Fortnine is Wrong. 285 Crossplane Twin Engines Do Not Have Better Balance than 270 Twins

Fortnine's video: • Why the 270 Degree “Cr...
time stamp is 07:26
Today I'd like to correct a mistake in a video made by one of my absolute favorite channels on youtube, and that is Fortnine, who produce some of the best motorcycle content out there, so before we continue Id like to say that this video is in no way meant to diminish the credibility of the fortnine channel or in any way tarnish their reputation. We all make mistakes, I make mistakes, universities, governments, scientists, you, everyone else. To err is human. But I believe it is important to identify, correct and learn from our mistakes.
So let's see where the problem is and learn about inline two cylinder engines in the process.
In their video Fortnine make the following claims:
A 285 inline twin cylinder engine has better secondary balance than a 270 degree inline twin
They imply that because of this better balance of the 285, Phil Irving, who can be called the father of the crossplane inline twin engine, originally proposed the 285 offset and not the 270
And finally number 3. They claim that manufacturing 285 degrees offset inline twins iis more expensive and that KTM is the only company that builds 285 inline twin engines because …..
Unfortunately all of these claims are wrong. First let us address the balance. In every reciprocating piston engine that is composed of a crankshaft, connecting rod and piston we have two types of balance to worry about. Primary balance and secondary balance.
Primary imbalances are created by the piston. Secondary imbalances are created by the rod.
If we plot the forces generated by a piston on a graph where force magnitude is the y axis and engine rotation degrees are the x axis we have peak upward force at top dead center and peak downward force at bottom dead center. This force shakes the engine up and down as it’s running and to restore primary balance all we need is another piston offset by 180 degrees from the frist piston. The forces of the piston can now cancel each other out and this is the logic we find behind a 180 degree inline twin.
Next tup we’re going to explain secondary forces and balances. Now the singular culprit behind secondary engine imbalance is the connecting rod and the fact that the relative length of the rod changes in relation to the distance between the piston and the crankshaf. Now the absolute length of the rod of course, hopefully stays the same but as we can see when the engine is at top and bottom dead center the rod is fully upright when the engine is at 90 and 270 degrees of rotation the rod is fully angled. Now a fully upright rod is longer in relation to the piston and crankshaft than a rod full angled.
This means that as the rod transitions from fully upright to fully angled it pulls the piston down by an additional little distance, this distance equals the difference in height between the rod fully upright and the rod fully angled. This additional distance, this action of the rod on the piston is what causes the piston to reach peak velocity before 90 degrees of rotation. Because moving from 0 to 90 degrees the rod is becoming shorter so it pulls the piston down.
First primary balance. In a 270 degree twin we have 270 or 90 degrees of offset between piston 1 and piston 2. So as piston 1 is at top dead center piston 2 is at 90 degrees of rotation. This means that piston 1 is exerting a maximum upward force whereas piston 2 is at peak velocity and is exerting zero force. So we have maximum upward force on one side of the engine.
Now in the case of the 285 engine when piston 1 is at tdc the other piston will be 75 degrees after tdc, so just 15 degrees before peak velocity. In other words piston is not at zero, it is still producing a small upward force. Which means that the engine as a whole produces an upward force which is overall greater in the case of the 285 because the other piston is also producing a small upward force. So the 285 has a worse primary balance compared to the 270.
Now secondary balance. First the 270 twin. Piston 1 is at tdc, rod is fully upright, so we have upward secondary force on piston 1. Piston 2 is at 90 degrees, rod fullz angled, so we have a downard secondary force. The two forces of equal magnitude and opposite direction cancel out.
Now in the 285 twin when piston is at tdc and exerting and upward secondary force piston 2 is at 75 degrees so it’s not exerting a maximum downard secondary force. In other words the secondary force of piston 2 is not sufficient to fully cancel out the force of piston 1 and we have secondary vibrations. The 285 degree twin does not have better secondary balance than the 270 degree twin, it has a worse secondary balance.
A special thank you to my patrons:
Daniel
Pepe
Brian Alvarez
Peter Della Flora
Dave Westwood
Joe C
Zwoa Meda Beda
Toma Marini
Cole Philips
#d4a #enginebalance

[@d4a]

Just in case someone is still confused. In the beginning I say how peak velocity is 75 but then show a graph where it's at 90. To understand this you have to keep watching because at 08:45 it's made clear how 75 is with the rod, 90 without the rod. When we speak of primary balance alone we imagine that the piston magically moves up and down, we pretend it's a free piston because we are isolating it from the rod to observe its forces. When we add the rod we get the total. In the beginning I speak of the total and then about the primary, but I don't think I stressed this properly so maybe that's why a few people got confused? Support the channel by shopping through this link: amzn.to/3RIqU0u Patreon: www.patreon.com/d4a Become a member: kzbin.info/door/wosUnVH6AINmxtqkNJ3Fbgjoin Fortnine's video: kzbin.info/www/bejne/h5-ce6WEZq94iKssi=ugzeqkMabvfo9h2f

[@John.0z]

Thank you, this was all very interesting material. I always thought that the largest source of secondary vibration came form the counterbalance weights on the crankshaft. These are rotational, and so cannot do more than a "passable" job of counteracting the reciprocating and rocking forces. That is what I had always read when I was young. This balance weight was supposed to approximate the piston weight, plus a part of the conrod weight. There can to be only a "reasonable" balance applied for all the reasons you point out about how pistons and conrods generate their forces; but mainly because at ~90 degrees that counter weight is creating a sideways force. I have seen illustrations of patents for engines using two crankshafts and conrods per cylinder to counter these half-stroke forces. The most commonly expressed way to balance the piston weight without balance shafts is the use a 90-degree V-twin with ~100% balance weight on the crankshaft - the half stroke forces from the piston tending to balance against the second cylinder's piston. As the two cylinders usually share the crankpin, the rocking couple is also small. In reality you can never fully compensate for *all* the out-of balance rotational and linear forces. If my memory serves me well, there are a few other really minor things in your presentation that were a tiny bit in error. I am reasonably sure that there was an mid-'70s Yamaha 500cc 2-stroke single motocross bike that used a balance shaft - and probably needed it! This was not at all a common bike, but when I was buying my TY250 I saw the ads for it, and thought it's technology was interesting. I recall it had only 4 speeds in the gearbox; presumably to fit more robust gears into the narrow crankcase? The other comment you made concerned the use of "big bang" technology, before the idea made it to the MotoGP "big bang" 4-cylinder 2-strokes. But the advantage of "long" pauses between the firing impulses was known in British big singles. I read about it in a UK magazine about a decade before those 2-strokes, in reference to a BSA 441 that had been turned into a road racer. It was noted as losing out badly to multi-cylinder 500s on the straights, but having better traction on the corners due to the relatively low revs and relatively large flywheels leading to the tyre still driving the bike between the impulses, and remaining in non-slip contact. Combining slow-revs with big flywheels to drive through areas of poor grip was exploited widely in Observed Trials. Modern Trials bikes have taken a very different direction.

