It went from You Meet the Nicest People to You Meet World Champions on a Honda in a very short span of time. In 1959, Honda was selling scooters in the U.S. Ten years later it was the CB750--and Honda's GP racing effort in those intervening years drove this change. Technical Editor Kevin Cameron talks with Editor-in-Chief Mark Hoyer about Honda's meteoric rise in Grand Prix racing during the 1960s and the technical innovations and revolutions that drove this success. Also, why Honda quit GP racing in the late 1960s. Listen to find out!
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00:00:00We've officially counted down. It's the new episode of the Cycleworld podcast. I'm Mark Hoyer. I'm with Kevin Cameron. He's our technical editor and
00:00:08this week's episode, we have a really fun topic.
00:00:13It's Honda.
00:00:15How Honda went from being a little maker of step-throughs that were being sold in hardware stores in the United States in the 1950s.
00:00:22For $265.
00:00:26$265. You meet a nice person on a Honda.
00:00:29You meet world champions on a Honda.
00:00:33It was not long before
00:00:36Honda was winning world championships.
00:00:42Making that music that we love from the 256, for example.
00:00:47Megaphone music.
00:00:51I was in Motegi in 1998 for the 50th anniversary of Honda.
00:00:57And
00:00:59they ran a
00:01:01256 around the banking. They were doing a great parade of stuff in the Oval at Motegi.
00:01:07They had outboard motors in the back of tiny Honda pickup trucks, cake trucks.
00:01:14They had all the rototillers and
00:01:18fabulous things. They had the RA71, which was their Grand Prix car.
00:01:22The V12 that would suck the air out of your chest as they warmed it up in the paddock there to do the laps.
00:01:29It was amazing.
00:01:30They ran the 256. Freddie Spencer was there running his NS
00:01:35500 and NSR, etc.
00:01:40They were holding signs at the end of the straightaways that said,
00:01:44Downshift.
00:01:46They were getting all their stars to make sure that they
00:01:48downshifted the motorcycle so we could hear that music. And one of those was
00:01:52the 256, which of course sounds spectacular and it revs to a billion RPM. And it's a great, great departure
00:02:01from a step through. So, you know,
00:02:04Kevin knows a little bit about this process. He was A, there, and B, he has spent a lifetime studying it.
00:02:10So we're going to talk about
00:02:11Honda's classic racers, 1959 to 1967.
00:02:16And
00:02:19what do we start with, Kevin?
00:02:21Well, I think
00:02:24Mr. Honda's
00:02:261954 trip to Europe was a great disappointment to him because he found that
00:02:32European motorcycles were making roughly three times more power than
00:02:37the four-strokes that they had switched to not that many years before. They started out making two-strokes.
00:02:44When Mrs. Honda said, I don't like the smell and I don't like the noise. He said, oh, we can engineer around that.
00:02:51But presently his partner came to him and said,
00:02:55Maybe you can, but we're not doing that. We're going four-stroke. And they've been four-stroke ever since with certain exceptions.
00:03:04But in the period in question, Honda was a 100%
00:03:09four-stroke manufacturer and
00:03:11like other Japanese companies, they had some
00:03:17relations with German
00:03:20manufacturers and it's often pointed out that
00:03:24early Honda street bikes with leading link suspension and deeply
00:03:29valenced Indian like fenders
00:03:33look an awful lot like NSU's of the final years.
00:03:38But
00:03:41Honda meanwhile
00:03:43decided they were going to win the famous volcano race in Japan,
00:03:48which took place on a on a cinder track. It was a sort of glorified hill climb as I understand it.
00:03:56And Yamaha and Suzuki just kept winning stuff, kept winning stuff.
00:04:03The Honda engineers were finally unleashed and
00:04:08the concept that they came up with was
00:04:12what they call cylinder multiplication.
00:04:15If you're running a 500 Norton and you're getting to about 7,200 peak RPM and it's
00:04:221958, that's all she wrote. You're not going to be able to turn 8,000 with that motorcycle because it will start to crack crank pins.
00:04:31And
00:04:33valves will bounce hard off of pistons.
00:04:35So
00:04:37NSU in their racing had run a 125 single and a 250 twin designed by two different engineers and
00:04:47they revved very high.
00:04:50And the Japanese engineers, of course, like any IC engine guys know that horsepower consists of
00:04:58displacement, which is usually set by regulation,
00:05:01combustion,
00:05:03stroke averaged net combustion pressure, which is pretty much limited by
00:05:10how much atmosphere can crowd into the cylinder and the time available. And
00:05:15the third thing was how often
00:05:18can you do the power producing cycle, which is RPM.
00:05:23So since they couldn't increase displacement and
00:05:26that everyone was working equally hard on just filling cylinders with nothing but atmospheric pressure
00:05:33to push the air in, that left RPM.
00:05:37So
00:05:39that was
00:05:40what they learned or
00:05:42the point on which they agreed with NSU engineers, such as Dr. Walter Schroeder and
00:05:52company.
00:05:54But people who have said, oh, well, those Hondas were just NSU copies.
00:06:01Those people are
00:06:03full of nonsense
00:06:05because the NSUs were two valve engines and they had conventional
00:06:13porting. The Japanese had a special
00:06:19and
00:06:20very important
00:06:22constraint on design, while the Europeans, with their two valve engines,
00:06:28often had only 300 RPM, safe RPM,
00:06:33above peak power. And I'm talking about mainly MV here.
00:06:38Hailwood said you had to watch the
00:06:41the rev counter like a hawk
00:06:43or you'd cross the valves, especially if the track was bumpy,
00:06:48i.e. the rear wheel getting airtime. Well, in the Volcano race, there was airtime to spare,
00:06:56which meant that their engines, Honda's engines,
00:07:00had to have a large
00:07:03safety band above peak power
00:07:06because you knew that the engine RPM was going to be going
00:07:11and all these little spikes were going into the red zone on somebody's tachometer.
00:07:17So what they did was,
00:07:19against the best advice,
00:07:22they adopted four valves per cylinder, a very old idea.
00:07:26But in this case, they were adopting it for a different reason, namely that four little valves,
00:07:35here's a fairly little one,
00:07:38are
00:07:4140% easier to control than two larger ones of equivalent area.
00:07:48Valve head area.
00:07:50So
00:07:51they tested with that and soon they were able to win the Volcano race
00:07:57and Yamaha was defeated.
00:08:00So
00:08:02they knew that they had made the right choice
00:08:05because they didn't copy the Europeans and in particular they did not copy NSU.
00:08:12Although some of their early racers had features like
00:08:15shaft and bevels cam drives that
00:08:19NSU had used previously.
00:08:22Once Honda got the formula,
00:08:24all of their camshafts were driven by
00:08:27trains of spur gears,
00:08:29typically up the middle
00:08:31on a four-cylinder that's between
00:08:33cylinders two and three.
00:08:35Because at the ends of the crankshaft, if there's torsional vibration, that might be a bad place to put your cam drive
00:08:42because if the cam speed is going up and down from this
00:08:48it could be that just as the valves are being lifted,
00:08:53this spring is unwinding and patooey.
00:08:56It flings the valve up off of the cam contour. Bang! It comes down
00:09:01and maybe
00:09:03the piston comes up and gives it a biff.
00:09:06Yeah, it would be logical to run from the center, you know, you would want.
