Inside A Motorcycle Carburetor - Idle Circuit | MC Garage

Pubblicato il 10 apr 2019
Does your motorcycle idle funky or not at all? There can be several causes for this, but the most common and first thing you should troubleshoot or tune is your carburetor. Today on MC Garage we are going to talk about the idle circuit of a carburetor.
With modern fuel injection a stable idle, no matter the conditions, is a given, but if you have a carburetor in your ride, things could be less consistent. Environmental factors such as altitude and temperature can require you to make some adjustments to your carb.
And of course the darn thing could just be full of crud from sitting too long or from not being serviced for a long time. Ari did a killer video on how to clean a carb a few years ago, we’ve included the link to learn all the ins and outs of cleaning below. For this video we are continuing on proper adjustments of all the systems of the carburetor.
How To Clean A Motorcycle Carburetor | MC Garage:
Inside A Motorcycle Carburetor - Float Bowl Height | MC Garage:
Understanding The Parts Of A Motorcycle Carburetor - MC Garage:
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  • didnt you say the baseline settings backwards it 1.5 for air and 2.0 for fuel

  • This video is among the most helpful explainations on the internet.

  • Dude, you look and move like an animated South Park character. It's uncanny.

  • hard to have a warm bike if it wont start

  • can anyone tell me the functions that those plastic tubes (the clear ones that connect to the carburetor) . Thank You

  • Well done - clear explained!

  • my two stroke ke100 idles fine possibly on the rich side. It doesn't really bog in neutral. It only bogs under load if I open the throttle more than 50% . If i gradually open it its fine.

  • This is an absolutely well explained video about carbs. I own a 1994 Suzuki RF600R and just from this video alone I've discovered my bike is running too rich! Exactly like he said, the bike would rev up normally but dip way below the normal idle. It's gonna take a day or too to get it right. Thank you Justin and MC Garage! You guys are life savers.

  • in india usually lower segment bikes till 200 cc uses Carburator and some higher uptill 500cc too and i own a 125 cc Scooter which has the carburator with Electronic choke. Tuning that At the beginner level(me) was not perfect and i learned a lot. seeing this video i can compare and revise the procedure to get better understanding of the sound the engine produces. My other 110 CC scooter had a traditional, no electronic nonsense Carburator which in recent month giving me a problem where its overflow oriface at top and bottom one completely ejecting fuel whenever the engine is cranked. thats problem was a nightmare to solve untill i got a float needle valve to replace with the old one and the problem stopped. thats how amazing and nightmarish the Carburators are. Thanks for the Content.

  • The best info videos on motorcycle,please make a video on throttle body cleaning on cbr

  • Will you post some video of how to tune multi-cylinnder carburetors?

  • Is it the same to use the choke to start a cold engine as is to keep open the throttle for a while? (Same revs sound for the same time)

    • @Ariel Cabrera Foix Yup. That's what it's there for!

    • @Ari Henning So using the choke would be finally more efficient to start a cold engine and heat it up. Thank you for your reply!

    • It is not. The choke either restricts airflow upstream the butterfly/throttle piston to create additional suction that draws more fuel into the carb throat, OR flipping the choke activates an entirely separate "enrichener" circuit that feeds more fuel through dedicated passages. In both scenarios, the choke supplies additional fuel into the existing closed-throttle airflow to enrichen the mixture.

  • I have been waiting for this video since 1885

  • Perfect timing, idle hanging at the moment.

  • SOMEONE PLEASE ANSWER....!! My motorcycle's RPM increases when it is kept for a minute to arround 2k RPM from 1.4K...and after riding it for 4-5 mins it's idle RPM reaches to 3 - 3.5k RPM....there is no problem for throttle cable.... The motorcycle is a japanese machine of 150CC....(Honda Unicorn) Due to this problem the mileage has reduced. Did not inspected the choke wire...A mechanic said the carburetor need to be changed...because the mixing screws are jammed... WHAT TO DO???

    • @Triumphrider let me check...Thanks anyways

    • Check the choke, if it's on or stuck that will cause exactly what you describe. And find another mechanic who's not out to sell you a carb.

