Story and Photos by new Contributor Scott Rook
I had wanted a BSA B50 for many years. They were the final distillation of BSA’s unit singles that won World MX Grand Prix championships with Jeff Smith in the 1960s and were the last competitive factory four stroke MX bikes in the early 1970s. CCM and Cheney built special framed purpose-built racers around the B50 engine that kept them competitive into the mid and late 1970s. The B50 also had the weirdest and one of the most beautifully shaped alloy gas tanks ever conceived for a motorcycle. It wasn’t exactly round but it wasn’t rectangular either. It was dubbed the lozenge. Triumphs had Pear shaped tanks and Harley had Tear Dropped tanks, BSA came out with a cough-drop shaped tank. The B50 was also recognized as one of the last great British singles in a long line of bikes that stretched back to the early teens and twenties. British singles won Grand Prix Championships with great riders like Geoff Duke and John Surtees. Names like Comet, Manx, Goldstar, Venom, Thruxton and Victor were all great British singles. The B50 also performed admirably in road racing and endurance racing, often bettering larger displacement bikes. I wanted a piece of that heritage.



The rebuild started immediately. The night I brought it home, I took it for a quick run around the block and then started taking off all the stuff that had been done to it over the years. Within a few days the engine was out and the frame was getting stripped for powder coat. We have long winters in western New York which becomes rebuild season. The goal was to have my Dick Mann approved BSA B50 D/R ready for spring. I sent the engine to the foremost rebuilder of B50s in the U.S. Ed Valiket of EV Engineering. Everything else I would rebuild myself. Rebuild season is a time of hope and optimism. All the parts you have gathered start to come together to form this thing that has only existed in your brain for years. Winter turned to spring and then summer. The B50 wasn’t ready. The engine was still in another state as was the alloy gas tank that I had sent out to have the dents removed. By August everything had arrived and the drive to complete the bike was in full swing. I took it out for its maiden voyage on August 2, 2018. The bike wasn’t finished but the only things left to do were more cosmetic than functional.

Restorations are never complete when all the parts are done, and the motorcycle is back together. Restorations are really complete after all the running issues have been cleared up and the tuning has been completed which usually takes some weeks and miles. My B50 showed some issues on its first run outside of my neighborhood. The gearbox was giving false neutrals and I couldn’t get it into 4th gear without it popping back out. I thought the gearbox might have some wearing in to do or maybe the clutch needed attention. The other problem was a flat rear tire about 20 miles from my house. The tube stem had been ripped out. I had decided against running a rim lock on the rear tire. My mistake. Clearly this bike needed some more attention. The dirt trails would have to wait. It was August already and I had other bikes to ride that didn’t give false neutrals. The late summer and fall would give way to winter soon and if I wanted to maximize my riding time left then I would take the Triumph or the Dunstall CB750. The B50 got put away until rebuild season started again.




It worked, kind of. I still would get a false neutral once in a while, but I think it was down to the shift lever not being in the ideal position and not getting a good purchase on the lever. The new old MCM Spark Arrestor sounded great, but it would pop and sometimes really POP on deceleration. Probably an exhaust leak. The bike ran great after about 15 minutes of me panicking that I would downshift rather than brake. There were no flat tires, it ran great below 2,000 rpm, and the rear rim is in one piece as far as I know. There are still some things to be done. When I got home there was a noticeable oil leak which is down to the frame being overfilled. I added oil after it wet sumped. My mistake. And the exhaust has to be sealed. I think the cursed bike might actually not be cursed anymore. I didn’t manage to actually get lost, but I rode some roads that I had never been on before. This bike needs further miles. Remember all restorations are only finished after they have been tuned and all the issues worked out. This bike took 4 years after its restoration before it was actually finished. It might not be, but it kind of feels like it for now. I might make Dick Mann proud yet and finally ride to one of those trails that don’t really exist in my part of the world (unless you trespass on county land). The Hammer may still live up to its name and thump once more.

