Honda decided to go dirt track racing in the 1980s and it wasn't long before it was winning--a lot! Technical Editor Kevin Cameron was the AMA observer at the resulting dyno tests as restrictor plates were tested to restore "parity" with the XR-750 and he followed the development of the Honda flat track racer from the early "sideways CX500" to the proper built-from-scratch RS750. Of course there is a lot about the Indian FTR750 and Harley-Davidson XR-750 as well, plus we discuss perhaps the most talented dirt tracker who every raced, so swing a leg over and ride with Kevin and Mark on the Cycle World Podcast. Bubba Shobert's Honda RS750 photo by Drew Ruiz.
Looking to buy? Get prequalified
https://octane.co/flex/1?a=171
Subscribe to Cycle World Youtube: http://www.youtube.com/c/cycleworld?sub_confirmation=1
Listen on Spotify: https://open.spotify.com/show/6CLI74xvMBFLDOC1tQaCOQ
Read more from Cycle World: https://www.cycleworld.com/
Buy Cycle World Merch: https://teespring.com/stores/cycleworld
Looking to buy? Get prequalified
https://octane.co/flex/1?a=171
Subscribe to Cycle World Youtube: http://www.youtube.com/c/cycleworld?sub_confirmation=1
Listen on Spotify: https://open.spotify.com/show/6CLI74xvMBFLDOC1tQaCOQ
Read more from Cycle World: https://www.cycleworld.com/
Buy Cycle World Merch: https://teespring.com/stores/cycleworld
Category
🥇
SportsTranscript
00:00:00This is the CycleWorld Podcast. I'm Mark Hoyer, the Editor-in-Chief.
00:00:04Our Technical Editor, Kevin Cameron, joins me once again.
00:00:08This week's topic is the Honda RS750 V-Twin flat-track race bike.
00:00:16Kevin is peculiarly qualified to talk about this motorcycle in detail.
00:00:21I mean more peculiarly qualified than normal.
00:00:26Like he's qualified to talk about all those bikes, but
00:00:29Kevin Cameron was in the room, he was in the dyno room
00:00:32when the AMA was looking at restricting the Honda
00:00:35to retain parity to keep racing, you know, I guess, more interesting.
00:00:41Somebody wanted it.
00:00:44Which we have discovered from doing the FTR750 Podcast,
00:00:48the Indian flat-tracker, and doing the XR750 Podcast
00:00:53that a lot of people wanted to talk about the RS750.
00:00:57And, let's say, the relationship between Harley and AMA
00:01:03to whatever degree that is true.
00:01:06But certainly, you know, the XR dominated for a long time
00:01:11and then Honda came in and did its thing.
00:01:18Pardon.
00:01:21And years later, Indian came in and did its thing.
00:01:24The Honda is interesting because I feel like the start of the Honda
00:01:29was very odd with turning the CX motor,
00:01:34which was a longitudinal crankshaft,
00:01:37turning that sideways and racing that a little bit.
00:01:40But they came to their senses and what we got was an incredible race bike.
00:01:46Yeah, they started out water-cooled and ended up air-cooled,
00:01:52which is another interesting step.
00:01:56But at all times, there are people who are struggling and striving
00:02:05to make a dirt tracker out of whatever is approved.
00:02:09And in the recent past, we've seen a long file of people
00:02:15with KTMs making 120 horsepower in stock condition,
00:02:21putting their engines into dirt track frames
00:02:24and then just being puzzled because they couldn't win anything.
00:02:31120 horsepower.
00:02:34Well, it turns out, as Gary Gray told us in the history of the FTR Indian,
00:02:43that when they got the engine from Swiss Auto,
00:02:47a little company in Switzerland that they bought for this, among other purposes,
00:02:52it was too powerful.
00:02:54And they had to keep chipping away at it to make it hook up.
00:02:59And that is the thing that is absolutely necessary in dirt track is
00:03:04if you don't hook up, if you can't accelerate off the corner,
00:03:09you can be powered by a rocket engine and you won't win anything.
00:03:14So the people who were developing this dirt tracker were not men of small stature
00:03:26wearing company caps, serving a giant electronic brain in the basement of HRC.
00:03:33They were regular folks.
00:03:38Jerry Griffith at Honda and Gene Romero was hired as sort of project manager.
00:03:47And overlooking the engine side, particularly with respect to the cylinder head,
00:03:55Jim Doerr of Megacycles Cams, the man you can't get in touch with
00:04:00because his wife doesn't want you to.
00:04:04She wants him to make money in the shop.
00:04:09And if he's jabbering with you, he can't do that.
00:04:13And also, Kenny Augustine was involved at some level.
00:04:20It was a project.
00:04:22Noted air flow specialist.
00:04:23Yes, noted air flow specialist.
00:04:25And who became interested in constitutional law in his latter years.
00:04:32But what happened was an extraordinary development of mutual trust
00:04:38between U.S. side and Japan side specialists
00:04:45because one side would do its part of the task
00:04:49and then ship the result to the other group.
00:04:53The other group would be impressed.
00:04:55Oh, they did that.
00:04:57That's really very clever.
00:04:58Why didn't we think of that?
00:05:00Back and forth it went.
00:05:02And Gene Romero there to provide a grounding in dirt
00:05:10and what it takes to go fast on it.
00:05:15And little by little, they developed the RS-750.
00:05:21Along the way came the evolution of the CX-500,
00:05:27the feeble little twin turned sideways in the form of the NS-750,
00:05:33which was water-cooled and which went through a couple of iterations.
00:05:39The carburetors were moved from one side of the cylinders to the other.
00:05:44And I think it managed to win a race or so.
00:05:47But then it was decided we have to build a proper dirt track engine
00:05:53from these bases.
00:05:56And what they ended up with was a four-valve 52-degree V-twin
00:06:03with staggered crank pins.
00:06:06Now, there are people who are dead sure that all that Honda did
00:06:11was buy an XR-750 and just copy it.
00:06:18Well, the XR, of course, has two flywheels, one crank pin,
00:06:24fork and blade connecting rods on that one crank pin,
00:06:28so the two cylinders are in the same plane.
00:06:31The Honda engine was designed to have no primary imbalance
00:06:35by means of Honda's staggered crank pin arrangement,
00:06:41so it didn't have one crank pin.
00:06:44The crank pins were separated by a large angle,
00:06:50and each one carried one connecting rod, and there were three flywheels.
00:06:55So, yes, it had a heavy flywheel mass like the XR
00:07:01and like any successful dirt tracker.
00:07:05But instead of the XR-750's two valves, the Honda had four valves,
00:07:11and instead of the XR's rolling element bearings,
00:07:17it had all-plane bearings, plane-bearing rods split and bolted
00:07:22and plane main bearings.
00:07:25I once asked a long-time Harley racing director whether...
00:07:35Bill Werner? Dick O'Brien?
00:07:38Dick O'Brien.
00:07:40OB.
00:07:41OB, yes.
00:07:43I asked him, if you had it to do again, would you have given the XR
00:07:51rolling bearings or plane bearings?
00:07:53And he thought for a while.
