How and why MOTORCYCLE parts BREAK

CW Technical Editor Kevin Cameron digs into his shop to show us broken motorcycle parts and explain how and why these failures happened. From bearings to crankshafts to connecting rods and more, Kevin has cataloged and saved broken parts for decades to help him recognize and understand how parts break and what he can do to improved his builds--and how he explains them to us! Editor-in-Chief Mark Hoyer has broken a ton of parts, and even took his Yamaha RD350 engine to Kevin’s shop for diagnosis and a rebuild.
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[@JackdeDuCoeur]

Has Kevin Cameron been declared a national treasure yet?

[@kiwialfa2083]

Make that 'International Treasure'

[@JackdeDuCoeur]

@@kiwialfa2083 Right you are!

[@blipco5]

"In those days of error and misinformation…" Well, now that we have the internet, we don’t have that problem anymore. 😂

[@micyclesport]

Kevin is a comic

[@oceania2385]

Been reading Cameron's articles since I was 13. Great to hear him in person.

[@ORflycaster]

I’ve been reading CW since 1986, and Kevin’s and Peter’s books are among the most prized on my shelves. That said, I could (and will) listen tirelessly to every discussion that Kevin and Mark have. Even the most trivial and esoteric topics suddenly become fascinating. Thank you both!

[@BABYPOP028]

Always a treat to see a new Kevin & Mark discussion pop up on my feed ! 🎉

[@tomtaylor6163]

I gave up trying to understand Kevin’s Cycle World articles 40 years ago . I would actually skip those pages way over my head.Glad to see Kevin speak in a way I can understand lol😂

[@ToddWright2]

He's got a Physics degree from Harvard. He's also a very cool guy. I think he explains as simply as possible, but no simpler. BTW, I have an MSEE and 50 years as a mineralogist.

[@WiekingderViking]

I think that this is GOLD!

[@ericjakobssonjr]

I feel incredibly lucky to have stumbled onto the podcast. I’ve owned several of the bikes and engines that you guys were talking about today . I could go on listening to engine failures and subsequent improvements all day.

[@jfess1911]

I just wanted to say that I really enjoy these videos. I'm glad that I watch them as videos rather than listen as a podcast because I learn a lot from the physical examples that are shown. I think I'd go nuts just listening to "here is an example of..." without a picture.

[@nickrider5220]

Many more people should watch these wonderful conversations, they would learn a lot - thanks guys 🍻

[@vxe6vxe6]

I went to the workshop of John Britten a couple of months after he passed away. I was with some friends, we were day bar-hopping (US Navy, Antarctica Program). I talked them into stopping at the Britten shop. It was closed, but we could see someone inside of the shop. We knocked, he answered and after we told him who we were he gave us a tour of the shop. I remember one work bench that had boxes and cans on the ground that were full of broken motorcycle parts. I was looking through one box, the guy that was there started pointing out the parts and what bikes they came out of.

[@HAL9000-su1mz]

In 1973, that squalling sound occurred to me on Interstate 5 as I rode my 1966 YM-1 at 60+. Some sage of a motorcycle scribe had taught before that one should always cover the clutch lever - especially on a 2-stroke. Upon hearing the unmistakable screech, I clutched and the engine stopped in about 1/2 second. Now, being unable to signal, how to swerve between cars to the shoulder and remain alive. Drivers were better back then and I am here to tell the story. One of the ball main bearings looked exactly like the one Kevin held up. Very colorful.

[@KLRFJR]

This is better than reading...watching you both in rapt conversation about these topics beats reading separate articles every time. Thank you!!!