Hmmm … though I’m a sceptic when it comes to anything being ‘ cursed ‘ … I have noticed over the years that some objects do seem to take on a life of their own . As an example ?
Owned a 77 Alfetta GT … highly modified with AutoDelta ( Alfa’s racing and performance arm back in the day ) bits and bobs
The funny thing ? That car hated my first ( long since ex ) wife . If I sat in it … or anyone but her sat in the passenger seat … no problem …. but if she was in it …. it would not start ….no matter what I did … but the second she got out ?
Vroom ….no problem … then if she got in after it was going … well … for what ever reason … that was OK .
Damn …. shoulda listened to that car
So your BSA ? Hmmmm …. lets just say .. its possible … and maybe you should listen to it as well
😎
Mate I think you must be a bit of a sook. I had a BSA B50 MX which was unfortunately destroyed in a bushfire in 2009. Prior to that I used it in 24 hour off-road reliability trials and also the Victorian Enduro Series. Mine was a beauty and I wish I still had it. I am looking to buy another one because they are fantastic.
Ahhhh … ever heard of the automotive/motorcycle/mechanical idiom …… ”
LEMON ?
Of which Btit bikes … ALL Brit bikes regardless of manufacture has a preponderance of ?
Seriously mate … ( full discloser I’m a huge Vincent addict .. and yes I know Vincents like all Brit bikes are a nightmare to own and work on ) … get with reality … if your BSA really does work so well … its a major league anomaly / unicorn … not the norm …. especially being a BSA
Sheesh … the self delusions of many individuals never cease to amaze me .. especially in this day and age … where self delusion … more often fueled by a delusional nostalgia .. is becoming the norm … in all of life
I know where there is one for sale. Its a beautiful bike with less than 200 miles on a rebuilt engine. It may require an exorcism or dousing with holy water.
I’ve ridden many – the best were wicked fast, but over 80mph a bit airborne as they’re super light with a short wheelbase. Fun!
PdO … ya forgot to mention … they also rust and fall apart faster than anyone in their right mind will ever ride one .
Ugh .. talk about British crap !
Been restoring British and Italian bikes and cars for a living since 1967. My daily ride is a ’69 BSA Thunderbolt with 6200 original miles. Original electrics and the engine tranny have never been apart. An absolute hammer of a bike. Everytime I pick it up it starts on the 2nd kick. It always works! It has never left me beside the road.
I taught bike mechanics for 33 years. The above story I’ve seen again and again. Novice mechanic not professionally trained blaming the machine for their short comings. If every system on the machine is restored to original spec per the mfg. using quality parts as well as professional tools and procedures the result will be a machine that performs as new. Possibly better given updated procedures and higher quality of parts manufactured with modern (as in not worn out from WW II) CNC machine tools.
As far as Italian machines. Replace the Magnetti spagetti electrics with Bosch and they are stone reliable.
This story about his BSA B50 brings back memories. My brother in the late 1970’s had a factory B50 MX race bike. The bike had been owned by Lebard & Underwood who was a large BSA dealer in La Habra California. Once it was no longer competitive against the two strokes they gave it to my brothers boss who eventually gave it to my brother. Although it looked like what you could buy at your BSA dealer it was different. Frame was made from Reynolds chrome- moly tubing and was brazed together. Motor internals were all polished and lightened. Bigger valves and flowed ports. All hardware was titanium including the wheel axles. Ignition was total loss and ran on a rechargeable battery that was good for 1/2 hour. The bike came with four extra motors all with the same VIN number. It was then bored out to 580cc and raced in the desert. It’s main problem was the clutch as the bike made much more power than the clutch was designed to handle.
I raced it once and it was very light and made more power than any other four stroke single I had ever ridden. He sold it to buy a Triumph 650 race bike. I wanted the B50 but forty years ago, I had no money.
My 1971 B50T was bought new in 1973, Elite Motors in London. Cancelled export order stock….. I fitted a CCM 545cc piston kit, and a Matchless ‘doughnut’ muffler….. that huge stock spark aŕrester had a habit of unzipping a seam when the motor back-fired. Like yours, mine had very poor header to exhaust port sealing thus the massive backfires on over-run. I started hammering in copper wire around the header entry, this worked pretty good, until the wire routinely vibrated out. It shook like a dog shitting logging chain….. I moved that electrics box to under the seat – the loom was *just* able to stretch that far …. it always started, and never broke down. The front frame tube cracked through just above the front engine mount – dumped all the oil. Luckily, I was at a traffic light, and saw the pool of Duckhams 20/50 spreading around my boots…… this bike coincided with my first ‘real’ girlfriend, so these two experiences got mashed together in my nostalgia.
It is a legendary bike & I acquired a lot of knowledge from your article