00:09:11It looks bent.
00:09:13It does.
00:09:15Yeah,
00:09:16Kevin's, for all y'all who are not using your eyeballs on this podcast, Kevin just held up
00:09:22a tiny little valve stem that is a little bit bent.
00:09:25So probably the head probably ran into a piston at some time in its life.
00:09:31Honda refined this. Oh, yeah.
00:09:33Oh, I want to go back to the torsional thing because if you do the cam drive off the end of the crank,
00:09:39which is actually common because we can control that better now, we're doing a good job with that
00:09:43torsional springing,
00:09:45but to run it up the middle makes a lot of sense because you'd have two short stubs of cam on either side of the
00:09:49drive and then you'd be taking it out of the center of the crank, but
00:09:53imagine the the torsional waves that could start to happen.
00:09:57You have a camshaft, which is not just spinning smoothly in space with equal resistance all the time.
00:10:04It's on a bumpy road. It's got cams all over it.
00:10:07They're kicking the valves open at different times and you're spinning this thing to a zillion rpm.
00:10:11So you have a lot of seat pressure and spring and then you have mass in the valve train.
00:10:15And so all that stuff is whipping back and forth and whipping back and forth and
00:10:21you can have a lot of problems.
00:10:26Well, what they did about this was highly professional.
00:10:33When you and I build
00:10:35a souped-up engine, we can
00:10:38buy racy valve springs and we can buy so-and-so's camshafts and so forth and we're just sort of a we hope this works.
00:10:45Honda had to know that it was going to work.
00:10:49So Mr. Honda, there's a photograph of him in the Motegi Museum with this big toothy grin on his face.
00:10:56He looks like he's having the best time.
00:10:58He's boarding a Northwest Airlines Strato Cruiser.
00:11:02He's flying to the USA to buy
00:11:05tooling
00:11:07and test equipment.
00:11:09So Honda, as soon as they started to make money from the 50cc step-through and other projects,
00:11:17invested in a high-class engine development
00:11:22setup.
00:11:24And
00:11:25you can bet that
00:11:27before they took their four-cylinder 250 to Europe,
00:11:31that it had been thrashed
00:11:35to the living end and tested in every way possible, which the normal method of test is
00:11:41to simulate
00:11:43a racetrack situation
00:11:45with constantly varying RPM and run the engine until something breaks.
00:11:51Redesign it,
00:11:53get it through the prototype process,
00:11:55which means
00:11:56being able to climb to the top of the priority list.
00:12:01Oh, you guys are making a new model? Well, get behind me,
00:12:06because we've got number one priority.
00:12:09And
00:12:10this is not a small matter.
00:12:13Pushing an engine until it is dead reliable
00:12:17is quite a process. In any case,
00:12:21they brought their
00:12:23125s
00:12:24to
00:12:25the Isle of Man in 1959, and I think they won a team prize and finished sixth in
00:12:32two or three other places.
00:12:34Sixth was the highest that they did. And of course,
00:12:38it was quite a novelty for the Europeans to see men from the Far East with these high-revving little twins.
00:12:47But
00:12:49in 1961, here they came with
00:12:52a 250 that revved to 14,000 and made 40 or 45 horsepower.
00:12:58And MV's 250 twin made 37 horsepower.
00:13:04And
00:13:06they just
00:13:07MV retired their 250
00:13:10that season.
00:13:12And Mike Halewood
00:13:15won
00:13:16a 125 and 250.
00:13:19So
00:13:20that's a very young Mike Halewood, mind you.
00:13:24And a busy guy, because at the same time in 1961, he won the senior TT
00:13:30on a Norton
00:13:31single.
00:13:33So covering some ground there.
00:13:37So
00:13:38at this point, Honda's method was lots of small cylinders
00:13:43so that you can raise the RPM without having an excessive piston speed.
00:13:47Four valves per cylinder.
00:13:50A fairly wide valve included angle.
00:13:56Which means a deep combustion chamber with a fairly tall dome on the piston. This is all conventional
00:14:04European-originated
00:14:06technology. Well proven.
00:14:08And
00:14:11the crankshaft was an all-roller rolling element crankshaft.
00:14:17And they
00:14:19move forward like that. And when the
00:14:23125 twin didn't win races, they built a four-cylinder 125.
00:14:29They multiplied the cylinders, in this case by two.
00:14:33And when their RC110 50cc single didn't get it done,
00:14:40they made a twin. Can you imagine a 50cc twin with valves like toothpicks?
00:14:46Oh, thimbles for pistons. Beautiful stuff. Beautiful stuff. Wonderfully made.
00:14:54So
00:14:55and the bore-stroke ratio was at the time
00:15:00a little bit behind the times. The bore was just a little bit bigger. We call that over square.
00:15:06Bigger than the stroke.
00:15:09Maybe 1.05 or 1.01 was the ratio of bore to stroke.
00:15:14So this was the conventional stream in Honda engineering for racing.
00:15:21And of course, they were able to perform testing adequate to assure results.
00:15:31In 1964,
00:15:34Honda hired
00:15:35Shoichiro Irimajiri,
00:15:38who was then 24 years old, had graduated from Tokyo University in aeronautical engineering.
00:15:45And he decided to
00:15:47give Honda a whirl.
00:15:49And what they did for him was they said,
00:15:53here's our 50cc twin.
00:15:55We
00:15:56designed it according to our normal criteria, and we projected that we would get this much horsepower, and we didn't get it.
00:16:04So something's wrong, and we'd like you to take that task on.
00:16:10Well, he took them at their word.
00:16:13I'm in charge of this. I can order all kinds of wonderful prototype stuff. If I want to change the stroke,
00:16:19I'll just phone
00:16:21the crankshaft department and say, drawings to follow. Get on it.
00:16:27And
00:16:29he first tried the normal soup up stuff. Well, we'll refine the porting a little bit.
00:16:35And we'll see what we can do about
00:16:39raising the compression ratio. Again,
00:16:42when you've got a steep
00:16:43piston dome sticking up into a deep chamber,
00:16:47it's hard to raise the compression because
00:16:51the surface area of that piston is nearly double that of the bore as a flat disc.
00:16:58So
00:17:00compression, porting,
00:17:04they really weren't getting anywhere.
00:17:07So far, he had only reproduced Honda's own results. Namely, we designed this. It's a disappointment.
00:17:16So then he decided, okay, we're going to have to deviate from this standard method.
00:17:23Let's reduce friction.
00:17:26So on this engine, for the first time,
00:17:29he used a suspended crankshaft. Now, we're accustomed to something like
00:17:35Honda or Yamaha parallel twin, where the crank cases are like
00:17:40clamshells. You open it up. There's the crankshaft, the two gearbox shafts, and the kickstart shaft.
00:17:47Well, they're horizontally split. Yeah, horizontally split.
00:17:50You know, so you had a tray for you to lay all the parts in. It's beautiful to put your top on.
00:18:00The trouble was that that only worked
00:18:03well with great big
00:18:06ball bearing
00:18:07main bearings,
00:18:09which
00:18:11had the balls rolling around a fairly large circle and
00:18:15the friction in ball bearings, a lot of it is
00:18:18squenching that oil out of the way of all those
00:18:21balls or rollers.
00:18:24So he shrank.
