1972 Honda RC125M
PPhoto Haim Ronen.
1972 Honda RC125M
Honda's first works motocrosser Taichi Yoshimura with his own
copy of Legendary Motocross Bikes
Order a photo CD of the RC125M
Honda Motocross the
When the 10 boxes containing the 1972
RC125M arrived from Japan, I was very eager to see exactly what
this bike was all about. Prior to this, the only time I had seen
or ever heard of a 1972 RC125 was back in 1972. The bike was
featured in a small press release in Cycle World magazine. It
looked super trick and competitive but that was it. It never
showed up anywhere and for nearly 40 years the details remained
unknown and forgotten. The truth is, very few were ever made and
they never left Japan. The bike featured here is the only one
left in the world and it is in 100% original condition. It is
the earliest known RC Honda motocross bike in existence.
When I started to open the boxes, Not only
was the bike in remarkable condition, I was stunned by the
quality of the individual parts and how lightweight everything
was; this is a very special bike. The attention to detail rivals
that of the 1980’s HRC bikes and in many ways surpasses them.
The quality and handwork is amazing and many of the parts are
like jewelry. Parts like the titanium exhaust manifold, needle
bearings in the clutch cover for the kick-start shaft and the
clutch assembly just to name a few. Everything in the engine is
machined with laser like precision. You spin something and it
just keeps spinning, no friction. I had never seen anything like
this and the weight at 138 lbs. is just mind-boggling! I have
seen inside Bob Hannah’s championship bikes. I have seen inside
DeCoster’s and Joel Robert’s Suzuki’s. The HRC Honda’s…. seen
them too. All unbelievable bikes but this was way over the top.
I had to find out what the story was behind this incredible
motorcycle. Fortunately Holly, the guy I acquired it from knows
and is very good friends with the guy that actually developed
and raced this very motorcycle in the “All Japan Motocross
Championship” back in 1972. Mr. Taichi Yoshimura. After asking
about the history, Taichi was kind enough to sit down with Holly
and his wife Masayo and tell the incredible back-story from the
beginning. This would be the first time this story would be told
and in print anywhere! To fully understand the history and
significance of this historic motorcycle a little background
history is warranted.
From the inception of the sport thru the
early 1960’s, motocross was dominated by 4-strokes. From the
late 1950’s thru the early 1960’s, companies such as Monark,
Lito, Husqvarna, FN, BSA and others made some awesome
well-developed motocross machinery. These bikes were designed
and for the most part hand built by some of the best engineers,
craftsmen and riders of the day. Their ability to travel at high
rates of speed over extremely rough terrain was truly amazing.
They were state of the art motocross bikes made in very limited
numbers and ridden by the best motocross riders in the world to
do one thing, win championships. But all of that was about to
change. By the early to mid 1960’s, European manufacturers like
CZ, Husqvarna and Greeves to name a few, started designing and
building 2-stroke motocross bikes. These bikes were lighter and
handled much better than the 4-stroke bikes that had dominated
the sport for decades. Almost overnight the 4-stroke motocross
bike became obsolete.
It’s no secret that in the late 60’s and
early 70’s, motocross had become the fastest growing motorsport
in the world. It’s also no secret that at that same time, the
Japanese companies Suzuki, Yamaha and Kawasaki were getting
involved in a big way and by the early 70’s were dominating the
sport at the professional level with super lightweight 2-stroke
works bikes. This dominance led to unprecedented sales of their
production bikes and to this day, the sales figures from this
era remain unmatched! People from all walks of life were now
getting involved in this new phenomenon of motocross.
1967 was the year that motocross
officially came to Japan. It was the year of the first “All
Japan Motocross” championship, sanctioned by the Motorcycle
Federation of Japan. At this time Suzuki led the way with a
development program that started in 1965 and was well on their
way to building a competitive 2-stroke motocross bike. By 1970
Suzuki had developed the incredible works RH70 and in the hands
of multi world champion, Belgium’s Joel Robert, delivered Suzuki
and Japan’s first FIM World Championship. Yamaha wasn’t far
behind with Sweden’s multi world champion Torsten Hallman and
Kawasaki was now involved too. Honda however, was not involved.
