SRM's Electrical Department (electronic Section pdf) (new Products pdf)
Electrics are often the most difficult, or intimidating aspect of classic motorcycle maintainence to approach, and can be the most troublesome of problems to fix. At SRM, however, we have years of experience in dealing with the electrical systems on a range of classic bikes. Most of the electrical servicing we do is carried out on BSAs, but we have experience in (and are more than happy to work on) Triumph and Norton also 每 just give us a call or email if you are unsure, or have questions.
SRM MAGNETO SECTION
At SRM for the classic motorcycle magneto , we offer a complete reconditioning
service for the Lucas K2F magneto,and other magneto repair such as the K2FC
and MO1 as fitted to the BSA ,Triumph,Norton models, We can offer the best
treatment for your Norton, BSA or Triumph magneto.
Each magneto is rebuilt in-house by our own qualified and experienced Jon Jolley (BSc Electrical and Electronics Engineer), using only the best quality magneto parts. A Crypton Magmaster is our magneto tester used to thoroughly test each individual magneto by running it at speed, as though it were fitted to the engine. The Crypton Magmaster was originally produced in the 1950s in order to test motorcycle magnetos and dynamos. The Magmaster shown here was refurbished by SRM several years ago and has been specially modified to allow a K2F Magneto and E3L Dynamo to be easily tested. The timing degree disc on the front of the Magmaster allows us to stroboscopically check the firing angle between the two cylinders.
Before any work is carried out on a magneto, it is checked on the Magmaster first to locate the problem.The most common problems found with the K2FandK2FC(competition)magnetos are
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Insulation breakdown of the coil windings in the armature
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Failure of the condenserArching in the Bakelite slip ring
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Uneven wear in the Cam Ring
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Carbon build up on the Slip ring
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Oil contamination
Problems (1) and (2) can be solved by rewinding the armature and fitting a modern condenser.
Exchange armatures are available from us here at SRM.
Old Bakelite Slip Rings (3) become very brittle with age and hairline cracks form 每 these cause stray arcs and misfires.
This problem can be solved by substituting a modern heavy-duty plastic replacement.
From our experience in setting up BSA engines for smoothness and power, we have found special attention must be given to the Magneto Cam Ring (4) as this controls the firing of each cylinder. Due to the construction and design of magneto bodies, the Cam Ring must be checked with a strobe and adjusted as required (by careful grinding of the Cam profile) or replaced as necessary. We achieve this using the Magmaster, with a timing degree disc and a strobe to accurately check the ignition timing.
Wear in the points and points assembly can also cause ignition problems. Carbon build up on the Slip Ring (5) causes a weak intermittent spark. This build up is usually caused by using the wrong grade of pick up brush (too soft) and too great a spring pressure. The slip ring needs to be thoroughly cleaned or in some cases replaced.
Oil contamination (6), due to failure of the oil seal, affects the carbon brushes (especially the Earth brush) causing poor performance of the magneto. A new oil seal and insulation washer should be fitted and the brushes changed.
On all magneto services, each one is thoroughly cleaned, and any magneto part checked ,all bearings and seals checked and replaced as necessary. Particular attention is paid to the armature shimming, as this is crucial to the performance of the magneto. All magnetos are tested over various working speeds until we are 100% satisfied with the performance, and the HT voltage of the spark is measured,
giving an accurate measure of the power of the spark.For all your magneto part lucas or otherwise, please see our catalogue.
The work is supported by a two year guarantee
and each magneto is supplied with a test certificate showing its performance after the work has been completed.
The control of the ignition advance/retard on the BSA A7 and A10 1950 to 1961 (except Road, Super Rocket and RGS) was by the Lucas Automatic Timing Unit. The unit was fitted to the drive end of the magneto, and expanding bob weights progressively increase the ignition advance as the engine speed rises.
Wear in the fibre gear wheel, springs or pins will cause problems with ignition timing and general running of the engine. We offer reconditioned units on an exchange basis 每 alternatively, we have new remanufacture units for sale. The BSA Road and Super Rocket and RGS use handlebar mounted manual ignition control with a fixed gear mounted on the end of the magneto. The teeth of the original fibre can wear or break off 每 a modern fibre replacement for the fixed gear is available also.
