This will be, for the time being, Honda's last year in Grand
Prix racing. They pull out of 50 and 125 cc racing at the end of
1966 and, at the end of the 1967 season, Honda withdraws from the
other three classes. They have achieved what they set out to do:
from a totally obscure and unknown company at the start of 1960,
they have become the biggest and best known motorcycle manufacturer
in the world. Yet, the decision comes unexpected – Hailwood and
Bryans have already signed their contracts for 1968. Moreover, there
are rumours about new, exciting racers – a 50 cc triple, a 125 cc
six cylinder and a V8 for the 250 cc class.
Suzuki also stops at the end of the season, and Yamaha follows
one year later.
In the 250 cc there is a fierce, ongoing battle between Read
and Ivy on the Yamaha fours and Hailwood and Bryans on the Honda
sixes, a battle that's only decided in the last race of the season.
The Yamahas have been improved and are lower and more powerful,
they have now some 5 horses more than the Honda six. This is compensated
by the fabulous riding of Hailwood, but on very fast circuits, such
as Francorchamps and Monza, the Yamahas have the advantage because
of their superior speed.
Hailwood and Read both end up with the same number of points, but
Hailwood wins the title, for he has 5 wins against Read's four.
Ivy ends up third. The Manufacturers' title goes to Honda, followed
by Yamaha, MZ and Bultaco.
During 1966, Mike had been complaining about the roadholding
and handling of the fours, and Honda decide to enlarge the 250 cc
six, about which Hailwood had no complaints, to give him a new weapon
for the 350 cc class. With more power than the four and nearly 20
kg less weight, the combination Hailwood and Honda six is so superior,
that Hailwood wins the title by winning the first five races, and
then hands the bike over to Ralph Bryans, who gathers enough points
during the rest of the season to end up third in the world championship.
Agostini is second with the MV. The manufacturers' title goes to
Honda, ahead of MV Agusta, MZ, Aermacchi and Benelli.
The battle in the 500 cc class is between Hailwood and Giacomo
Agostini with the MV. Hailwood complains, that he has to fight two
opponents: Ago and his Honda, which, although it has a superb engine,
has very bad road holding. At the end of the season, both riders
have the same number of points and both have 5 wins; Hailwood has
two second placings, but Agostini has three seconds and so becomes
world champion, with Hailwood second and John Hartle (Matchless)
The RC166 of 1967 is the same bike as the one of the previous
season, the only difference being an increase in power : now 62
bhp at 17,000 rpm.
In the one but last GP of the season, in Canada, a new six cylinder
appears. It seems this bike is clearly more powerful than the RC166,
and, according to Nobby Clarke, has a shorter stroke than the RC166,
and a smaller valve angle. At left is the RC166 as taken in the
paddock at Assen.
Image below is probably one of the most famous racing pictures
ever – it shows Mike at Clermont-Ferrand, leaning to the limit.
1967 250cc RC166 Honda - taken in the paddock
The RC174 is the enlarged version of the RC166, the total cylinder
capacity of 297.06 cc is achieved by retaining the bore of 41 mm
and increasing the stroke to 37.5 mm. Compression ratio is 10.6
: 1. Inlet valve diameter is 16.5 mm, exhaust valve 14 mm. Carburettor
diameter is 22 mm. Power output is 67 bhp at 17,000 rpm, maximum
torque is 2.8 kgm at 16,000 rpm.
Image at right shows Mike at the Isle of Man TT with the RC174.
The RC181 this year no longer has the bolted-on sub-frame, and
the megaphones have lost the reverse cones.
Capacity is increased to 499.7 cc by enlarging the bore to 57.5
mm; the stroke remains the same at 48 mm. Power output is now nearly
90 bhp at 12,000 rpm, maximum torque is 5.23 kgm at 10,000 rpm.
Refer images at right.
One of the experiments to improve handling is mounting the front
wheel in excenters, so the trail could be altered – it didn't bring
Dry weight is 151 kg, top speed is given as more than 260 km/h.
When Honda showed for the first time on the Isle of Man in 1959,
nobody could have foreseen the impact that this obscure Japanese
brand would have on the motorcycle world in general and the GP racing
scene in particular. They caused a revolution in racing bike design,
and paved the way for their Japanese competitors – Yamaha and Suzuki
appeared in 1961, followed in 1966 by Kawasaki and Bridgestone.
Year after year the number of cylinders rose to enable higher engine
speeds and hence higher power output. Had they continued racing,
we would no doubt have seen a 50 cc triple, a 125 cc six, and a
250 cc V8. Alas, it was not to be. After nine successful years,
sixteen world championships and hundred and thirty-eight GP victories,
Honda had achieved their goal, and retired from GP racing.
Their influence on engine design was profound. When they arrived
in Man with four-valve cylinder heads, the opinion was voiced that
those Japanese were a bit behind the times – four-valve heads had
been used extensively in Europe, and had shown no advantage over
two-valve heads. But when Honda started winning with that "outdated"
construction, those voices from the European "experts" were silenced.
Benelli was the first to take a leaf out of Honda's book and converted
their 250 cc four to four valves – which gave them an increase in
power of 5 bhp and made an end to the recurring valve breakage.
They were soon followed by MV Agusta and Jawa.
The specific power of the Honda racers, bhp per litre, has,
as far as I know, never been surpassed by engines running on commercial
fuel. Their actual power output should be food for thought for those
people who, taking a standard Honda CB350 twin or CB500 four, and
putting in a number of tuning goodies, claim powers that not only
rival that of the Honda works racers, but often surpasses it! Hard
to believe, to say the least!
After 1967, Honda's race activities stopped, but on a much more
modest scale, the Honda RSC, the Racing Service Club, continued
making special parts, race kits and complete bikes, e.g. the CYB350.
Another development was a light 750 cc racer, developed from the
CB500 four. Alas this development stopped when the development engineer
and test rider, M. Sumiya, was killed in a race accident.
Gradually, the factory got involved again, leading to their
participation in Daytona in 1970, and their ultimate re-entrance
in the GP scene. But that's another story.