[@davidbanks1193]

In the early 1950's, my dad owned a sprint car with a flathead Mercury engine. He and his buddies built a new engine for it, and it coasted into the pits at its first outing. He asked the driver what happened, and the driver responded, "I was going down the backstretch, and it went 'ding.'" They opened the bonnet, and a catastrophic failure had turned the front half of the engine into shrapnel. The sound had clearly been much, much more than "ding." Ever since, "It went 'ding'" has been pointed to in our family as the greatest understatement ever. To conclude the story, my dad decided after that event to become a former sprint car owner. However, a decade later my brother and I were racing Bultacos, CZ's, Ossas, Kawasaki triples, and various other two-stroke motorcycles that were mechanically simpler if not less prone to failure. Fifty years later, when I view an online video of a two-stroke motorcycle, I can still hear the sound and smell the exhaust.

[@nzkgb1486]

Thanks for taking the time to do the pod cast...long may it continue.

[@BG-gr7fh]

Thanks for doing these podcasts they are gold

[@fullthrottlepowersports6927]

These podcasts are FANTASTIC ! I have been a professional motorcycle tech since 1975 and I can relate to so much of what you are talking about now. I am fortunate to have been taught by some of the greatest minds in motorcycling like Tom Barnsley from Yamaha and Fred Dehart of Kawasaki. I enjoy looking back at the triumphs and the tribulations of racing 2 strokes.

[@micyclesport]

These are great discussions! Excellent explanations and analogies!! Well done

[@creigmacc]

My Stratoliner has rubber tubing over the side stand spring. Now I know why! 👍💯

[@Larpy1933]

That was another big pinch of catnip for me. Thank-you!!!!!!

[@LTVoyager]

I wish we could have created a library of interviews/discussions with Gordon Jennings before his passing. He is still my favorite technical author, but Kevin and Tony Foale are right up there at the top also.

[@JohnNewton-ev8ch]

Rossi, Marquez and Cameron.....all Aliens....!

[@videomks]

Thank you ! ! ! These talks are truly the best. Many thanks ........

[@AlField-dm9sx]

Another most excellent adventure. Thanks guys.

[@cogentdynamics]

A most wonderful video article. Kevin has always be the most interesting and inspiring scribe of all time to me. Thank you sir!

[@gregsidel3557]

I think both of you for all you that you have given on all these podcasts I have watched I am one of the real technicians from a Yamaha dealership back in the 70s it was a wonderful time in my life racing every weekend and I really appreciate what you guys are saying about the experiences of what you went through thank you very much you guys are great please continue

[@stevedavies4953]

I love these videos. Always learn something. When I first start racing I bought the Carroll Smith Engineer to win book. After reading that years ago I understand everything Kevin says.. I wish he would write another motorcycle tech book. I have every book he has published..

[@Mike40M]

Lovely talk about failures, bringing joy to my darker side. First failure I saw was a 30 year old Harley with 1/16 wear in crankpin. Bike still running. Remember old race engines with aluminum conrods. Over time getting longer and longer. Until letting crankshaft breathe fresh air. Once found a crankcase piece 200 feet from the track. Most recent break is a T20 classic racer. Never seen a 3 piece conrod before.

[@paulvanhout9695]

Deep into the minutiae of metallurgy and motorbike engineering evolution - don’t understand much of it but enjoy trying. Outstanding podcast👍

[@cpuuk]

This is such a font of knowledge and experience. Thank you.

[@cogentdynamics]

Interesting that I have built an RD350 and I serviced and worked on a couple of Stearman aircraft, including a 4 aileron 985 (450hp) planes. Cool stuff gentlemen.

[@bobherman936]

Great stuff. Thanks!

[@guylr7390]

Well that was enlightening as expected. Kevin neatly explained the use of C3 bearings in my Yamaha crankshafts and why all those modern cylinder studies are waisted to make them resistant to breaking. He also mentioned the 1974 Road Atlanta National that I spectated at. I was at a party last October that Kevin attended and was so in awe that I completely forgot what I was going to ask him. Oh well.

[@unwrangler11]

Great info, thanks.

[@HAL9000-su1mz]

RD redline 8500 at least per the +/- tachometers. I have a 9K redline TX500 tach, but after hearing this, I think I'll stick with the 8.5K unit, thank you very much. In '73, broke a 283 Chev crank halfway through the rear main - that thin thrust flange apparently a stressor. To this day, some do not believe I broke a SBC crank.

