On a trip to Japan, Olle swaps his RH68 for a works 50cc road
Motocross History part 1
Kasuo Kubo on the RH65.
Just before the start of the 1970
Grand-Prix series for the world motocross championship, Suzuki
team manager Ishikawa was asked if the 250cc Suzuki RH70 could
take the title. “Without fail”, he answered.
It was a bold prediction but
Ishikawa’s confidence was not misplaced. Very few machines have
so completely dominated a motocross season like the RH70 did in
1970. By the end of June that year, after taking 7 of the first
eight races, Suzuki had the Maker’s Cup clinched-this with 4
more Grand-Prix's to go through September on the brutal European
circuit. Further, by season’s end, Joel Robert and Sylvain
Geboers, two of the three-man Suzuki motocross team, had locked
up the first and second positions in individual standings. Olle
Pettersson added sixth place to cap an outstanding year.
Success stories are always
impressive, but they usually involve many long steps before the
realization of a dream. To really understand what goes into
winning and more importantly, why Suzuki fielded the effort, we
must look back to 1965 and ’66 when the firm made the first
tentative steps into motocross and began development of the RH
series motorcycle. Ultimate credit must go to the man who was
really the father of motocross at Suzuki, Mr. Okano, general
manager of research and development; and the entire racing
department headed by Mr. Ishikawa.
Motocross was a significant
departure for Suzuki at that time. In the 1950’s and ‘60’s all
the Suzuki competition effort had been concentrated on road
racing, which has vastly different machine requirements from
motocross. Initial impetus to go motocross racing came from
Japanese enthusiasts, who were racing Suzuki's in motocross,
running stock bikes with homemade modifications until the
competition arrived with specially designed machines. At the
urging of some influential racers, Suzuki began development of a
single purpose machine in 1965. The first effort was a complete
failure. In fact, the first bike was as far off as the RH70 of
1970 was right on.
The RH66 and RH67 of those years
were primarily development bikes. When Suzuki committed to
investigate the European motocross scene in 1967, they sent
their top rider, Kasuo Kubo, (who won the inaugural "All Japan
Motocross") a pair of RH67 bikes, and team manager Ishikawa off
to the races. Ishikawa, it should be noted, was no novice to
racing; he had been a European road race manager. And he had an
excellent technical background including a Masters degree in
mechanical engineering from Michigan State.
Ishikawa knew that they would
need a top rider that was dependable and always finished at or
near the top 4 or 5 places. He also understood that the rider
had to be very analytical, with the ability to ride fast enough
to determine the motorcycles short comings, and the mechanical
knowledge to pinpoint necessary changes. After attempts to sign
Torsten Hallman had failed due to prior contractual obligations,
Suzuki signed Sweden’s Olle Pettersson, and he was to become a
vital link in the RH development chain.
In 1967, Pettersson was 30 years
old, considered past his prime by some but well respected and he
understood motocross machinery better than most. That winter
Pettersson was invited to the Suzuki factory at Hamamatsu to try
the RH68. As he tells it, he went purely on speculation; there
was no contract for the coming season. A possible deal to ride
for the factory depended on whether he liked the machine. He
took 10 long days and examined and tested the machine from every
angle-then he gave his report. His first suggestion: “Redesign
it.” The basic model had to be changed, he said. It was a very
short bike bike because the Japanese riders tend to be smaller
than the Europeans; and a short wheelbase bike is was more
suited to the typical Japanese course at the time, rather than
the European GP tracks that Olle was used to.
Pettersson had exact
recommendations for changes; he’d found that the engine was too
far forward for optimum weight distribution; he wanted the foot
pegs moved further back, a slightly longer swing arm, a new
steering head angle, and a different frame configuration. All
were changes that would take time to accomplish.
He returned home with a new
contract and to prepare for the GP season, awaiting the new bike
but fully expecting that it would be impossible for all his
requested changes to be made in the time remaining before the
start of the series. “In less than a month,” he said, “I had the
new RH68, and I was astounded because they had done everything:
stretched the frame, changed the swingarm to the length I
wanted, moved the engine back, altered the steering head,
changed the fork damping plus other minor alterations. “We were
ready to go racing.”
According to Pettersson, the
only real problem they found after the season began was the air
cleaner. The air box that housed the filter was in a position
where mud thrown from the chain would plug the filter. “We’d
start out in a muddy race, running well, and the engine would
starve,” he said. “It was easy to modify, the important thing, I
think, is that the chassis was basically correct.”