In-fact, Honda’s founder and President Mr. Soichiro Honda went
out of his way to say “Honda will never build a 2-stroke
Mr. Honda was a very competitive man and
under his supervision, Honda Motors was very much involved in GP
road racing. His attitude and approach was much the same as Enzo
Ferrari’s of auto racing fame, “win at all cost.” Second place
was not an option and everyone on the team understood this. He
hired the best engineers and technicians that graduated from the
most prestigious universities in the world to design build the
best race bikes ever built. Some amazing machinery was conceived
and built by this early Honda Motors works R&D team like the
RC166 250cc six-cylinder 19,000rpm road-racer or the 5 cylinder
125cc. These bikes were 4-strokes! The result of all this was
complete dominance in the super competitive, highly prestigious
world championship road race series in Europe. The cost of this
was staggering but Honda achieved a global status that no
ad-campaign could buy. They proved to the world that they could
design and build anything better that anyone else. When they
achieved all their goals, they stopped and after the 1967
season, Honda pulled out of GP road-racing.
Now that Honda had pulled out of GP road
racing, at about the same time motocross started in Japan, some
of the younger engineers in the works R&D team formed a
voluntary group called “The Association to Study the
Motorcycle.” This was an independent group, not officially an
arm of Honda, even though they all worked for Honda. These guys
were race enthusiasts through and
through and collectively, they turned their eye and attention to
this new sport of motocross.
Since it was common knowledge throughout
Honda Motors that the president disliked 2-strokes they were
limited to using a 4-stroke Honda machine in an attempt to make
it competitive against the 2-stroke machines from other
manufacturers. The bike they chose to start with was the Honda
production SL125. After spending considerable time reducing its
weight and modifying the engine they felt they were
ready to put their highly modified SL to the test. In May of
1969, as Honda’s first official motocross team, they entered the
6th round of the MFJ Motocross Grand Prix in Kurume,
In their first real competition in a
sanctioned race against the best 2-stroke works machines from
the other Japanese manufacturers, the sobering reality set in.
Although they finished the race, Honda’s highly modified
4-stroke was easily outclassed and their attempt ended in
failure. They were made acutely aware of the progress of the
state of the art 2-stroke engines and that any attempt to win
with the 4-stroke would be very difficult. They also realized
that the more motocross pervaded as a sport, the more Honda
would be left behind as long as they hesitated to build a
The atmosphere within the company was
still very strong against the 2-strokes but the Honda race team
did make the company aware of the situation and understand the
problem. This however did not dampen their enthusiasm. At a
request made by the younger engineers to R&D management, they
were allowed to purchase two European motocross bikes for
evaluation. This was a private and unofficial arrangement made
by the R&D management and the independent voluntary group. One
bike was a Greeves and the other a Husqvarna. When the bikes
arrived, the young engineers examined the cutting edge machines
in great detail and often dreamt of the day when they could
Development of project 335
At Honda, development of a new 4-stroke
machine was underway. It would be the successor to the “CL”
scrambler series. It was the 250 single SL250. Many of the
members from the R&D Team gave it a very careful consideration
as the foundation of a race bike but considering it would have
to compete against 2-strokes they couldn’t help having
misgivings about its potential. The rest of the bike seemed good
and so they decided to submit a proposal for developing a
2-stroke engine for the SL250T, as it would be called (code name
335). This would run parallel with the original plan of the
development of the 4-stroke engine. The proposal was submitted
in January of 1971. R&D management allowed this to happen mainly
because of the enthusiasm of the young engineers. It cannot be
stressed enough how taboo the idea was for Honda to build a
2-stroke at this time.
When the SL250 4-stroke development was
completed it was a huge success as an off-road bike and the
2-stroke project quickly lost its importance. The new 4-stroke
single was in some ways a break through, but it still was not up
to par with the 2-stroke race engines at any level as far as
Even though the project was shelved, the
young engineers proceeded to develop the new engine and at this
time the code name was changed to 335B. Within 6 months they had
the engine power level clearing 30ps/7000rpm. This was their
With this goal achieved, they started on
the chassis. At first the frame was copied from a Husqvarna.
Then the remaining components were from other various
competitors. The final bike looked like some sort of homemade
bike patched together but this was of unimportance to the
enthusiastic engineers. They wanted to test the engine in a real
life motocross environment in a real race and they wanted the
results as soon as possible. In a strange way, this was the very
first 2-stroke Honda motocross bike.