00:18:26He got rid of those big ball bearings, and he got rid of the idea of clamping the
00:18:32parts of the engine between two horizontally split crankcase halves.
00:18:37And what he did was made the main bearings as caged needles
00:18:43built in the form of little miniature steel pillow blocks.
00:18:49A pillow block is a bearing with a kind of foot on the bottom of it with holes through it
00:18:54so it can be bolted on to something.
00:18:58So here is this little twin with three main bearings of this kind, and they bolted it
00:19:04to the bottom of the cylinder,
00:19:07which was in unit with the upper case.
00:19:12And they tested with that engine.
00:19:15And they did get a gain because they had reduced the velocity
00:19:21at which
00:19:23oil was being squenched out of the way of the little tiny needle rollers.
00:19:28Can we talk about bearings?
00:19:30Sure, let's do that.
00:19:31Because, you know, we're talking about a big,
00:19:35a large diameter roller bearing with big round rollers
00:19:38and the amount of mass that that carries. And then as you're saying, it's moving
00:19:43because it's a larger diameter, it's moving over a longer distance for every rpm. So the speed
00:19:49is higher.
00:19:50Yep, and it's squishing all that. It has more mass, so it's going to tend to skate more if the
00:19:57Crankshaft rpm varies rapidly.
00:20:00Yeah, and so making those bearings small and squishing them down into needles removed the mass.
00:20:06And as you say, it lowered the speed of the bearing, so it was not kicking that stuff out as quickly, the oil.
00:20:13And
00:20:14INA,
00:20:15a German bearing manufacturer,
00:20:21popularized caged needle bearings. And their work came down to us from
00:20:29a
00:20:32study done by a German physicist named Hamp, I don't know his first name, H-A-M-P-P.
00:20:39His paper is in the INA
00:20:41company library, technical library.
00:20:44And what he did was to calculate the speed at which
00:20:49rolling element skidding
00:20:51would take place.
00:20:53Because, particularly in a connecting rod bearing, because the connecting rod bearing, the rod is rotating around the wrist pin
00:21:01at about one quarter of the speed of the crankshaft.
00:21:05Because the rod is roughly four times as long as
00:21:09the radius on which the crank pin is revolving.
00:21:13So that meant that the rod bearing
00:21:16instantaneous rpm was varying by plus and minus 25 percent, which means the rollers were kind of going
00:21:24just like a tennis game. Which way do we look?
00:21:27And when they began to skid,
00:21:30trouble began and there were failures.
00:21:33And this fellow, Hamp, was called in to make this study
00:21:37by the German Luftwaffe.
00:21:40Because they'd had some engine failures during the Battle of Britain
00:21:45that were a plague upon their house.
00:21:48And
00:21:49they intended to solve this problem. And Hamp did just that by
00:21:54recommending that they make the rollers smaller and lighter,
00:21:58so that the frictional forces in the bearing would be enough to keep them from skidding.
00:22:04So
00:22:06that
00:22:07those
00:22:08solutions that Hamp developed are all around us, but nobody talks about it because it's lost in history.
00:22:16Except for
00:22:18curious persons like ourselves. Well, and we don't have to think about the bearings if they just work.
00:22:23Well, these bearings are great. Put them in and don't think about it, you know.
00:22:27Silver plate those rod bearings.
00:22:31Yeah, he found that making the crankshaft main bearings smaller in diameter
00:22:39reduced the friction even more. So he reduced the diameter in steps until he was able to break crankshafts.
00:22:46And then
00:22:48he's moaning about this and somebody
00:22:51said to him, well, you know about the Korean War agreement, don't you?
00:22:55No, what's that?
00:22:57Well, during the Korean War, we had this deal with the Americans that if we had
00:23:02trouble with anything that we were making for them,
00:23:06Toyota was kept alive,
00:23:08kept from closing
00:23:11the doors
00:23:12by a truck order
00:23:15from the U.S. Army for the Korean War.
00:23:19Hey, would you like to make some trucks? Oh, we'd love to make anything. What do you want?
00:23:24So there was this wonderful agreement by which you could phone up
00:23:28U.S.
00:23:29high technology companies and say we've got a problem. Can you help us?
00:23:34And Irimajiri
00:23:36got in touch with people at
00:23:38Pratt & Whitney and
00:23:40General Electric.
00:23:43We need a steel that has
00:23:46excellent fatigue resistance,
00:23:49but is surface hardenable so the rollers can run on the surface of it directly.
00:23:54Oh, you might want to try this.
00:23:57Here,
00:23:58take it to Nippon Steel. They could run you up a batch right away.
00:24:04So they made
00:24:06improved rollers and they were able to make the crankshaft journals smaller again.
00:24:11And when they got that one to break, they knew they'd sort of reached the limit there.
00:24:16So another thing that he started working on
00:24:19was valve included angle.
00:24:21He saw that big piston dome and it looked like heat loss to him
00:24:26because it had so much surface area. So he began to
00:24:31bring the valve angles together, resulting
00:24:35in a flatter combustion chamber.
00:24:39And in order to keep adequate valve area, he made the bore bigger. So from 1.1,
00:24:46he went all the way to 1.4 at the end. So he was moving in the same direction
00:24:52that
00:24:54Keith Duckworth was at Cosworth. And of course,
00:24:58the Cosworth combustion chamber is the basis of practically all motorcycle engines today
00:25:04and automobile engines, the ones with
00:25:06four valves per cylinder.
00:25:08So the descriptive audio here, folks, is Kevin held up two of his tiny valves. So think of
00:25:13pencils with a flat top
00:25:16and he rotated those from being in a V-shape with a wide angle to being very near parallel.
00:25:24And so this was what Irimadri was working on. He also reduced friction by
00:25:31testing with two ring pistons,
00:25:33two ring pistons, one plain oil scraper and one gas ring.
00:25:38He also shortened
00:25:41the piston
00:25:42so that there wasn't as much of it
00:25:45grinding along against the cylinder.
00:25:48And
00:25:50he
00:25:53went at all these little details in a meticulous way
00:25:57such that the RC115 version
00:26:00of their 50cc twin was able to win the
00:26:0450 championship in 1965.
00:26:08And I think again the following year.
00:26:11So management
00:26:14sitting at their
00:26:16walnut conference table
00:26:18with whatever they liked to drink at such times
00:26:22said,
00:26:23let's give this guy some more projects. He seems like he's got something going.
00:26:28So the next thing they gave him was
00:26:31they wanted to build a more powerful 125 because the Suzuki's
00:26:37were
00:26:38on the Hondas like flies. Buzzing, buzzing.
00:26:42And of course we have to remember
00:26:45that even though two-stroke
00:26:48cylinder filling wasn't very good in those days,
00:26:52the engines fired twice as often as the four-stroke at a given RPM,
00:26:56which is an important advantage.
00:26:59So Irimajiri
00:27:02decided that he would make
00:27:05a
00:27:06five-cylinder
00:27:08125
00:27:09by using what he had learned about the RC115 50cc twin.
00:27:17So soon they were making
00:27:20gobs of extra power because they
00:27:23they adopted the suspended crankshaft, the short skirted pistons,
00:27:28the larger bore, shorter stroke, and all of those other things.
00:27:34And
00:27:36they had a championship winner.