[@jetranger47]

You are wrong!!!! Just giving you wanted to see in the comments! 🤪 Thank you for your explanations of mechanics (physics?) in all your videos. Teachers should strive to be as clear as you are..

[@dufus7396]

I heard pistons on 70s two stroke Kawasakis are not semetrical in mearsument ant material thickness to adjust for thrust offset and exhauast heat

[@dufus7396]

My take is if it need balance shaft adding to rotating mass then design is not elegant

[@steinrogereliassen517]

Nitpicking is fun, and I’m here to tell you that Irving actually suggested 76 degrees ATDC for maximum piston velocity. 😊

[@alcobra88]

An intelligent and thoughtful man respectfully and succinctly peer-reviewing another intelligent man's work, all while acknowledging the FortNine channel's brilliance and success. This is A+ content.

[@cowmath77]

Don’t forget to clean yourself up with a Kleenex.

[@alcobra88]

Kleenex has that gross waxy lotion infused into it. Paper towels is what I prefer.

[@veltruski]

That's what real men do. It takes a lot of self reflection to overcome the ego.

[@herbertsiegl7762]

👍

[@SiRedCat]

Now to see if they have the integrity of removing their video... If they do I will keep watching if they dont... well it was good while it lasted.

[@blar2112]

Life hack: Hydrolock one of your KTM cilinders to fix it back to 270º

[@L3v3LLIP]

Why dont manufacturers use this trick instead of making the crankshaft glow orange and twist like cave men?

[@blar2112]

@@L3v3LLIP because big glowy does not want them to

[@dabrula]

See that's what they don't want you to know

[@RealDougFields]

bent rods wont help you do this.

[@blar2112]

@@RealDougFields you just dont know how to do it correctly

[@Da5idc]

As a trainer/lecturer I must congratulate you on the clarity of your explanations and the use of visuals to illustrate the concepts

[@davidbrayshaw3529]

As a fellow who has been described on more than one occasion as a sandwich short of a picnic, I agree. If someone can knock knowledge into me, they can drive a thumb tac into a brick with a broken finger. This guy is good.

[@Sinister_fartbox]

What about adolf

[@wjcferguson]

... though I'd have loved to have seen the overall imbalance graphs with the easily-counteracted primary vibration subtracted, to see what is left over.

[@biker1715]

absolutely

[@matthewchin6454]

better than college

[@3v068]

As a fortnine viewer, this should be interesting. EDIT: The respect you show to him as a viewer and also a creator in a similar space is NOT TO BE UNDERMINED. Its so different than just going at each others throats. You two are awesome!

[@VeritasEtAequitas]

Yeah. I quit watching him years ago after so many mistakes and pushing his opinions as fact. He's a hipster rich kid who knows a few things, enough to sound like an expert but far from being one.

[@BRZDR]

@@VeritasEtAequitas Ryan is a salesman. Ever since the channel took off I did notice a hint of ego in each of his videos. In the end, he's really just a salesman and fellow rider.

[@kevinhealer3497]

​@@BRZDRRyan has a degree in physics from one of the most prestigious universities in Canada...so there's that.

[@PMitchell106]

​@@kevinhealer3497 He has been a social media influencer for all of his professional life. A bachelor's degree from 10 years ago is a helpful starting place for knowing how to think about science, but it doesn't give him any usable expertise. He is a very intelligent and knowledgeable person, but his profession is content-creator, entertainer, and marketing professional, not educator, journalist, scientist, or investigator as some of FortNine's content portrays him.

[@d4a]

I know I know I know what Ryan is! Pick me! He's a person. A person that obviously works hard to entertain and inform you. I prefer to enjoy and appreciate what someone does rather than try to pin subjective labels onto their personalities or careers in an attempt to somehow minimize their achievements and make me feel better about myself.

[@HorizonOfHope]

Where is the Fortnine / D4A collab we all want?!😊

[@xuevgermanist]

Yeah, really

[@daniel_77.]

unreal engine update fire 💥💥🥵

[@matthewpeterson3329]

This would be awesome indeed! I would imagine both of these guys having a thoughtful discussion about this topic, and then having a few laughs about plenty of other things. Could make for a terrific live podcast type of interaction.

[@mehmetgurdal]

@@matthewpeterson3329 yess :D they can name it 'internal combustion' :D

[@lifted_above]

Independent competition is a healthy thing in the public sphere.

[@operator0]

I'm a machinist who works with fixtures and dies, and I have a lot of manufacturing experience. I came to the same conclusion you did about the manufacturing process after watching Fortnine's video. While I may not have much experience in an engine manufacturing plant (very little and none relevant to the question at hand), It seems to me that creating a die and platen that can stamp out a 270 crank would mean that you could do the same for a 285 crank just as easily. From my experience, the time and cost difference to make the tooling would be negligible. Again, I have no experience with heavy forging like what you would need to create a crankshaft, but I'm having a hard time believing that it would take any extra steps to create a 285 crank vs a 270. Even the finishing machine work would be very similar.

[@mastercricket7626]

Just want to say much respect to you brotha ... my grandfather was a tool and die maker and that is a dying art so I say much love and respect to you my friend and thanks for the good memories you reminded me of when my pepeir was still alive and well and owned his own land and such he had a big red barn (go figure right all old barns lol)and it was full of nothing but machinist tools , giant lathes, mills , presses and all kinda shit I still don't know but they were so cool and all done by hand and man did he make some cool stuff ... rip to him but man if he was in his prime doing that as I am building cars now , me and him could made some super radical 1 off parts for mooorrrreee powa baybay 😅 lol ... peace and love bro keep it rad stay safe and build on l8z fam and much respect to you friend

[@spankeyfish]

If it's a 3 journal crank you could even use the same forging dies; just take a freshly forged, glowing hot 270° crank and twist it ever so slightly to make a 285° one. It's an established process on crankshafts for engines with more cylinders- kzbin.info/www/bejne/o5ubnZiNqKdnrZY

[@kender1412]

Tooling is tooling. It would be more expensive to retool for 285° or whatever other offset you want than to continue to produce whatever you are already producing. If you are starting from scratch, you're going to be tooling for whatever it is you want to produce, it will be no more or less expensive to set up for 270°, 285°, or 180°.

[@oawgaming219]

Hello, I share your opinion @operator0 but I think that adding an 15° angle to the die would add transverse forces that would not help the two parts of the die align well (could still be achieved??) ... But I am still a student in this domain so take it with the biggest pinch of salt.

[@Fightre_Flighte]

​@@kender1412 That's the exact same reason that Boeing still makes the nose of their 737 the same, even though more efficient shapes have been found. "Tooling is tooling," and reshaping would require different tooling, so the legacy shape remains.

[@kannermw]

The 285 degree parallel twin most commonly mimics KTMs 75 degree V-twin. Turns out it is a KTM brand character thing and nothing else. Great presentation!

[@marcusgeorge1825]

Exactly. Well said. It is close in sound however my ears prefer the KTM’s inline twins.

[@francescoporcari8597]

As 270° is imitating a 90° V twin. And the forgotten Husqvarna nuda 900 (italian engineered high-bored f800) has 315° crankshaft, mimicking the 45° V twin (Harleys).