Once the bike was completed they decided
to enter it in the All Japan Motocross Championship. Since this
was not an official Honda, they chose a race in the series that
was far away from any large city where the crowd would be
smaller and hoped that they wouldn’t draw any attention. They
entered the race as a private team. The event was held August
22, 1971 at the 9th round in Mine, Yamaguchi.
Contrary to their expectations, they were recognized immediately
and got all kinds of attention from the other teams and the
media. They DNF’d their debut race due to suspension problems
and not enough preparation to a hastily built machine but they
were able to get enough feedback on the engine performance. Most
of it was positive. The magazines and other media outlets wasted
no time in reporting about Honda’s new 2-stroke at Mine,
Yamaguchi. The horse was out of the barn!
Mr Matsuura awaits the start on the 335a
at Mine Yamaguchi Japan. Note the Yamaha DT2 gas tank..
Much attention and interest was now
directed at Honda and this new 2-stroke motocross bike. The
trouble was it wasn’t an official Honda project. It was just
some enthusiastic Honda engineers from the private club, “The
Association to Study the Motorcycle.”
What would happen if Mr. Honda
found out? After all he hated 2-strokes and publically said the
company would never build one. Now
that the secret was no longer a secret the R&D management
decided that the 335B project idea was successful and due to the
enormous interest from the media, they decided to make an
official proposal to Mr. Soichiro Honda himself. They were going
to do the unthinkable. Ask Mr. Honda, the same guy who said
Honda will never build a 2-stroke, to build an official Honda
2-stroke works motocross bike.
It’s official Honda enters
motocross with a 2-stroke
Those that were at the meeting remember it
well. After quietly listening to the proposal, Mr. Honda’s
response was very short and to the point. “If you insist on
building a 2-stroke engine, you can do it.” Once you start, it
had better be the best 2-stroke bike in the world and the engine
should be superior to any of the competitors!” The young
engineers dream had come true, they got the green light, but the
pressure was on. Mr. Honda
was a very driven man especially when it came to racing. He did
not accept losing or failure and did not handle it well when it
happened. Some of the best engineers in the company learned this
the hard way. You did not want to be on his bad side if you were
part of something that did not work or win. This coupled with
the fact that he did not like 2-strokes really put the heat on
these young enthusiastic engineers.
They absolutely could not fail. They had to dominate like they
did in the road-race GP’s and build the best motocross bike in
the world. To this day, no one knows if Mr. Honda ever knew
about the secret Honda 2-stroke 335B.
Once the President gave the OK, the
project was renamed 335C. The same R&D engineers that built the
incredible works road-racers that dominated the GP’s in the 60’s
would now start with a clean sheet of paper and attempt to build
the best 2-stroke motocross bike in the world from the ground
up. Nothing would be spared in this attempt. They had to
was a huge deal,” says ex-Team Honda racing manager and
current Honda R&D employee Dave Arnold, who helped build Team
Honda into the biggest, baddest and most successful motocross
team ever during the ’70s and ’80s. “Mr. Honda was absolutely a
win-at-all-cost sort of guy, and he was also a little crazy – so
I’m positive the team was very, very nervous about going to him
with the idea. Mr. Honda’s temper was well known throughout the
company, and there were several incidents where he publically
abused engineers emotionally and physically for mechanical
failures.” "Mr. Honda did not like 2-strokes, that’s for sure.
But he was also no dummy, and he obviously realized where things
were going. And since Honda was first and foremost an engine
company, it made sense for him to want to dominate, and right
out of the gate. It was all about proving Honda was the best
engine manufacturer in the world – just as they had so
successfully in the ’60s during their GP roadracing experience.”
As far as putting together a race team for
the AJMC, Honda already had the pieces in place. They had an
excellent administrative staff such as manager, mechanics,
engineers and coordinator with plenty of professional race
experience. Kunihiko Aika was the chief engineer. Katsumasa
Suzuki was the chief mechanic and Kazuhisa Sekiguchi was the MX
team advisor. In November 1971 the negotiation of two of the
best riders in Japan were being pursued in profound secrecy.