00:27:38Now, of course the two-stroke people were
00:27:41not sleeping either
00:27:43and
00:27:44it became the bane of
00:27:47Honda's existence in the same way that Honda had been the bane of MV's existence. In 61,
00:27:53MV was driven out of the 250 class. In 62,
00:27:57Redmond drove them out of the 350 class.
00:28:02And
00:28:04so in this case,
00:28:06at a point they gave up on 50 and 125.
00:28:10And that brings us to 1966
00:28:13and 1967.
00:28:17Meanwhile, Irimajiri had been
00:28:20asked to go over the six-cylinder 250, which had first been fielded in 1964,
00:28:27and was not immediately successful, and it was not successful the following year either.
00:28:33So he gave it the business.
00:28:35So I want to pause for a second to talk about the, you know, as we discussed the podcast, November
00:28:431965 after season's end,
00:28:45the 50 cc triple operates to 25,000 rpm. Yes.
00:28:50That's
00:28:51that is what they're trying to do to beat two-strokes, which you have to spin a four-stroke this much to
00:28:58you know, basically twice as much. Yeah. Yeah, make it fire enough times to be sensible with a two-stroke.
00:29:05And although you will read rah-rah accounts of Honda's
00:29:11years of dominance, and they did, they were the ones from whom
00:29:21excellence flowed
00:29:23up to a point.
00:29:25And you will find people who switch from the rider's championship to the manufacturer's
00:29:30championship in order to say, ah, in these years Honda dominated all solo classes
00:29:3750, 125, 250, 350, and 500.
00:29:41Well,
00:29:43it's okay to be a fan. We like to clap and be enthusiastic,
00:29:47but we also like to know what is the case.
00:29:52And what was happening was that the two-strokes were making things tough
00:29:57for Honda. The reason that Honda developed a six-cylinder 250 was because
00:30:03Phil Reed on the upstart
00:30:05Yamaha RD56, which was air-cooled still,
00:30:10he won the title in 60, 250 title in 64 and 65.
00:30:17And that did not sit well with Honda management.
00:30:21Do something successful.
00:30:25And
00:30:27they hired, they had Hailwood on staff for a while.
00:30:33And
00:30:34so the plan was that Hailwood would
00:30:36ride the 250 and 350 and that Redmond would ride the 500.
00:30:43And in 66,
00:30:45Redmond
00:30:47was injured
00:30:48in such a way that he couldn't continue his riding career.
00:30:53And so they said to Hailwood, now necessary also you ride 500.
00:30:59So that meant
00:31:00three classes
00:31:02per weekend.
00:31:03The 250 six-cylinder, the 297 cc
00:31:08six-cylinder, which was ridden in the 350 class, and the old-time design
00:31:15of 500 cc RC181, which
00:31:20at the beginning of our story made about
00:31:2385 horsepower.
00:31:25And you will read from
00:31:28various
00:31:30authorities that the Honda made 112 horsepower
00:31:34again, it's nice to be a fan and to applaud our favorites.
00:31:39But
00:31:41making
00:31:44adding
00:31:46to
00:31:47insisting on 112 horsepower as the output only makes
00:31:52Agostini's success
00:31:54in winning the championship both years
00:31:56more outstanding.
00:31:59I actually believe that they had about 85 horsepower in
00:32:031966 and that they were able to make it give as high as 93 horsepower the following year. This is reasonable because
00:32:11not so many years after that
00:32:14MV were able to make
00:32:16just over 100 horsepower from their their new four and this would be
00:32:221974-75
00:32:24thereabouts.
00:32:26So
00:32:29the the 256 didn't make as much power as the Yamaha, but it look at those long megaphones.
00:32:37Those long megaphones are effective
00:32:40in boosting the intake process over a wide range of rpm.
00:32:44Not the usual 1200 rpm of a Manx Norton
00:32:49or the 1500 rpm of a common superbike.
00:32:53So
00:32:55they were trying to make those motorcycles easy to ride
00:32:59so the 250 and 350 classes
00:33:03were a walkover
00:33:04for Hailwood.
00:33:06The 500 class
00:33:07was the problem
00:33:09because
00:33:11not only was Hailwood riding three events per weekend
00:33:18but the 500 handled in a in a peculiar way.
00:33:25What Hailwood had to say about it was
00:33:28imagine oil on the back tire and a hinge in the middle of the frame.
00:33:34Redmond has been very
00:33:37disparaging of this and saying things like well, I rode without sliding and I never had a problem
00:33:44maybe because Hailwood slid the tires
00:33:47that created the problem.
00:33:50I was at the Canadian Grand Prix in 1967 and I saw Hailwood come off of corners and his bike was
00:33:57and the harder he tried to get off the corner the worse
00:34:03it wobbled.
00:34:05Pardon me engineers. I should have said weave. Wobble is the front end
00:34:11and weave is the much slower motion of the rear caster.
00:34:15So at the Canadian Grand Prix all that
00:34:19Agostini had to do to win his second 500 championship against Hailwood was finish.
00:34:27Hailwood
00:34:29made a manful attempt to mess with Ago's mind.
00:34:33Ago was
00:34:36imperturbable
00:34:37and just rode around and finished second.
00:34:41And
00:34:43unfortunately another problem that Hailwood faced was sometimes the press joints on the 500 could slip
00:34:51and there were at least two instances of
00:34:54gear selection trouble. In one race he started in fifth. It was raining. He managed to lead the race
00:35:03with five out of out of the normal ratios five out of the six.
00:35:09But then the gearbox began to get worse.
00:35:13So
00:35:15he was DNF that day.
00:35:17So it was a it was a
00:35:19Hailwood was trying hard to go up a pretty steep hill.
00:35:23Agostini was very steady
00:35:26and his motorcycle was
00:35:30really
00:35:31pretty flawless.
00:35:33In the one tremendous classic duel between Hailwood and Agostini in the 500 class
00:35:39Ago's chain ran off.
00:35:43OTT, right?
00:35:45Uh, yeah
00:35:46and
00:35:47um
00:35:48I think he was
00:35:49not leading by a tremendous amount but uh, the chain ran off and that was that.
00:35:55So at that time the 500s, um
00:35:57Honda's 500s did not have the extreme bore and stroke ratio of the smaller bikes. Not at all. They were
00:36:03they were the original
00:36:05cylinder multiplication square bore and stroke
00:36:09um
00:36:11ball bearing
00:36:13uh
00:36:14method.
00:36:15This was the the original method that Honda had developed at the beginning and
00:36:22in this case, we have to look at Irimajiri as having been
00:36:27a force driving into the future with new solutions.
00:36:33And
00:36:35I think it must it would it would have been fascinating to know
00:36:40whether it was easy for him
00:36:42to get them to agree to such large changes like changes in in valve angle
00:36:49or changes in bore stroke ratio
00:36:51or
00:36:52changes in the nature of the crankshaft
00:36:55because
00:36:58many of you have seen photographs of the
00:37:01250 six-cylinder crankshaft and it's like
00:37:0512 and something inches long. It's just a tiny little thing
00:37:09and instead of having the full circle flywheels
00:37:12of the early
00:37:14uh, 250 four-cylinder racers
00:37:17it doesn't have flywheels at all. It has
00:37:20bricks.
00:37:21All it is is a bar.
00:37:24There's a
00:37:25main shaft coming out of one side of it.
