One of two major British industrial firms to switch

from the manufacturing of guns to motorcycles,

BSA has done very well with their two-wheelers, and are

today one of the best-known, and respected, names in the

field. They offer a very wide range of motorcycles, with

engines of various sizes and specification, for a variety of

purposes — virtually the only common denominator being

the standard of finish, which is very high for all models

in the line.

We have tested BSAs before; this time it is the B40,

SS-90, Star Sportsman, which is a longish model designa-

tion for a machine that is basically very straightforward.

The most outstanding characteristic of the SS-90 (if we

may be permitted to shorten the title) is that it fits per-

fectly into the gap between the true lightweight and the

really big motorcycle, having many of the best features of

both. It is small enough to be easy to handle; and it has

the displacement required to torque itself (and its rider)

up and over hills without a lot of stirring at the gear lever.

The engine is a 350cc single, developed from BSA’s

250, and it is a design both recent and modern, enough to

have the transmission and engine constructed all in a

unit, within the same major casing. The cylinder barrel

is of iron, but the crankcase/transmission casing and the

cylinder head are of aluminum alloy. The valves arc

pushrod actuated, from a gear-driven camshaft mounted

in the side of the crankcase. The pushrods travel up

through a tunnel cast into the cylinder barrel and cylinder

head. With all of the valve gear enclosed in a chest, and

external oil lines held to a minimum, the engine stays

clean. This cleanness will be appreciated, for there is a

lot of polished aluminum on the engine, and it looks so

nice that it would be a shame if the bright work was hid-

den under dust and oil.

This particular version of BSA’s small single is fairly

highly tuned, but not to the extent that shows any signs

of being fussy. No output figures are offered by the

maker; we would guess that it was delivering about 25

bhp at 7000 rpm, and although the power falls away

rather sharply after the peaking speed is passed, we found

that best acceleration was obtained by overspeeding the

engine to 7400 rpm. Valve float occurred at about that

point.

Most of today’s smaller engines are being designed

with wetsump lubricating systems; the SS-90 follows the

traditional, and meritorious, dry-sump pattern, with the

oil supply contained in a two-quart tank. Pressure feed

for the bearings and crankcase scavenging are done

through a two-section gear-type pump, and there is a re-

strictor in the tank outlet pipe that forces part of the oil

scavenged from the sump to divert off into a line that

feeds the rockers and valves. A wire-mesh cylinder, lo-

cated in the bottom of the supply tank over the outlet,

acts as a filter (of a sort) for the oil. There is also a

cleanable sludge-trap incorporated in one of the crank as-

sembly’s flywheels.

One of the more attractive features of the SS-90 was,

we found, the closeness of the transmission ratios. Low-

gear was just about as “tall” as the second-gear in most

motorcycles, and quite good speeds could be reached in

all of the three intermediate ratios. Top-gear was just

about perfectly chosen: at the engine's peaking speed of

7000 rpm, the bike is doing 90 mph, and we are of the

opinion that going up or down on the ratio would ad-

versely affect this flat-out top speed. Experiences in rid-

ing the SS-90 showed us that first and second gears are

perfect for levering the bike up into its cruising range,

and third, which is good for about 80 mph, if you care

to press the engine that hard, was a ver}' useful ratio for

highway passing situations. Frankly though, the engine

has enough torque to show quite good acceleration in the

40-70 mph range without any downshifting.

Astride the SS-90, one finds that it feels like a big

bike, but is not quite so intimidating for the novice

rider. Also, it is easier to maneuver around in close

quarters than a true heavyweight. Plenty of steering lock

has been provided and there is enough leverage available,

due to the length of the handlebars, to allow one the fun

of going out and pounding around back-roads and plowed-

fields. The SS-90's wheelbase is a bit long and the gear-

ing somewhat tall for that kind of work, but the engine is

well protected by the frame, which forks out into a cradle

under the crankcase and if the bike were fitted with

trials-universal tires, it would make a reasonably good all-

purpose-pottering motorcycle.

There have been motorcycles with a better seating/

handlebar/footpeg layout. The seat is comfortable enough

with one's posterior planted back about midway, but when

this is done the pegs are too far forward and the rider

has to lean into the bars too much for comfort. Slide

forward, and the pegs and bars are fine, but the seat gets

a trifle narrow. We did like the large-diameter handlebar

grips; the control levers, which did not have ball-ends,

made us less happy — although in all fairness it must be

said that these are of more value on a scrambler than a

touring bike. A real irritation was the compression-re-