Ducati Desmodromic Valve Timing Demystified | MC Garage
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- Опубликовано: 26 июл 2018
- Ducati may be one of the most well-known motorcycle brands in the world, but not a lot of folks know about the unique cam technology that all Ducati’s use. What is desmodromic valve timing and why does Ducati use it? We’ll explain in this video from the MC Garage.
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Unless you ride a two-stroke or an electric motorcycle, your motorcycle’s engine has poppet valves that control the flow of air and gas into the combustion chamber and the flow of exhaust gases moving out. All four-stroke engines use a cam to push the valves open, often via rocker arms as on this example, and all motorcycles use strong springs to force the valves closed. All motorcycles, except Ducatis.
How Do Desmo Valves Work?
Ducatis use desmodromic valve control, called desmo for short, and the difference is in how the valves are closed. Instead of relying on springs to push the valves back against their seats, desmo heads have separate, complementary cam lobes and forked, L-shaped rocker arms that rest against collars on the valve stems and act to pull the valves closed. So whether opening or closing, the valves’ motion is positively controlled at all times and follows the cam timing exactly. In fact, the word “desmodromic” is a combination of the Greek words “desmo,” which means controlled, and “dromic,” which means course.
Why does precise valve control matter? It’s how you make good power, for one, but it’s also how you ensure your engine doesn’t barf its guts out the exhaust pipe. And that was actually fairly common back in the ’40s and ’50s when race engines were beginning to rev really high. The metallurgy of the day wasn’t great, and valve springs would often break or fail to return the valves to their seats fast enough, resulting in a loss of power or a grenaded engine if the valve hit the piston. And that’s definitely not a good way to win races.
So, in 1956, Ducati, under the guidance of the great Fabio Taglioni, decided to sidestep the valve-spring problem altogether by putting a desmodromic valvetrain in its 125 Grand Prix racer. The system kept the valves under control at high revs, Ducati won a bunch of races, and today, all Ducati’s use desmodromic timing, from the Scrambler lineup on up to Ducati’s MotoGP bikes.
Ducati and desmo may be synonymous, but Ducati didn’t invent the technology. Norton actually implemented it before Ducati, and Mercedes and other car manufacturers gave desmo a try too, but Ducati is the only company to put desmodromic timing into mass production and it’s become a hallmark of the brand. Another common misconception is that there are no springs whatsoever in a desmo head. There aren’t coil stacks under each valve as on a conventional head, but there are fairly substantial hairpin springs on the closing arms that help the valves seal and make sure the closing collars stay in place.
What Are The Benefits Of Desmo Valves?
So the big benefit of desmodromic timing it that it frees you from the weaknesses of conventional valve springs. The thing is, metallurgy and technology have improved a lot. Spring-valve engines can rev to 15,000 rpm or more without floating a poppet, and when was the last time you heard of a valve spring breaking? The truth is, the problem that prompted Ducati to start using desmo doesn’t exist anymore, and the system has, historically, presented some problems of its own.
Why Is Ducati Maintenance Expensive?
For example, Ducati’s are famous for having frequent valve-service intervals. These Italian bikes are more difficult and time-consuming to service since they have twice as many shims to check and change-a shim on the opening arm and the closing arm of each valve-plus there are two cam belts that need to be replaced and tensioned whenever you check the valves. And, assuming you’re taking your Duc to a Ducati dealer, you’re probably going to pay a higher hourly rate for the work.
Read the full breakdown of Ducati's Desmo valve train on Motorcyclist: www.motorcyclistonline.com/du...
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Read the full breakdown of Ducati's Desmo valve train on Motorcyclist: www.motorcyclistonline.com/ducati-desmodromic-valve-timing-demystified/
As a Ducati mechanic, I will say this is very informative. Despite what people think, they actually aren't much more difficult to work on. The cam belts take maybe an hour. They are super easy to get to. The valve adjustments aren't any more difficult than typical valves. Just a little more time consuming.
May need to pick your brain too. In the future if that would be ok.
I personally still think desmodramic valve actuation is still superior, More accurate, quicker, more efficient, probably more reliable too
Razor, just bought a late mdl Ducati ST2 and I love its looks and sound... One quick question though--I have the dry clutch and want 2 get the corrigated open clutch cover 4 the look and sound. Any problems with these? Thx, Brent
The only time you should have a problem is if you forgot to tie your shoes, or if you ride in the winter. The road salt can cause problems. I have an 02 ST2 and I use the close cover in the winter to prevent it. Other than that, it is beneficial to use an open cover. It allows air to get in and cool the plates since there isn't any oil to do it. Depending on the cover you get, you can even inspect the wear without removing anything. It will make the clanking sound a lot louder though. Personally, I love it but not everyone feels the same way.
