Top Gun


It’s a classic bike. But it need not be treated as vintage stuff. If restored properly, it can be your daily rider, says Shahwar Hussain.


Photographs: Ramesh Pathania


The Best Motorcycles In The World," that’s what the BSA ad proclaimed and with good reasons too. At that time most of the world was or till recently had been a part of the British empire and BSA motorcycles were exported to all the colonies. That the motorcycle market at that time was a fraction of what it is now is another matter.

Over the years, India has been a major recipient of the good work of the British motorcycle industry. Since India was one of the last British colonies, it has one of the largest concentrations of British bikes in Asia. A large number of these bikes are from the immediately pre- and post-WWII period with a sprinkling of mid-1960s and mid-1970s models. And a very high percentage of all British bikes in India are BSA.

A couple of weeks ago, I bumped into my bike restorer friend Gurmukh Singh. He had recently restored a 1952 BSA BB31. He had moved his residence out of city limits a couple of years back

and my visits to his garage had gone down drastically. But when he invited me to ride the bike, I decided that a trip to the suburbs, even in this hot and lousy weather, was well worth it.


When I reached Gurmukh’s place I realised that this particular bike was one that I almost bought two months ago. But what a transformation! The bike looked gorgeous in its black and silver paint scheme and oodles of chrome, a far cry from the dull red paint job it sported a few months earlier.

Classic motorcycles are generally ridden in a very loving way, lest they break down. But the BB31 is a practical classic. You don’t have to be too apologetic about the way you use this bike. It is an everyday-use classic. But then, in order to ride a 52-year-old classic bike like a modern day bike, restoration and workmanship has to be of a very high order. And that’s exactly what Gurmukh Singh did.

Eric O’Connor who works with the Canadian Consulate-General has bought this BB31 and he plans to take it with him to Canada in a few months. Eric also owns a Kawasaki, Honda and an Ariel Red Hunter that is under restoration.


Riding this BB31 is pleasure and confidence personified. This 350cc bike is not the fastest of British bikes of that period but makes up for its lack of speed with its surefootedness. There was nothing drastically wrong with the motorcycle when it came to Gurmukh but there were some niggling problems which, if not addressed, can raise their ugly heads at the most inappropriate of times. Gurmukh decided to strip the engine and gearbox and undertake a ground-up restoration.

Although the bike ran reasonably well, there was still a feeling of tightness in the engine. It was almost as if the timing was retarded which in fact was not the case. Stripping the engine revealed that the size 20 piston was fitted in far too tight in the barrel and this restricted its free movement that caused overheating. Whoever fitted in the piston obviously did not bother lapping the barrel adequately. Inadequate lapping often leads to overheating and engine seizure. Gurmukh put in a brand new original piston of the same size after polishing the barrel lightly.


The crankshaft was repaired in the form of filling in metals and polishing. There were some marks on it, not life threatening ones, but then it is always better to be safe than to be sorry. And being sorry in a classic bike means a huge investment of time and money. Original valves are the next-thing-to-impossible to come across and so stainless steel valves were manufactured that were a few millimetres bigger than the original ones. This results in much better breathing and invariable leads to a smoother engine. In an overwhelming number of cases, the valve guides get worn out and oil seeps in to the valve leading to the bike giving out smoke. To avoid this, Gurmukh had fitted in guides made from gunmetal. I have come across innumerable enthusiasts who have had bent push rods in their classic and vintage bikes but thankfully this BB31 had no such problems. The push rods were straight and true.

This BB31 has a bigger gearbox, but the BB31 that were manufactured later had swing arms that sported a smaller gearbox. These BB31 with smaller gearboxes were raced all over Europe.


Although the gearboxes of most BSA bikes are virtually indestructible and can go on practically forever, this particular one had quite a few problems. The third gear slipped repeatedly which is a rather dangerous thing especially if you are overtaking. The gear selectors were also worn out making it difficult to engage the gears. The new gear pinion and selectors have blended perfectly with the existing pinions.

There is no point in cutting corners while restoring a classic but this not to say that anything and everything should be replaced. But since Gurmukh had stripped the entire engine and gearbox, it made perfect sense to replace the bearings and bushings that carried even the slightest of doubts. The crankcase of the BB31 and all the other B-series bikes has been derived from the successful M-series. The crankcase features a roller bearing on the timing side and a ball and roller bearing on the drive side. Once the crank was repaired, it was only logical that the caged roller big end bearing be replaced.

I have come across many riders of classic bikes who overlook seemingly minor details like the mobil oil filter. In the BB31, the filter is located inside the oil tank and very few people ever bother to replace it. The conical filter is made of fine stainless steel wire mesh and it pays to have it in its place.

The earlier generation BB31 sported girder forks at the front and had rigid rear suspension with the only form of damping being the springs under the front saddle seat. Not the most comfortable of suspensions, I must say. In 1948, the more sophisticated teledraulic front suspension and plunger at the rear replaced this combination. The teledraulic is a huge improvement but the same cannot be said about the plungers. They have a travel of three and half inches and this is not adequate. There is a lot of backslap. The front suspensions wore new bushings but they were too tight and while I was riding, the suspension got stuck at a fully compressed state. Gurmukh reworked it and it is just fine now.


As with most bikes of that period this one is also powered by 6-volt electricals. I have seen a lot of people convert their bikes to 12-volt ones but I think it is a shame. Well, the headlight beam is a little bit dim but it is nothing that you cannot live with. The perfectly working dynamo and magneto were both manufactured by Lucas. Compared to the overall authentic look of the bike, the white battery is a big let down. A period-looking black battery can be fitted but they are notorious for leaking acid all over.

The bike runs as good as it looks. The silver coloured petrol tank and the chrome superbly complement the shiny black paint job. Gurmukh had the entire engine sand blasted and buffed the timing cover, push rod cover, and the gearbox cover. Since this is a civilian model, it sported a lot of chrome.


Riding the BB31 gives you an easy feeling and you can almost hear each slow stroke of the engine. It is a rather nice handling machine too and you can easily lean into corners. The single downtube frame coupled with the 3.25 x 19" tyres contributes to the good balance of the bike. And yes, it runs well too. The Mikuni carburettor is doing sterling duty in place of the original Amal monobloc carburettor. I took a longish spin in this particular bike and the jerky needle of the Smiths chronometric speedometer jumped to 50mph in no time and there was still throttle to spare. I did not want to go any faster. No point in pushing a classic so hard. The 8-inch brakes are good enough without being spectacular, but then, you don’t really ride these bikes at breakneck speed that you would need twin discs!

A BB31 is real value for money if you can get it restored in a proper manner. It can be used everyday and the spares are pretty much available even today. So what if it does not have the slingshot acceleration or the glamour of a Golden Flash but what it offers is bulletproof reliability. In fact all the B-series models of BSA are highly practical.

I have never owned a BB31 and I certainly wouldn’t mind laying my hands on one. One problem though…the single saddle seat. '