[@RandallSoong-pp7ih]

Thank you!!

[@bren42069]

i just found yall's podcast tonight, it's great, i love all this nerd stuff

[@chriserskine3527]

Detailed drawings of new designs, why they're going in this direction, what might come in the future, electronics in motor design in suspension, give Kevin some big drawings and a laser pointer, that would kill a lot of space and keep us riveted

[@andrewwellman]

Brilliant

[@josephreisinger33]

Thank you Gentlemen for a wonderful show. Hello Mr. Cameron, did you have trouble with the dual baring behind the clutch on the RD350's ? Spinning in the cases?

[@davidciesielski8251]

Hi, thanks. had a gs1100 et broke the outer clutch boss, and of course the end off the crank without any key way... not much else....in a lot of years of riding ...

[@user-jn3hm4fx7p]

Damn I love listening to this shit!!! Please don't stop, keep it coming !!!!

[@ksheehan330]

Great conversation. You guys compliment each other well. Very informative. Question: I ride 25,000 miles a year. My 2019 Hypermotard Testastretta has 63,000 miles, my 2021 MSV4S Granturismo engine has 52,000 miles. What can I expect for engine wear related problems, on these motors? My Ducati dealer does meticulous maintenance. But, no one can give me a sense on what the future holds. I’m going to ride them until they won’t go anymore. They are both wonderful bikes! Just curious what to expect and look for. Thank you. No worries if you can’t answer back.

[@Scott-sb1xi]

Glad to see someone that's a real rider, not a wanna be.

[@magnograil6825]

On a CNC you can lead out the thread over a length so the stress rise is spread out. However, the weakest point on a bolt is where the highest stress point is.

[@lucbrouillette5021]

Another subject; The Honda EXP-2 engine technologie was probably shelved with the 2 strokes, but is the technology in anyway appliable to 4 strokes?

[@kd350]

Working on my RD engined R5 (in my service since 1977) today. Simple swap of a rusty stock header for an ebayed improvement. What, no RZ crank flywheel parts at hand? Never had bottom work done on my bought new RZ, but I've seen mine every so often for fresh pistons and occasional bore. Their design is quite different with a more conventional pork chop style.

[@chriserskine3527]

What came from behind the iron curtain, MZ 2-stroke technology?

[@DavidAdie]

The Best!

[@chriserskine3527]

Show a lot of pictures of great designs, motors front suspensions the feather bed, detailed drawings of the winning motors

[@hectorshouse7348]

Grinding thread major, and re-rolling (burnishing) thread can increase fatigue life.

[@noidreculse8906]

The podcasts are always concise and informative but I have to say, your headphones are a distraction. Are they supposed to be pistons with rings?

[@user-uo9cy2ep2h]

Quality and craftsmanship. That starts with good engineering.

[@lcambilargiu]

I once found a door window motor held in place by a bolt that had 2 threaded zones of different diameters, the larger and inner one to hold the power window motor and the smaller outer to hold the door panel. The bolt had radius' in place to reduce stress points and was the 1st time I thought of a fastener being over-engineered. This fastener was not even used for racing. I can imagine the designer who dreamed this fastener up was a junior as it was for a luxury car door component, but why? Now its clear he wanted to be picked up by the motorsport division of the company. Maybe? The bolt was for the window regulator on the rear door of a 2006 Audi...

[@WBD86]

Thanks again!! Only negative feedback from me: too short casts! 🤗

[@martykath4427]

Every time someone dies a whole lifetime of knowledge of all sorts is lost forever unless recorded in a book or other media . Yamaha S kart engines that can rev to 15k have plastic ball cages in their bearings. And they do the business.

[@frederickking1660]

Kevin Baxter does tear down videos on harley engines. Heat is a big problem.

