Hello, I have this kind of Mikuni on my '91 dr250. I've been having a hard time tuning it. I have a steady idle and with a light flick of the throttle it seems to react well. When I give throttle above 3000 it goes up quickly above and then stays at 4000 for 15-30 seconds. When accelerating I don't get much power at wide open.
What a perfect animation of how that carb works. Slowing playback to .5 makes it much easier to understand. Now I know why my Honda Recon needs the choke pulled 3/4 out to run great for years. Adjust pilot mixture screw or pilot circuit is partially plugged. Great job, Thanks so much, Subscribed.
I've always been able to picture it in my head but this is by far one of the best animations I've ever seen. This is why shimming the main jet seat can increase/richen up afrs in the rpms sooner
When I worked at a bike shop one summer, the mechanics would hook up IV bottles of gas to the carbs. Some bikes had 1, 2, or 4 carbs. They would point the exhaust out the door, and rev the holy beans out of them while doing all the carb adjustments to get the idle, off idle, deceleration, full throttle settings all working in harmony. Your ears play as much of a role as the screwdriver during adjustments. Earplugs a good idea.
Helped me solve my idle problem on my ATV. Been stumped forever. SEEING WHAT SHOULD BE HAPPENING helped my understand what was NOT HAPPENING. The second the choke was closed the ATV would "sneeze" and stall. I cleaned the idle circuit and nothing changed. I started by opening the pilot air screw in quarter turn increments until I was a additional 1.25 turns out from the starting point of 2. This is the first time it has idled right since I bought it used a few years back. Big thanks...seeing the concept of operations helped me understand what I was seeing and hearing and zero in on the cause. YOU THE MAN!
Hi, I just wanted to point out that not all CV carbs have this same throttle vacuum passage that routes through the top cap. If you don't have that extra air tube running thru the top cap (not decelleration enrichment circuit), then you probably have a cylinder shaped slide with a hole in the bottom. High velocity air past that hole causes a vacuum to form above the diamphram and when it builds up it will overpower the spring and the slide will lift up. When you close the throttle the air velocity under the slide slows down, the vacuum above the diaphram reduces and the spring lowers the slide back down.
I've watched more than 100 videos about the working of carburettor.. but this video explained everything without even a single word. now I've understood the working of carburettor and I'll adjust my bike s air screw for best mileage.
Awesome simply awesome explanation. Cleared up the fog in my head as to how this type Of carb works and the sequence with which components work together. Thank-you
Superb job. It should also show the filters that let air in/out of the carb chamber above the fuel and under the rubber diaphragm. If the foam in these filters deteriorates to particles, then the particles ca get into the carb chamber and cause all kinds of trouble.
Thnx to you. Many people though that, when the slide valve opening, the pilot jet and main jet will supply gas together. This is wrong because I have also study with the video from suzuki it self. Thnx to you bro. Kepit up
One of the best video in RU-vid regarding Carburator.Excellent video.Please upload cooling system with thermostat in a Vehicle and more and more..Thanks.
just suggestion..make video focus to ratio oil and air..how to set main jet and pilot jet,.thats too many questions actually in my head but i cant explain to you bcoz i dont know much english.. sorry about my english..thanks and you're very kind.;D
i dont remember actually,either white or blue.. this problem just happen after i install a component ..today when i start the engine, smoke still have and i try to setup air screw ..its work after 5 minute..disappear .thanks a lot dude for helping..;D
My idea was jut to use a pipe T joint with a pipe going into a fuel tank. In the pipe to the T Joint is a piece of carbon felt wick. This wicks fuel up to the pipe T joint where air flows around or though the wick to make a fuel air mix. You can even use a small canister with a gas line and a return with a slow flow fuel pump of 30ml a minute. As long as most of the fuel returns to the tank and the wick is soaked in fuel. and you can have a fixed fuel level for the canister for the wick system. A spark arrestor and air filter are used on the top of the pipe T for the intake a small air filter and the output runs through a spark arrestor.
I don't like CV carbs very much. Everything has to be perfect with the diaphragm and the throttle slide for it to lift perfectly. If there is any sticking on the way up the engine will stutter & there'll be a flat spot (usually IMO between 3000 and 4000 revs), if there;s sticking on the way down, the revs will stay high (until you load the engine). Aftermarket diaphragms seem not to be the same rubber material as the original and maybe don't work too well. Didn't have this hassle with the Dellorto pumpers on my old Guzzi, they just worked!