I've heard that sound on Duc's n its awesome! As of yet I haven't ordered one though. Is Ebay good? I buy Mercedes parts from them all the time..
Superb explanation of Desmo timing, I've gone from wtf is that to looking forward to impressing my mates down the pub. Thanks a lot.
Ducati was the first bike I lusted for. It was the Desmo valve system that captured my heart. Back in 1969, the 350cc ducati single cylinder was beyond my budget. Ten years later, Ducati dealership couldn't be found in Thaialnd. Now I proudly own a 939 SuperSport S.
Only thing Ari forgot to mention was THE SOUND of a desmo engine at redline
During the second Desmo service on my Multi the tech brought me back and we talked about the Desmo valvetrain - was very cool to see it on my bike (after 36,000 miles) and have some of the details of operation explained by an expert. It's a very reliable drivetrain - as long as you keep up with service.
Much of what Ari outlines here is what fuels the passion many Ducati owners have for their machines. Working on them as an owner is a fulfilling experience. Riding one that you’ve successfully worked on is another level of pleasure. Some of my greatest highs (and lows...yes Ducati electrical circa ‘01 I’m looking at you) over the last 6 years have come from my relationship with a ‘01 748 and ‘02 750 Monster.
Hypermotard owner here! Thanks for the easy to follow explanation!
I'm not a mechanic, I was an English major in college. I acquired a 2001 Yamaha Roadstar 1600 5 years ago. Because I was not so very happy with the service the bike got at various dealerships, I decided to breakdown the bike to its individual pieces and service the bike myself.
I started at the rear tire and swing arm and am moving my way forward.
The engine itself scares me. But I'm determined to have it sitting on my work bench in a couple of months when I'll start poking it with screw drivers and wrenches.
And, that's why these videos are valuable to me. Take away the mystery, and I'm comfortable working on the bike.
Thanks for the videos.
Take photos before disasembly and put everything like screws etc into little bags and mark tem
In response to Felix's post: it might have been on this channel, the suggestion to bag and label everything that I do do that. I take photos galore; I'd take videos, but editing would be an effort. All the parts are boxed-up and labeled.
And, I'm happy to boast that I've gone broke buying (investing in) tools.
I've been wrenching on bikes for 11 years since I was 16. my $0.02, get a good set of tools and a paperback repair manual. also, working in a comfortable, well lit setting is key. headlamps, box fan, case of cold beer, whatever floats your boat. working on a bike with a clear mind will make you do better work. happy wrenching 👍🏻
@ Paul/ Quoting thatallredheaddude 1 working on a bike with a clear mind will make you do better work. Then do not have a case of beer cold or otherwise. That is a recipe for disaster. save that beer for after.
Complete Nonsense.
Ducati is the only motorcycle (other than Harley...) that I don't have to see to know what I'm hearing. The bike has a sound all it's own, and is simply unmistakable for any other. Beautiful machine!
oh yes, I was lazy to try to understand this, but you made it quick and easy, and still put it in a historical context, great! I have a Ducati Scrambler.
All the others that tried the desmo could never get the power out of the engines. Ducati is the only company that made it all work.
Also, the valve travel distance can be longer, because valve spring binding is eliminated and therefore resulting in better volumetric efficiency (breathing). This works in concert with a larger diameter valve and a longer stroke when compared to high revving "valve spring" engines.
Whatever the tech is... Ducatis are one of a kind... Lovely to hear them... I will be owning of them very soon
did you pull the trigger on a duc?
Good luck
@@SirSpinalColumn not yet dude probably 2022
It is a common misconception that opening a stiff valve spring wastes a lot of energy. Yes...it DOES take effort to open the valve, but then the valve pushes back against the cam which returns all of the stored energy save for a little bit lost via friction. Anyone who has ever set the valves knows that as you rotate the engine by hand it will resist until it reaches a certain point then jump ahead as the springs push the cams forward. The Desmo system still has friction so it's advantage over modern valve springs is minimal if any.