00:07:56And he said, well, I'd like to think I would,
00:08:01but the problem was that the rolling bearings in that engine
00:08:05were designed for 7,600 rpm.
00:08:08And over the years, in order to stay ahead of all the upstarts,
00:08:15the XR had to be revved up and souped up.
00:08:19It underwent continuous development.
00:08:22There's a little booklet that outlines this.
00:08:26Well, actually, it doesn't outline it.
00:08:28It details it.
00:08:31And it is wonderful to see the number of changes they went through
00:08:35on main bearings to get what they wanted for that engine, Harley Davidson.
00:08:41So, in a way...
00:08:44I want to say they went up to, what, 9,800?
00:08:47I know that 92 was supposed to be like a ceiling for a while,
00:08:50but I think talking to Chris Carr...
00:08:52Oh, yeah.
00:08:53At the end, they were really...
00:08:55Well, what he said, I saw him in the infield parking area at Indianapolis,
00:09:04and we had a little conversation, and he said,
00:09:06they were replacing the bottom end, the connecting rod big end bearings,
00:09:14every weekend.
00:09:16And that was very characteristic of early days roller bearing engines,
00:09:22that roller bearings accumulate fatigue cycles very quickly.
00:09:27And if they're revved up more than they were designed to be,
00:09:32the bearings are going to become unreliable.
00:09:35And that's what happened to it.
00:09:37Also, the XR had a problem with its cam drive gears.
00:09:42There could be unscheduled breakages.
00:09:46So, and I was present at Sacramento when one of those took place.
00:09:51It's just, oh, the motor stopped, and you kind of go around saying,
00:09:55oh, what was that?
00:09:57Oh, yeah?
00:09:58Oh.
00:09:59And then only later do you find out it broke a cam gear,
00:10:03because that was its other Achilles heel.
00:10:07Of course, you have two feet, two heels.
00:10:10Rolling bearings was one, and the breakage was the other.
00:10:14Well, you had one drive gear going through the cam drive, right?
00:10:20You had one drive gear.
00:10:21It drove one of the middle.
00:10:22There's four in a row there, one for each tappet,
00:10:26which is why the push rods are parallel to the cylinders, basically.
00:10:32You can position the cam so that the push rods are in a straight line,
00:10:36whereas if you have a single cam in the middle of the V,
00:10:38they've got to be kind of crossed over.
00:10:39They're all going off, yep, like in the latest single cam,
00:10:43or the original of 1936, 37, thereabouts.
00:10:49Anyway, they had run the course.
00:10:56I'm sure that if Harley-Davidson had wanted to put 100,000 or two
00:11:03into the program, let's stamp out cam gear failures.
00:11:07Just redesign that part of the engine.
00:11:09Stamp that nonsense out.
00:11:11We don't want it anymore.
00:11:12Well, I know this is an RS 750 podcast, but man,
00:11:16what I wish Harley had done is just taken exactly, okay.
00:11:24Gary Gray, Indian product development manager guy,
00:11:31conceived the FTR idea and program with his team,
00:11:36and then they built this bike.
00:11:37And of course, what do you do?
00:11:38Just like Honda, what's the reference standard?
00:11:41Why would you not copy Dick O'Brien's work?
00:11:45Absolutely.
00:11:46A lot of smart people over decades came in to build that bike,
00:11:52and then they just kept improving it.
00:11:53Of course, you would use that as your reference.
00:11:55What I wish Harley had done is taken that exact engine,
00:11:59don't change anything else, just update the bottom end.
00:12:06Just make it pressure oiling, plain bearings.
00:12:10That's all you had to do.
00:12:12That's what I think all you had to do.
00:12:14I just would have loved to have seen that.
00:12:16Yeah, it would have been grand.
00:12:17But it is sort of what Honda did.
00:12:21The Honda came good, and it had a period of winning
00:12:29several national championships.
00:12:31And then in 1986, the AMA, doubtless under pressure from people
00:12:38with whom the Honda and its achievements were not popular,
00:12:42said, well, NASCAR does restrictors.
00:12:46Maybe we could do them.
00:12:48So they made an arrangement with our friend Jerry Branch
00:13:00at Branch Flow Metrics to test these engines with restrictors
00:13:08and see what the results were so they could make a decision
00:13:12based upon some facts.
00:13:15And I was sent out there as the AMA's observer.
00:13:22And the first thing that I noticed was that Jerry's dyno room
00:13:28was designed such that if there was an engine explosion and fire
00:13:35on the dyno, to get away from it, you would have to open the door,
00:13:40the only door from the control room led into the dyno room,
00:13:44run through the fire, and then go out the door.
00:13:47But there was no fire.
00:13:49There was no explosion.
00:13:50We did a lot of running.
00:13:53Jerry Branch was a brand old character.
00:13:57After all, he was the one who told Harley Davidson people,
00:14:04look, the old way of doing things with these great big ports
00:14:08and these huge valves won't cut it.
00:14:11And I'll tell you why.
00:14:13I'll show you on the dyno.
00:14:14Oh, we've been doing it this way a long time.
00:14:17So he described his relationship with the Harley people as love-hate.
00:14:23But I think that love pretty much prevailed because Jerry had a row
00:14:29of cylinder head stands with universal angle adjustment on the top
00:14:36and a, what would we call them, operative at each of these stands
00:14:42with a die grinder churning out modified Harley Davidson street cylinder heads
00:14:49one after another.
00:14:51It was a wonderful business.
00:14:53And so there we are running these tests.
00:14:58And the result of the tests was that the RS has the same torque curve
00:15:05as the XR, except it's a little bit lower in foot pounds
00:15:13and a little bit higher in RPM so that the torque curve
00:15:18at the rear wheel is essentially identical.
00:15:21It wasn't hugely more powerful.
00:15:25It couldn't turn tremendous RPM.
00:15:29It was simply consciously designed to hook up on a dirt track
00:15:36and accelerate off of dirt turns.
00:15:39And that's the job.
00:15:41And I think it's a score for engineers that both Honda and Indian were able
00:15:50to do that engineering job and come up with a winning bike.
00:15:55So the restrictor episode, Honda sort of canceled after 1988.
00:16:02And then a privately owned Honda won another national championship in 1993.
00:16:09And then those bikes went to the museum.
00:16:12With the famous, talented Ricky Graham, late Ricky Graham.
00:16:16Oh, yeah.
00:16:17A thing of beauty on a dirt track for sure.
00:16:20Yes, indeed.
00:16:22And the Honda people said that in developing the engine,
00:16:29their M.O. was first get the torque.
00:16:35Learn to fill the cylinder and to burn the charge in it.
00:16:40Because Keith Duckworth famously said at one point,
00:16:45I believe I can tell more about how an engine's going to run
00:16:50by putting my forefinger into the intake port
00:16:53than all these other companies with their flow benches.
00:16:57Because what he was doing was not just trying to get a lot of airflow,
00:17:02to get a lot of air, a lot of mixture properly into the cylinder,
00:17:07but also to do an efficient and correct job of burning it.
00:17:14And that's what this Honda informant was talking about.
