How CARBURETORS and cv carbs work - EXPLAINED
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- Опубліковано 30 вер 2024
- I realized that during my recent bike carb conversion videos of my 4age engine I have been saying the words carburetor, carbs and bike carbs without ever explaining how they work. In this video we fix that, while also paying homage to the Royal Carburettor Society of London.
We are going to cover the general principles of how carburetors work, as well as a take a look at the more advanced constant velocity or cv carburetors, which is what my Honda cbr 600 carbs that are going on my 4age engine actually are.
We are also going to talk about the Bernoulli principle, the venturi, main jets, pilot jets, jet needles, slides, butterflies, diaphragms, the float bowl and the float among other things.
Intro song is "Kiss" by Escape
Check out my blog: www.driving4ans...
#d4a #carburetor #howitworks #explained #tutorial
Considering how much better you have gotten making this kind of content since this video, would you ever consider redoing or making another video explaining how carburetors work?
Please yes
If you are just like Jeremy Clarkson let me translate it for you. Air pulls fuel by magic and you go Braaaap
Video sponsored by Takumi Fujiwara
Arigatou gozaimasu Fujiwara san
Could you make a video of the working of piersburg 2E3 carburettor? I have one on my old T3 and it has some weird working principles compared to other carbs and it would be really interesting to hear of the method of their function :) It's paired with WBX 1.9 petrol engine
Karburetttaes are simple, cheap, and you can fix' em on the side of the street.
Efi is more complicated, more expensive, but very prescise, and reliable, and it creats less emissons. *Also Efi does not care you are below sea level or you are driving on top of MT Everest. No need to choke. No need to rev to warm up. More power. Do EFI
this style carburettor doesn't use a choke :D, and i never has issues at cold start. actually my car started faster on my bs36 mikunis than my current efi setup, but that's due to the ecu syncing process
Instead of taking a sip I'm going to take a hit
I understand karburetttaes much better now thanks to you. Much love
Someone help me! All I want to do is get a modern bike carb to replace an old carb that is impossible to get missing parts for. I was given a FREE = ( Honda CM250. It has twin cylinder running off one carb. Part 16100-KB4-672. All I want is a NEW carb that works and gets me from A to B. Is there a conversion algorithm like i saw for cars? Why can I not find any info on a simple carb to carb transition? Post a link or something. Thank you.
When needle is up and main jet is open , is pilot jet still working or its close?
Thank you
great
slight correction the needle doesnt raise with the throttle alone, part of the reason i like this style carburettor so much is because the needle responds solely to the engines request, you give more throttle but the engine can only open the needle based on its own efficiency at various rpms for the various percentages of throttle openning. there was a cool video of a camera mounted infront of an old mini cooper cv slide carb showing different load and rpm combinations and how the slide reacted. great watch aswell. :)
ua-cam.com/video/gtSam0RgPl4/v-deo.html at 1:05 he goes full throttle for a short bit and the slide is about half open, due to the engines volumetric efficiency at that rpm. these carburettors are amazing and the basis on why I was researching yamaha's use of the cy slide (without a needle) in the first gen efi 4 cylinders. (turns out to be noise reduction and fuel efficiency) I currently have my slides locked fully open (note for those reading, my setup is efi now)
Nice explanation
I should be standard to take a drink a carburetor is mentioned, ever. Praise be
stil at 1.27 and i know you'll get me drunk with wine :D
The butterfly is not the throttle...the slide is the throttle. You can go from idle to full open butterfly in an instant, but the slide opens more slowly to maintain constant vacuum inside the carburettor. CV is better called Constant Vacuum vs Constant Velocity even though the flow through the carburettor remains somewhat constant due to the position of the slide...the slide position is controlled by engine vacuum and moves up and down to maintain a constant vacuum in the intake manifold. What you describe here is the Stromberg carburettor where the operator activates the butterfly and throttle action is by the slide. The Stromberg carburettor design allows the engine to run at low speed low load and not stall when the butterfly is opened quickly. SU carburettors have mechanical connection to the slide so the operator moves the slide up and down...the biggest problem with SU carburettors is going from low speed and low load to WOT (ie slide closed to slide fully open) cannot be done quickly bec engine will stall (throttle needs to be opened slowly to maintain constant vacuum in the carburettor).