  • Carburettors? Okay I agree quite a lot of motorcyclists want to know about them and use them, which even includes me, but even this large group is tiny compared to the vast majority of bikers who are all on fuel injection nowadays.. let's talk about that guys, carb videos can be an additional bonus but don't focus on it at the very first instant..

  • Mehh

  • I’d check for vacuum leaks before pulling the carb.

  • His prompter is below the camera which makes him look lazy when speaking

    • Hrishikesh Sabde it's time to unsubscribe brother, this channel sucks now

  • Yeah, I'll stick to fuel injected bikes.

  • Carburetor are a work of art and I'm loving to work with it as it is simple and no electronics failure will happen to this bad boy. If you want more power from your bike just slap on a bigger carburetor with the right jetting and your bike are already good to go. Fuel injection on the other hand need a Dyno tuning which never be good on your wallet and all the upgrade parts are expensive as hell.

  • Thanks for the examples. Although I didn't really hear a sputter in the rich video.

  • Bring back Henning

    • Both of you get the *FUCK* out lol

    • Ravi Kumar unsubscribe brother, I'm about to, this channel sucks now

  • Great video. Who tosses their carb into the air?

  • Heyy. I love mc garage. Was off for some time. Can anyone tell me. Wheres ari?

    • @Ari Henning thx for answer. Cheers m8

    • Zack and I are both making videos for Motor Trend now. You can see our shows (Throttle Out, Throttle Out Garage, and Throttle Out Commute) at

  • Great info. I had a hard time watching the video, because I was focused on the shadows from your glasses on your face. Maybe change the angle of the lights

    • Unsubscribe brother, this channel sucks now

    • Christ Tom you must be a hard man to please... "Yeah honey, you were hot an all, but unfortunately the shadows your thighs made when you were riding me looked a bit like Paul McCartney's face. Not all the time honey, I don't want you to get a complex, but, you know, some of the time"....

  • Anyone ever used the self adjusting carbs? I've always been intrigued, but never wants to drop the money on them.

  • Thanks. Great series. But can you drop the disco beat?

  • Justin looks like the middle of a "On a scale of Ari Henning to Lemmy from Revzilla"

  • Can't stand this guy. In addition he sounds and acts bored. Seems like he sees this content as work and not as his love

    • @David T. I've told one person to cut out the same repetitive comment that has zero merit and zero chance of happening. Hardly the situation that you portray. All I said to C Bat here is that this work is my love. And my life.

    • Unsubscribe brother, it's what I'm about to do: their little moderator is threatening to ban people if they give any criticism; this channel has lost its way

    • Yup: they were like "quick get a frumpy guy with a beard to read the cue cards, that'll be relatable to the viewers " 😐😒

    • I can assure you it's quite the opposite.

  • Carb. are deads

  • ok so i have a question. I got a 250cc 2 cilinders and 2 carbs. And why does it seed in the "manual" that i need to turn carb no.1: 2.5 turns and carb no.2: 1.5 turns? The manual is a old copy and do not know if it is the original bit the the bike is a 74". And no aftermarket filter or tuning all is stock. And its 2 stroke

    • @Chris#55 but i do not have a V engine. I have a inline 2 engine. The bike is a moto guzzi ts 250. i'm hoping that the mixtures are right i do not want to destroy the engine.

    • This is common for V configuration engines. Usually the cylinder in the back gets a slightly richer tuning, than the front cylinder. That's due to the higher temperatures of the rear cylinder because it doesn't get as much cooling as the cylinder in front.

  • Great info. Keep up the good work!

  • Videos about F-CR Carb´s please!!!! Thanks and keep going with good work!!

  • Great content and good presentation. But..miss you Ari Henning.

    • @shroomingnewman 3 I not sure if he resigned or retired. Maybe he decided on doing other stuff. He sent his farewell remarks though.

    • @Jas Ride Motovlog what happened to him?

    • Ari's awesome! Miss him too!

  • Great tips! bike is idling on the high side, so perfect timing with this vid.

