[NSU]

Got started on this as a tangent in another thread, and I thought it deserved its own area.

Let's talk about Honda's incredible tiny inline six race motors of the 1960s.

I came across this article a while back:

Honda RC174 Replica - Classic File - Motorcyclist Magazine

Some excerpts:

At JPX, the original engine was thoroughly photographed, then carefully stripped, and a detailed assembly handbook created. Every item was measured to the minutest accuracy and X-rayed, and had detailed three-dimensional drawings made-502 in all. Sophisticated hardness testing and metallurgical analysis was conducted on every piece, which revealed some interesting issues. Not a single engine bearing was a standard size, and some of the alloys and surface treatments used were quite unknown to modern science. Soichiro Honda, founder of the company, was also a gifted metallurgist.

...

The Six's crankshaft is pressed up from 13 components, each no bigger than a domino. Unsupported, it is so flimsy it can be deformed by hand, yet it would have to spin without deflecting at more than 17,000 rpm. Pressing it together with the necessary accuracy-0.01 degree-would require an elaborate set of jigs weighing more than the complete bike; if even one part became slightly misaligned, the entire assembly would be scrap. Ludovic Surcin, designer of the jigs, likened the task to balancing 13 billiard balls on top of each other-and persuading them to stay put.

...

The engine is riddled with galleries and tiny oilways, unseen by anything but X-ray, with some only 1mm apart. Sometimes two narrow oilways are combined, saving perhaps 0.5mm in width on a single, larger one. Cumulatively this allows the engine to be perhaps 3mm narrower than it might otherwise-yet another minute but worthwhile return on the work involved.

And this page with some video of these 18,000 rpm beasts (they had early issues with stalling when engine speed dipped below 14,000 rpm!):

Sweet sounding Honda Six ~ Return of the Cafe Racers

You can read quite a bit about these bikes and so much more Honda history in a book of which I have a copy:

The Honda Story:Road And Racing Motorcycles From 1948 To The Present Day: Ian Falloon: 9781859609668: Amazon.com: Books

 

[6fOOt6]

^ Thanks very interesting I'm all into this kinda old Honda stuff. I'm gonna log on to Amazon and order that book can't wait to get my hands on it!

 

[Luke]

I love this quote (JPX is a French Aerospace company that was engaged to help build a replica of this engine):

"Other details emerged that showed the remarkable lengths to which the Six's design team had gone to reduce the mass of moving components. JPX was astounded to discover three different types of con-rods in each engine, with progressively larger big-end bearings for the rods nearer the center, where loadings are higher. Even 40 years ago the benefit of such a strategy was well-known, but no one else bothered to take advantage of it. Any other manufacturer would have made six identical rods, each able to cope with the highest possible loading. But Honda's obsessive desire to have no component heavier than it need be caused the engineers to tailor each pair precisely for their function."

 

[Luke]

And - 65hp @17,000 rpm!

Thanks NSU - this thread made my morning!

 

[MrShadow]

Wow. Just... Wow. It's amazing that even now, with all of our "advanced" technologies, we still can't easily replicate some of the things that were done 30+ years ago.

 

[Aufitt]

Wow. Just... Wow. It's amazing that even now, with all of our "advanced" technologies, we still can't easily replicate some of the things that were done 30+ years ago.

We can, we just cant afford them, that thing was a million dollar works bike in todays standards.
Even the cbr250RR MC22 was $9990 here in 1994 when the current 250's are $6k
Which is why we laugh when ppl say they want a new 2013 version of the same MC22 or RVF400 etc.

 

[Luke]

We can, we just cant afford them, that thing was a million dollar works bike in todays standards.
Even the cbr250RR MC22 was $9990 here in 1994 when the current 250's are $6k
Which is why we laugh when ppl say they want a new 2013 version of the same MC22 or RVF400 etc.

+1 - if you read the article, you'll see where they talk about using a CNC-machined crankshaft instead of the splined and pressed one, but they couldn't get it to fit. The engine is pretty much hand-built - and you need a reaaaaaally good (and rare) set of hands.

A friend who works at a car dealership and I were talking the other day about mechanical skills. New vehicles (and motorcycles) are designed for ease of maintenance and controlled by computers - most of the time the mechanic starts with computer diagnostic and does component replacement. The argument was wheter it was cheaper to go this route or to actually try and fix the problem, and the truth is there aren't a lot of people left that have the knowledge and skill to to do the latter.

Even with water-column vacuum gauges, setting the 4 carbs on a Honda 750 so that it ran smoothly at all loads and engine speeds took a bit of tinkering and finesse - most everyone could "get it running", but to get it "running right" took some time - I can't imagine the talent required on, say, one of the mid-70s Lamborghini Countach with 12 carbs, but I can say I've heard one tached out that was tuned right, and it was exquisite.

 

[NSU]

As a gearhead, nothing really beats the inline six: perfect primary and secondary balance with the fewest numbers of cylinders to achieve this.

It's why I love, love, love that BMW has an inline 6 for their big touring bikes, and why I hope they've stuck with that design (or expanded it to other models!) by the time I'm ready for one.

 

[Luke]

Yeah, that bike has a beautiful motor, standard ABS, and an optional adjustable suspension (on-the-fly, of course). A lot of neat features, including headlights that rotate the beam into corners.

But it weighs almost 800 lbs with nothing in the saddlebags! That bothers me more that the $23,000+ price tag.

 

[slapshot2516]

The piston head looks like its not much bigger than a thimble...

 

[mattcbr250]

So awesome. Thanks for sharing.

 

[MrShadow]

We can, we just cant afford them, that thing was a million dollar works bike in todays standards.
Even the cbr250RR MC22 was $9990 here in 1994 when the current 250's are $6k
Which is why we laugh when ppl say they want a new 2013 version of the same MC22 or RVF400 etc.

Hence why I said "easily"...

 

[Aufitt]

As a gearhead, nothing really beats the inline six: perfect primary and secondary balance with the fewest numbers of cylinders to achieve this.

It's why I love, love, love that BMW has an inline 6 for their big touring bikes, and why I hope they've stuck with that design (or expanded it to other models!) by the time I'm ready for one.

 

[ceejaybee]

Full gallery of the BMW Concept 6

BMW brings back the six-cylinder motorcycle with its hottest concept bike ever - Image 1 of 21

There is no denying that one sexy machine.

 

[CBR250R ABS]

Than the Honda RC174 300cc inline-6 came along and pulled a Kawasaki Ninja 300 move on the poor little under displaced RC166. History sure does rhyme. LOL

 

[CBR250R ABS]

And the man who attempted to recreate this marvel of technology was gobsmacked by what Honda achieved in the mid 1960's. A lethal two-stroke annihilator with engine tolerances closer than a NASA space craft.
Honda RC174 Six Motorcycyle - Motorcyclist Magazine

 

[CBR250R ABS]

RC174 on the dyno. They put out 65-70 HP to the wheel.

 

[CBR250R ABS]

Now enter a time machine and journey back to the sixties and ride a lap on the RC174 with Mike Hailwood. He was known as "Mike The Bike" because of his natural riding ability.
Pardon the Bowie music, I would rather hear the sweet engine sing !!!

 

[NoSkillsMcSuckington]

omg....i wonder if i could put that sound through headphones synced to engine revs....one of the best engine sounds i've heard in forever.

 

[CBR250R ABS]

Nostalgic return of the Honda RC166 250/6 to Isle of Man.