[@user-lw6iz7zy2o]

This is the correct answer. And lets not forget, parallel twins are just the cheaper to make alternative to the real v-twin as you only need one cylinder case and half the camshafts. And you also get rid of the cooling issues of the back cylinder.

[@marcusgeorge1825]

@@user-lw6iz7zy2o Agreed. Plus it enables more space than any V twin for a bit of creativity and possibilities.

[@kannermw]

@@user-lw6iz7zy2o The cooling of back cylinder issue only applies to air cooled v-twins.

[@kOlbThreeTimesOne]

as a mechanical engineering student who has done a semester long project developing a MATLAB model simulating exactly what is discussed in this video (acceleration and force modelling, advanced kinematics and kinetics of mechanisms) i have to say your style of lecturing is WORLD CLASS, you never lost me once during this video and I imagine even someone who has never taken high school physics can follow along the fundamental concepts explained in this video, even though you make no sacrifices in justifying your claims. Well done!

[@AirSKWolf]

Not saying the video wasn't good, because it was. But "not losing a mechanical engineering student that did a semester long project in exactly what's discussed in the video sounds like " sounds like the absolute bare minimum no?

[@ludwigkumpf8304]

No, not really. It differs from person to person, but especially in mechanical engineering, sometimes you get a professor that does not do a good job explaining complex topics, so you can get lost pretty quickly. I think what he meant was that even with his knowledge on this, it was easy to follow, simplifying it enough that it is digestible for most people. One can also get lost when someone is explaining a topic that you already know. I remember once that a classmate of mine explained smt in thermodynamics that I already was familiar, it was just the way that he explained it that got me confused and lost. @@AirSKWolf

[@daegueric]

Were you able to follow this at full playback speed? 0.75 was much better for me.

[@wickedcabinboy]

@@daegueric - No shame whatsoever in that. That's how I watched it.

[@estebanamador7601]

As someone that wanted to study mechanical engineering and chenged my mind, oh Man, 6 months doing a project in MatLab, I chose my career correctly 😂😂😂 just kidding, I don't have enough patience to do that kind of work.

[@liver.flush.maestro]

Each time you re-explain secondary balance, you do it better 🙂

[@minklmank]

Nice! Two of my favorite youtubers in constructive and respectful debate! This is so insanely wholesome compared to the usual primitive beef amongst communities. My inner scientist is happy

[@d4a]

This is more monologue than a debate :) But thank you very much.

[@langhamp8912]

With a few notable exceptions, that's how scientists critique each other. The usual mud-slinging is by people not educated in the scientific method.

[@mehmetgurdal]

@@d4a please consider reaching out to them for their future content. I'd love to see Ryan's humor and your professionalism in one video.

[@Morpherinc]

It is no a debate... yet :D

[@Fightre_Flighte]

​​@@d4a It's important to note, this is the exact same setup it took for the great Steve Mould / electroboom debate of 2022.

[@latituderider]

I'm no mechanical engineer and there have been a few rare instances where I did not agree with Ryan's conclusions. However, I appreciate anyone that can come forth with a logical, well-presented explanation on why something is incorrect. That's simple scientific process.

[@misterwait806]

Boink!

[@mehmetgurdal]

wow. a professional and respectful critism to my favourite motorcycle channel. I no longer have a favourite motorcycle channel anymore, from now I have 2. :) thank you very much for taking your time and correcting their mistake. Please consider collaborating with them in their future engineering related content. now if you excuse me I'll be binging your videos :D

[@d4a]

Thank you. That's the attitude I really hope to see after this video. I really don't want this video to take away from the amazing content f9 produces. As I said this really is a complex topic and all the other points in their video are excellent

[@trevorkarrett3041]

​@@d4aGreat video as usual! I would love to see your take on some more motorcycle engines, potentially comparing v-twins? Ducati vs Moto Guzzi vs Harley vs Indian etc would be pretty cool, maybe too many for one video though!

[@d4a]

Thats a great idea actually. "The many faces of the v-twin"! Thank you.

[@trevorkarrett3041]

@@d4a wow thanks for the reply, I'm glad you like the idea! A video on desmo valvetrain alone would probably be a lot, and then maybe euro v-twins could be one, and American v-twins as another... Just thinking out loud. Lots to cover but whatever you end up doing I'm sure it'll be great. Thanks for all the content!

[@r.j.bedore9884]

Yeah, I did think the 285° thing sounded a bit off from previous videos and research I had seen about engine balance and crossplane engines, but I didn't have the time to check F9's work, so I'm glad you did. As far as the forging goes, yes it is cheaper and easier to make a 270° crank than a 285° crank. When forging a 270° crank, you can set up the 2 halves of the forging dies so that you forge in one journal then turn the crank 90° or 270° and forge in the second journal without affecting the first journal. Due to how the two forging dies come together, you can't really do that if the journals aren't either parallel or perpendicular to each other. Thus, for a 285° crank you would first forge in the journals for a 270° crank, then use a separate machine to twist the crank that additional 15°. Since this requires a completely separate machine along with an extra step, most companies just stop at forging in the 270° crank.

[@steveblackwood1202]

Hi r.j.bedore9884. You seem like you are very confident in your statements re: twisting of the 285 degree crank after forging. I'll be honest, both these guys seems to have a much better grasp on this than me... although I understand the math, but not the manufacturing process. I am just wondering where your confidence comes from? Are you someone who actually has some experience in this field? It certainly seems so... I'd be curious to know. Thanks! :)

[@r.j.bedore9884]

@@steveblackwood1202 I have some experience with creating forging dies while getting my engineering degree in college, but I will admit I haven't forged a crankshaft myself. This is just what I remember the guy heading our machining lab telling us when one of the guys in class asked about making a new crankshaft for an old motorcycle he was restoring and having trouble finding parts for (this was back in 2006/2007 before buying parts online was as easy as it is today). Because forging generally involves smashing two large plates together with the shape you want carved into them, you tend to have trouble making dies that would let you have angles that aren't either perpendicular or parallel to the direction the forging press is moving in. For crankshafts whose journals aren't either all in one plane or perpendicular, you can either forge a blank then twist it, forge multiple pieces then spline or bolt them together at the correct angles, or machine the entire thing from one large billet of material. Making the forging dies can be expensive, but making the parts with them is faster and cheaper than the other methods, which is why most mass produced parts are made this way, and why most parallel twin bikes have a 180° or 360° crankshaft since that is easiest to forge. Machining a part from a billet is more expensive per part, but if you are only making a few for a prototype, or say for a race engine, this is almost always cheaper than getting a custom forged part. Hope this helps.

[@steveblackwood1202]

@@r.j.bedore9884 thanks! I appreciate the explanation.

[@seth094978]

​@@r.j.bedore9884 Most parallel twins are 270° now.