What's the purpose of the slide?
The Stromberg CD carburetor and the SU both operate on the same basic principle, except for the fact that the Stromberg uses a diaphragm instead of a piston as in the case of the SU carburetor. The mechanical connection you seem to be referring to on the SU, is the cold start system the physically lowers the main 'orifice' that surrounds the needle, thereby enriching the fuel mixture. The slide itself still operates independently only in response to engine demand, just as in the case of the CD type. Early SU carburetors were one of the first Constant Vacuum types available. In fact, the first version actually had a leather bellows instead of a metal piston to control the slide. In this respect, it was technically closer to the later diaphragm types.
Hey d4a, Have you ever considered doing a 7age hybrid build? I've seen this idea tossed around alot on forums and thought it sounded good as an idea and seems like a pretty cheap addition to any 4age build due to the availability of the 7afe block. just wanted to know if you had considered it or had any take on 7age in general.
FR1TZ I've considered a lot of things :) the 7age is a good idea, you sacrifice a bit of the rev capacity of the 4age in exchange for more torque. This often makes the 7age faster in the real world. Personally I prefer the 4age as I'm not a huge power nut and like an engine that needs to be driven hard to go, plus I really like engines that rev high. What I would really like to build is a 10.000 rpm formula atlantic style 4age. After that I would really like a turbo 9age built by mrp. :)
Next explain what is electronic carburettor
how to add a power jet to this carb any one knows?
Now true question: Mikuni RS or Keihin FCR ? Carbs swappers can relate.
TheCabillaud94 Mine are Keihin. First and only carbs I ever had. I prefer the name Mikuni though, sounds like a sexy Japanese lady.
driving 4 answers same. I believe the FCR is superior but Mikuni RS just sounds better as a name. What are yours ? I need to find 28mm carbs for my project bike.
Mine's are just some civilian Keihin cv carbs from a Honda CBR600 :) No mechanical slides or pumps.
driving 4 answers Well that sucks. Although you do have a round slide, no pumps that is sad.
bro explain about fuel system components like pcv ,prv ,etc if possible
wonderful work bro.i had missed your worjk when my phone was stolen
Where u from?? Cant rly put it sure by ur accent😂... Nice vids man keep it up
Thank you; great stuff. If you wish to do another one on constant vacuum carburettors, might I recommend that you look at and demonstrate on an SU? These were used on lots of British vehicles in the 60s and 70s such as the "iconic" Morris Minor. The vacuum slide is a piston and the annular main jet orifice is very easy to see. These carburettors make the transition from the straightforward carb (such as an Amal) with a barrel-type slide to a constant vacuum one very easy to understand. The CV carbs with diaphragms, like yours, are another step. Best wishes, Luke Wiseman
Yeah, but you annoyed all the Australians who call them carbies
Lol
Good one brother
Wanna ask is there a hole diameter dofference between the pilot and main jet?
it goes up by engine rpm
You def need a whiteboard like Engineering Explained. Makes you look more like an expert.
Cant wait for the engine firing up.
Cheers.
Lin Chester lol, you're right. Maybe get some glasses too. First start is coming soon I promise :) Thanks for watching.
Very good explanation! Thank you a lot.
Just wondering what u do for a living
Hello there! Please explain me why auto carbs do not use needles... what is the difference between a carb with needle and a carb without one. Hope it is not a very stupid question.
Thank you for your time!
I was always blow away by fact that engineers came up with cabrurated gasoline engines first. Fuel ingection seems so simple and obvious in comparison, not only as an idea but in the amount of different variables as well, excpecialy when looking at old car carbs
I know right! I was thinking the same thing while making this vid. Takes 2 min to explain fuel injection to a 10 year old. Try explaining carbs. But they are a testament to old school engineering ingenuity where you had to find a way to get something done without relying heavily on electricity and printed circuit boards. They may be fiddly and obsolete nowadays but they are still truly charming and have their place.
I happened to notice an electronic sensor in my Honda CV carb like a plug in type,what is that for?