Thanks for sharing. After decades of motorcycling... I finally understood Desmo
I must say, I always love the way you "hit the point". Very good!
Thanks for the great video! This is the best, most succinct overview of Desmo engines I have seen.
Redheaddude: I'm with you. My bike is in the living room. That's my shop now ....great lighting, air-conditioned, food and cold beer right there in the kitchen. Plus, three work benches in the back yard.
I am a happy dude.
This channel just gets better and better.
These guys deserves more than 1million subacribers!!!!
Smaller content providers and many more of them rather than just a few giant content providers.
Desmodromic technology was actually courtesy of the Maserati brothers who started out racing bikes and making spark plugs.
As always, love your MC Garage videos. And this was something not known to me. Now I know a few things that make a Ducati unique.
Don't own a Ducati but it's Ari and MC Garage therefore like and watch, in that order.
Got it . Before this i did not know that Desmodromic Valve Timing exist. All thanks to Ari.
The beauty of Desmo heads is the fact they allow the engine to rev without valve bouncing. Just pure simplicity!
As always a great vid!
Next vid should be: How to do a Desmo-Service in your own garage! ;)
Oh yeah, would love a good quality instructional Desmo-service video, I've got a valve timing adjustment coming next week on my S4RT, would love to do it on my own some day!
Here's one I watched before doing mine. Best one I've seen. m.ruclips.net/video/9_VEPAwiLB8/видео.html
The aircooled Desmodue is about as far as DIYers get on valve service. The Testastretta (Multistrada, Super Sport, Monster 1200, Hyperstrada, X Diavel, and older superbikes) and Desmoquattro (Panigale) are considered largely too complex with too difficult access to DIY the valve service.
I got a multistrada 1200 a year ago this winter and 19.000 miles later I will check the valves. Found a very good utube how to. Google multistrada valve adjustment.! Desmo not that big of a deal, 3 Ducati, 400.000 + miles 😎🏍🏍🍺
I've tried googling "DIY desmo service for Multistrada" and mostly what I've found are lots of forum threads where people have given up on trying to DIY the desmo service on the Multi, it is apparently almost as bad as doing the service on a Panigale.
As a Ducati owner for the past 22 years (that's how long I've had my 23 year old 900SS) I knew how the valves worked, but still learned a lot from this video, thanks.
Nice! That's great to hear, thanks Trevor.
Amazing video, and for all those comments about reliability, I have my 750ss (2002) for three years now, and never had a trouble with valve timing, never had to take it to the dealer to deal with anything related with valves and the bike works great! love the mechanical sound and I use it a lot is almost my daily commuter except on rainy days.
The animation of the Desmo valves provides loads of understanding
I met one of the engineers at Ducati factory and they moved on Pass this old tech and now are on the way for the future of electro-magnet valve operation.
Frenchy Moto 87 any link?
Lots of good info, great delivery style and length. Keep those videos coming. Greetings from Toronto, Canada.
WOW! What a great video! Very simple yet very interesting! I loved the mix of history and mechanics! Awesome video!
Super happy owner of a black stealth Streetfighter 848 from 2012. Thank you for your explanations !
This was actually a neat little video. Thank you
Fantastic video. I had no concept of how desmo worked before this.
This video is an example of why I subscribe to your channel.
I would like to see a series explaining differences between engine types, why its being used and what various technologies do. I would love to also have an explanation of the new suzuki gsxr VVT system :)
Thanks Ari, I'm a new Ducati owner and was not aware of this. Still learning and this is very helpful. You guys are great!!!👍
my friend i hope you have a big bank account or know how to spin a wrench lol welcome to the club enjoy your machine
I watched this a couple years ago, but after buying a Monster 1200s today, I thought a refresher was in order. My first Ducati after always shying away from the dreaded maintenance and reliability woes. Turns out they actually took this seriously, and my 2019 should be (hopefully) not much less reliable than the Japanese bikes I've always preferred. I'll be interested to see which has more problems; my recently purchased 2021 Husqvarna FE501S, or the 2019 Monster 1200S... Hopefully they are both flawless, because, damn, they make all the Japanese bikes I've owned feel stale.
I love the way it sounds. Gets my juices goin
Desmo and dry clutch is what makes a Ducati 😊
Very interesting to know. I’m a motorcycle mechanic but never have I had my hands on the internals of a Ducati motor. Enjoyed the video! Thanks!
Great timing. I just got myself an '02 S4!