[@r.j.bedore9884]

@@seth094978 No, while 270° crankshafts are becoming more popular, many are still 180° or 360° like the Kawasaki Ninja 300/400, Versys 300/400/650, and W800, the Honda CB500 series of bikes and a few others, several BMW parallel twins, some Royal Enfield bikes, and until recently nearly every Triumph parallel twin was a 360° crank. I think there might have been some Yamaha cruisers in there as well, but I'm not super familiar with those, and I'm not sure about Suzuki since I'm mostly familiar with their V-twins. Also, I believe the motor in the RS660 and its sister bikes is the only Aprilia parallel twin with a 270° crankshaft. Thanks to the popularity of the Yamaha MT-07 and KTM 790/890 bikes, crossplane crankshaft twins are certainly on the rise, but they haven't taken over the market yet.

[@brunocarmona4958]

It is always said that the main reason the KTM LC8c parallel twin has a 285 degree offset is to mimic the feeling of the bigger KTM LC8 V-twin engine which has a 75 degree opening of the V. And thank you for this explanation, it was great!

[@Bandy64]

Yeah, this is the reason I first heard as well. Though I admit that I liked F9s interpretation because it “elevated” my 790 into a special premium category that could have been used for a few extra bucks on resale. But not anymore. Damn.

[@philadv]

After some research, I found exactly the same, but on a BMW f800gs, crank is 180, but the firing is 360 due to the layout and in result it will mimic the sound of the R1200gs (that rich sound of the boxers)

[@steamixion]

There is a diagram of the BMW f800gs 360 degree crank at 14.53

[@philadv]

@@steamixion (I did before watching the video, but tks anyway) I can't stand the vibration in my 800GS, really annoys me, looking for a V twin now. (probably a Vstrom 1050de)

[@ShittyUserName]

I just now realized I never subscribed to this channel. I've been watching for years, the videos always just appeared in my youtube front page and I didn't think anything of it. It is now corrected

[@jannegrey593]

Same. IDK if there is facepalm emoji, but I wouldn't even know how to use it. Still I feel a bit daft.

[@Jiggajignesh]

You made me doubt myself but upon further inspection, thankfully I don’t need correction.

[@jannegrey593]

@@Jiggajignesh I personally do feel like I was subscribed at some point. It wouldn't be a first time YT cancelled subscription without consent or notification. But I'm not 100% certain with this channel.

[@justinedzard]

KZbin unsubscribed me from a lot of channels 3-5 years ago, maybe they're still doing that and you're actually subscribed already

[@ShittyUserName]

@@justinedzard i think it's possible, but I'm still subscribed to some Minecraft channels I haven't watched in 10 years so I doubt that's the case

[@c63amgblack]

I dont think ive ever skipped your engine balance explanations, even though I have already seen you explain it before. You do such a great job and tweak the lesson each time to fit the video, so its always valuable

[@ShalomBrother]

0:24 There’s not a man been born yet that’s never made a mistake

[@d4a]

Exactly!

[@awakenotwoke1973]

Yes, there is. He's never done anything. I thought I was wrong once, but I was mistaken.

[@dalegawne5286]

​@@phillgizmo8934to live that way would be a mistake

[@LG-ct8tw]

Once, there was a man who went through life denying all of his mistakes, surrounded by lawyers to make the wrongs right.

[@miguelJsesma]

You don't wno me (opps)

[@DltaRL]

I legit was like "wth is fortnite doing with engines?"

[@user-hd4wf5gq8r]

Fr 😭

[@stef2465]

Same

[@rleger123]

Same!!!

[@niftyjig]

Me too

[@ya33a]

Fort9 has lost their 'way' so trying a few different things. Phil Irvine was a legit legend...

[@ChooseBrian]

As someone who does not have any background in any types of engineering, I found this video and explanation to be extremely enlightening. If you can bring Normie’s along for the ride in such a way, I think you’re both winning.

[@fidobite3798]

You are the BEST, my man, at explaining these types of mechanical issues!! Your graphics and explainations are superior to any others I have come across on YT, or anywhere else for that matter! Kudos to you... especially since English is not your "native" language! BRILLIANT WORK!! 👍

[@BigDiksha]

Čestitka za milijun subscribera!!! Videi su ti za svaku pohvalu, uvijek nam preneseš puno znanja na jednostavan način i hvala ti na tome što obrazuješ ljude širom svijeta!!! Pratim te dugo vremena i srce mi je puno kad vidim ljude iz regije kako uspijevaju na youtube-u, ali mi je pogotovo drago zbog tebe jer daješ inspiraciju i meni i drugima da se bavimo automobilizmom i mehanikom. Lijepi pozdrav za tebe i tvoju obitelj, neka vas Bog čuva i sve najbolje u budućem radu!

[@Dzerom-on2zh]

Prvi put vidim ovaj kanal i odma mi je palo na pamet da covjek izgleda kao Srbin. Nista nacionalisticki nego me bas zanima da li sam pogodio, jer po lajku komentara ocigledno jeste balkanac 😂. Pozdrav iz CG

[@lemster101]

Awesome to see a video response from you to the F9 video. To me the only thing that felt weird originally watching the F9 video was your last point on the production of the crankshaft. Instinctively it feels there shouldn't be a difference. Yamaha for example also makes the CP3 engine with 120° between cylinders so it's not like Yamaha can only do variations on 90° affordably.

[@jakub.anderwald]

That's a person with true passion - dropping everything they do and making a calm, profesional video help viewers understand better something they've seen on another channel. Thank you for staying true to what you do.

[@enordquist1]

Love your video's. I sometimes struggle with English as a second language accents, but you come through clear as a bell! The graphics are excellent. They are simple and not cluttered, and perfectly illustrate the subjects.

[@jackoconnell2204]

Getting called out by D4A is like getting Eminem to rap about you

[@tonyb9735]

Yew! What a horrid thought. I would definitely prefer that Eminem not rap about me. Or anything else, for that matter.

[@carlosandleon]

Eminem is the workshop. D4D is machine gun kelly.

[@Fightre_Flighte]

It's like McNally abusing your lock. IYKYK.

[@LifeInJambles]

@@Fightre_Flighte I mean not really, cause if D4A calling you out means you have to have some idea what you're doing, where McNally abusing your lock probably means you're masterlock and that doesn't *really* have the same implication.

[@Hawk7886]

​@@carlosandleonwhat

[@VwR28]

I love watching your explanation of engine balance slowly get refined more and more each time you talk about it

[@Maesloable]

Happy to see you react as I am pretty sure he's taken inspiration in your channel. You are both my absolute loves here on KZbin :) ❤

[@yukinarija8204]

Glad to see your channel growing, best of luck to you! I remember it was quite smaller not too long ago :). Now we watch it together with my family 😁

[@isakmlster4453]

You are so good at explaining these concepts. It's like I can hear my own visual thoughts being spelled out to me! Thank you.

[@nedmilburn]

This is great! And the KZbin algorithms worked great, too, since I just watched F9's video on this yesterday. You sir, are truly a top level teacher!! 👍🏼👍🏼

[@HardwareG33k]

Thank you for this incredible video. Upon watching the F9 video, I was annoyed because I couldn't find anything substantiating their claims and honestly couldn't make sense of it because my last lecture on engine balance is a few years back. Something about their simple geometrical explanation irked me, and you explained how it actually works so freaking well. Fantastic stuff.