00:37:27There's a crank pin sticking out of the other side and the place for two tungsten balance weights at the far end of the bar.
00:37:36The usual explanation that's been given for
00:37:39getting rid of all that weight was oh, it's to make it
00:37:43more responsive and accelerate faster and so forth.
00:37:47No.
00:37:50Not at all because the one thing you don't want the crankshaft to do is to store
00:37:57torsional energy.
00:38:00And the amount of energy that it can store
00:38:03is proportional to the weight.
00:38:06So in order to raise the frequency of the crankshaft so that it is
00:38:11its stiffness to weight
00:38:14favors the stiffness and not the weight
00:38:17is to do away with most of the flywheel. Just have the balance weights and the crank pin.
00:38:23And everything between is an absolute minimum.
00:38:26So there you have the six-cylinder crankshafts
00:38:30looking so attenuated.
00:38:33So different from a normal motorcycle crankshaft.
00:38:37But I think that the reason for this was that they wanted to avoid
00:38:43slipping the joints.
00:38:47Here's what else
00:38:48Irimajiri did. He said to himself
00:38:52the drive
00:38:53is coming from this single gear in the middle of the crankshaft. There's no gears of any kind anywhere else.
00:39:00So the gear to the jack shaft that drove the clutch
00:39:04comes off of there and also
00:39:07the spur gear drive to the camshafts. And this drive is not between the cylinders. It's behind them.
00:39:14So the cylinders can
00:39:17be squeezed in
00:39:18as close to one another as that center gear will permit. Yeah, so you're making the bore center.
00:39:24So if you think of four cylinders in a row
00:39:27if you stick something between them, you know the center, you got to move the two cylinders out to have the room to do that.
00:39:32So what they did was just making the beer cans, you know, all as
00:39:36snuggy up to each other as comfortable and close as possible to make that narrowness.
00:39:41Well, they're saying this gear in the middle is the most stable part of the crankshaft.
00:39:48And
00:39:49the press fit that is closest to the center is going to be
00:39:54transmitting the power of three cylinders on either side. So they made
00:40:00the crank pin
00:40:02bigger.
00:40:04And then the next one they made a little smaller.
00:40:07And the last one, the outboard ones, they made smallest yet.
00:40:12So stepped
00:40:13crank pins
00:40:16so as to provide the grip necessary where it is necessary. Just enough. That's engineering, folks.
00:40:23That's engineering
00:40:25101. Because I can build a really strong crankshaft and I have no CFD capability, but it will weigh too much.
00:40:33And it will have bad qualities. And engineering is finding the good qualities and making it weigh just enough to not fail
00:40:39and to do the job that we want it to do. In the
00:40:42Indianapolis Motor Speedway Museum is a
00:40:46just a bare crankshaft, and I think it dates to 1914.
00:40:49And it looks thoroughly modern because it has hollow main shafts and hollow crank pins.
00:40:58And everything has been machined away except what needs to be there.
00:41:03Because
00:41:05people ran into these problems of torsional vibration very early.
00:41:10And they understood math and they understood physics.
00:41:15So they were able to tediously calculate using slide rules or even
00:41:23pieces of paper.
00:41:27Pencils, you say. And pencils.
00:41:31So
00:41:32they were able to calculate
00:41:36how to go about making a crankshaft that had
00:41:40enough stiffness in relationship to its weight that it would be safe from
00:41:46destructive torsional vibration
00:41:49in the speed range they needed to operate.
00:41:52And that's what Irimajiri was doing by making that nothing crankshaft. Instead of flywheels, it had little bricks.
00:42:00Or candy bars, whatever you want to call them.
00:42:04And when they warmed that thing up,
00:42:07the mechanics had to be trained to do it properly because you could blow the engine up by just
00:42:13hanging on a moment too long.
00:42:17Because the revs picked up so fast
00:42:20that it could easily, as Hailwood said, cross the valves.
00:42:26So when I heard the six-cylinder warming up
00:42:30at the Canadian Grand Prix,
00:42:32it sounded like dogs yelping in a kennel.
00:42:37It was very strange. I loved it because it was so strange.
00:42:42I was in the presence of something
00:42:45new and
00:42:47for the moment, unknowable.
00:42:49And so
00:42:50it's been a delight to learn more about it over many years.
00:42:55Well, what a contrast from, I mean, a Manx or a G50. They sound great, but they're like,
00:43:01I mean, they rev quick, but it sounds like ancient history.
00:43:06It just has nothing to do with the turbine-like wail and shriek, you know?
00:43:10Well, the thing that the English did, and they did it so well,
00:43:14was they accepted one cylinder and the RPM limit that that set.
00:43:21And they focused their energy on cylinder filling. They learned to get a lot of air into the cylinder and they learned
00:43:29to burn it in an acceptable length of time
00:43:34by offsetting, if this is the cylinder bore,
00:43:37offsetting the intake so that instead of coming in on a diameter,
00:43:41it came in on a tangent, causing
00:43:43the mixture in the cylinder to swirl.
00:43:47And
00:43:48the Italians
00:43:49really never got onto that offset intake and swirl except for Dr. Taglioni.
00:43:56The other engines, it was
00:43:59just past that. The English do it that way. We don't do that.
00:44:02Well, imagine just putting a bowl down and using the flexible
00:44:07sprayer from your sink and put the bowl in the sink and
00:44:11just put the water straight in the middle of the bowl and it's just going to kind of
00:44:14splash around and do all kinds of chaotic things. But if you angle it and you end it and you shoot it around,
00:44:20you shoot it around, yeah, shoot it around the bowl, it's going to spin like your toilet.
00:44:25We all did that when we were little and somebody said, go get a bucket of water, your mother needs it in the garden.
00:44:32And you're standing there waiting for the bucket to fill and you're playing little games.
00:44:36Oh, I can make it spin to the right, I can make it spin to the left.
00:44:38That's what they were doing.
00:44:39That's what a good, especially a two-valve, because you could make it stick to the chamber and make it swirl around and really
00:44:45whip it in there. Let's go to,
00:44:49we've kind of glossed over the crankshaft a little bit about all these things with roller bearings, but they are pressed together.
00:44:56So what that means is the bearings are a continuous circle and there's a pin
00:45:01and that bearing goes on the pin for the connecting rod or etc. And it has to be put into a great big press
00:45:07and squeezed and built up and then
00:45:09aligning all those things that can move and slip unless they're, you know,
00:45:15have flanges with teeth on them. What's that?
00:45:18So all the mains are on the same center line.
00:45:21Yeah. Tap, tap
00:45:23into the gate with the dial gauges. You pull the handle, the gauges come down, you turn the crankshaft.
00:45:30Oh, that's still not good.
00:45:33I might miss dinner.
00:45:35I mean the six, I mean the amount of time that I've spent
00:45:39truing a two, you know, a twin like an RD crank is, that can take a long time and then you have to ask yourself
00:45:47are you going to beat it mercilessly down to zeros? Because there are people out there who want to do that, who want to get it
00:45:52just zero, zero.
00:45:54You taught me that
00:45:56you're not going to feel that thou
00:45:58or whatever.