Pettersson rode the first half
of 1968 with such unusual success (beginning with a win in the
first heat he entered) that he appeared destined to finish among
the first three in world standings. He was doing better than
anyone had hoped on a development bike. Meanwhile back at the
factory, things were humming. Suzuki’s racing department was
already preparing for the next year. They already had an
advanced version of the RH68, the RH69, and Pettersson was to
test it in Poland in mid-July.
Then disaster struck. On July 7th,
riding in a Swedish National event, Pettersson broke his thigh.
“It was an unfortunate time to get hurt”, he said. “I was in the
hospital two weeks, in plaster three months, and then I had to
have a skin graft. I was out of racing for eight months.”
To Suzuki’s credit they kept
faith in Pettersson. There was, after all, much at stake, and
Pettersson knew more about the competition potential of the RH
than anyone else. In March, he began some small races in
Belgium. He was back in business and so was the RH69, a little
behind schedule but racing.
The new machine was good. Most
of the changes made by the Suzuki engineers had to do with the
engine, following a trend suggested after Pettersson's initial
testing in Japan. At that time he noted that the rated 30 hp at
6500 rpm was more power than the bike really needed. Furthermore
it was too peaky, and much power was wasted in useless wheel
The RH69 was rated at 30 hp at
7000, not much different on paper than before but the effective
difference was felt on the track. The engineers had changed the
cylinder ports and exhaust pipe shape combinations and the
result was that they held the peak power but they created a much
wider power band than the 1968 model. Much time and effort was
made in altering the compression ratio, ignition timing,
carburetion, port timing and exhaust dimensions to achieve this.
One lesson learned and applied was a change in bore and stroke
between the RH67 and 68 models, from 66 x 73mm to 70 x 64mm. The
result of going to a shorter stroke was to give a higher rpm
peak power and this formed a better base to achieve a wider
Along the way and to Suzuki’s
credit, they concentrated on reducing the weight of the bike.
This was a priority and the RH69 was now down to an astounding
187 lbs, by far the lightest machine on the GP circuit. Some 24
pounds had been lopped of the RH68, while the RH67 at 235
pounds, had been by comparison a real heavyweight.
Pettersson knew that in the RH69
he had his dream machine. In spite of a still tender leg, he
finished third place in the 1969 World Championship standings.
The development time was complete and it was now time for Suzuki
to mount their all-out effort.
In January 1970 they invited
Joel Robert and Sylvain Geboers to Japan to try out the brand
new RH70. The two GP stars had nothing but praise for the light
weight, precise handling, good power band and excellent peak
power of the bike. They liked the way the engine ran vibration
free right up to the 7000 rpm maximum. The steady throttle
response, without unwanted power bursts in the rev band, made
the bike tractable. One of the first things Joel commented on
was how the light weight of the bike reduced rider fatigue and
how easy it was to control. Both Joel and Sylvain believed that
the bike was so much better than anything else they had ridden,
that they would easily win the World Championship.
Technically, the RH70 was
similar to the RH69 in that the frames both weighed about 16
lbs. Swing arms were constructed from aluminum. The front forks
were similar to Ceriani’s and had 6.5 inches of travel. The rear
shocks were very light and had superior damping qualities but
had to be changed often. Both bikes used full width hubs using
single leading brake shoes. The RH70 used up dated poly
propylene fenders where as the RH69 used aluminum. The engines
made considerable use of sand castings because of it’s limited
production for the factory race team only. Much weight was saved
in the engine through the use of magnesium components. The
transmission was a five speed and the clutch was a wet six plate
The RH70 was the result of constant small changes which added up
to a beautifully integrated racing unit. In 1969, Pettersson got
a dramatic example of the magnitude of the changes when he rode
the original bike offered him by Suzuki. He said he could
scarcely believe the difference that a few seasons had brought.
Even he had not realized the overall difference that had taken
place between the preliminary and final design until he rode the
early bike and compared it to the RH70.
The RH68 parked in the
With spikes in the tires, Olle tests the RH68 in the Winter.
Somewhere in Europe. Suzuki had a lot of faith in Olle's ability
to develop their motocross bike.
Victory on the RH69 in Sweden.
Check out the stinger on Olle's RH69.
Joel Robert on the RH70.
See the Suzuki RH68 and RH70 in rare
footage on this DVD
Suzuki RH70 thru RH73 in action on this DVD