Likely a throttle position sensor
Hi! I was thinking of fitting bike carbs on a project car, a bmw e30 with a 'm50b25 non vanos' engine for dirt racing because of problems with the injection system. So what type should I use for this 2.5l 6cyl. engine?
Doing a 6cyl is a bit more tricky but doable. You will likely need to buy two sets of 4 carbs. I assume you want good torque low down for dirt racing so I wouldn't get carbs that are too large. Definitely below 40mm, something between 36 and 38mm might be ideal depending on other engine mods. Those can usually be found on 600-750cc motorcycles. Make sure you get two identical sets that come from the same make and model of bike. You will also need a few custom bits to keep the 6 carb setup together but nothing too complex. I also suggest that you get in touch with DanStengineering, they really have a lot of know how with bike carb conversions.
@@d4a That's true! Also a good midrange would be nice. Thank you very much for the info. That will help alot! I will let you know if it worked or not. ;)
Wat fuelpump are you going to use? i use a yamaha r1 pump to have the right pressure for the carbs
I'm going to use a motorcycle fuel pump as well, one that's compatible with the Honda CBR600 carbs that I have. I didn't want to fiddle with fuel pressure regulators, but I also figured out a way how to keep the in-tank fuel injection pump intact. A detailed video on the fuel supply is coming up soon.
Another great one, thanks.
Very cool video and you deserve more likes.
My formula student team is using CBR600-F3 CV carburetors. I wanted to know if the carburetors can operate at higher fuel and air pressures. I assume the fuel and air pressure must always be the same, but could we compress both the fuel and air to 10 bar and still have the carbs working?
Thanks, glad you like the video. Motorcycle cv carburetors are extremely sensitive to fuel pressure. They want 3-4psi and that's it. When the fuel pressure is too high, even just a bit too high, it will flow past the float valves resulting in an overly rich condition and a loss in performance. Are you restricted to using carburetors?
@@d4a As far as I know we currently have a Honda CBR600 f3, engine and carbs included, but don't have enough resources to design and construct an injection system. We are required to install an air restrictor after the throttle. Originally we had talked about moving the throttle but your video helped me to understand that the throttle must remain where it is in order to create the vacuum above the diaphragm.
The only remaining questions we have are if the down-flow restrictor will cause issues with the carbs, and if it will be possible to use a single carb instead of 4 to prevent the need to make a converging manifold as well as not needing to align multiple throttles.
I like your sense of humor
Thanks i learned alot
great explanation....i saw the Italian guys video too....his animation is good and your explanation is better....just had one question why do air mixture screw has o ring and a spring and a washer inside them.....i know they are crucial but there is no proper explanation for this topic..... please throw some light on this topic....it would be of great help
Yes, the Italian dude's was an inspiration for this video, that's for sure. His animation is top notch, but I'm glad to hear you found my explanation better :) When it comes to the air mixture screw, well that's a wrong name for it. On almost all CV carburetors that screw actually meters the amount of fuel in a circuit through which fuel passes. The o-ring is there so that fuel wouldn't leak out from the screw. The spring is there to keep the bolt in place and prevent the vibrations from turning the bolt into any direction, which would of course upset the setting. The washers are there to keep the spring in place :)
okk but i disagree on the washer part its there i think to prevent the oring for getting cut under pressure....i was curious to know about the oring part because i accidentally while tuning the carb misplaced the oring ....i tuned the engine with a new o ring of same size but i am getting hesitation while reving up the engine..... hiccups....i tried to richen the mixture but it was of no help....by the way please correct me if i am wrong...i am no expert in this
Yeah, the spring needs something to rest on, hence the washer, which does also prevent the spring from deforming the o ring. When it comes to your condition, I doubt the o-ring is the culprit if you replaced it with an exact same size. Are you 100% certain that you didn't touch anything else, maybe some of the gaskets haven't been installed properly and you have a vacuum leak? Or a clogged jet?
driving 4 answers i only replaced the oring and nothing else i did not open the carburator i just took the fuel screw out and the washer and the o ring....i replaced it in correct order also first the spring then the washer and next the o ring and set it to two turns out where i could get the max rpm.....i have the pics of the fuel screw too
anyways thanks for replying was very kind of you thanks