[@steenlassen5718]

Thanks! Number 4 error is that 270 crossplane cranks is NOT a new thing! They have been around for almost thirty years in Yamaha TRX's and TDM's!

[@steinrogereliassen517]

I had issues with Fortnines claim. I do however rarely comment on anything. So this is one of those rare occasions! 😅 Keep up the good work. As a certified gear head your channel is one of my favorites. 👌

[@VeritasEtAequitas]

He says a lot of things that aren't true. Especially when it comes to what gear or parts are best. He has enough shallow knowledge to pretend to be an expert.

[@druegeme]

Thank you. I was wondering about the claim that manufacturing the 285 is more difficult. It didnt sound quite right. But you went even farther to analyze the secondary balance forces. Very insightful. I am not a mathematician but there has to be a formula to calculate the crankshaft offset to achieve minimal secondary balance on a parallel twin.

[@thatboysims3k879]

70% of the explanation went straight over my head but man I really enjoyed watching this. Well spoken, well detailed and laid out, awesome video 👏🏾👏🏾

[@bogdan1207]

Fortnine is wrong in many of his clips. His presentation of the issues, however, is top tier and very entertaining.

[@dylanc2806]

the phone mount video hugely comes to mind, that one was pretty bad

[@Ramonatho]

​@dylanc2806 I mean they did fix that one up properly in what, 2 days?

[@dylanc2806]

@@Ramonatho ummmm... our definitions of "properly" may differ a little. they re-released the video but i still had some qualms

[@IslandArt61]

Very few channels write their content scripts with such quality, mechanical accessibility, and wit like FortNine. So many wonderful lines semi-hidden in the presentation. One of my favorites, "it's said that every time a CBX hits redline a mechanic finds his 10mm."

[@valentinomanontroppo4675]

yep. In an older video they used unscientific tests on some gear (was it helmets? oil? both?). I pointed out the issues in a comment but they were not addressed. Love their story telling, but I won't trust their tests

[@skyrocketautomotive670]

This is how someone who knows what they're talking about proof reads someone else's work. Beautifully done! So nice to not click a video and listen to bitching and snide comments, just eloquent facts and research. Love the channel dude, cheers!

[@plap.]

Sweet video man, truly nicely done. I watch and love both your videos. Came here for the MK1 MR2 and 4A GE, I have a red 86' with one of the last new available engine and tranny shipped from Japan years ago with about 60K mi on them. I come back because you talk about the same stuff of interest the way all will listen and grasp along with great accuracy. He is more the rainy day movie that is entertaining to watch but you take everything with a grain of salt. Both are great entertainers with equally well executed different styles. Viva la difference

[@JoaoZagoSJC]

Even knowing about engine balance (or imbalance).I always watch your explanations over and over. Your are awesome. Thank you.

[@oawgaming219]

I learned about forging in class not long ago, and I think that you are right about the need to add a twisting motion in the manufacturing. However is is true that adding an 15° angle would add transverse forces that would not help the two parts of the die align well.

[@gchoquette299]

Your physics are spot on and so are your conclusions. A couple of minor points. (1) the angle of the peak velocity can be different depending on the length of the connecting rod relative to the stroke. The specific equation can readily be developed with a little trigonometry, it can also be found in Taylor and other engine textbooks. (2) a primary method to reduce the first order vibration are the counterbalances on the crankshaft itself. Now open the Pandora box on balance opposed (e.g. Boxer) engines. Perhaps an upcoming video of yours

[@jannegrey593]

IDK if he ever mentioned what you said in point 1, but I know that many times he mentioned what you said in point 2. Just not in this one. I'm almost certain he did cover boxer engines, but it could have been in the video about something else. I would have to check.

[@josealejandrovelezquiroz5970]

I didn't notice so much errors in F9's video but it was a little out of his regular content so, is OK to make those mistakes at first time, I hope he will watch your video and get the feedback that otherwise he will not receive from his audience. As always pretty good stuff!

[@quattrobajeena8954]

Never skipped the engine balance ibtroduction once, I just can't get enough of your brilliant presentations!

[@thegreatestshowcries2380]

I’m a huge fan of d4 and fort - my only favs. I am so grateful that d4 pushes me/its audience more than fort in grasping the more difficult. I love it when my brain hurts.

[@thegreatestshowcries2380]

I’m embarrassed that fort got no disagreements in their comments. We’re all sheep. Lesson learned here kids in all things: we always might be wrong, don’t ever let the nicely packaged stuff pass as gospel. Take the time and respect those who fiercely question conclusions and be aware of those who ostracize the doubters, as if they’re hiding from truth.

[@Bobby-wn5yr]

Just found your video because something about the Fortnine explaination of 285° didn’t sit right. Amazing content, thank you!

[@pappyman179]

I really enjoy your videos. I think your accent has lessened over the years or I'm just getting used to hearing you, because it used to interfere with my consumption, and now I never have to replay a sentence to hear it properly. Your explanations are excellent and I thank you for sharing your knowledge and experience.

[@68404]

One of my favourite bikes ever was my 1998 Yamaha TRX850, a splendid machine that was the first (mass market) 270 degree parallel twin to hit the streets.

[@davidbrayshaw3529]

An old acquaintance of mine owned one of those when they were brand new. He loved it, and I was in awe of it. On paper, they appeared to be a fairly "middle market" machine. He was the first to admit that top speed wasn't its strong point, but in the "real world", he could round up just about anything on that bike. And when I say "real world", I mean on the track at ride days, as well. Yes, CBR 900's would have him on the straights, but at the end of a lap, there was nothing between them. And on the road, nothing could keep up with him, and he wasn't riding like a lunatic, the bike just did it's "thing" with ease. I would have loved to have ridden it but never got a chance. l don't know why I own a Kwaka. I'm a huge fan of Yamaha.

[@stevebayross7248]

​@@davidbrayshaw3529I had 3 .... Did plenty of trackdays on them ... The genius of them is they made you look much better than you actually were.... Only negative was a gearbox like a bag of bolts....

[@davidbrayshaw3529]

@@stevebayross7248 I wasn't aware of the gearbox issues. That's very un-Yamaha like. You're pretty much echoing the words that my acquaintance said. I always thought that they were a fantastic looking bike, too. Great note, to boot.

[@1crazypj]

I worked at a dealership when the 'Super Tenere' XT 750 came out. That was in late 80's. Yamaha barely mentioned the crank design. A 137mph trail-bike was totally crazy (I did one of the very first modified carb / air-box / exhaust ones)

[@1crazypj]

@@davidbrayshaw3529 the Yamaha gearbox is almost always terrible the first year, usually second gear breaks' Always gets fixed second year with stronger parts that retrofit early models. That was my experience at dealers until I left in 1990

[@F3udF1st]

Lol I commented on that video yesterday - "I can't wait for D4A to take this on!" =D The KTM doing 285 cranks is similar to how OMEGA has co-axial escapements, it's essentially marketing.