[@frederickking1660]

Will Conkrite who was a nascar car builder spoke about stress concentration in car springs. Dale Earnhardt sr. Got a big break racing Wills car. Will is cut from the same cloth as Kevin. They came from a time before computers.

[@chriserskine3527]

Which race track had the worst food

[@lesmontgomery6498]

Threw out more thn one b s a crank because the machine shop wouldnt maintain fillet radius quarter inch radius if i recall

[@manuhonkanen2111]

Too low idle rpm might starve the head from oil pressure on some bikes

[@lesmontgomery6498]

Honda put crank bearings with resin separators in 84 crs heat caused failures all the balls would migrate had to put 83 bearings in . That engine also had excessive piston clearance

[@RockyMotoX]

The root of every problem that plagues humans: "a tangle of atoms that are not doing the right thing" 😂

[@chriserskine3527]

What was the greatest dirty trick

[@chriserskine3527]

Who were the real comedians at the racetrack

[@dogpaw775]

this is as if P.E Irving came back with a utube channel.

[@diavuno3835]

When it's failed, it has blue balls....😂

[@blipco5]

Sooo, stay away from redline. Got it. 👍

[@stan0matic]

Is there something odd going on with file compression, or Mark's microphone? I'm finding it difficult to hear him, compared to usual.

[@markhoyer1736]

Sorry to say the first part of recording the proper mic was not picked up and it defaulted to the computer mic. We noticed about halfway through and fixed it the best we could.

[@stan0matic]

@@markhoyer1736 Thanks for your reply. These things happen, sometimes. The content is, as always, without peer; sic itur ad astra.

[@vernonkuhns3561]

They broke because you USED them!!! HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAA

[@chrisssinstockholm]

KTM LC8c (790 & 890) cams fails. Cause unknown. KTM says the problems were fixed on the 890. But... They also fail. KTM seems to believe they can get away by denying that there is a problem. KTM attitude towards customers stinks.

[@karlh6700]

"Euphonious" etc. someone has become a very cunning linguist!

[@Strawman333]

Like today’s vehicle parts manufacturers, motorcycles and other mechanical parts are made to fail after a certain amount of use. Which is not very long. The metal and other materials for parts today are drastically inferior than they used to be just a few years ago. It sucks.

[@JayBee-cr8jm]

My 2013 Triumph Tiger 800XC broke because it was carved out of cheese. Had it been designed and manufactured by sober people it might have been a decent bike.

[@Scott-sb1xi]

Was that the Green Bay Packer Edition?

[@chriserskine3527]

Remember you're not that funny and it isn't your bread and butter

[@tobberfutooagain2628]

Wait…. Hold on I know this…. To make you go buy another one….? Morons….

[@chriserskine3527]

First thing, stop with the inside baseball code words like an early marriage, regarding seizure, that was the only good one, talk more about the people involved what were they like who was killed because of faulty technology, talk about duckworth and how his high turbulence flat top pistons 4 valve design change the entire world, talk about the hard tire era and how they went in the wrong direction to fight high temperatures in racing tires, show a lot of pictures of the eternals of truly advanced designs the V4 2 strokes and how they fit the rotary valves in, the Moto guzzi V8, early low quality gasoline, why things were done this way or that way in the day, try to be more serious a lot of good men were killed playing this silly game

[@johnbauby6612]

Waste of time. Why do things break? Get a grip

[@tonyhilliam2407]

I get what you two arsoles are banging on about but you are missing the point!! All your pissing about with this and that is just suck it and see, test and adjust. You don’t really understand why this does that or something else with these different components. We can drill right down and not understand what properties that the molecules have, it doesn’t matter how much we split the atoms, there’s still smaller particles that divide even smaller and smaller. It’s called the ‘God effect’ and it stems from the moment in the minutest of time, just before the‘Big Bang Theory’ happened. We might not ever know or understand what happened just before the Universe was created and continues to expand, so all the testing and development is just hit and miss??