Honda CB900 FZ Road Test
Honda's sixteen-valve 900 has been billed as something
special. So we arranged a slightly special test for
it. As it is derived from the successful RGB endurance
racer, we ran one in our 24-hour test reported in
the November issue. But what counts is how it behaves
on the road, so we took the same bike, fresh from
its circuit thrashing, and put it through the rigours
of our usual road tests.
After the 24-hour test, the machine went back to
Honda UK for servicing. They were just as interested
as we were in the final state of the 900 and completely
stripped it to check for wear and damage.
During the test, the bike had lost fourth gear, the
front mudguard had detached itself and the bike suffered
minor damage in a crash.
A new mudguard was fitted, using bolts instead of
rivets and, as this wasn't a unique happening, we
understand that Honda will be fitting a more reliable
The stripdown revealed that the fourth fear cogs
and selector were badly worn, here were also signs
of wear on third and fifth gear components, although
this could have been caused by the need to shift straight
from third into fifth after we lost fourth. Third,
fourth and fifth gears were replaced, along with the
selector forks and drum.
Valve clearances were checked but did not need adjustment,
although the cam chain tensioneer had to be reset.
Nothing else needed attention. On the cycle parts,
the air cleaner element was replaced and the steering
head bearings adjusted.
After servicing, someone noticed that one of the
front fork oil seals was weeping so they were changed
as well — only Honda didn't have any spares
for the 900 and seals from another model had to be
used. Even if it was only a temporary hold-up in spares
supplies, that isn't a \ery good recommendation for
Honda's parts department. And wouldn't it be in Honda's
interest to use the same seals (along with a stack
of similar, fast-moving components) on all of their
The gearbox problem was the bike's only real blemish
and, considering the level of the 900's performance,
it came through the long-distance track test very
Mechanically, it is a fairly refined unit although
it doesn't give much more power than other bikes in
the one-litre class. What is an immediate attraction
though, is the well thoughtout layout. It makes the
bike comfortable and easy to use in any condition
from meandering around at lowly speeds right up to
using the full force of the 901 cc motor.
The seat to handlebar relationship is particularly
good; it gives maximum use of all of the controls
with minimum effort. This leads to a riding position
which gives the rider just the rignt poise for confident
low-speed control and, as the speed goes up, allows
a progressive crouch against the wind. From walking
pace right through to getting flat on the tank at
maximum speed, it makes the CB900 one of the most
comfortable bikes around.
The footrests were in the right place, but the deeply
grooved rubber was too flexible; a more rigid structure
would feel a lot better. My only other complaint was
that the gear lever, although it is fully adjustable
on its remote linkage, was too far away from the footrest.
We had track-tested the bike at maximum effort and
found virtually nothing to criticise. The front
brake was very powerful and with massive weight transfer
under heavy braking, the back end got so light that
the rear brake could be too fierce. Under normal
road use, the 900 was slightly under-braked at the
back. There's no way around that problem because a
more efficient brake would make the wheel lock up
too easily during hard braking; reducing the back
brake's efficiency would only make things worse for
Under touring conditions, the tyre wear showed a
vast improvement over what we had seen at the track.
On tyres which were about half-worn, 500 miles of
road use removed only 0.2mm from the back and, oddly
enough, 0.4mm from the front. That projects quite
a reasonable tyre life in view of the bike's weight
and performance. But, in practice, the tyre's life
is cut short. As the tread depth got down to 3 mm
— about half of the as-new tread — the
handling began to go off.
The most obvious sign was the way the bike started
tracking over any surface ridges. And there was also
a sensation of the front tyre squirming when the machine
was heeled over in a slow turn.
This was on the Bridgestone tubeless tyres which
had worn slightly faster than the Red Arrows during
the track test. Although the Red Arrows gave better
grip, particularly in the wet, they allowed high-speed
weaving once they had worn and the Japanese tyres
kept this tendency under more control.
Handling, under all conditions, was positive, with
a firm yet light steering. Ground clearance was no
problem for our purposes, the footrest scraping down
first. But immediately after the footrest goes down,
the right-side engine cover touches the ground. Ours
was lightly grazed but it has caused bigger problems
for some production racers and not only in the
physical restriction on cornering. They are associating
the scuffed cover with generator failures —
the cover and stator apparently deforming enough
to let the stator coils touch the rotor.
Although there are six combinations of bump and rebound
damping.on the rear springs the suspension seemed
too hard for 60mph riding along typical country roads.
On smoother main roads, or at higher speeds, it was
just right. I suppose that it is another of those
compromises which cannot work well under all
conditions. What would give a comfortable ride at
60 mph would probably be far too sloppy when tne bike
was used to close to top speed.
And, at 60 mph, the 900's engine is almost shut right
down. This also accounts for its poor fuel consumption;
at most road speeds the rich, idle mixture is still
having significant effect — but whatever the
reason, the 900 didn't want to go any better than
40 mpg. Deliberate attempts at riding slowly and gently
gave us 36 mpg. The best tankful, at 40 mpg, was used
mostly in 70 to 80 mph cruising and included 20 miles-worth
of full throttle testing at MIRA. At full performance,
the consumption dipped to 22 mpg.
The result was that the range of the main tank was
rarely more than 130 miles and was often closer to
110 miles. On what would otherwise be a good, effortless
touring bike, this is one feature which cries out
With a steady 80 bhp available, spread over a band
of 1,500 rpm and a long, flat torque curve, performance
is no problem. It seemed that the gear ratios were
spaced too far apart — for full performance
or even for ordinary road use, the bike would be that
much sweeter to ride with a close-ratio box. And after
the gearbox had been overhauled, gear selection was
slow and clunky.
Actual flexibility was quite remarkable. The 900
could be ridden down to 1,000 rpm in top and still
pull away, taking anything up to full throttle just
as quickly as the rider cared to feed it in.
During the performance tests at MIRA it poured with
rain, although this didn't prevent the 900 from
running a standing start quarter in 12.7 seconds.
What it would do in the dry is anybody's guess, but
it would have to be substantially better. The rain
seemed to have a greater effect on top speed. We were
looking for 130 mph or maybe more, but the first two
runs were only just above 120. On the next run, the
Honda picked up a groove in the surface and turned
itself sideways as it went through the lights —
at 119.8 mph. With a few violent wobbles it straightened
itself out and the next time round it managed 125
mph. It quite obviously wasn't going to go any faster
and the tyres, down to about 2mm of tread, were having
a hard time coping with the heavy rain.
The overall impression of the CB90 is that it is
more than just a performance machine: it is a highly
usable performance machine. It fits equally well into
the sports or touring categories, is very well thought
out and particularly pleasant to ride.
Competition is fierce in the big bike class, and
the 900 is quite reasonably priced for what it offers.
Most Japanese machines are shaved down by their production
engineers until there is little room for error. The
big performance machines will be the first to show
whether too many corners have been cut.
We noticed signs of weakness in the test model and
on other machines. Points like the mudguard failure
and engine covers which seem rather flimsy. The field
coil brushes failed on our motor and we've heard of
one of two alternator failures plus coils which seem
to be barely adequate. There are also extra stresses
in using a four-valve head — if extra power
is extracted as a result. We've seen one machine which
has cracked its head, along the casting joint where
the twin ports divide, and heard of others with similar
cracks. Whether it is simply the way they are made
or whether it is likely to cause a mechanical failure
are open to debate.
These points will probably not cause trouble
on a bike in normal use; but they do suggest that
the bike has been developed and whittled down until
its components are only just up to the job. While
they are doing this job they do it wonderfully well.
On!y time will tell if there's anything left in reserve.