  • How do I adjust the carburetor for high altitude roads?

    • Higher altitude means the air is thinner. If you go from low to high altitude. The bike will run richer than normal. So you need to lesser the fuel intake. That will normalise the engine.

  • i like how you explained the tuning of the carbs by listening to the bike. but how does it work with 4 carbs on an inline 4 engine? i mean, when 3 carbs are perfectly tuned, but one is slightly or a bit more than slightly off, will i be able to hear it? i also wouldnt mind a more complex explanation of the system, the cycles etc, maybe even by using some sketches on a whiteboard like some other channels do ;) anyways, keep up the good work

    • We will be doing a video about multiple carbs in this series. hang tight.

    • You'd need to do an idle drop. Instead of listening, you use the tach to watch the rpms as you make adjustments. Turn them all out a quarter turn in sequence until the rpms stop rising. Then tighten the first screw until you see a 50 rpm drop. Go back out a quarter turn, then move on to the second screw. It's tricky but satisfying

  • Why does cold engine require richer mixture?

    • @AussieGuy There's also the fact that the engine (intake tract, piston crown, combustion chamber, cylinder walls, etc) are cool and therefore the fuel is less likely to vaporize and may even condense on surfaces. The solution is to supply more fuel to ensure sufficient combustion until the engine warms up.

    • Ivan Arifin exactly

    • @AussieGuy by "more air" you mean denser air?

    • Because when an engine is cold, so is the air, and when air is cold there is more air therefore needing more fuel in order to start up

  • What could be the issue when the carburettor dumps fuel (in the intake) when the bike is off? After many tries to start it, when the fuel evaporates it runs fine. It has an automatic, electronic choke.

    • Check out my previous video on the float. It should help with what you've got going on.

    • Check your float valve. Sometimes it's misaligned or the rubber seal has worn out and need to be replace.

    • @Socrates Nicolaou A slight chance yeah, but I'd change the floatvalve for sure when youre in there.

    • @Socrates Nicolaou Check if float is not cracked or punctured, doesnt take in gas and if it operates freely. Also would be good idea to replace float needle valve.

    • @Jens Eskildsen The bike runs totally fine when it's warmed up. Could adjusting the float height be the solution?

  • Mine seems to be too rich, like you said, it's slugish and then it dips bellow idle, it does turn off some times. Ugh. Thanks for the video, amazing info.

  • I’m always amazed a carburetor works at all.

  • 480p Are you fuc***g kidding me

  • We want ari Henning as host not this old uncle

    • @David T. Sorry to see you go. Can't please everyone.

    • Unsubscribe brother it's what I'm about to do: check out motorcycleMD he's legit

    • Justin Dawes your content is slacking and you're threatening to ban a viewer? 🤔 Please don't stress yourself, I'll start by hitting the unsubscribe 🙄🖕

    • I don't see you producing content. Justin's doing a great job; screw off.

    • One more time man. Ban hammer at the ready.

  • What is the value of the idle RPM of any bike? Is it 1100 RPM? My bike's needle drops below idle 1100 RPM but it automatically shuts down at 500 RPM if I rotate the screw and bring the needle at 500 RPM. What RPM value should the bike automatically shut down when it is in neutral or within how much time and RPM value should the bike automatically shut down in neutral? Please show the screw turns of resetting idle mixture of carburettor.

    • @tentacleslap Ok.

    • @Nathaniel Peter It doesn't really matter. Pretty much anything will stall at 500 rpm

    • @tentacleslap My another question is what RPM value should the bike shut down if we decrease the RPM needle by turning screw? My bike shuts down at 500 RPM if I bring the needle down at 500 RPM but previously it used to shut down when the needle comes at 800 RPM.

    • 900-1000 rpm is optimal, but if she runs rough or stalls at those speeds, 1100 is fine

  • make an video for inline 4 carns

    • Its the same principle, just multiplied by 4, and you need to syncronize them. Theres plenty of videos of that.

    • You mean *carbs??

  • 0:45 0:55 No links found in the description 🤔🤔🤔

  • Gas gas

  • First

  • oh