00:46:00But imagine, so yeah, so you have a, you know, a crank with a
00:46:04or you have a flywheel with a hole in the middle and then you have the offset hole that's for the
00:46:09connecting rod
00:46:11and those ones along the middle
00:46:13have to be perfectly aligned and everything can move and everything can move and then
00:46:18all those crank pins relative to where they're supposed to be
00:46:21have to also be perfect. You want the pistons to come to top dead center.
00:46:27The ones that are moving together, you want them together.
00:46:31Yeah, we had the opportunity to time
00:46:36one of Aprilia's
00:46:37very exotic
00:46:40V-twins and the two pistons did not come to top center together.
00:46:46So the fellow who was building the engine said, well, don't worry, he said I'll make an offset pin.
00:46:53Wow.
00:46:54So the difference is folks, you know,
00:46:57I'm sure a lot of you have been inside more modern engines than a big roller thing that you press together, but now, you know,
00:47:04MT-09s or MT-07s, parallel twins,
00:47:07it's all a big, you know, some of them are even forged. You have a forged single piece crankshaft
00:47:12that's made with just enough stuff and then it's got everything machined off of it and it's all
00:47:17stout and amazing and it has plain bearings and we've talked about that many times before but
00:47:22you know, you put your connecting rod or your mains on and it's got a
00:47:27smooth insert that goes in and it bolts over. You don't have to press the crankshaft together. You just
00:47:32bolt on your
00:47:33connecting rods and you bolt on your main bearings and it slides on a
00:47:38pillow of oil that has to be taller
00:47:41than the asperities.
00:47:43Yeah, the oil film is supposed to be somewhere around one and a half microns. A micron is a millionth of a meter.
00:47:51So it's fairly small
00:47:52and
00:47:54if the roughness, the asperity height
00:47:57on either the bearing or the crank pin, the journal,
00:48:02is more than
00:48:04one and a half microns, there will be contact.
00:48:06Yeah, so this is a shout out.
00:48:08There will be cheaters.
00:48:10I have to shout out to
00:48:13my buddy Joe again, who's the engineer. He's doing something else now, but he worked on great big hydraulic equipment.
00:48:19I mentioned him once before and we had texted back and forth and
00:48:23he said, hey, thanks for the shout out.
00:48:25It made my day and I was like, asperities forever, because he said he used asperities in his job all the time.
00:48:31And he says, yeah, asperities forever, as long as they aren't taller than the oil film is thick, lambda ratio for the wind.
00:48:40So, yeah, party in the engineering house, folks.
00:48:44Well, on the one hand,
00:48:46Mr. Honda was a firm believer that rolling element bearings provided the least friction.
00:48:53And Enzo Ferrari
00:48:57around 1953
00:49:00had two V12s built, one with all-rower crankshaft and the other one with
00:49:07Tony Vanderbilt's three-layer
00:49:10plane bearings.
00:49:11Ooh, tri-metal.
00:49:12Yep.
00:49:13That's a podcast.
00:49:15Yes, indeed.
00:49:17Goes right back to Indianapolis, in fact,
00:49:20and the Allison company.
00:49:22But
00:49:25Mr. Ferrari had the two engines built up in this way and he tested them.
00:49:30They were run on the dyno and careful engineering data collection
00:49:35took place and his conclusion was, hands down,
00:49:40plane bearings
00:49:41are best,
00:49:43or I should say better, because there are only two in the comparison.
00:49:48So
00:49:49he stopped with all that.
00:49:51Porsche kept on until about 1966.
00:49:54I think they had a formula car at that time that had a roller crank in it still.
00:49:59But today...
00:50:00Oh, the 4CAM. Yeah, that 4CAM Carrera. Oh my gosh, like just bearings and
00:50:06jackshafts.
00:50:07Wonderful German XS.
00:50:09Just
00:50:10absolutely amazing, but just get it right. That's the thing. Just get it right.
00:50:15When I was at the
00:50:17Canadian Grand Prix and I heard the mechanics warming up the Honda 6, I thought,
00:50:24they're warming that thing up as if there's five more crankshafts in the truck.
00:50:29I wonder if there are.
00:50:33But then we can go back to what was it, 1972 when
00:50:40or 73 when Saarinen won Daytona.
00:50:44And
00:50:47he wanted the crankshaft replaced every night.
00:50:54And finally, Kelker Brothers was getting quite
00:51:00tired of this.
00:51:02And yet the insistence went on. So according to the story, he tossed the crankshaft, the last remaining one
00:51:10across the shop,
00:51:12across the
00:51:13garage unit.
00:51:16But
00:51:18needing a fresh crankshaft for every race was common in European racing in the 50s. The Mondial
00:51:26125 single revving to 13,000. They had to put a crankshaft in it for every GP.
00:51:33And
00:51:34some of the little Suzuki
00:51:36high-revving two-strokes needed a fresh crankshaft for the race
00:51:41in order to be sure.
00:51:44And
00:51:45I think when Yamaha were running
00:51:48250 twins in USAMA races, they didn't want the crank to run more than 450 miles,
00:51:55which is about half of its
00:51:58reliable lifetime.
00:52:00So anything with rolling bearings, each time the roller,
00:52:06a spot in the roller
00:52:08bears against either the rod or the crank pin,
00:52:13it flattens,
00:52:15which generates a shear stress under the surface.
00:52:20And eventually,
00:52:21a mattress that has been lain upon by many a body over many years
00:52:28gives up.
00:52:30The same thing happens to rolling element bearings.
00:52:34All the little atom-to-atom bonds in the metal are constantly being tried.
00:52:40And for a long time, everything is hunky-dory.
00:52:43But eventually, a tiny crack develops below the surface,
00:52:49and it may migrate to the surface, and the tip of the crack
00:52:54pieces break out.
00:52:57And this is the way it was described to me in a wonderful engineering paper that I read.
00:53:04Oh, I think it was 1965.
00:53:07When those little pieces start to break out,
00:53:11trouble is imminent.
00:53:14But the Class A pits are the ones which are just where the crack tip has
00:53:21arrived.
00:53:22Class B pits are when
00:53:24two or more pits
00:53:26join hands to become a larger threat to success, and it
00:53:32the failure comes soon.
00:53:35So
00:53:36this is why I
00:53:39tried hard with
00:53:41three-cylinder customers who wanted to have
00:53:44just the main bearing that had failed
00:53:47replaced.
00:53:48All of those main bearings have had the same life, so the other five are ready to go.
00:53:56Other, yeah. So it's just one of those things.
00:54:01Honda had
00:54:04a wonderful... Oh, one other thing that I wanted to mention about
00:54:08the difference between the NSUs and the Hondas is that
00:54:12the
00:54:14Honda engineers looked at the problem. Well, here's a conventional valve. This valve,
00:54:20the stem,
00:54:21is 2.3 times
00:54:23the diameter of the head. This is a conventional old-time valve from a British single.
00:54:31There's got to be a valve spring here and a valve spring retainer at the top, and there has to be a little
00:54:36washer at the bottom to keep the spring from scrubbing against the aluminum head. So that much is
00:54:43reserved.
00:54:44And so there isn't much room down here at the head for the airflow to come in and
00:54:51turn down into the cylinder.
00:54:54And
00:54:56the Honda guys made these tremendous long valves
00:55:00so that the spring was out here and it left
00:55:04a lot more length in which they could gradually turn the intake port
00:55:10so that it would flow out from under the valve more uniformly. And you will see that
00:55:16you'll see that type of
00:55:19construction on any modern motorcycle. They don't have
00:55:24a valve with a port air coming in at a low angle and then trying to turn suddenly.