[@DefinitelyNotJ749]

Yup, the 285 crank exists for the same reason as the 270 crank became popular after the MT-07 (though it obviously existed long before that). It's marketing the exhaust noise and engine "feel", imitating that of a 90 degree V-twin. There's no actual real world performance benefits to this setup over a 180 degree twin, if anything the 270/285 need balance shafts where the 180 doesn't. But the 180 sounds flat and has a lumpy feel. The 270 degree crank is being widely used because customers liked the sound and feel of Italian 90 degree V-twins in the middle weight, with the parallel twin being vastly more economical to produce and fit in a smaller frame/overall wheelbase.

[@gamebrigada2]

Except d4a's graphs are all wrong making this entire video incorrect. If the piston reaches max velocity at 75 degrees, it's force will cross zero at 75 degrees. The wave is squished at the top, it's not equal top and bottom.

[@DefinitelyNotJ749]

@@gamebrigada2 Have you tried emailing him this? Seems that's the most likely place to get an answer

[@gamebrigada2]

@@DefinitelyNotJ749 Ha didn't realize that. Emailed.

[@JulianKent]

Yeah even the 75 degrees depends on the rod/crank proportions. A different engine will have a different angle.

[@ryteulopki8069]

You have been referenced in multiple videos across YT! There is a lot of moto creators who were sent to your channel for small, sometime big, update ;) Amazing stuff!

[@billyrubin262]

Once again a perfect video! I would really really love to comment on F9's video saying that the best engine for motorcycles, regardingvibrations, is a V4. Thanks again for the YT university that you have built in this channel

[@SamuelCid]

I never get tired of the explanations of primary and secondary balance and even so it is still difficult for me to understand them 100%. I'm looking forward to the video coming to the Spanish channel, maybe it will be easier to understand then. Thanks once again for your videos. I have translated this comment with Google, there may be errors.

[@d4a]

Google translate aced it!

[@confuzionn4843]

Finally an actual analysis and explanation. Fortnine makes great content, but as an engineer, it frustrates me how he gets the reasons wrong for many things. He explains things beautifully, but I believe he misunderstands fundamentals of why engineers make certain decisions. Same thing with his materials video.

[@K777John]

This is a very detailed but easy to understand and follow description of the way the different forces balance out-so well done sir. I have some limited experience of this having spent some time making 360, 180, and 270 degree parallel twin cylinder crankshafts-and balancing them on a computerised Schenck balancer. The crankshaft were all machined from solid using EN30B grade nitriding steel, and were in the main for Nourish/Weslake 8 valve twins of various capacities.

[@1crazypj]

That sounds really 'fun', envious you got to make them. I've had to 'make do' with re-phasing Yamaha XS650's as I can't afford a Triumph plus all the parts to go with it.

[@jessemontgomery60]

I wouldn’t know if you were right or wrong, but you explained things in a way I and others could easily follow and have a reasonable idea of what to look for in reference to not only these engines but many others. Good job.

[@gronkgrunk]

Congrats on the 1mil sub, D4A!

[@Zarcoil]

like your approach and politeness

[@ninjarobotmonk3y]

This was a beauifully simple explanation to something that is much more complicated than I initially thought it would be. Thanks for taking the time to create, edit, and share

[@MadChalet]

I'm glad you spoke up and clarified things. I saw that F9 video and thought I'd been properly edicated. Thanks for your detailed and thoughtful explanation!

[@turbotoblast4]

I actually found that Fortnine video very strange, so I'm glad you ended up explaining these things in more detail. Thank you

[@filipbrecelj669]

I propose a 277.5 degree offset so you have half of both hehe

[@razvanciurez]

and 1.5 balance shafts

[@ulogy]

@@razvanciurezmake it use 7 valves, too, with one that doesnt connect to anything but has a deep well behind it, just to add complexity and keep the mechanics on their toes

[@Fightre_Flighte]

​@@ulogy At that point, might as well have a three to one exhaust manifold, with one just capped off.

[@jaguarke069]

@@razvanciurezcame here to say this; you beautiful bastard!

[@ulogy]

@@Fightre_Flighte True, maybe make the air intake have a second, smaller filter right before its output as well, and require a special tool to service it.

[@RedRupert64]

Thank you very much. I said to a friend that I didn't believe a fair bit of what F9 said, but I'm incapable of explaining why! You're a real genius.

[@zedfragg4134]

This is a really good video. I was going to ask about inertia but you answered it whilst I was typing it lol This is a really interesting video, I appreciate the effort and thought into this. And the explanations!

[@Mathik01]

Man so glad u responded to this. I read somewhere that the KTM parallel twins are not arrenged 90 degrees apart but ruther 75 deg apart. This was to mimic the big brother motor used in the super dukes and super adv. So maybe KTM they want to maintain sound/signature throughout their models.

[@bikeaddictbp]

I''m with you on that ... I think KTM did 285 instead of 270 to make it sound as similar as possible to their 75-degree (with balance shaft...) V-twin engine. Mechanically, I think 270 would be "better" (as D4A so very well explains) but 285 is "close enough" and let them keep the sound as close as possible.

[@BlueRice]

i respect this guy. i remember he debated about brakes and even some engineer ( as they claim ) were wrong and i agree what he said. sometimes someone who has higher education or a degree may be wrong . just like Veritasium who did a debated about acceleration of energy can move faster than what energy it has. thats the beauty of science though. you debate and prove each other wrong and the accept it as when they been proven wrong. thats how science becomes more accurate because when its proven wrong or right it added the level of extented experiment to validate.

[@vaibhavkadu4512]

I like the content and accuracy of your channel and very much appreciate it. I am also a viewer of the fortnight channel i like the cinematography and video quality of it. From that what I understand is why Fortnight's viewers don't raise a question or counter-argue because of how you present yourself in front of your audience. If you present yourself as smart, intelligent and wise (don't matter whether you are or not) in front of them they will listen to you. The world is full of

[@Allan-zv6cc]

I found this explanation of a relatively complex issue incredibly and refreshingly straightforward and I am very grateful for the opportunity to understand primary and secondary balance much better than I did before. Many thanks.

[@B1bthinkin]

Your explanations are brilliant. I came to this channel with the most basic understanding of how engines work, but learn a lot from every video, and find them all fascinating. My respect for mechanical engineers has also increased massively. Also love your to communicate the complex, in understandable terms, and with humility.

[@freely_messy]

I like watching you explain balance every single time because you constantly explain and update it better. Big engine enthusiast, enjoys your videos a whole lot.

[@flechette3782]

Excellent. I am really enjoying both FortNine and this channel talking about the engineering of motorcycles. Also, excellent presentation. I wish my professors were as good as you.