00:17:18He said, first you get the torque,
00:17:20then you learn to carry that torque up to the RPM range that you need to cover.
00:17:27And he said, this takes you into a territory where torque and horsepower are at odds.
00:17:39Because to make horsepower, you have to have higher RPM.
00:17:42You have to perform the power producing cycle more frequently, more times per second.
00:17:48And torque, as we know from using a torque wrench, continues down to zero RPM.
00:17:56It's just a twisting force.
00:17:58So lots of projects have foundered on this problem.
00:18:04To make torque, you need to have high compression,
00:18:09and you need to have good cylinder filling.
00:18:12But you may not be able to make that burn at high speed,
00:18:16because the combustion chamber at high compression is squeezed so tight...
00:18:23that if you imagine lots of little people with matches trying to hand them to each other,
00:18:28while squashed into that space,
00:18:30combustion is going to take a long time,
00:18:32and consequently there'll be a lot of heat loss,
00:18:35and there goes your top end up in smoke.
00:18:39So it used to be, for example, with five-valve Yamahas,
00:18:44you had to decide, okay, we're going to a short racetrack, we're going for torque,
00:18:49we're going to raise the compression and damn the RPM.
00:18:53On the other hand, if you're going to Daytona, you might want to open up the chamber,
00:18:58lower the compression ratio in order to provide room for combustion to spread rapidly,
00:19:06and go for it on top end.
00:19:08So I think they probably worked out a good compromise on the RS,
00:19:12because they were able to win races with it.
00:19:15And, like Indian, they hired front-row riders.
00:19:21They weren't planning to do some kind of home project here.
00:19:26Their job was to win the Grand National, and that's what they did several times.
00:19:36And I am sorry, like Mark, that the Harley XR was not updated when it needed to be.
00:19:48I suspect that at that time, they were pondering such developments as LiveWire,
00:19:57the wonderful, well-designed, electric Harley-Davidson motorcycle,
00:20:03the fastest accelerating Harley put into production.
00:20:08And spending money on dirt track racing, is that the spirit of the moment?
00:20:17Well, as it turns out, for a lot of Americans, it is. It still is.
00:20:23So we were able to get a lot of interest in our podcasts on the XR750 and the FTR Indian.
00:20:34It's definitely resident in the American motorcycle psyche, that track racing.
00:20:39I don't think it's, you know, it's never been a mass-market racing series.
00:20:44It's never been huge, but it's been there, and it is some of the best racing.
00:20:50Like when it is expressing itself, and when the mile is expressing its beauty,
00:20:54it is truly, it is just epic. It's so beautiful. It's so beautiful.
00:21:00Hard, you know, I was thinking about water cooling versus air cooling,
00:21:05and, you know, it only needs to be heavy enough to store the heat that it makes on the straightaway,
00:21:10and then it gets a rest, basically, after every straightaway.
00:21:15And the RS Honda had piston-cooling oil jets.
00:21:21The other part of the hot combustion chamber, one part is the cylinder head,
00:21:26which has all those fins growing out of it.
00:21:29The piston gets quite hot, too, and they heat the incoming mixture,
00:21:34so that before the spark, there are pre-flame mixtures, pre-flame reactions,
00:21:40which chemically alter the stuff in the cylinder,
00:21:46so that some small fraction of it can act as a self-igniting violent explosive
00:21:54in the phenomenon called knock or pinking.
00:21:58And that, it sets the upper limit on what you can do with a particular engine.
00:22:05You say, well, we'll give it some more cooling fin area.
00:22:08Oh, well, we'll give it oil jets. We'll do this. We'll do that.
00:22:12But all the time, you're trying to run as much compression as you can without provoking knock,
00:22:18because compression produces torque.
00:22:23And diesels produce tremendous torque,
00:22:29because they have compression ratios that start out at 16 or 17 to 1.
00:22:35But we can't do that with a gasoline spark ignition engine,
00:22:38because the demon, knock or detonation, is waiting to blast your hopes.
00:22:47And it does it by excavating metal out of the piston until, in extreme cases,
00:22:53the piston rings are just arcs sticking out into space.
00:22:58Yeah, imagine the disappointment when you pull your spark plug
00:23:02and you see little flecks of sparkly dust. It's like, oh, no.
00:23:07And sometimes the spark plug is full of aluminum.
00:23:10Yeah.
00:23:11It's just crammed with it.
00:23:13I was shocked to learn years ago that the predominant amount of heat
00:23:20that comes out of the piston leaves through the rings.
00:23:23Yeah.
00:23:24And I just thought, man, that's amazing.
00:23:27But, of course, it has the closest contact with the cylinder wall.
00:23:30It is really intimate. It's much less than... It's on the order of one and a half microns.
00:23:37Yeah.
00:23:38It's small.
00:23:39You've talked about in other podcasts and other engines where somebody says,
00:23:43oh, we're going to use one piston ring because, you know,
00:23:47we're going to lower that friction, but then the piston gets too hot.
00:23:51Yeah.
00:23:52Add a second ring and everything's okay.
00:23:55That was Udo Giedl's experiment with the BMW Superbike.
00:24:00And they tried doing what AJS had done to put a single L-ring on top
00:24:08and then the oil scraper ring with no second ring.
00:24:13And he said they had to run more clearance than normal to make that combination work,
00:24:19which meant piston temperature was up.
00:24:22So he decided at that point, I've learned something.
00:24:26That second ring is a heat transfer ring.
00:24:29And if you pull out Pounder's authoritative book on marine diesels,
00:24:35you'll see that they have a whole stack of heat transfer rings on their pistons.
00:24:41One of these days, I'll bring in my B-25 piston that's marked NG for no good.
00:24:46So it came out of a B-25 at rebuild.
00:24:49I think it was a commemorative Air Force plane.
00:24:52And so they sell that stuff to you.
00:24:56And I had to have it when my brother got it for me, which is why I had to have it.
00:25:01And it's got, I want to say it's got five rings.
00:25:05It's got an oil scraper below the pin.
00:25:08It is completely full skirted.
00:25:10You know, it's like this coffee cup.
00:25:13It just goes completely full skirted.
00:25:16The pins up here, a scraper ring down here, compression ring, and I think three rings up here.
00:25:22It has a lot of rings.
00:25:23Six and an eighth bore.
00:25:25And then inside the skirt, this piston had fins inside the skirt to cool.
00:25:33But I don't know if you want to cool the skirt.
00:25:35You want to cool the crown, which I think is why we stopped doing the interior fins
00:25:39and started squirting oil at the base of the crown.
00:25:43There's another reason.
00:25:44When you have fins on a hot object like the piston crown,
00:25:49you have thermal stress and eventually you have cracking.
00:25:53So Wright made the R2600 that you're talking about.
00:26:02And it had those fins.
00:26:04But when they built the later versions of the big engine, the 3350,
00:26:10the inside of the piston was just like the inside of any forged piston.
00:26:14It's completely smooth.
00:26:16Thermal stress, meaning that a fin sticking out.
00:26:19The fins are cool.
00:26:21And this is really hot.