00:55:31But
00:55:35it takes time for
00:55:37the old guys to retire and the young guys
00:55:40to
00:55:41gain control of the department
00:55:44and
00:55:45bring their fresh ideas into
00:55:49use.
00:55:50Yeah, you tell that story at Ducati about them locking the doors of the shop.
00:55:55Yeah, that's in their black book.
00:55:57You boardy out.
00:55:59Yeah, boardy and his guys were out testing.
00:56:03And the Taglioni faction
00:56:07were in the shop and when the
00:56:10the test team, boardy and the test team got back, they wouldn't let them in.
00:56:16And there were fisticuffs.
00:56:19Pretty nice. Good times. That's all, you know, we got to believe in what we're doing. So let's fight for it, I guess. Yes.
00:56:26Well, that's
00:56:29anyway,
00:56:30it's interesting to note that
00:56:33what was going on at MV
00:56:36was very similar. They were reducing the valve included angle. They were
00:56:41making the bore larger and the stroke shorter.
00:56:44And eventually somebody's name was going to go on to the combustion chamber that resulted.
00:56:52And it is Keith Duckworth's name that is remembered.
00:56:56But we also should
00:56:58give some credit to
00:57:00Shirichiro Irimajiri
00:57:03and to
00:57:05the people at MV who
00:57:07probably were not degreed engineers. They were simply
00:57:11very experienced men
00:57:15who
00:57:17responding to
00:57:19what they were seeing on the dyno every day
00:57:22felt
00:57:23a wind of change on one cheek.
00:57:28And they realized that
00:57:31we might need to change things in order to wriggle out from under some of these problems.
00:57:37So the excessive heat loss that comes from steep
00:57:41piston domes
00:57:42and deep combustion chambers, Harley went through the same thing in 1970 and 71.
00:57:49Their first
00:57:50XR engine was made of cast iron and it had a true
00:57:54hemi combustion chamber
00:57:56with twice
00:57:58the surface area through which heat could be lost
00:58:01versus a flat disc
00:58:03of cylinder diameter.
00:58:06In 71
00:58:08they
00:58:10made the chamber much shallower,
00:58:14closed the valve angle up somewhat,
00:58:17and made the ports
00:58:19smaller.
00:58:22So
00:58:23what's
00:58:24progress comes
00:58:26from encountering problems that you cannot solve with what you know.
00:58:34When that happens it obliges us to think
00:58:39rather than simply
00:58:42quote what we've read all our lives.
00:58:45Oh,
00:58:47we need to change this.
00:58:50This is also a problem that has
00:58:53caused
00:58:54alternative front ends to persist as long as they have even though they have not solved any problem.
00:59:05Motorcycles improve as the problems
00:59:09that we can't solve when we're riding them.
00:59:12I can't do this. I can't do that. Why is it?
00:59:16You need someone who's willing to think about it in terms other than the traditional.
00:59:22Yeah, let's qualify that.
00:59:25Alternative front ends have not succeeded in racing, but we have good examples of them making a good application.
00:59:31They're perfectly adequate. You can make a satisfactory motorcycle in a variety of ways.
00:59:36And I think Telelever does a nice job.
00:59:40The sort of hot cossack thing on the Goldwing
00:59:45that is really nice. So they are there, but when we're talking about that, when we're talking about racing, you know, you're not
00:59:53talking about the Tasey style, you know, all that nonsense. It's very cool, but it doesn't actually...
00:59:59Well, we had high hopes at the time that something would come from it. And when it didn't,
01:00:06we had to question the whole process and go over it again.
01:00:11So anyway, I think we have to credit Irimajiri for his work.
01:00:16Keith Duckworth
01:00:19working in the same direction under the same pressures
01:00:23and
01:00:24the people at MV who were constantly on the dyno,
01:00:29constantly looking for higher reliability, boosting horsepower
01:00:34and
01:00:35striving for broader torque. So
01:00:40hats off to these
01:00:43people who innovated because they had no alternative.
01:00:47Yeah.
01:00:48But then what, so here we are and we're making
01:00:52ultra high rpm 256s and we're winning 500 world championships and then we're
01:00:58not racing suddenly.
01:01:00Yep. And that's where business, you know, when you make some business decisions, you got to
01:01:05make some hard choices sometimes because
01:01:09resources are not unlimited. Oh, they moved those engineers over to their car program
01:01:15and
01:01:16also to the CB750 program.
01:01:20The racing
01:01:21put the words
01:01:23Honda 4
01:01:24into millions of minds worldwide.
01:01:27So that when the CB750 actually
01:01:31arrived in showrooms at the quite moderate price that was charged for it,
01:01:38it sold very well.
01:01:40So
01:01:41they were, they were reaping what was sown
01:01:46by the racing program, which the purpose of which was
01:01:50to make the Honda name a household word worldwide.
01:01:59And it worked. What do you know? And then, you know, Honda, Honda wandered back. They, they made their
01:02:06impression in automobiles. It was a little hiccup, you know, let's make it air cooled and
01:02:11and all that, but they came out with the Civic, which was water-cooled and they had the CVCC combustion chamber.
01:02:17And they were passing, they were passing emissions without a catalyst.
01:02:21They were burning so completely with that combustion chamber that they didn't need a
01:02:25catalytic converter at the time, which is
01:02:29what a great thing to accomplish. That means we understand combustion and all that obviously came
01:02:36from trying to spin a 50cc motorcycle at
01:02:4022,000 to 25,000 rpm because you got to light it and you got to get it burned
01:02:45and burn as much as you can to get the most out of it and move on to the next cycle folks.
01:02:50Yeah, but what Honda, there's a Honda paper from, an SAE paper from
01:02:55I think 1965 in which it said that they had explored four-stroke combustion out to 27,000.
01:03:03And
01:03:04although some people expected to find a flame speed limit
01:03:10that would cap
01:03:12rpm
01:03:14because there wouldn't be time for the combustion to occur before the piston had moved so far that
01:03:20it was being burned at a very low compression ratio and having little effect.
01:03:25They found that
01:03:27in-cylinder turbulence kept
01:03:30pace
01:03:31with
01:03:33crankshaft rpm as far as they had pushed it.
01:03:36So that when the spark occurred
01:03:41the flame kernel was shredded into little pieces and
01:03:46rapidly distributed around the combustion chamber so that
01:03:50combustion occurred within a reasonable time, i.e.
01:03:5550 degrees of ignition timing or even a little bit more.
01:03:59So the combustion was slow. At those crazy high rpm. Yeah.
01:04:04Yeah.
01:04:05About 50 degrees at that kind of rpm. You were gaining power from the very high rpm. You were losing something
01:04:11from the heat loss involved in having hot gases held captive
01:04:17with heat rushing into the metal all around piston combustion chamber
01:04:22longer.
01:04:23So they call that a time loss. Anyway.