[@leslieaustin151]

Thank you, that was clear and concise (enough) to clear up some tinkling warning bells I had when I watched the FN video, specifically the comment about the need for ‘twisting’ of the cranks during manufacture. I’m no expert, just a very old ex-motor-mechanic.. but your video made a lot of sense. Regards from UK 🇬🇧, Les

[@fmpinto]

Dear D4A, I think you are quite right. I do not know anything about your academic and scientific background and I sometimes miss numbers, equations and functions, and calculus and all those beautiful engineering stuf in your channel. However I admit that those things may be boring depending on the subject and the audience. Anyway, I will try to do the math and let you know in the comments whether or not there is any chance of you being incorrect in some minor details - I just need to model the piston movement and take the first (velocity) and second (acceleration/force) derivatives. And, before I forget, thank you for yet another amazing content.

[@kwahoo5746]

Do it, you will notice an interesting (but minor) simplification done in velocity/acceleration equations.

[@fmpinto]

@@kwahoo5746 I suspect that the length of the rod plays some role and is being neglected and fixed at an arbitrary number in order to obtain those magic 75 degrees as the moment of peak velocity.

[@kwahoo5746]

@@fmpinto Yes, this is true. But there are other interesting things (tip: simplification with the Taylor series expansion) to find...

[@fmpinto]

@@kwahoo5746 Thanks! I am not sure if I will be able to follow you that deeply, but In fact the secondary movement got complicated very quickly. Some simplifications are tempting or unavoidable to take me somewhere.

[@hupiscratch110]

The moment I saw Fortnine's video, I knew this one was coming. There's no way you would leave a engine balance topic out in the woods. Nice work (and I like Fortnine too, awesome channel)

[@gort8203]

Great video. I would love to see you do a video explaining the balance of a radial piston engine as used in aircraft and some armored vehicles.

[@user-ze2ei5jj1l]

Great article again, gave me a lot of pleasure watching it. In a 360 or 180 vertical twin, where both the pistons stop simultaneously, the flywheel must use energy to get them moving again, but this is not so in the case of the 90 and even better the 76 crankshaft when one piston is at top dead centre while the other (76) is moving at maximum velocity. However; The ideal off set angle of the crankshaft where the second piston is at maximum speed is depending on the ratio of connecting rod length to crank radius. F.I. If the connecting rod would have an infinite length there would be no secondary imbalance or secodary piston speed.

[@genelong1748]

I agree with balance. Let's look at torque production. More importantly let's look at how the firing order is striking the tire. Does the tire have a recovery time from ignition shock? Another well made video.

[@bikeaddictbp]

Yamaha's big deal with the cross-plane-crank R1 involved the rotation speed of the crank being more uniform because it never had all pistons starting and stopping together the way a conventional inline-4 has it. Off the cuff I'm thinking the 270 twin will be closer to achieving this than a 285 twin, and this was only briefly touched on in this video, but the math starts getting really hard! The uneven-firing-pattern and tire-recovery situation seen in MotoGP is a whole 'nother situation on top of this, the ever-so-vague "rider feel" playing a part, with the current (known) interesting best example being the Ducati 90-degree V4 with 70-degree-offset crankpins.

[@adrianvalbuena8158]

I also got a bit shocked by the better 285 better balance affirmaton on fortnine's video. Thanks for analysing that fact. At least I completly agree with the polution reason for the return to that configuration nowadays,

[@tedarcher9120]

Why does anybody produce them if they are harder to produce and have worse balance?

[@d4a]

@@tedarcher9120 They don't really have worse balance but they also don't have better one. Also, I doubt they're significantly harder to produce. It's all in the video.

[@snapcountersteer]

@@tedarcher9120 ktm's v-twins are 75 degrees apart, so I assume they make 285 inline twins to keep a similar sound signature.

[@adrianvalbuena8158]

@@tedarcher9120 Maybe for the sound and the uneven power transfer to the wheel, don't really know...

[@lifted_above]

@@snapcountersteer I was going to say this if someone else hadn't already. Why KTM's LC8 V-twins have run 75° instead of the more common Ducati style at 90°, I'm not really sure. Packaging a Vtwin with a wide angle is a problem in bikes. V-twin engine are already expensive to manufacture and make everything else more complex (cooling, intake, throttle body packaging, airbox, exhaust routing, transmission placement, camshaft actuation, and a lot more). I think the crowd who loves to criticize the lowly "parallel twin" engine configuration does so on the basis of having an emotional connection to V-twins, which of themselves, are sort of a historical rebellion against the trend of inline-4's. I'm not really sure even the Vtwin folks who criticize parallel twins understand why they have the emotional reaction they do. Sound signatures between a Ducati and a CP2 Yamaha are nearly identical. Close enough to be hard to distinguish. Certainly the vibration and sound between the two configurations is not identical as a Vtwin lopes and bucks irregularly while idling, and the Parallel twin tends to have various RPM where buzz appears and disappears, in my experience, the Vtwin stays pretty much the same vibration at all RPM ranges.

[@craigcox9178]

So what hasn't been mentioned is that KTM has preferred this firing interval for all it's twins now...that's why the 1290 has a 75° firing order, the opposite angle is....285°.

[@fixento]

Interesting, thank you for the explanation. Honda Transalp 750 engine also has two balancing shafts, " Primary drive gear can serve as a balancer drive gear for both front and rear to reduce weight and size. The 270-degree crank was adopted to cancel the secondary oscillation. Thanks to this application, even though the basic arrangement includes one weight for the light and compact front balancer and another for the rear balancer, the primary vibrations and force couple can be cancelled with ingenious efforts made to the layout and orientation."

[@ChroniclesofKToyoda]

I'm so glad you've been educating yourself & passing on that knowledge Otherwise not knowing no better I'd've taken F9 on his word commiting myself a disservice

[@Danger_mouse]

Thanks for keeping it real D4A🙂👌 I like the F9 video channel, but the 285 crank video looked to me to be a KTM ad.

[@Ramonatho]

Eh when Ryan himself says you're gonna pay for the difference I'm not sure thats what a manufacturer would like someone to say

[@charleshaggard4341]

I have noticed that on a lot of the content creators this seems to be the case or they have personal bias of one brand over another. I was raised in a Chevy dealership and I couldn't be very objective if I was comparing other brands back in the day.

[@lifted_above]

What's more likely is the deflating balloon of the F9 fans and the rage that follows. I have nothing against Ryan. I just think a channel with their production slickness will box itself into corners from time to time, as fans mistake slickness of production with objective fact.

[@Danger_mouse]

@@Ramonatho But the KTM faithful do it and don't even think about it. They pay more believing them to be superior, forgetting that many of the bikes are now made in India or China 🙂

[@RainShadow-yi3xr]

I don't even think he owns a KTM

[@user-qv5lr1sy9o]

I am one of those 50% so I will correct you :D TL:DR The reason KTM went with the 285 is experience. What once used to be a necessity for creating a compact V-Twin has helped KTM in creating a well performing Inline 2 without having to start from scratch Back then KTM only made single-cylinder bikes. The idea for a KTM two cylinder idea came from a university student project; a V-Twin made from two KTM dirt bike singles. The students didn't want to use a 90° cylinder angle because the engine would be too long. So they decided to move the cylinders closer in a 75° arrangement with a multipurpose shaft between the two cylinders which balances the engine and drives the water and oil pump aswell as the the alternator. Shortly after Pierer started developing the LC8 (Liquid Cooled 8-Valve) The basic arrangement stayed until today. KTM spent more than a decade on perfecting the 285° V-Twin so when they wanted to join the midpriced segment they designed the engine in a way that they can use their knowledge from LC8 development to make the LC8c. (c for compact)

[@anchinkan]

Very well and clear explained. That and your respect towards Fortnine shows you not only in the know but also a decent human. Actually, I accompanied a project at a crankshaft maker for three years. We set up a complete turnkey crankshaft production line and during that time I learned and saw a lot. I am no technician but still I don’t think that production of a 285 cs should be more expensive than a 270 cs. The tools within the press as well as the necessary procedures before and after the actual forging should be (nearly?) the same. At least costwise it could be neglected.