Have cv on my ktm 950. And notice a flat spot, thanks for explaining how this comes. Also i find gas response is not so quick, engine not so aggressive as I want. Or as aggressive as an 990 injection. A way to make cv carb more aggressive?
a friend of mine has a scooter lml 150. It's running pretty rough. The other day the exhaust went pop and it cut out while riding in second gear when the choke was pushed in (not sure if you should push the choke in mid scoot, i tend to wait for the lights). She started again and although warmed up would only run without the choke pulled out.. She's also slow to react to the throttle. We were thinking dirty fuel, but looking at this i think it could be blocked pipe in the carb. Sorry i know nothing about engines, but i'm interested to figure this one out. I've got the LML 125 and she's running sweet. great diagram, i've replayed it about 10 times and i'm just getting my head around it. You have to watch one piece at a time.. Super informative! well done Athanasio. thanks..
Great explanation, however the diagram never showed the 2-3 additional transition jet holes situated behind the throttle butterfly(idle position) that flows from the pilot circuit, to supply the engine with extra fuel before the mainjet kicks in, also this particular carberator style, does not cover an accelerator pump circuit.
Excellent explanation and animation but notice of carb working ranges: from 0 to 1/4 throttle (jet pilot), from 1/4 to 3/4 throttle (needle jet and jet needle), 3/4-full throttle (main jet) and throttle valve cutaway is missing.
Awesome demo. Only thing it misses is the four tiny holes at the base of the butterfly throttle valve. Can you add that? Also, the air exchange passage for the diaphragm is missing and the choke / enricher passage is a little different on most carbs. Stil, an awesome effort! This fine points show how complex the carb is.
as i renember correctly ... the "pilot mixture screw" adjust: on 4t the amount of fuel drawn from float bowl, on 2t the amount of air added to mixture. On this animation it doesnt regulate any of those two. It should be placed just after "Pilot jet" or "Pilot air jet" (didnt even know that we have "pilot air jet") to control one of those.
The pilot screw regulates either the amount of air or the amount of fuel depending on the model of the carburetor which is identified by it's position on the carburetor body. On models such as mikuni bdst it regulates the amount of mixture because the air & fuel amounts are pre-regulated by the pilot air jet and pilot fuel jet. Also it doesn't matter at all on what kind of engine it is applied on, 2t or 4t. Hope this helps
OMG THANK YOU!!!!!!!!!!!!!!!!!!!!!! Jesus, where was this thing 5 years ago when I had that fucking Vulcan 750. Oh....it was right here....well fuck me.
I just saw this now, let me say thank you very nice explanation. Im doing some carburetor work for the first time, the one thing that took some time to understand is when the throttle is open there is no linkage to the slide its just vacuum that pulls it open?
Zasada działania gaźnika. Gdyby ktoś nie znający języka angielskiego chciał zrozumieć komunikaty do schematów to przedstawiam tłumaczenie na polski. Myślę że najłatwiej skopiować sobie do worda i wydrukować. Z góry przepraszam za ewentualne nieścisłości w tłumaczeniu ale uwagi będą cenne. Carburetor - gaźnik air intake - wlot powietrza combustion chamber - komora spalania throttle valve diaphgram - membrana przepustnicy throttle slide - suwak przepustnicy needle jet - dysza główna (iglicy) jet needle - iglica floater - pływak float value - kowadełko zamykające dopływ paliwa Main jet - dysza główna Pilot jet - dysza wolnych obrotów pilot mixture screw - śruba składu mieszanki butterfly valve - przepustica choke plunger - tłok ssący (ssanie) fuel inlet - wlot paliwa floater raised floater valve closed - pływak podniesiony / pływak zamyka zawór choke plunger pulled - pociągniecie tłoka ssącego (uruchomienie ssania) air sucked through pilot air jet - Powietrze zasysane przez strumień powietrza pilotażowego fuel sucked through pilot air jet - paliwo zasysane przez strumień powietrza pilotażowego choke circuit squirts extra fuel - dławiące obwód tryska paliwo dodatkowe choke plunger closes - zamknięcie ssania throttle rolles on - przepustnica otwiera się butterfly valve open - przepustnica otwiera się throttle vacum passage opens zassanie powietrza z przepustnicy throttle valve diaphgram retracts - wciągany membraną przepustnicy throttle slide rises jet needle rises - iglica podnosi się a strumień powietrza wzrasta air passes throught main intake - powietrze jest głónie zasysane throttle rolled slightly on & off - przepustnica otwiera sie i zamyka. engine idles - silnik pracuje na biegu jałowym throttle rolles on wide open - przepustnica jest szeroko otwarta throttle valve opens wide - to samo throttle valve diaphgram retract more - membrana przepustnicy chowa się więcej
That's fantastic.. Do you have the sound effects of a lean and or rich setting ..that way I know which way to adjust my settings ..to make it better ..