01:04:26Well, it's surprising to me that
01:04:29I
01:04:33guess intuitively, which is which is the worst thing you can say about engine tuning
01:04:38intuitively, you would think that the speed of combustion would accelerate with turbulence up to a point
01:04:46and then what you said about
01:04:49the pressure rise, you know combustion what is happening with combustion is you're raising the pressure in the cylinder. Yeah
01:04:55Which is meant to push the piston down
01:04:57But could you get to an rpm where the piston could outrun the pressure rise and the answer at least for Honda was no
01:05:05If you do up to the tested maximum of 27,000
01:05:10Don't try this in your small block
01:05:14No
01:05:15And of course it's it's well to bear in mind
01:05:19that the flame speed in
01:05:22If we put a spark into a jar of static not moving
01:05:29A correct air fuel mixture
01:05:32This flame travel is quite slow of the order of a foot per second
01:05:37And if you then make a computation based on that
01:05:40Internal combustion engines are not practical
01:05:44Because the pressure peak pressure would be reached at bottom center or something worse
01:05:52So there obviously had to be a different mechanism by which flame was distributed and that was area by shredding
01:05:59the flame kernel
01:06:01into little pieces
01:06:03and
01:06:05lighting many of the little turbulent cells which
01:06:09professor
01:06:10Taylor depicts as lots of little gears meshing with each other. It turns 180
01:06:16holding a match
01:06:17When the match reaches the next turbulent cell it ignites rotates 180 onward
01:06:24That this process is as fast as the gas movement
01:06:30So, uh, no problem up to 27,000 so
01:06:35And things don't go that way. Yeah. Yeah for mortals like us where we're tuning our Norton commandos and
01:06:41You know, I never had a Norton then I bought a Norton and uh
01:06:4674 850 and I went through and did all the ignition timing because it still had points when I bought it
01:06:50I I got rid of that stuff because it wore out but uh, we used electronic but you still time that motorcycle
01:06:57Its maximum advance is 28 degrees. Yeah, and that's a real positive. That's excellent. That means that the flame
01:07:05Is the the combustion is great because it's happening quickly
01:07:09Yeah, and it's not it's not taking 27 000 rpm of turbulence it's happening at normal old street rpm and
01:07:16Norton commando third gear rolling 2500 and letting it swing through 3500 rpm is a thing of beauty
01:07:23That's why it's and when you have and that's that's not to say that the commando is some magical motorcycle
01:07:29but it goes back to the breathing and the combustion chamber and that's where
01:07:33As we talked about in a previous podcast a happy engine a great engine really is
01:07:39Combustion chamber and the flow to fill the cylinder. Yeah fast burn and excellent cylinder filling
01:07:45Yeah, and you get 28 degrees and if it's bad
01:07:47At at you know 3000 rpm on a commando. You're all in at 3000 rpm
01:07:52That means you've you've advanced the ignition to 28 degrees at 3000
01:07:56And with the limitations of ignition systems at the time
01:07:59You're just holding 28 degrees until you shift at 6000 or whatever it might be
01:08:04um
01:08:06with a combustion chamber that's slow like you've talked about the five valve yamaha where
01:08:11You just you're lighting you have to it wasn't when they went five valves. It didn't have the topography to kind of
01:08:18Squeeze everything together in a nice nice tight little package and it took more ignition timing
01:08:23There's been plenty of motorcycles that have 45 degrees maximum advance. They're everybody get ready to take a drink
01:08:30a bellassette ignition timing
01:08:33Uh on a 500 cc single is something on the order of 38 degrees maximum advance in the book
01:08:40Yeah, and it's a hemispherical head
01:08:43Some guys have modified them to squish you can take a 350 and make it into a squish head
01:08:47which is where you get the turbulence and
01:08:49concentrating the uh
01:08:51mixture around the spark plug, but it's a hemispherical head and
01:08:5638 degrees is what they called for and you can't get away with that without good gas these days
01:09:01So I go to 36 folks
01:09:0335
01:09:04Here's the argument
01:09:06if we could
01:09:07Suddenly produce the pressure peak pressure
01:09:11Just as the piston is really starting to move down
01:09:15Then we would be expanding
01:09:17the entire charge
01:09:20from
01:09:22The volume above the piston at that point
01:09:24To the volume above the piston as the exhaust valves begin to open that is the expansion ratio
01:09:31But if we're burning more slowly, so the piston is moving several millimeters
01:09:36Before peak pressure is achieved
01:09:39Then we're burning we're going to have a lower expansion ratio
01:09:44Which means we're going to take less energy
01:09:47out
01:09:48Of the hot combustion gas because we're past peak pressure and it's dropping
01:09:55So this is why we want to confine
01:09:58The combustion phase to
01:10:02The shortest that we can that we can readily achieve
01:10:06It is possible to make engines that have so much swirl that their combustion is
01:10:11Rough. It's so rapid that it's sort of setting things into
01:10:16and
01:10:18That's not tolerable because parts won't last under that kind of rapid
01:10:23pressure
01:10:24rise
01:10:25but
01:10:28The idea is
01:10:30to do the combustion as close to
01:10:34the point of
01:10:35Piston motion really getting underway
01:10:40So that we will have the rest of the stroke down to exhaust opening in which to take energy
01:10:46out of that hot gas
01:10:49and if we don't if we postpone that by a slow combustion, it means that or
01:10:54that
01:10:55We don't start counting until the piston has moved to several millimeters
01:11:00We're going to get a lesser effect at the crankshaft in the form of torque
01:11:06Hence
01:11:07the concern that people have engine builders in
01:11:11Trying to achieve rapid combustion
01:11:14and a minimum amount of
01:11:17Spark timing before top dead center
01:11:20Well, thanks, uh, thanks for listening folks we'll wrap it up there, uh and point out that the um
01:11:27We have done a podcast on the
01:11:29Two-stroke hondas so we could book in you can connect this era. Think about your honda civic in 1972
01:11:3774
01:11:38and then jump into uh
01:11:41Honda's grand prix development in the future. We did that podcast a while back. And so if you look at the at the playlist
01:11:46You will find that among the other near 50 topics that we've covered over the past year
01:11:51um
01:11:53It's our pleasure to do this, of course, how can I not be happy to spend an hour
01:11:58Talking about this stuff with kevin cameron and the ability to sit around with you folks and have you listen and and
01:12:04Especially have the conversation in the comments
01:12:07And the real expertise that we see come out in some of in some of the comments is uh
01:12:12The real expertise that we see come out in some of in some of the comments is uh is spectacular and that's what we found
01:12:18In my history, uh 20 year history 25 year history with cycle world
01:12:24Um, the audience has always been really spectacular. We would do a story in print
01:12:28About some engineering thing and even even the great kevin cameron and there would be some guy
01:12:35Whose whose title under his name on the letter?
01:12:37He wrote us or the email that we got with had a little bunch of asmes and xyzs and pdqs
01:12:44And some guy who's working in that and say actually we found that this occurs and we and kevin would correspond with that guy
01:12:50And learn something learn something. Yes
01:12:53well, that's what's that's what's so great about it plus just the
01:12:56just the very active interviewing engineers over the years, uh
01:13:00at press launches or getting the opportunity to go into the shop and talk about microns and
01:13:06Asperities and using language that engineers barely, you know
01:13:10They go to parties and they just sit by themselves on the swing because no one knows what an asperity is, right? So
01:13:16That's what happens with me. Like nobody wants to talk about welding
01:13:20Yeah
01:13:21Um, yeah, we appreciate you listening and um, we'll catch you on the next episode. Thank you