PMU121 is a beige Golden Flash with plunger rear suspension. W M Oliver of Tottenham, North London sold it on 23rd May 1950 to a resident of Enfield against order number RT 91791. After passing through two more owners in Cheshunt, Herts, it was bought by Ronald Hummerston on 13th May 1955 from Grove Garage & Motors of Edmonton, North London for £100.

It was a means of transport and worked hard. During the 50’s minor knocks and wear damage meant a number of items were replaced with non-original parts as one might expect. Maintenance was minimal and lack of it was ultimately the reason for the bike going out of regular use in the early 60’s. In fact, evidence uncovered during restoration showed that the sludge traps in the crankshaft were blocked – the inevitable result being a failed timing side main bearing. On the plus side there had been no butchering. All nuts and bolts had their edges, all cylinder barrel fins were intact and the original tool kit plus a number of other bits and pieces were still in the toolbox, there was even some documentation. Only the horn was missing and who needed that?

The bike had languished in family garages and lock ups for about 30 years until it was rediscovered and it was decided to bring it back to life. The challenge being to restore it to a high standard but back to the state it was last used by Ronald Hummerston rather than to factory original - it is a family heirloom after all. Having the experience of restoring three basket cases before (Ariel, Norton and Hesketh), this complete bike looked a good prospect. Obvious problems were uniform rust damage and very heavy mechanical wear.

The bike was trailored to Northamptonshire and the careful process of documentation, dismantling and labelling begun. A number of essential reference books were obtained to help:-

BSA Illustrated Spares List 1949 – 1953 from Bruce Main-Smith

BSA Twin Restoration by Roy Bacon

Haynes Owners Workshop Manual for the BSA A7 & A10 Twins

BSA Service Sheets 201 onwards – these came with the bike!

BSAOC Members Handbook (especially for information on transfers)

... all of which proved to be vital.

The petrol tank was a bit of a mystery. It was chromed and painted and looked correct apart from having water slide transfers rather than screw-on metal badges. A superb freehand sketched ‘tank catalogue’ was provided by Dan Pincham of the BSA Owners Club to help but after considerable thought it was decided to honour the original intent rather than worry about originality. Extended searches and a letter to The Star (the BSAOC magazine) eventually produced a new pair of transfers from Digger - wherever he may be, many thanks. Lewis and Templeton restored the tank and supplied the ‘polychromatic silver beige’ paint to finish the rest of the bike.

All remaining painted parts were bead blasted and immediately sprayed with two-pack etching primer – rust was now no longer an issue. Over a number of summers the parts were filled,

painted, lacquered and polished – no major problems other than availability of good spraying conditions for the optimum finish. Some chromed parts were replated such as the kick start and gear lever but replacement parts were used where rust had won.

Considering the terminal shortage of oil that befell the bike, the engine and gearbox were OK - ish. Bores and pistons were remarkably good and retained unchanged apart from new rings. As a matter of course, all bearings were replaced; this is when it was discovered that the timing side main bearing had molten; this was replaced with a standard item. Frank’s of Church Stowe reground the crank and supplied new shells from stock. The sludge trap plugs were a serious problem to remove; in fact, they were chipped out in fragments at a time taking care not to damage the internal threads.

SRM and C&D supplied all remaining engine parts over a period of time. During assembly, trouble was experienced with big end torque settings. After a bit of research it was discovered that the correct setting is officially "really tight" but after some further consulting this was found to mean 8.5ft lb. The problem then was setting the correct torque AND getting the split pins fitted.

The top end was given a complete overhaul with new valves, guides and springs. Fortunately, only the barest minimum of regrinding was needed. Perhaps the new guides were actually manufactured to specification and truly concentric.

Engine and gearbox re-assembly was simply ‘the reverse of disassembly’ as they say in all the workshop manuals – dream on. Nonetheless, although time consuming, the BSA engine goes together quite well and proved fairly trouble free, time will tell if there are any hidden gremlins.

With the engine and gearbox assembled and placed to one side, the rolling chassis was built up – carefully. How do you avoid paint damage from tightening nuts and bolts on lacquered cellulose?

Front forks were in good shape but new seals and shrouds were fitted. The job is near impossible without special tools but, once you know what is needed, they are easy to make up. It might be useful if the BSAOC reproduced some drawings of easily made special tools including the engine stand which also proved invaluable and, again, easy to make.

Wheels were rebuilt with new rims and spokes with Lewis & Templeton dealing with the paintwork along the rim centres. It was surprisingly easy to rebuild the wheels providing any alignment adjustment was taken in small steps and evenly distributed. To get the centring correct the wheels were set up in the frame – you can’t go wrong then.

Seat restoration was entrusted to R K Leighton for recovering – a superb job as usual.

The engine and gearbox assembly dropped neatly into the rolling chassis and it was then beginning to look like a motorcycle. One problem annoyed; the foot brake pedal rose too far and to overcome the problem a neat modification could be visualised to provide a stop. A small bracket was duly made up and fitted to the footrest, which worked fine. A few weeks later the

very same homemade part was discovered amongst the odd bits that came with the bike – spooky. This was resprayed and fitted – now that’s what you might call original non-originality.

With no excuses remaining it was time to fire it up. A few final checks first.

No sparks!

The magneto slip ring was clean and the new brushes were making good contact. Was the winding faulty? The magneto was taken off and, just as a last minute thought, driven at moderate rpm from a polishing mop – sparks aplenty and painful they were too! Refitted back into the bike and with fuel in the carburettor the engine was turned over gently. It willingly fired up and burbled contentedly. Once the oil pump was delivering oil back to the tank the engine was stopped on the kill button just for checks – all still OK and no blood on the floor.

With most of the major worries dealt with the final stages approached. The specified 100 link rear chain proved a fraction too short such that tightening the spindle nut just fouled the plunger bottom cover. For the time being, one of those awful half links is in use but once the chain stretches a little it will be removed.

The bike originally had the registration painted on but having had a disaster in the past with some shoddy work, pressed aluminium was initially chosen. This looked OK on the back but the radius of the front plates was matched to pedestrian slicers and did not fit well on the sides of the mudguard. At C&D a small card in the window advertised Carl Maskall Signwriting and a Bantam in the shop displayed his workmanship. For a modest sum Carl, a retired signwriter and former James employee, very quickly produced an excellent job.

A short road test revealed no running problems; it ran true, the engine pulled well and it ticked over evenly once warm. It even stopped, albeit gradually. The wonderfully rorty note from the Armours pipes may not be appropriate for the residents of a quiet country lane but they’ll get used to it.

A nice sunny day and MOT time. Having run for all of 500 meters without falling apart it was decided to get it tested. Traffic should have been light but someone had decided to dig up the local dual carriageway and it was necessary to weave through two miles of stationary cars in blistering heat. It was a steep learning curve. The clutch is heavy. It works well with gear and neutral selection clean but a combination of cable routing and newness made it hard on the left hand. Directional stability was excellent. The steering geometry is lazy and made for a comfortable ride at all speeds including walking pace.

Testing was a formality – even the brakes were regarded as "typical". In the course of the 25 mile round trip, the front brake did start to develop some bite.

The only task to complete the bike is to locate an original horn. Currently, a cheap modern alternative is discretely hidden under the nose of the dual seat. That will keep it legal until a decent alternative can be located.

That’s it. PMU121 is now legal, back in circulation and back in the family. It should survive many generations yet to come.

david.w.sharp@virgin.net