Ari,you are an ocean of knowledge.
I mostly just like to do research :)
Outstanding video as usual keep up the great work ARI!!!
Actually the DESMO potion indeed comes from the Greek word ''Δεσμός'' (pronounced THe-smόs) though it does not translate as "controlled" but as "bonded" or "tied" e.g. linked together. The DROMIC portion also indeed comes from the Greek work "Δρόμος" (pronounced THrό-mos) which can be translated as "track" but in practical terms means "road" or IMHO in this case, "fast movement". And truly, Ducati's method is nothing else but the tied, linked fast movement of the valves with the cam.
This is a more accurate information for the word desmodromic:)
Informative, useful And not condescending. Thnx
Just bought a Ducati... what a pleasure to watch...
Nice timing, my Multistrada is in the shop this weekend for it’s first desmo service.
I had no idea. That’s cool. I have a new found respect for Ducati now.
LITERALLY the James Willems of motorcycles.
Awesome explanation of the desmo valves
Excited for more vids Ari, keep em commin
Thanks, for the video. I love my 06 monster. Always wondered about Desmo.
848 owner. Thank you for explaining this to me 🙂
Hi Ari,
I ride a Ducati and know how the Desmo works. This is a great review and now my go to way to explain it to other people,
Keep up the great work,
Cheers,
Glad it gets your approval. Thanks for watching.
Coolest part of this video is between @0:01 & @6:25
I actually really liked the History aspect of this vod... Thnx Ari, Thnx Zach, and thnx other dude & unsung heroes or MM! I forgot your name, I'm sorry bro. :[
Really good summary here. This is a few years old, but still relevant. 18K mile Desmo service interval for my 937 Testastretta...honestly not too bad 🤷♂
Love the video Ari! You have taught me so much thanks!!
Awesome history lesson and explanation, thanks!
The desmo valves have a nice sound to them, too!
Well you learn somthing new every day
Decent time explain for sure ya got here, the desmo valve system is wild for sure!!
Just found this channel , have learned alot
Great video. Covered all angles great.
Class is in session 😊 Awesome video. Thanks for the insight.
Purely informative. Thanks!
Great date Ari
Thanks 😉🤘
Best wishes
WoW! Definitely learned something new today, thanks.
Great talk, much more detailed than 99% other videos on the topic. I think Ducati still has some usages where desmodromic cams give them advantage. Desmosedici is still the most powerful MotoGP bike (no power loss for pneumatic springs) and Panigale V4 is probably the only street legal >=liter bike hitting 15000 rpm.
Great vid. Great words of wisdom from Ari as always. You guys should do an MC commute on the hypermotard
Ari, best motorcycle expect on youtube
great video used it to explain to my wife why im always working on my bike lol
Great video. I love Ducati. Coolest thing about them is the desmo valves. The reason I DON'T/WON'T own one? The desmo valves!
Haha,WELL SPOKEN upside downdog!!! Same with me as well!!! :)
$$$$$$$$
N A I L E D I T !
Learn to wrench a little, no big deal. Love my Tre desmo... Cheers
Desmo service is a bit steep... but at the new service intervals it really doesn't amount to much more compared to all the other costs of ownership. It's about $400 more ($1000-$1200 vs. $600-$800) than a Japanese sportbike major service - but only needs to be done every 15-18k miles - that 5-6 per 100k or (likely less than $2k over the full life of the bike). Not really something people who aren't scared of the purchase price are going to worry about.
Very informative vid. Looking at new Monster 821 next year. Desmo service. 35000kms. Way better than the older models for sure
Great video, keep up the good work!
Works for me.😁I love this thing. It is so much fun and hasn't cost me to much more than a gsxr1000 to keep.
I love all bikes fron Harley to Suzuki but Ducati is amore passione emocione all mix, i love my streetfingther thanks for the video, grazie !!!!!!!!!
I own a '91 900 SS and honestly it is IMHO no different to any other Bike I've owned over the years , it is for all intents and purposes similar to any re maintenance . IF an owner is wanting the Prestige of owning a great marque and he is prepared to pay the premium service charges then so be it . In reality learning about your own bikes heritage and maintenance is a wise move , and I for one can honestly say that I seriously doubt that my general maintenance costs either in Parts or time is any different to any other bike I have owned.
