HOW DOES A CARBURETOR WORK?

welcome back you guys today we're talking about carburetors and how this little simple spray bottle will help you understand how the carburetor actually works if you're new to the channel make sure you do a spinning freaking drop kick onto this subscribe button because our whole goal here at rolling ranch is to make your life easier whether it be through these videos or our products so let's get started so if you understand how this works that's step one now let me show you how this corresponds to the carburetor so I'm going to show you really quick this is the same type of carburetor that we're gonna be looking at here's our intake boot right the carburetor plugged right into the engine and if you notice the air filter is plugged in there here is our choke let me come around the side here and here it is looking at the side the motor here's your fan not all motorcycles and scooters will have the same I just want to give you a visual of what we're working with this is your carburetor now that you kind of got a visual and you know how the carburetor plugs in this is your intake fuel comes out of here that it's mixed perfectly and goes into your engine your air cleaner plugs in on this side gas enters in through this little nipple which has a cap on it which 10 this is your gas hose that plugs in gas goes in this nipple and into that what this is called the float Bowl goes into the global I'm opening this up it's not screwed in there's three screws that I've already pre loosened and pulled off just like that so again this isn't upside down or anything this is right the correct way it needs to be gas will fill up in this float Bowl what tells the gas to stop flowing so it doesn't overflow out of here that'd be your flow this guy it works just like a flapper in a toilet or a float in a toilet now I'm gonna flip it upside down remember that it sits to up just upright like this I flip it upside down like this I've got the flow now I can unscrew this screw here you're think of a toilet how a toilet works most people know how that works so here is the flow I'm going to pull that out when I pull that out there is a what you call a needle a needle and this is the seat that it sits in so that little needle right there goes in that hole which is this nipple remember it goes this way actually this is the bottom gas goes in and through this hole and starts filling up the float Bowl once that's full this needle will stop the fuel flow to adjust that float height you have this little tab it could be different on different carburetors but that's what this tab is for I can move it up or down to adjust the flow height 99.9% of the time you're not going to adjust that at all so if I mentioned the words needle and seat that's the needle and see now a lot of times if your carburetor is dirty and you get a chunk of something in there this is like put your foot in the door the needle and seat get stuck it can't seal and you just have gas all over the floor so now that you guys understand how the fuel delivery works this is the float this is the needle that kills the flow some carburetors you can remove the seat not this one so here's our spray bottle just like I explained when you pump it you get suction up the hose so imagine your piston in your engine going up and down up and down right on and then you've got this hooked up this carburetor now that you have that suction coming right through the carburetor just like the spray nozzle you're gonna have Windex fluid whatever come through this spray bottle up the straw here's our carburetor same things happening here's our straw right here there's two of them you've got one right here that's a lot bigger than this one right here so of course the one with the smaller hole just you suck through a really big straw it's gonna be harder to suck through then it would be a smaller straw you're always gonna get fluid gasoline in this case go to come through a smaller straw than a bigger straw so here we've got our main jet that's what they call this this is like the straw inside not this one this one right here this is like the straw inside the Windex bottle and then you have this one - this right here is your main jet this is good for 3000 rpm and above and this is our pilot jet so now that you guys understand how that works the the pressure comes through here fuel comes up through the straw the needle and seat control the end the float control the fuel level so when you're at an idle that's going through this really tiny pilot circuit or pilot jet or idle jet they all have different names or there's like three different names we'll call this the pilot jet it's got a super teeny hole I don't know if you're gonna see that like needle and thread size hole that's your pilot jet if your carburetor sits around with bad gas in it gas is like milk it curdles up and then it gets stuck inside this pilot jet port or idle jet same thing and then you have no flow you have no flow the bikes not gonna idle so there's that then I'm gonna set that aside so our pilot jet okay so you're sitting here idling it's just idling you've got this butterfly valve which is your throttle just hooks up to your throttle cable think about as I pull this like this it's opening up that butterfly valve in there well if you're idling you're not it you're not pulling the throttle at all it's just idling at 1,000 rpm or less and it's going through this really tiny hole known as the pilot jet and it's idling now if I wanted to start giving a little bit gas a little bit of gas one as I give it gas this diaphragm back here if you notice that you grab a screwdriver see that goes up and down just like this I lift it up it comes back down that works on sure that's gonna smooth out the transition from this pilot jet to this thicker hose just like