00:26:23And so the expansion, it puts stress on the part because the temperature difference
00:26:28for the same material is extreme and cracking ensues.
00:26:34One response to that is to switch from fins to stalactites.
00:26:40And there are some pistons that were made that way.
00:26:42And the cylinder head of the famous AJS porcupine had that type of fin.
00:26:49And so I think in their case, the reason is it didn't have any systematic cooling,
00:26:56so they wanted it to be able to air to blow through from the sides
00:27:00or down from the top, wherever there was air.
00:27:03There was a fin reaching for that cooling effect.
00:27:06Yeah, I always wondered about the RD350 cylinders
00:27:10because they have gaps in the fins.
00:27:12The fin is not a complete fin around the cylinder.
00:27:14There are places where they had gaps.
00:27:17And I always figured that that was where the cracking occurred,
00:27:19and they decided to remove that material so that it could breathe.
00:27:24It's like slotting your brake discs.
00:27:26It's like putting a slot in your old iron brake discs
00:27:29and then drilling that no-crack hole at the root of that slot,
00:27:34which I saw at ARMA, by the way.
00:27:36I saw a guy on a Honda that had those exact cuts.
00:27:41And there was a TZ500 in the Barber Museum that has them manufactured that way.
00:27:50I had a question about the XR750 roller bearing versus plain bearing.
00:27:56RS750, plain bearing, you basically have no bearing problems if everything's okay.
00:28:02If you have good oil pressure and the clearances are right
00:28:06and it's not flexing, it's not doing anything bad,
00:28:09you kind of spin that sort of as much as the connecting rods would allow.
00:28:13The crank kind of doesn't care.
00:28:15Whereas with roller bearings, I think counterintuitively on the XR,
00:28:19you think like, well, we're thrashing these dang main bearings.
00:28:24We better put bigger bearings in.
00:28:26But it's actually the opposite, right?
00:28:28You make them lighter and smaller so that they don't skid and skate
00:28:31and they have less mass.
00:28:33Especially for the connecting rod bearings because they're not only rotating,
00:28:38they're whirling around while they do it.
00:28:41And so the fellow who originally did the math for that was a German gentleman
00:28:49by the name of Hamp, H-A-M-P-P.
00:28:53And his paper is in the INA Museum or their library, the corporate library.
00:28:59And when INA entered the bearing business after World War II,
00:29:07their first big contract was gearbox bearings for Volkswagens.
00:29:12And it does seem counterintuitive, those little tiny rollers,
00:29:18often with a little cage that looks like a miniature squirrel cage blower
00:29:23with the roller in each opening.
00:29:26RD-TZ350 rod bearings are just these tiny little things.
00:29:32The silver-plated ones, of course, are the ones you want.
00:29:36They're just cute and small, but away they go.
00:29:40Well, we used to figure with the TZ Yamahas, the racers,
00:29:47that a crankshaft would fail.
00:29:50The big end would tie up in about 900 miles,
00:29:54somewhere between 900 and 1,000 miles.
00:29:57And factory projects supported riders and so forth.
00:30:01They wanted to change the crank at like 450 miles.
00:30:05So half of what you might call the actual service life,
00:30:15the time before failure.
00:30:17So it's just rolling bearings were an excellent solution
00:30:24for the first motorcycles.
00:30:26When the pioneering motorcycles were built,
00:30:31they had bronze bushings everywhere
00:30:34because that was the railroad technology.
00:30:37If you were a technologist,
00:30:39the chances were you knew a lot about railway technology.
00:30:43So they would throw…
00:30:45W.O. Bentley.
00:30:46Yes.
00:30:47W.O. Bentley, man.
00:30:48He was in the Rolls-Royce fella.
00:30:52And the pioneer of aluminum pistons in Britain.
00:30:55Yeah.
00:30:56The Bentley rotary aircraft engine was very successful
00:31:02with its aluminum cylinders and aluminum pistons.
00:31:06And that was a jumping off point
00:31:08for a lot of design work after World War I
00:31:11was all those men who were mechanics or engineers
00:31:17or in some way associated with aviation in that war
00:31:21went on to apply their skills to the motorcycle racing problem.
00:31:27And Dick O'Brien, whom we mentioned earlier,
00:31:30was with an Air Force unit whose job was to take down
00:31:37but possible to make serviceable enemy aircraft,
00:31:42restore them to flight status
00:31:44so they could be flown by U.S. test pilots
00:31:47to discover their strengths and their weaknesses.
00:31:50So Dick O'Brien is one of those people
00:31:52only with relation to the Second World War.
00:31:55And there were many others.
00:31:57I suspect that Tom Sifton,
00:32:01who is the first user of piston cooling oil jets
00:32:08sometime around 1950 that I've heard of,
00:32:11there probably have been others,
00:32:13but he's the first one I'd heard of.
00:32:15And I think he learned that from World War II aviation.
00:32:21So all this stuff ties together.
00:32:26Maybe one day it'll just be useless history
00:32:30like keeping track of all the advances in technology
00:32:35made with the linotype machine.
00:32:38Linotype machine?
00:32:40What's that?
00:32:42Yes.
00:32:43For the moment, I find it interesting.
00:32:46Yeah, World War II aircraft development
00:32:49was a beautiful time.
00:32:51It was a terrible time for humanity,
00:32:55bombing itself and making huge fires in Dresden
00:32:58and all the horrors that go with that.
00:33:0140 to 60 million dead, yes.
00:33:04But what we also got out of that
00:33:10was cubic zillions of dollars and people hours
00:33:15devoted to discovering how to keep pistons cool
00:33:19when you're turbo-compounding your radials
00:33:24and you're stuffing air into cylinders
00:33:27and they're all air-cooled.
00:33:29Not all, but the Navy certainly stuck with the radials.
00:33:33It was a highly concentrated, highly funded development
00:33:37that was not necessarily tied to commerce
00:33:41in the sense that victory wasn't making a profit.
00:33:44Victory was something else entirely
00:33:47that was more important than a profit.
00:33:50The wartime development of reliable transport aircraft
00:33:56was the birth of the world commercial aviation industry
00:34:03because before that, transatlantic aviation
00:34:07was by flying boat, the big Boeing 314.
00:34:10And there aren't usable waterways
00:34:15close to all the cities where you'd like to land.
00:34:18And the war put airfields everywhere,
00:34:23everywhere around the world.
00:34:25So the moment the war was over,
00:34:27people were on constellations and C-54s
00:34:32flying commercially to places
00:34:35that had never been imagined 10 years before.
00:34:38And then, of course, in 1960, the jet revolution came
00:34:42and that was that.
00:34:44But I want to repeat that Honda's RS 750
00:34:50was not an HRC creation.
00:34:53It was a co-creation of American hands-on know-how
00:34:59from the listed persons
00:35:02and Japanese manufacturing technology, among other things,
00:35:07and their ability to test and provide meaningful results.
00:35:14So it was a cooperation between US side and Japan side,
00:35:19not something that was handed down from the HRC Olympus.