They hired Koichi Ueno, and from the works Suzuki team, Taichi
Yoshimura to be the development riders and compete in the AJMC.
The announcement of this caused a huge sensation in Japan and
immediately put the duo in the limelight. Shortly after the
development started, Ueno developed an illness that would keep
him bedridden the remainder of the season and this left
Yoshimura alone to develop and race the bikes.
In January 1972, the official name RC250M
was given to the 335C. This was the official name for any
machine developed under “Honda Works.” If is designated RC it is
works and that means this will be Hondas best effort for
Design, developing and testing began very
soon and the work was very intense and focused. The bike was
getting better and better at a very quick pace. The bike had
progressed to the point where the team felt it was time to enter
it in the AJMC. The opening round was March 12, 1972 at a
high-speed track in Yatabe, Ibaragi. In the bikes debut race,
the result was a 6th place. The RC250M had a few
setbacks such as an over heated engine, carburetor jetting was
off and wrong suspension setting. The team’s inexperience in
motocross was evident as this was completely different than road
racing. Catching up to the other teams experience and surpassing
them was a priority.
After the first race the team worked on
all the issues one by one. Trial and error until it was
perfected. “We want to catch the front runners and somehow
overtake them no matter what. We want to gain the top technology
in the 2-stroke world.” It was those days that such enthusiasm
gave them energy to carry out the unique research at the
racetrack. For example; One of the team members went up to a
competitors works machines from behind, and pushed the palm of
his hand onto the exhaust pipe so that the mark could be
measured to learn it’s diameter that had a big influence of
engine power. Another member stayed at the track late and after
everybody left, went through the other works teams trash to try
and find anything such as a broken piston ring or gasket so they
could analyze the material. After a great deal of trial and
error, the team felt the RC250M was ready to win.
Koichi Ueno #1 and Taichi Yoshimura
#3 on the 335c
The first motocross victory
On June 4th
1972, round 6 of the AJMC at Kannabe ski area, his Highness
Prince Takamatsu of the Imperial Family of Japan and founder and
president of Honda Motor Company Soichiro Honda were in
attendance in the honored visitor’s gallery. They were there to
see the first official 2-stroke works Honda compete for the
championship. The team was extremely nervous because of his
presence. It was just eight Months before that Mr. Honda
approved the 2-stroke and everyone there was fully aware of Mr.
Honda’s words. The bike had to be the best in the world.
In the first heat
after getting the holeshot, Taichi was in a close battle for the
lead and ended up with a 2nd. It was his best moto
finish of the season so far. In the second heat, Taichi used the
fantastic Honda power, got the holeshot again and went wire to
wire for the win. Winning in front of Mr. Honda was a great
satisfaction and the team that worked so hard had finally won.
The research team and their RC250M had taken an important step
into making the best 2-stroke engine in the world.
original 1972 factory Honda jersey. This was the first official
works Honda jersey and one of only a few remaining in the world.
The word Honda and T. YOSHIMURA are embroidered. Way before HRC,
it was called "Technical Sports Honda." Note the patch at top
left. The jersey was donated to MXworksbike.com by Holly and
The following photos were taken
moments after Taichi's historic win on the RC250M at Kannabe ski
area. Taichi Yoshimura archives.
History is made. The motocross world would
Order a photo CD of the RC125M
development on the RC250M was complete, it was decided to put
the same effort into developing a 125, the RC125M. This was
started in 1972 and much of what was learned developing the
RC250M was applied to the RC125M. And because of this the
development proceeded at a much faster pace. When completed the
bike was extremely fast and very lightweight. The new RC125M
competed in its first race on July 2nd at the 7th
round of the AJMC and finished a very respectable 4th.
In the 8th round, they moved up and got 3rd.
In the 9th round, Taichi Yoshimura and the RC125M
won! This was Honda’s first ever win in 125 motocross and it was
only the third time the bike had ever been raced. An amazing
achievement since they were competing against the works
Yamaha’s, Suzuki’s and Kawasaki’s, all of which had many years
of experience and very good bikes.
first 125 motocross win is moments away at Aso Japan.
