance are used. Boyer-Bransden have a wealth of knowledge covering a vast range of motorcycles, and advice about matters such as this is available from an engineer, simply telephone between 4pm and 5pm on any weekday. Alternatively, consider upgrading to the Micro-Power system which is supplied complete with its own Digital Power coils.

The Mk3 system is now superseded by the Micro-Digital and Micro-Power units. Both are contactless systems and advance the timing electronically, featuring a microprocessor which can compute more than a million decisions every second. These units constantly monitor engine speed and time the spark precisely to suit. In addition, the programming of the 'mini computer' offers control over ignition coil energy, starting speed, tickover stabilisation and rev limits if required.

In both systems,-ignition timing is controlled - in bands of 50 r.p.m. over the entire speed range, this gives the ability to programme any firing angle required. To help engine power at idle, the timing can be advanced, on and below the idle speed, this stabilises and reduces the chance of stalling. From idle, the advance can be sharper than provided by the previous Mk3 system, giving even better throttle response. The Micro-Digital system makes the best possible use of standard coils, whilst the latest Micro-Power system is supplied with miniature digital coils matched to the unit, for incredible performance.

This system is designed to work only with our special digital power ignition coils (type 00007 single output, or 00008 dual output). Up to three of these coils may be run from one ignition box, providing very high energy sparks for single, or twin plug cylinder heads. The ignition cycle is produced by a high current pulse lasting for a short period of time; this is controlled by the microprocessor program. The total current consumption is reduced by over a half and the spark energy is greater; average current consumption is less than 1.5 amps at maximum r.p.m.

The Micro Power Coils

The miniature digital ignition coils have a very low primary resistance and a very high quality iron core. Single and Dual output types are available as mentioned previously. The HT cables are detachable and the primary connections are by spade terminals. As these coils are controlled by current input and not voltage, up to four coils can be run in series from one ignition unit.

With most dual output coils it is good practice to have only one output feeding a compressed cylinder, but with 35,000 volts it is possible to have both outputs feeding a compressed cylinder at one time.

The Boyer Bransden Micro MarkIII

The Boyer-Bransden Micro MKIII is a contactless ignition system utilising an advanced and patented trigger switching system and featuring electronic, advance and retard. Engines function best with a retarded spark for starting and low revs, but need ignition advance to run at high speed.

The Micro MKIII'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.

Currently available in MKIII versions:

KIT00062 Kawasaki KH250/KH350/S1
KIT00083 Suzuki GT380/GT550/GT750 3 cylinder, 2 stroke (modifications required to fit)

The Boyer Bransden Micro MarkIV

The Boyer Bransden range of Analogue MKIII ignition units are being progressively changed to improved MKIV versions. The changes are designed to improve the timing stability if engine starting with a very low or variable battery voltage.

The design changes are internal and do not affect the external appearance of the unit. Identified by the 'MKIV' caption on the label the new units are fully interchangeable with previously produced MK3 and MK1a units, and offer improved performance for both electric and kick start machines. All Digital and Power designs will remain as before.

Currently available in MKIV versions:

KIT00047 Norton Jubilee/Navigator 12v (modification required to fit)
KIT00051 Triumph/BSA Single Side Points 12v
KIT00052 Triumph/BSA Twin 12v
KIT00053 Norton Atlas/Commando 12v
KIT00054 Triumph/BSA 3 cylinder
KIT00059 Triumph/BSA Distributor Single 12v
KIT00060 Triumph/BSA Single/Twin 6v (Dynamo only)
KIT00064 Enfield India Bullet 350/500
KIT00079 Triumph/BSA Distributor Single 6v (Dynamo only)