Twins Electronic Magneto Conversions
Suitable for all K2F and K2FC magnetos.
Kit Includes Ignition Box, Small Micro power coil, bolt in unit with pick ups and instructions. Unit when running only uses 9 watts of power 每 little more than a tail light bulb!
In our constant search for ways to improve the performance and reliability of BSA Twins, we have focused attention on the A7 and A10 ignition system. Whilst a magneto will perform the task it was designed for, there are some areas in which an electronic ignition system superior:
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Accurate ignition timing;
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Electronically controlled advance and retard
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High energy spark, even at low speeds
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No wear at points or on the Cam ring
With experience gained using other electronic ignition systems, we decided to produce our own system using low power consumption electronic ignition units, with the latest compact twin spark coils and our own specially manufactured ＆insert＊ to fit inside your existing magneto housing. The electronic pick-up insert fits in place of the original armature, its rotating magnets produce the signal impulse to activate the ignition box. The ignition box itself contains a digitally-mapped advance/retard curve which allows for improved ignition control at tick over and increased spark energy at start up. The ignition box and coil can be placed out of sight under the tank or in the tool box.
The kit provides full instructions for setting the timing. The ignition requires 12v electrics (a 6v to 12v converter is available).
The low power consumption design of the electronics allows plenty of power for the lighting system.
As the electronic ignition controls the timing with greater accuracy, so it becomes a lot more important to ensure the ignition timing is set accurately. This is achieved by checking the timing, whilst the engine is running, with a strobe. By fixing a Timing Degree Disc to the end of the crankshaft (primary drive side using nut SRM-42.0071) and using a piston stop, Top Dead Centre (TDC) can be found. The engine can then be set at the correct firing angle (degrees BTDC) to approximately set the timing.With the engine running a strobe can be used on the timing disc to accurately set the timing at full advance.
Singles Electronic Magneto Conversion
Almost identical to the Twins kit, we have also developed an Electronic Ignition System to replace the M01 magneto. The magdyno body is retain with part of the electronics fitting in place of the armature (retaining the original appearance). The system uses rotating magnets to produce a signal from the magdyno unit. This is then sent to a specially developed ignition box.
The ignition box has a digitally mapped ignition advance/retard curve allowing far superior control of the ignition timing at any particular engine speed. It also provides for better ignition control at tick over and an extra amount of energy for the spark at start up. The ignition box electronics have been designed to keep the power consumption of the ignition system low, aided by the use of the Boyer low resistance digital coil (as used in modern Triumph motorcycles). The coil is small enough to fit under most petrol tanks. The ignition system runs from a 12v supply 每 if your bike has an original 6v system, this can be converted using a 6v to 12v electronic regulator, and changing the battery and bulbs to 12v.
As the electronic ignition controls the timing with greater accuracy, so it becomes a lot more important to ensure the ignition timing is set accurately. This is achieved by checking the timing, whilst the engine is running, with a strobe. By fixing a Timing Degree Disc to the end of the crankshaft (primary drive side using nut SRM-42.0071) and using a piston stop, Top Dead Centre (TDC) can be found. The engine can then be set at the correct firing angle (degrees BTDC) to approximately set the timing.
Electronic conversion kit for Magdyno singles, including:
↓ Rotating pick up unit;
↓ Boyer Digital Coil;
↓ Low consumption electronic ignition box with special advance curve;
↓ All leads and connectors, and full set of instructions
DYNAMO SECTION
As we specialise in the BSA Twins, we are particularly familiar with the LUCAS E3L Dynamo lucas (as fitted to the BSA A7/A10). Being BSA owners and restorers, we have seen most of the problems that afflict dynamos and charging systems and (most importantly) how to put them right!
If you have a charging problem, then it is important to find which part of the electrical system is at fault.
We can carry out a comprehensive restoration (both electrically and cosmetically).
On completion of a dynamo rebuild, the dynamo is once again mounted on the Magmaster and thoroughly tested to achieve the best output under running conditions. Just rebuilding a dynamo with just any new dynamo part , does not always mean it will charge straight away on the bike 每 many dynamos need magnetising to restore the correct polarity and rotation.
Every dynamo rebuild carries a 2 year guarantee, and advice is freely given if you find that you still have charging problems.