00:35:25And just as the Indian project, the FTR,
00:35:31the engine as it came,
00:35:33making over 100 horsepower and 11,000
00:35:38as it arrived in the US from Swiss manufacturing,
00:35:43had to be toned down because it wouldn't hook up.
00:35:48So this is how a dirt track project is brought to success,
00:35:53is by realizing what the goal is.
00:35:57If we don't hook this up,
00:35:59if we don't have the kind of torque curve or torque table,
00:36:03because that's what you want, it's flat,
00:36:05not something that is like the cross section of Switzerland.
00:36:11If you don't provide these things,
00:36:14then it's a series of iterations.
00:36:16So that's better.
00:36:17Oh, well, what about if you come to a result that can be successful?
00:36:23And these two projects, Honda's RS, the Indian's FTR,
00:36:29both were successful.
00:36:31It's the story of racing though.
00:36:33I mean, it's what you're describing that,
00:36:37I don't know, you have the engineering side
00:36:40and they're theoretical
00:36:41and you certainly have practical experience,
00:36:44but they're theoretical
00:36:45and they're instrumenting things and measuring combustion temperatures
00:36:48and pressures and crown temperatures
00:36:51and doing all that very lab-like.
00:36:53And then you hand it over to the farmers is what,
00:36:56I forget who that was that said that, Honda.
00:36:58Yeah.
00:36:59Martin, maybe.
00:37:00No, it was Gary.
00:37:04Mathers?
00:37:05Gary Mathers at Honda.
00:37:06Gary Mathers was a tremendous asset for them
00:37:09because of his insistence upon practicality.
00:37:14But that's the thing.
00:37:15And so you hand it over and he told that same story to me
00:37:18in the paddock at Laguna Seca.
00:37:20He says, we're the farmers.
00:37:22It's raining.
00:37:23The equipment's not working.
00:37:25We have to fix it.
00:37:26We've got to get the hay in before the rain.
00:37:28That's it.
00:37:29That's we have to do that.
00:37:31And we have to find a way.
00:37:35And that's what's cool.
00:37:38That's always what I've loved about racing is that,
00:37:42it is happening less now.
00:37:44It certainly is happening in the ARMA paddock.
00:37:47A guy rebuilding his 650 Nighthawk on a blanket overnight
00:37:52so he can go out and win a race the next day
00:37:55was pretty cool to see.
00:37:58They're not rebuilding engines in MotoGP,
00:38:00but they're certainly taking practical information back
00:38:03to the places where it gets done.
00:38:05And that's, I don't know.
00:38:09I just love that kind of development.
00:38:10I love people in the field cutting, welding.
00:38:13Cal Carruthers is my hero.
00:38:15Because this is the thing.
00:38:18This is a way to approach the truth by small steps.
00:38:24Now, in engineering, each step costs something.
00:38:26Either you have to put in time, or you have to put in money
00:38:30and other resources.
00:38:32But this is a way to approach truth by steps.
00:38:36And truth is winning races.
00:38:40And it's a careful process.
00:38:43It calls for experienced people who say,
00:38:46oh, I remember this, something happened at DeCoin.
00:38:49And this is putting me in mind of it.
00:38:52Let me think about this for a minute.
00:38:55And somebody comes up with something that works.
00:39:00I was just reading this morning that Francesco Bagnaia,
00:39:04who's currently second in the MotoGP World Championship
00:39:07and has two titles to his credit,
00:39:12says that he likes to brake with the front end bottomed.
00:39:19Because then he can feel the tire absolutely.
00:39:24The connection is direct.
00:39:26And there's another benefit.
00:39:28And that is, and he knows the other benefit,
00:39:31because otherwise he wouldn't have put it this way.
00:39:33He said, this enables me to run essentially the same spring
00:39:39and damping setup as for rain.
00:39:42Which means it allows him to increase mechanical grip
00:39:48by using a rain setup.
00:39:50Softer, meaning that there aren't these hard jolts
00:39:54that are delivered to the motorcycle by the bumps.
00:39:57The jolts are softer.
00:40:00The wheel conforms to the bumps more accurately
00:40:04rather than skipping from crest to crest,
00:40:06as it does when the springs are stiff.
00:40:09I cannot argue with him and his riding.
00:40:14What I will observe is Nicky Hayden going into turn 11
00:40:18at Laguna Seca in MotoGP, forgetting the year,
00:40:22trying to make a pass, braking so hard.
00:40:27And you watch the bike compress,
00:40:29and then you watch the tire compress,
00:40:31and then he hit a bump, and you saw light.
00:40:34And down he went.
00:40:36So it works to a point.
00:40:39And obviously he's making it work for himself.
00:40:43And Godspeed, amazing.
00:40:47How can you do that?
00:40:49As long as you don't hit that one bump,
00:40:51or maybe he's so supernatural, he's feeling it.
00:40:56I'm sure he knows where the bumps are.
00:40:58Because there was that case at Indianapolis
00:41:00where a reporter from the Indianapolis Star
00:41:03became hot, hot under the collar,
00:41:07because Casey Stoner told him that the track was lousy.
00:41:13Oh, this track has the massive weight of dignified tradition.
00:41:19How can you say such a thing?
00:41:21And besides, where are these bumps you're talking about?
00:41:24Stoner told him where they all were.
00:41:28And you have to know to be that good.
00:41:31You have to know.
00:41:33Yeah, all the top people,
00:41:36you can ask them about a specific race
00:41:39in 1982 at Ontario or something,
00:41:42and they'll be like, oh, yeah.
00:41:44The seam at the outside of seven,
00:41:47it's just mind-blowing.
00:41:50Yep.
00:41:51Yeah, the memory of a racer is remarkable.
00:41:56So I was thinking about the NS750,
00:41:59the early one.
00:42:00Spencer raced that,
00:42:01and I think we did get a race win
00:42:04with basically the CX turned sideways bike.
00:42:08Clarified CX motor, yeah.
00:42:10But that was the water-cooled one,
00:42:13and there were issues with cooling on that
00:42:15that were not readily apparent
00:42:17in kind of normal tooling around.
00:42:19He said it could take 10 or 12 laps
00:42:21for steam bubbles to accumulate
00:42:23in a place from which the flow
00:42:26did not scour them away from.
00:42:28They accumulated until you had a hot zone
00:42:31with no cooling,
00:42:33and then there was trouble.
00:42:36And the whole snowmobile industry
00:42:39had an episode like that a number of years ago
00:42:42because the first designs were basically
00:42:45the air-cooled essentials
00:42:48with a pot of water around.
00:42:51And it looks like that pot of water is...
00:42:54You know how long it takes
00:42:56when you're boiling water for spaghetti or noodles.
00:42:59It just sits there sullenly simmering
00:43:02and refuses to boil.
00:43:04Hence the saying,
00:43:05a watched pot never boils.
00:43:07But believe me,
00:43:10such pots do boil,
00:43:12and the snowmobile industry
00:43:13had to redesign their cooling jackets
00:43:16so that they were much closer to the cylinder
00:43:19to increase the water velocity
00:43:22so they could scour away steam bubbles
00:43:25that were forming in hot places
00:43:27and bring water to those places
00:43:29that would cool them.