[@k1ll3rvc]

At 18:37 the 5-cylinder crank fairly clearly has the pins at the correct angles; no.3 is horizontal, 2&4 are 144deg out (furthest from the centreline), and 1&5 are closer to the centreline. Unless there's some weird overhangs on the crank I don't think there's any reason to twist it, the forging dies can be made to the final crank pin positions without a problem, just anything other than flat-plane needs more complex dies with deeper (more difficult/expensive) machining. The only time I've heard of twisting a crank was one of Audi's DTM engines, turning a cross-plane V8 production crank into a flat-plane V8 for racing, and I'm not sure I believe that other than as a justification for skirting the rules.

[@rightwingsafetysquad9872]

Sometimes they're twisted to pre-stress the steel to mitigate tertiary vibrations. Not because it's necessary to get the shape.

[@rightwingsafetysquad9872]

I suspect KTM does the 285° inline twin to more closely match the character of their 75° V-twin, which I assume they do because it packages better than 90°.

[@gdaytrees4728]

Exactly right, man. Consistent sound signature. Like Harleys signature sound, only the KTM sounds much better, to me...

[@mehmetgurdal]

yes thats the reason. I've checked their marketing material and they dont claim to have better balances in their engines. so its completely a matter of preference.

[@maxharris4208]

I've said it before, I'll say it again - I LOVE this channel!!! Brilliant explanations and a fabulous, engaging presentation style. Thank you 😊

[@zinser642]

Top notch job to you both, and respect to each for tackling this topic. One variable i have not seen anyone cover or even mention yet is crank centerline offset to bore centerline and its impact to balance. I know it is done in order to increase engine efficiency by reducing thrust loading of the piston skirt into the bore wall on the power stroke due to rod angle. I also know that at least yamaha has this offset on the 270° CP2, but not sure what other manufacturers might.

[@StephanKusch]

13:49 The Rotax 652 single cylinder engine in my motorcycle has two balancer shafts regardless of space and weight constraints... 🤔 It's a pretty smooth thumper, I should add.

[@xrhst0s2114]

got aprilia 650 with rotax that thing is unscrewing its self if you going over 5k rpm's

[@StephanKusch]

@@xrhst0s2114 You mean the Aprilia Pegaso? Same engine, just carbureted. Mine (in a BMW F 650 CS) is relatively smooth until 6500 rpm, a bit viby in the right foot peg.

[@xrhst0s2114]

@@StephanKusch Yes I'm talking about pegaso i think it's worse with injection cause you get more power so more dorces literally I screw to spec all the bike except engine after like 2 months of riding

[@spankeyfish]

I have one and discovered that if I sit in exactly the right place at a certain speed it blurs my vision. It's the only thumper I've owned so I'll take your word for it. It vibrates less than a CX500, at least.

[@osmentist2857]

Hi @StephanKusch , i can't find the second balancing shaft, where is it?

[@SGTvolcan]

I am so happy that i ride a KLR650S and not having to worry about any of this.

[@dylanc2806]

i love having 40 hp

[@stevejones1318]

A single cylinder intrinsically has more vibration than a twin or four.

[@SGTvolcan]

@@stevejones1318 Yes, but a great deal less problems. My 650S is 100 pounds heavier then 2nd gen KLRs. Mostly from rubber mounts. It has little to no vibration until you get to 70mph. From which; where i live it's a rarity to get to 70mph.

[@marcusgeorge1825]

A great, humble, backed by facts to showcase this without trying to discredit someone else’s work by explaining each point logically. Well done.

[@sidwilson9556]

What a brilliant explanation. And your preamble not trying to put Fortnine down was very respectful. I’ve subscribed after watching this. Thank you so much.

[@ilombra4496]

Would love to hear your thoughts on the Husqvarna Nuda's 315 degree firing interval !!

[@RealNotallGaming]

as a CNC machinist with 15 years jobs on shoulders at many levels, i can say you dont TWIST a forged piece you just build another die for make a different piece at a "irrelevant" price (maybe 50k-100k euros) and CNC machines for work on forged pieces can just reprogrammed at different degrees of work with few hours ^^ basically there is no additional costs for make similar pieces because all pieces need those costs 285 or 270 cost the same and if there is a difference is minimal and can be nullified by market selling another topis is about protos, when you make 1 engine and thats it there is no selling so only costs

[@catherined.398]

This bothered me too. Start with a different part. Cut a different cam lobe for the crank grinder.

[@cristianobriarava6260]

You're exeptional. I have searched videos like youre for years! Thank you so much!

[@likita779]

Aaand...another great video Thank! Was wondering may one day speak about vacuum and aspiration?

[@IngOehman]

So you missed my comment to Fortnines video? 😉 I corrected the Fortnine video in my comment, and also added the historical reason presented by KTM! As you guess - it IS a sound/character thing, not an attempt to minimise vibrations. I’m pretty sure that most engineers reacted to the videos erroneous claims, but youtube-viewers don’t always point out wrongs they see, even if they are engineers. We are not all difficult, just… you and me. ☺️

[@Citizen-5349]

Twisting a crankshaft after forging has no additional significant cost associated with it, even more so if the price charged is premium. I had to call up a friend working at the Bajaj/KTM/husqvarna factory to verify this. While the factory he works at doesn't manufacture KTM's over 490cc , He worked in Spain factory before with larger engines. Here is the direct text from him " Balancer is in all engines from 250. Brand goes for that few percent of performance so used 285. Bigger ones use V twins and sell more. Cranks are made with same machine for 790 and 1200. dye is different thats all" Original text was in native language and I translated it so grammar is not right.

[@danielklopp7007]

... and "dye" is misspelled (in this context); Dye (noun) is a substance that imparts color; die (noun) is a tool for imparting a specific shape to a material.

[@balajig3556]

I watched almost all your videos, ur effort is tremendous, I noticed that for one vedio ur your effort is huge, thanks for sharing, my one suggestion could you please make vedio on where we need to adjust the reciprocating and rotating masses for balancing, especially crank web & counter weight

[@ricksorensen9480]

Very good explanation for people that can understand what you are talking about,,and I think you are very intelligent,,sad thing is,,just like in Tesla,s time, many people had no idea what he was talking about and thought he was crazy,,so I say don't let anyone stress you out about things they don't understand and keep up the good work. Thank you.