The 1972 RC125M was
the result of two years of solid non-stop development. Even
though construction of the bike started in 1972, much of the
data that the research team learned from the 335/RC250M project
was applied to the 125. The bike was excellent almost from the
A 125 is much more
sensitive to weight and power than say a 250. Nowhere is
lightweight more important than on a 125. To produce low lap
times, the bikes momentum on the race track is very important
and must be maintained. A 125 simply does not have the engine
torque to pull itself out if any lost momentum like that of a
larger bike. The Honda engineers understood this and to build
the best 125 possible, weight reduction was a primary goal. Each
part was designed and made as light as possible without
sacrificing reliability. Parts like the swingarm, wheel hubs and
suspension components that make up the un-sprung weight were
given much attention to be very lightweight. At just over 3 lbs,
the all aluminum swingarm is a great example of how much
attention was paid to weight reduction. The rear shocks were
made with extra large bodies and large shafts but were very
lightweight. Since the RC was made to be raced and serviced by
Honda’s works team only, extreme measures could be taken in
reducing weight as cost was not an issue and the bike was
maintained by some of the best engineers and mechanics in the
Honda has always
had pride in their engine development and the RC125M was no
exception. The engineers applied every bit of knowledge from
their master’s degrees in engineering and then some when
designing the little 125 power plant. Several engine designs
were initially tried with different configurations. Five and six
speed gearboxes were used and the ratios were very carefully
matched to the engine power band. Only 350cc of oil capacity was
used in the transmission case. The engine components were made
with the lightest and strongest materials possible. They were
machined with extreme precision at very close tolerances. This
greatly reduced any friction of moving parts. The entire clutch
assembly was fastened to the main shaft with a large cir-clip to
save weight. The complete engine weighed less than 30lbs and
made 21 horsepower peaking at 9500rpm.
Overall the bike
was a huge success. With a very lightweight chassis and a very
highly tuned engine the acceleration of the RC was overwhelming.
The extreme lightweight of the machine was also a huge advantage
on the rough tracks as well as improving handling and braking.
Every single aspect of the bikes performance was greatly
enhanced because of this.
The result of
producing a bike of this caliber is an incredible achievement
especially since it was Honda’s first effort at a 125 2-stroke.
For a 125 to be over 60 lbs lighter than a standard 125 of the
day and carry an engine that has near 250 performance puts this
bike on the short list of one of the most advanced motocross
bike ever built in relative terms. The young engineers in
Honda’s works R&D shop that started out as a group of
enthusiasts with a dream succeeded in building a bike that I’m
sure surpassed even their highest expectations. But when
Soichiro Honda is your boss and says it had to be the best
2-stroke in the world, they really didn’t have much of a choice.
Order a photo CD of the RC125M
It is amazing that the bike is in this all
original un-restored condition. .Only
the number plate backgrounds and the Honda logo on the tank were
remade. A tremendous amount of research went into getting them
exactly to original spec.
Throttle Jockey in Kokomo Indiana did a
fantastic job making the number plate backgrounds and the 1972
font gold "Honda" logo on the tank.
Photo Haim Ronen
The Number plate from the bike was sent back to Japan for Taichi's autograph.
Taichi Yoshimura, Honda's first works
rider (center) tells Holly the incredible back story about how
Honda secretly first got into motocross (Mr Honda said he would
never build a 2-stroke) and about the development of the first
RC works Honda's. Holly's wife Masayo takes notes.
Taichi Yoshimura Reflects
At the end of the
1971 season I received an offer from Honda to develop and race
their new 2-stroke motocross bike. I knew of Honda’s high
standards and thought they would do a good job so I decided to
accept the offer. Prior to this I was a factory rider for
When I saw the bike
for the first time Mr. Matuura and Mr. Kihara was riding it at
the Nishinihon Circuit. At the time I never heard or thought
Honda would make a 2-stroke. I thought the bike would be
successful though because Honda was involved.
When I first rode
the bike the instantaneous power of the engine was much more
powerful than I was expecting. There were some durability
problems though in the beginning, mainly overheating.