00:43:31A friend of mine is a professional drinker,
00:43:34and she said she would take her beer,
00:43:37the warm beer that she wished to be cold,
00:43:39and she would put it in the hotel bucket
00:43:42with ice and wouldn't just leave it there.
00:43:45She would sit there and diligently rotate it.
00:43:49Just like you peckle the water in the bathtub
00:43:52to bring the warm water, the hot water,
00:43:54up against your skin.
00:43:55Because if it just sits there,
00:43:56it becomes an insulator,
00:43:57and that's why we've got to blast that water out.
00:44:00Steam sucks as a coolant.
00:44:02As I discovered on my pickup truck,
00:44:04I redid the cooling system,
00:44:06and I didn't want to hook up the heater
00:44:07because it was still cleaning.
00:44:08I was trying to clean the block,
00:44:10and I didn't want to run that
00:44:11through my new heater core.
00:44:12And I thought,
00:44:13well, I've got this take-off,
00:44:15it's actually the suction side on the pump.
00:44:18And I'm like, I'll just put the hose on,
00:44:20and I'll just lay the hose in the engine compartment
00:44:22up to where the heater core goes.
00:44:26And I left it there,
00:44:27and I plugged it with a 3.25-inch socket extension
00:44:32because it's nice and smooth,
00:44:33and it's the right size for a 5.8.
00:44:35It just slides in.
00:44:36Clamp it on there.
00:44:37And everything was golden as I just drove around,
00:44:40and I just tootled around.
00:44:41It's a 460 V8.
00:44:42I didn't really rev it,
00:44:43and I'm running the air conditioning
00:44:45because I fixed that.
00:44:46And then, I'm like, well,
00:44:48I want to take this across Utah towing a UTV.
00:44:53I better hammer it.
00:44:54You know, let's hammer it.
00:44:55So I hooked up the trailer,
00:44:57turned on the AC.
00:44:58It was a 100-degree day,
00:44:59and I started hammering it and revving the engine.
00:45:02And I just, you know,
00:45:05moronically left a giant,
00:45:07that 5.8 hose that was three feet long
00:45:10was full of air.
00:45:11And it was fine if I wasn't revving the engine,
00:45:13but as soon as I started revving it,
00:45:15it was pulling air out of this long repository.
00:45:19And I got overheating.
00:45:20I got foaming coolant.
00:45:22I'm like, oh, my God,
00:45:23I have a blown head gasket.
00:45:24I had nightmares of pulling this motor out.
00:45:27And, no, it was just me being dumb.
00:45:29But steam sucks.
00:45:30That's all I'm getting at
00:45:31is I have firsthand experience with that.
00:45:33And I'm, you know,
00:45:35I'm still kind of a fan of air-cooled motorcycles.
00:45:37Air-cooled motorcycles
00:45:38and usually pre-war or 50s are not bad
00:45:41because you don't have to deal with brake fluid.
00:45:44I hate brake fluid.
00:45:46So, yeah, cable-operated brakes.
00:45:49Anyway, that's maintenance tips with Mark.
00:45:53Steam in the cooling system.
00:45:57And that was the problem with an S750.
00:46:00Yeah, eliminated.
00:46:01Steam would accumulate
00:46:03in a place around the wet liner, I guess,
00:46:07after a number of laps.
00:46:08And then they would have all the symptoms
00:46:10of overheating and power loss that go with it.
00:46:16So, that's our story right there.
00:46:21I think we've covered it.
00:46:23Well, I was going to ask you about,
00:46:25I don't think we have the Jerry Griffith name
00:46:27in this narrative yet, do we?
00:46:29Well, Jerry was at Honda, as I understand.
00:46:32And he was the sort of the person
00:46:36who made parts, did fabricating,
00:46:40did put things together so they could be tested.
00:46:43And that is an essential role, certainly.
00:46:52There have been other people in that role
00:46:56who have similarly been essential
00:47:00because consider the racing teams
00:47:06in European road racing
00:47:08that all had to have a Kelker Others,
00:47:12an Irv Canemoto, a...
00:47:19Oh, what was his name?
00:47:24I can't think of it right now.
00:47:26But he worked with Doohan
00:47:29and he worked with...
00:47:31Oh, Jerry Burgess.
00:47:32Jerry Burgess, yes.
00:47:34Jerry Burgess is a goldmine of detail
00:47:38from what you might call the middle period
00:47:41or the late period of two-stroke racing
00:47:45in Grand Prix.
00:47:48So much experience.
00:47:50And Kelker Others, of course,
00:47:53is the one who took an ill-handling frame
00:47:56to Barry Sheen's shop
00:47:59and sawed the steering head off
00:48:01and welded it back on at an angle
00:48:03that he thought his rider would like better.
00:48:05And he did.
00:48:07It was that kind of thing
00:48:09that Jerry Griffiths was involved in continuously
00:48:12during the development of the RS750.
00:48:14Somebody had to do it.
00:48:16Somebody had to actually lay hands
00:48:18on the material parts
00:48:20and put them into the arrangement
00:48:22that they wanted to test next
00:48:26over and over.
00:48:28Yeah, I think it was Jerry...
00:48:30I think this is a Jerry quote.
00:48:31It says,
00:48:32The problem wasn't lack of power.
00:48:33This is the CX-based motor.
00:48:35In the end,
00:48:36we got 90 to 92 horsepower out of it.
00:48:38We were spending money trying to win.
00:48:40I did a lot of dyno work with it myself.
00:48:43Lots of other people helped, too.
00:48:44Jim Doerr at Megacycle,
00:48:45Jerry Branch,
00:48:46Kenny Augustine.
00:48:47The biggest problem was
00:48:48that they'd boarded out so big
00:48:50going after displacement
00:48:51to get that 10 miles an hour
00:48:53they were lacking on the straights.
00:48:55We didn't have enough room
00:48:57in the water jacket around the sleeves
00:48:59and it would get steam pockets and overheat.
00:49:02We couldn't run antifreeze.
00:49:04If we could have run antifreeze,
00:49:06it wouldn't have boiled out
00:49:08because you raise the boiling point.
00:49:10But you can't run antifreeze
00:49:11because it's so slippery
00:49:13when it comes out.
00:49:14That's why, you know...
00:49:1650-50 antifreeze and water.
00:49:19It was a rocket for four or five laps.
00:49:23It was like an air cool.
00:49:25Yeah.
00:49:26Hank Scott told me
00:49:27it was the best handling bike
00:49:28he'd ever ridden.
00:49:31He said,
00:49:32I know Jeff Haney.
00:49:33I think it ruined Jeff Haney's career.
00:49:37He got to a point
00:49:38where he had no confidence in the bike.
00:49:40He was just a young kid.
00:49:42Jeff Haney, you know,
00:49:44he was successful at Daytona
00:49:46and he became an instructor
00:49:48at Freddie Spencer Riding School
00:49:49because they obviously knew each other.
00:49:51He was really something, Jeff.
00:49:52He was a man of great humor and mischief
00:49:56and also much talent.
