Journal: Honda's RC166 Had More than Met the Eye

Honda’s RC166 Had More than Met the Eye

By Alan Franklin
April 5, 2013
16 comments

Perfection, one hundred percent, ten out of ten—that’s what utter domination looks like, and it also happens to be Honda’s 1966 250cc motorcycle World Championship Series record. With GP racing great Mike Hailwood in the saddle of the incredible RC166, Honda easily secured that year’s rider’s and constructor’s titles, an accomplishment he repeated in 1967. The RC166 would still be a legend today if its only accolades were for competition success and sheer physical beauty, but there’s much, much more to it than that—beneath its delicately shaped fairing and iconic livery there’s a hidden universe of miniature mechanical magic.

In only 250cc Honda managed to squeeze in six tiny cylinders, four cams, and 24 valves the size of pencil erasers. Fed by six diminutive carburetors, it revved to nearly 20,000 RPM and made 65 HP—extrapolated over two liters, that makes for a 48 cylinder, 192 valve, 32 cam, 520 HP motor. In conjunction with a seven speed gearbox, it propelled the RC166’s tiny frame to a top speed of well over 150 MPH. The quality of construction and engineering needed to achieve such amazing complexity and miniaturization is simply mind-boggling, especially considering it came from an age when designers relied on slide rules and drafting tables—the age of computer-aided design was still well over a decade away.

With a crankshaft made of 13 separate components, each no larger than a domino, it was said to be so delicate that it could easily be deformed by hand, yet held up to the astronomical forces exerted upon it when spinning 333 times per second and twisting out the equivalent power of an average Japanese family car of the day. This was only made possible by the use of incredibly precise construction jigs that allowed the crank to be assembled with the kind of accuracy normally reserved for achieving space flight. Ludovic Surcin, designer of the jigs, likened the task to balancing thirteen billiard balls on top of each other and then making sure they stay put.

The engine had effectively no flywheel to speak of, and could rev from idle to past redline with one blip of the throttle, destroying the whole thing in the process. To minimize flex and maximize inertial efficiency, camshafts were barrel shaped, concentrating their mass at the center—this meant that each valve’s geometry varied wildly from one cylinder to the next, with different lobe shapes for each one. Many oil passages are as narrow as half a millimeter, unseen except through the use of x-rays. How they kept the thing running with simple hand tools rather than lasers and microrobotics is a mystery for the ages.

This is the type of engineering excellence that once defined Honda, back in the day when Soichiro was still at the helm of a company he saw as his own personal design playground, before market share and MPG dictated corporate strategy. It’s the Honda whose first-ever car was an F1 machine with a gem-like 1.5 liter V12, whose first road car used an all roller-bearing engine and independent chain drive to the rear wheels, whose use of double wishbone suspension in inexpensive hatchbacks and economy cars made them the first choice among several generations of young enthusiasts. It’s the Honda we miss like an old friend, the one we hope to see again someday soon.

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16 Comments on "Honda’s RC166 Had More than Met the Eye"

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John A. Frye
John A. Frye
1 month 13 days ago

” It’s the Honda we miss like an old friend, the one we hope to see again someday soon.” The tired old phrase…

Look at the brilliance of the RC213v and it’s dominance within regulations that allow little innovation. They still produce some of the most fantastic engines in the world- the competition has just gotten tougher.

Ron A Smith
Ron A Smith
1 year 7 months ago

Saw this bike run twice, Willow Springs in the pits & on the track & at Del Mar Concours in the paddocks, & was totally mesmerized both times. If morphed into a litre GP bike, it would make over 250hp, which is modern day MotoGP performance. That fact alone is mind-boggling given Honda designed & built the machine fifty (50) years ago. Get your hands on the April 2004 MotorCyclist magazine & read the story about cloning this bike. The modern day engine guys who cloned the motor stated Honda’s technology could NOT have existed in the mid-60’s… absolutely impossible!!

John Hanson
John Hanson
1 year 11 months ago

I can remember being in the paddock with my Manx and the Honda firing up it brought the paddock to a stand still and giving me goose bumps and then hearing it come up behind as it lapped me in the race

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2 years 3 days ago

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Neil Morton
Neil Morton
2 years 4 months ago

Saw and heard one at a race in Ireland probably 67. Mike the bike wasn’t riding but it lapped every thing on a very short track.
One of the loudest machines I have ever heard.

Kain Baigent
Kain Baigent
2 years 8 months ago

Hi Alan
I emailed the info line at ‘Petrolicious’ to ask some important questions. I hope you get it passed onto you, especially after reading your wonderful article on the RC166.
Many thanks
Kain

Ray143
Ray143
3 years 5 months ago
Ivan Wagar was the asst. editor of Cycle World in ’62/’63. He and I raced m/c’s all over Calif. He got to go to Japan after Joe Parkhurst had been there. He said the first impression of Japan was the bullet train that he rode from Tokyo down to Hokido (sp). But he said the train was nothing like the Honda facilities. Ivan was from England, and his thoughts were that England had a lot of catching up to even get even with what Mr. Honda had created. Now 50 years later Soichiro Honda san standards that no one has… Read more »
Rip Curl
Rip Curl
3 years 7 months ago

That motorcycle is such a wonderous piece of engineering. Thank you for sharing it as I was ignorant to its pedigree.

pjrebordao
pjrebordao
3 years 7 months ago

So true the last paragraphs…

I’ve owned 5 Civics, but sadly, they dont turn me on anymore.

Richard Love
Richard Love
3 years 7 months ago

I have actually heard this bike run 2 vintage races. It sounds like it could break glass! Jim Redmond tells the story of how they got it from Japan to Italy for it’s first race by flying it first class.made it look like a 4 cylinder by removing 2 pipes. That way theirs rivals couldn’t tell what they had until Honda got it to the track. Let’s have some more bike articles.
Dick

Andreas Lavesson
Andreas Lavesson
3 years 7 months ago

Absolutely amazing article. I’m not a motorcycle-nut, but I sure am fascinated by them. Especially when they are as beautifully engineered as this one.

Kingshuk Mukherjee
Kingshuk Mukherjee
3 years 7 months ago

YES. More motorcycles is always a plus.

Beck
Beck
3 years 7 months ago

Thanks for the great read! Honda, please make the 2014 F1 return to get your soul back.

Niklaus Gingro
Niklaus Gingro
3 years 7 months ago

Never heard of this bike before but this is a feat of engineering magic – and that exhaust noise is insane!

CJ David
CJ David
3 years 7 months ago

Loved everything about this article. Those last couple of sentences especially.

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