Welded frame with larger diameter top tube for strength
Front Suspension
Telescopic forks
Rear Suspension
Swing arm, 2 shocks wiith dampers
Front Brakes
8 in. drum, leading shoewith snail cam shoe adjustment
Rear Brakes
7 in. drum with floating cams
Wheels
Steel, spokes
Front Tyre
3.00 x 20
in. Trials
Rear Tyre
4.00 x 19
in. Trials
Dimensions
Length: 2159 mm / 85.0 in.
Width: 737 mm / 29.0 in.
Height: 1105 mm / 43.5 in
Wheelbase
1372 mm / 54 in.
Ground Clearance
191 mm /
7.5 in.
Seat Height
813 mm / 32 in.
Dry Weight
135.0 kg / 298 lbs
Wet Weight
184 kg / 406 lbs
Fuel Capacity
UK: 18.2 L /
4.8 US gal
US:
9.1 L / 2.4 US gal
Standing 0 - 100 km/h / 62 mph
7.4 sec (B50SS model)
Top Speed
145 km/h /
90 mph
.
Of the 5,700 or
so that were built, survival rates are low. Which is partly why today the
B50 is as rare as a priest with a clean conscience. It’s not the easiest
bike to live with. And it needs a good dose of retro-engineering to get the
very best from it. But you can be sure that ownership of one will, at least,
never be dull.
But was it ever worth the hallowed Gold
Star name that was bestowed upon it? It’s a debate that still rages.
Overall, these are great little BSA
singles. You wouldn’t want to ride two-up on one—unless most of your journeys
were shorter rather than longer. But as a solo mount, it’s a stylish thumper
with a hidden chunk of lead in its glove.
1. The unit single crankcases were
originally designed for a 250cc engine. Accordingly, the B50 pressures beneath
the piston are considerable and put a huge load on gaskets and seals. A timed
breather is vital to keep the crankcase at negative, or at least neutral,
pressure. Well-fitting mating surfaces are essential if you want to keep the oil
in rather than out.
2. Poor handling is often attributed to the swinging arm
bearings. These pivot on needle rollers and need plenty of grease to avoid
seizure. Raise the bike and check for play. Replacement is straightforward.
3. The extra torque of the B50 means that clutches are
prone to slippage and so need need to be kept in tip-top shape. Solutions
include an extra friction plate, an extra steel plate, stronger clutch springs,
and an alloy pressure plate.
4. The bore can be opened up to 90mm giving 572cc for
extra stomp. You’ll also need to gas flow and fit a larger (32mm) carb.
5. Ignition coils were always weak leading to poor
starting, irregular tickover, and misfires. Fit the best quality replacements
you can afford along with a new condenser and quality plug lead.
6. Whilst good enough for general use, high performance
B50s will require an upgraded crankpin such as Alpha. A Carillo conrod is also
highly recommended.
7. Rocker boxes are prone to leakage which can be sorted
by careful linishing.
8. Poor crankcase scavenging seems to affect some bikes
more than others, and is said to be due sometimes to mismatched sump covers
blocking oil pick-up holes.
Any corrections or more information on these motorcycles will be kindly appreciated.