00:49:58The kind of guy
00:49:59who also liked to pass you
00:50:02at your riding school
00:50:04and he'd come by
00:50:05in a right-hander
00:50:06and his hand would be on the throttle
00:50:08and he would reach over
00:50:09and he would point like this
00:50:11while you're basically
00:50:13almost riding at your limit.
00:50:15He's taking his hand off the bar
00:50:16and telling you,
00:50:17I don't know,
00:50:18come in tighter over here.
00:50:19It was pretty good.
00:50:22So restrictor plates,
00:50:23you know,
00:50:24Honda had enough success
00:50:25that AMA thought
00:50:26something should be done
00:50:28or somebody thought
00:50:29something should be done.
00:50:31And so we got restrictor plates
00:50:32just as happened with the FTR.
00:50:34The FTR was restricted quite a bit,
00:50:37almost 25%.
00:50:40I forget the millimeters,
00:50:41but it might've been 38 down to 34.
00:50:43Does that sound right?
00:50:45The 20-odd percent
00:50:47reflects the area change.
00:50:49Area.
00:50:50It doesn't sound like that much
00:50:51when you just say,
00:50:52well, it's only a couple millimeters.
00:50:54Well, the area is quite a bit
00:50:56and Honda had to deal with that.
00:50:58I think also to stave off
00:51:00any possibilities of restrictors,
00:51:03we had the famous story
00:51:05about Bubba Showbert
00:51:07being told not to win by too much.
00:51:10Like, just roll out
00:51:11at the end of the...
00:51:12No, don't show them what we got.
00:51:14Just win by just enough.
00:51:16And I think there's a long tradition of that.
00:51:19Oh, there certainly is.
00:51:20And there've been a lot
00:51:21of other applications for it.
00:51:23So when you were in the branch shop,
00:51:25that's where you saw the...
00:51:26That's the reason you were there
00:51:28is to observe the restrictors working.
00:51:30The restrictors were very different
00:51:32from the ones that were applied
00:51:34to the TZ750.
00:51:36The TZ750 restrictor
00:51:38had a bell mouth entry,
00:51:41just rounded entry,
00:51:43and then a long divergent conical exit
00:51:47to recover the pressure
00:51:49from the velocity,
00:51:51which is very high at the throat.
00:51:53And they didn't restrict at all.
00:51:57They made the motorcycle more rideable.
00:52:00Kenny lapped the field.
00:52:03And it was...
00:52:06A Venturi is a very effective...
00:52:10It's highly efficient
00:52:12until you get near the velocity of sound
00:52:14in the throat,
00:52:15and then everything gets different.
00:52:17But when they did the restrictors
00:52:19for the dirt trackers,
00:52:21what they did was essentially
00:52:23to have a flat washer
00:52:27with a hole in the flow path.
00:52:30And the edge of the washer
00:52:32had to be a certain sharpness
00:52:34and all this business.
00:52:35And that creates a tremendous amount
00:52:38of downstream turbulence
00:52:40that does not recover pressure
00:52:42like a Venturi.
00:52:44And so it can be made to restrict.
00:52:46And so we made run after run
00:52:49with restrictors of different diameters.
00:52:53Were they after the carburetor?
00:52:55Between the carburetor and the intake?
00:52:57Yes.
00:52:58Because they'd have to be
00:52:59a certain distance from the valve anyway, right?
00:53:01You would have to regulate
00:53:02the distance from the valve.
00:53:03Would you not?
00:53:04Yeah, it was all spelled out.
00:53:07In the TZ750 Venturis,
00:53:10they were actually pushed
00:53:11into the carburetor.
00:53:14The thing is,
00:53:16it's a slick little part.
00:53:18You just slip it into a VM34,
00:53:21and that's all you have to do.
00:53:23Stick that on the engine,
00:53:25you're ready to go.
00:53:26But the AMA restrictors
00:53:28were more like the NASCAR restrictors,
00:53:35like a washer in the way.
00:53:39And they turn that lovely high-speed jet
00:53:43into a turbulent mass
00:53:47that can't fill the cylinders as well,
00:53:50and that's why it's restrictive.
00:53:52I guess you get a homogeneous charge
00:53:54out of that.
00:53:55Oh, lots of mixing, yes.
00:53:59Oh.
00:54:02Well, Bubba was a character.
00:54:04He had that American rural speech
00:54:07that we all find so strangely charming.
00:54:12It's far from Northeast Coast broadcast English.
00:54:18Yeah.
00:54:19I find when I'm down at Barber,
00:54:22surrounded by people who talk that way,
00:54:25it's all I can do to just
00:54:28hang on to my own way of speaking
00:54:30because their way of speaking is beguiling.
00:54:34It makes you fall in with it,
00:54:38and that's mimicry,
00:54:40and it's disrespectful.
00:54:44But you'll hear plenty of it
00:54:48in the dirt track paddock.
00:54:50Yeah.
00:54:51Well, it was one of the things
00:54:53that made Nicky Hayden
00:54:56at the world championship level so charming
00:54:58is because he was certainly
00:55:01a different person than I met when he was 16,
00:55:03and I was interviewing him
00:55:04in his motorhome at Willow Springs
00:55:07racing a Hypercycle 600
00:55:12at a race prior to the national
00:55:15that was going to happen out there.
00:55:18He grew up a lot,
00:55:19and he was obviously very intelligent,
00:55:23but he also had that down-home sound,
00:55:25and he used it to his great advantage.
00:55:29What was that interview?
00:55:33In early times,
00:55:34whoever was messing with him,
00:55:36like Max Biaggi's messing with him
00:55:38or Valentino Rossi,
00:55:41all the things happening on the track,
00:55:44we're going to shake him up,
00:55:45and he's like,
00:55:46once you've been around Springer
00:55:48and Scotty Parker,
00:55:50this is like grade school stuff
00:55:52or whatever it was,
00:55:54like getting messed with at the dirt track
00:55:56by those guys.
00:55:57Those are pro-level mess-with-you peoples,
00:55:59so pretty cool.
00:56:02Do we know ultimately why Honda
00:56:05officially left,
00:56:06just got tired of restrictors
00:56:08and decided to go?
00:56:10I think that it was a situation
00:56:13in which their estimate of the market
00:56:21might have shown them
00:56:22that being too insistent
00:56:26upon being first in everything
00:56:30just made them seem like bullies,
00:56:35and that was something to be avoided.
00:56:37Yeah, the mid-'80s
00:56:38was also not a great time
00:56:41in the motorcycle market in general,
00:56:43and particularly there was the famous
00:56:47Honda-Yamaha kind of sales war,
00:56:49and they were stuffing the pipeline
00:56:50with a zillion bikes
00:56:51trying to be the biggest manufacturer,
00:56:53and then sales kind of went off a cliff.
00:56:56Harley was on the upswing.
00:56:58I mean, that was kind of Evo times,
00:57:00and sales were increasing for Harley,
00:57:03so it makes sense to not, you know,
00:57:06why Honda might pull back
00:57:08in that period of time,
00:57:10but they soldiered on.
00:57:12The bikes were used for years
00:57:15and years afterwards,
00:57:16and even, you know,
00:57:18we saw an XR racing this season
00:57:21as those bikes are no longer
00:57:25going to be able to be used.