The big secret is having the correct clearance BUT once set there is little wear or impact that effects the Valve or the Valve seat. That is the beauty of this system , and why the Cam belts generally do not suffer any where near like those that are largely under load all the time driving against spring loads . Honestly the Desmodromic Valve System was great innovation at the time it was conceived, and was a revolution for the times.
But as stated metallurgy has come a long way since it's inception particularly Valve springs , given the time that this valve system was conceived and the mechanical constraints that needed to be overcome at the time. Now while so many of the issues of the day have largely ceased to exist the general simplicity of the Desmodromic Valve operation is still just as valid today as when first introduced .
mozzmann my most expensive outlay to maintain my m900 is tires. Its a1996 and I have owned it since new and havent put anything into it other than regular maintenance which I do myself
Outstanding video in every way!
Very cool and informative video.
We are really going to miss these videos from @Motorcyclist Magazine even if they were way too overly simple for experienced enthusiasts ..
Great video as always. Thank you a lot.
Awesome vid! Love the channel!
I love the work y'all do. Thank you for this video. :))
Glad you like 'em.
"When was the last time you've ever heard of a valve spring failure?" You, sir, have never owned a Jeep Liberty...
Lol!
😂🤣
Friend had complete titanium valve break caused by a valve spring failure in his 16k km yamaha r1 2005. Valve fell into cylinder blocked the engine, broke the piston and bent the conrod. It was a very expensive repair. I will chose desmo any time. I do all the maintanence for my ducs by myself. It is not a rocket science...people are just lazy a.f. nowadays. Even a monkey should do a cambelt change, there are tons of quality, dumb proof videos and pdf docs out there. Also it is not true desmo is just a tradition in these days, just try any other v2 bikes and you’ll see, the torque curve of a ducati desmo is second to none.
😂😂😂😂
Thanks for the lecture..never knew about those valves. Only knew about those rattling dry clutches, another thing that makes Ducatis "famous".
Yes, there's a certain irony there 🤔
Cool, I finally know what those Duc owners are talking about :)
Educative video. Learned interesting stuff. Keep these coming. Thanks.
We'll do our best!
The desmo sound !
Great vid Ari.
Great video as usual, I'd love more videos like this if you can ! :)
Great vid! I learned something!
As a Ducati owner, I thank you.
As a former Ducati owner who was taught how to adjust the valves on my 900*, I commend you for your clear anf thorough explanation of the system.
*I only did it once and it took three days but it did save me $500!! Replaced it with a Bandit 1200...much easier valve adjustments =D
Ah, but doesn't that Bandit 1200 have 7500-mile intervals and 16 valves?!? I had a B600, and I recall adjusting the valves in a parking lot (while on a road trip) in New Mexico. It was a stressful afternoon.
Ari Henning
Why didn't you do it before the trip? I didn't take you for a slacker with poor decision making. :P
It was a 20,000-mile trip. I had to do it twice while I was on the road ;)
Ha! Point taken! It was an annual thing for me. Did manage to crack a valve cover once because I missed a gasket. And that other time I missed a gasket and had oil pumping out of a spark plug hole =D
Thats a story I'd like to hear about! Did you ever write any articles about it? Archived anywhere?
love your vids
A top video. You really got a load of content in there well. I'm approaching the 30,000km service on my hyper and plan to DIY the service. Sure it may take me longer but hey, half the fun of a motorbike is dismantling it right? Keep the good vids coming. My favourite of all time is the scrambler vs scrambler adventure.
The biggest reason to do desmo at this point is so your large displacement V-twin can run large, heavy valves, and still rev like a proper motorbike engine. Rather than something lazy like a HD engine. Same if not more displacement than a Duc engine, but half the HP per litre of displacement, half the redline and less low end torque.
HD motors are a joke.
Other manufacturers make big V-twins that rev just about as high, with regular springs.
The only advantage to desmodromic valves is it ensures there will be no valve float - that's it.
Damn, I love this channel.
'93 900ss owner bought new here. Great vid Ari... I've done about 12 valve checks/adjustments on my 2 valve. Pro Itialia in LA put out a VCR (remember those?) video on how to do a 2 valve demo tune-up. Watched it every time before going to work on the bike. There are over 300 shim sizes and I still had to hand polish a few into spec clearance. Old and worn out now, I'm done with doing any more but I've enjoyed over 40,000 miles of joyful Duck noises from Canada to S. Cali. and most curvy roads in between. Quack!
Right on Dennis, good on you for tackling the service yourself.