One of the problems
we had initially was to learn the correct silicone content for
the piston. For example; originally the material of the piston
was made on the basis of our 4-stroke pistons that are always
soaked in oil. The tolerances were not as critical on a 4-stroke
machine because of this. On the 2-stroke, the cylinder had
portholes and because of the portholes the cylinder temperature
was not consistent with the temperature of the piston. This was
compensated for by the silicone content of the piston. We had
many engine failures because of this in the beginning. All of
this was new to Honda because prior to this, they only built
4-strokes. Cylinder studs that went from the case to the head
also contributed to engine failure. The stud gets very hot but
has no way to dissipate the heat and will cause the cylinder to
distort. We solved this by fastening the cylinder to the case
near the transfer port. We had to learn all of this through a
continuation of trial and errors.
We had a lot of
knowledge of 4-strokes but knew very little about 2-strokes when
we first started. I gradually understood the importance of the
exhaust chamber. It was similar to the camshaft of a 4-stroke.
Gradually we became accustomed to the 2-strokes, but they were
very noisy! Also, in the beginning the suspension was not so
good. By the time the 1972 race season began, we had the engine
very reliable and the bike was ready.
I was very
confident and thought if the bike didn’t break down I could win.
When I won with the 250 and the 125 for the first time, both
races were rainy days and the bike was not as big of a factor as
it would have been in dry conditions. The 250 win was at Kannabe
and the 125 win was at Aso. These were the first wins for Honda
for the 125 and 250.
In those days
technology was not like it is today. Back then, If the bike
didn’t fit the rider you would lose. When the rider is in
agreement with the bike the gears mesh and you get good results.
I was a technical rider and very confident in my ability, this
was good for development. We did some mean things to the young
engineers back then. I remember sometimes kicking the machine
when they didn’t get it right. They must have been upset with me
at times and when I look back on it now, I was sorry for kicking
the machine that many people made for me. However, these days
there are many young people who could use a good kicking.
I enjoyed my time
at Honda very much. I liked developing a new bike more than I
liked racing a developed one. Honda gave me a spot that I really
enjoyed. It was a pleasure to work there developing the RC works
bikes. While developing the bikes, I could feel the difference
in performance of the machine little by little until it was
right. Honda is superb at development in an unknown field.
The first races I
won with the RC will always be in my memories. But I don’t
forget about the races I rode with determination even if I won
Summary of the RC125M
Way back in 1972
when I first saw the press release in Cycle World featuring the
RC125M, I remember being much more impressed with it than I was
with the 250 (335) bike that was announced a little earlier. The
top production 125 bikes at that time were the 200+ lb. Penton’s
and Monark’s. In comparison, the Honda RC was in another world.
It was very sleek and had that all business “no frills works
bike” look to it. Everything just seemed like it was in the
right place. Probably the most impressive part that stood out in
the press release was the stat sheet. They had a claimed weight
of 154 lbs. listed. This was unbelievable! It also showed how
serious and to what level Honda was getting into motocross. From
that point on, the 1972 RC125M has always been my favorite Honda
even though the closest I ever got to one was that photograph in
Cycle World magazine.
examination, the bike has far exceeded any pre-conceived
expectations. The thirty eight year old mystery is now a
reality. There are so many things that set this bike apart from
the other works bikes but the thing that amazes me the most is
the same thing that amazed me the most back in 1972. The weight,
only it is 16 lbs lighter than the stat sheet said it was. I am
a firm believer that when Honda wants to win, “get out of the
Holly, the man who made this
acquisition possible with his good friend and Honda's first
works motocross rider Taichi Yoshimura.
Two great friends after the exclusive
interview Holly and Taichi Yoshimura.
Before heading to the states the RC got
the official "Peter Rabbit" weigh-in by our good friend Masafumi "Holly" Horiguchi in Japan. We will be doing many
projects with Holly in the future. He is a first class guy and a
true enthusiast. Check out his web site
It is official.....63 kgs! This makes the
1972 RC125M the lightest motocross bike ever built. Holly (on
the right) and his assistant Toshio balance the RC for the weigh-in.
These guys are crazy!!!
Honda factory rider Taichi Yoshimura at
the "All Japan Motocross" in 1972 aboard the RC125M.
RC125M assembly page
Taichi Yoshimura Today
So what does Taichi Yoshimura do today?
Taichi is as busy as ever. He owns the famous RS Taichi clothing
company. An international high end motorcycle apparel company
www.rs-taichi.com. Also Taichi is still very active in
motocross. He is the team manager for the Suzuki factory
motocross team in Japan.
Order a photo CD of the RC125M