00:57:27Commonwealth Racing road raced
00:57:30those things in Battle of the Twins,
00:57:32and because they needed to turn
00:57:36over 10,000 RPM rather than the 8,500
00:57:39that was the nominal peak power point,
00:57:45they had to change the crank every,
00:57:47what, 150 miles, I think,
00:57:49because of the staggered crank pin thing.
00:57:53That seems to be a real theme
00:57:55in all history.
00:57:56Staggering crank pins
00:57:58leads to crankshaft problems.
00:58:00Yes, sir.
00:58:02It does seem to,
00:58:03because I think that naturally
00:58:06you want to make that center disc
00:58:07that allows you to connect
00:58:09the two crank pins together
00:58:11as thin as possible,
00:58:12because the Harley is ideal
00:58:18because it has that fork and blade
00:58:20arrangement of the connecting rods
00:58:22so that the bore centers
00:58:26are in the same plane.
00:58:28Whereas BMW has the problem
00:58:31that their cylinders are offset.
00:58:33This is looking down on top of it,
00:58:35and as the crankshaft turns,
00:58:37it causes the engine
00:58:38to wobble back and forth that way,
00:58:41and finally they put balancers in
00:58:43to stop that action.
00:58:45Well, when you stagger the crank pins,
00:58:47that center disc,
00:58:49being as thin as they cross your fingers,
00:58:53could make it,
00:58:55causes some stuff to flex
00:58:58and eventually produces cracks,
00:59:00particularly if you've boosted
00:59:02peak RPM by 20% or 25%.
00:59:07Yeah, the knife and fork connecting rod
00:59:10is, it sort of seems like something
00:59:15I wouldn't choose to design.
00:59:17I'm not a designer,
00:59:19but you wouldn't, you know,
00:59:20you basically have one connecting rod
00:59:22that's like this,
00:59:23and then the other connecting rod
00:59:24fits in, and so it's two rings.
00:59:28And there's three rows of rollers, yep.
00:59:30Three rows of rollers,
00:59:31and then you just slide the one
00:59:32into the other and put it on the pin
00:59:35and then stick the cheeks together
00:59:37and away you go.
00:59:39Both the Rolls-Royce Merlin aviation engine
00:59:43and the Allison had fork and blade,
00:59:47and it was very much a thing
00:59:50in the early days.
00:59:52Well, and tower bevel shaft overhead cam.
00:59:56Yep.
00:59:57I mean, are the British just designed,
01:00:01do they make mechanical things
01:00:03to torture themselves?
01:00:06Like, how much shimming,
01:00:08and that's the thing with the Merlin,
01:00:10God, the valve checking intervals
01:00:14are staggeringly short on an hour's basis,
01:00:20and it is no joke.
01:00:22I saw a guy at Plains of Fame
01:00:24out here in Chino, California.
01:00:26It's a museum where most of the stuff flies,
01:00:28and they had a guy working on their P-51,
01:00:32and he's up there,
01:00:33and I was talking to him about it
01:00:34because I've shimmed the bevels
01:00:36on my old Bellasat, my 37 overhead cam.
01:00:40That's just one cylinder, you know.
01:00:42I mean, not that shimming the bevels,
01:00:43but you have to go down the line
01:00:45and do all the valves.
01:00:46Anyways, crazy complexity.
01:00:52Well, I think that's probably it, folks.
01:00:56We're going to see a new era in flat track,
01:00:59we guess.
01:01:00We'll be really interested to see
01:01:02what engines kind of surface up to the top,
01:01:05and they've invited kind of an adventure class
01:01:11out there in flat track.
01:01:14And here's the thing.
01:01:15They're acting as though,
01:01:17hey, we can just take the engine
01:01:19out of this old whatever it is
01:01:21and put it into a race frame,
01:01:24probably just take the engine
01:01:27out of our old bike
01:01:28and put this production engine in there
01:01:30with an hour or two of welding.
01:01:33And we'll get out there
01:01:35and give her a try.
01:01:37But as Gary Gray of Indian pointed out,
01:01:40well, AMA is letting them run
01:01:45non-standard cylinder heads.
01:01:47Somebody's got to pay for that.
01:01:49Non-standard cams, they're not free.
01:01:52Non-standard connecting rods
01:01:54and a crankshaft of a different stroke.
01:01:57Estimate the price.
01:02:00And put all of this together.
01:02:02It doesn't fit together snap like Lego.
01:02:05Someone will have to supervise that.
01:02:08Oh, we're going to have to use
01:02:10an oversized bearing here
01:02:11because this one's a little fat.
01:02:14So when you're done,
01:02:16will you have the people's racer
01:02:19for under 10,000 bucks?
01:02:21Yes.
01:02:22What is production?
01:02:23That remains the question.
01:02:25What actually is production?
01:02:28Of course, you're starting
01:02:30with a production design.
01:02:32And I used to hear people tell me,
01:02:37you know, I always wanted to ride a Harley.
01:02:40And recently I decided to take the plunge
01:02:43and I bought a new one.
01:02:45And I took it to my favorite shop
01:02:47and they put it in S&S cases
01:02:49and Thunderheads and so-and-so's gearbox
01:02:52and all this other stuff.
01:02:53Finally, you get it running.
01:02:55Everything is ace.
01:02:56It is so great.
01:02:57Harley have come such a long way.
01:03:01No Harley parts.
01:03:03Well, that's an exaggeration,
01:03:06but you can go down that route
01:03:08and that's the route that production
01:03:11flat track is going to have to travel
01:03:14because when you find that your cylinder head
01:03:17is holding you back,
01:03:19you're going to want those trick cylinder heads
01:03:21that so-and-so over here is making.
01:03:25To Harley's credit,
01:03:27you can buy a 135 cubic inch crate engine
01:03:31that makes...
01:03:32Let's start tracking.
01:03:35Oh, that would be something, wouldn't it?
01:03:39Would have torque.
01:03:40It would have torque.
01:03:44Well, thanks for listening, everybody.
01:03:45That's the Honda RS 750 flat tracker.
01:03:50See us down in the comments.
01:03:51We're sure appreciating the discussion.
01:03:54Lots of cool stuff.
01:03:55Comments about my mustache.
01:03:56One guy said,
01:03:58I'm having a harder time telling you two guys apart.
01:04:02Which I thought was good.
01:04:04Yeah, we appreciate all the conversation
01:04:06and, of course, all the views.
01:04:08We've got, oh, 45 of these things in the bank,
01:04:12so if you haven't listened to them all,
01:04:15go back in time.
01:04:16They're there for you.
01:04:17We hope they'll be there forever.
01:04:19It's great to have these conversations
01:04:22and to share the time with you guys
01:04:25and have that discussion in the audience.
01:04:27And, of course, I always enjoy spending my hour with Kevin
01:04:31going down all the rabbit hole topics that we love.
01:04:35It's nothing but fun for us,
01:04:38and we're glad you're on the ride with us.
01:04:41We will catch you next time.
01:04:43Thanks for listening.