our Windex bottle known as the main jet which I can unscrew here is our main jet let me set this down let's make things see that whole lot bigger bigger than a needle and thread size hole which plugs into a emulsion tube here it's kind of like the straw in the spray bottle I'll set that aside so that's how that's how the carburetor delivers gas in order to get more gas or suction through here I would open the butterfly valve remember the Pistons going up and down up and down up and down so if I open this more air more suction is going to be drawn through here and this is known as the jet needle that needle comes pokes right through the middle of our main jet and emulsion tube and this as that's happening this needle jet or diaphragm is going up and down to smooth out the transition between the pilot jet and the main jet so let me open the top of this carburetor so you guys don't get confused this is the choke right here and I just pulled that out there's some screws in there and this choke moves up and down just like that electronically some of them you pull with the cable to open up a more air okay so now I'm gonna pull this off figure that's the diaphragm cap and then notice there's a spring that's what that's how it was returning when I push that up now if you have a rip in your diaphragm here can give a little pull and or hold it up to light to see then you're not going to get any suction and this needle or diaphragm is not going to go up and down smoothly or at all symptoms of that would be you can't rev it up at all so no fuel actually kick comes in contact up here because remember our float and everything's down here so I'm just gonna pull that out and I want to show you that needle that needle if I flip it upside down and pull the needle out here it is if you notice that c-clip attached to the needle there's there's a bunch of different groups let's see there's 1 2 3 4 5 grooves and it's right in the middle now this is a tune this is a way to tune by moving this clip up or down you can tune the needle remember that's the transition that's like the mid-range throttle between the main jet and the pilot jet alright back to the pilot circuit when somebody refers to an air fuel mixture screw this right here is a fuel screw the reason I know that is because it's closer remember this is our air filter side of the carburetor this is our engine side of the carburetor and always almost always the fuel screw is going to be on the engine side if this screw was somehow built in over on this side that would be an air screw the other way to identify that is you see that oh ring come off see how pointy that is if they're really pointy like that it's definitely a fuel screw if it's a rounded corner a rounded tip it's gonna be an air screw so I'll set that aside what does the air fuel screw do so if you notice I don't know if you can see this but this is where it screws in right here you can kind of see the little Junction go into our little pilot circuit right here so what you're doing as you're loosening that screw out you're increasing more fuel through this pilot circuit known as the pilot jet or idle jet because if you screw it in then it's going to do the opposite every carburetors gonna have a spec basically if you're at just to make things simple if you're at sea level your elevation is a sea level then screw this in lightly seat it don't ever crank this one down if you do you're gonna have big problems lightly seat it and back it out to turns if you're a mile above sea level do two and a half turns that's just quick and easy but if you get in your manual it'll tell you exactly where it's set from factory if it says two and a half turns that means lightly seated and back it out two and a half turns so we have a pretty bare carburetor at this point so now let me go back so you can identify all of the parts keep in mind this is called the throttle body and there's one more thing I need to go over with but if I screw this down but I can just install it for now but as I pull the throttle you know your cables attach this I pull the throttle do you see that little lever moving up and down well I'll go around just like this let me flip the back see that it's pushing down just right there if I do that there's gonna be gas in this float and it's gonna spray right out of here just like the Windex bottle just like the Windex bottle so that's known as an accelerator pump so if I get if I give it full throttle like that you're gonna get a little bit of spray and it's gonna spray directly into our intake just like this I have the flow bowl off see if I squeeze just like that you got gas it's gonna come straight through here up this little channel here out this nozzle that's your accelerator pump most of the time they're not adjustable and the reason why you have that is for you can use that for cold starts pump it Pump It pump it when you pump it it's spring spring spring and then you're gonna start easier and the other thing is when you give it a bunch of gas let's just get just needs that extra amount of fuel to give that acceleration so that it doesn't lean out which would be not enough fuel okay let's quickly go over this so you understand a hundred percent the pilot jet which looks like this some of them look different it's got a tiny tiny little hole if your bike won't idle and hat and it only runs on the choke you need to clean this guy this is good for 1,000 or p.m. and below about a quarter throttle no more than that that's what this circuit is so if you're having any type of idling issues or anything a quarter throttle or less take a look at this pilot jet here's our air fuel screw the reason why it says air fuel because some carburetors have bear some carburetors have fuel screws this here is a fuel screw to see how point it is and notice there's an o-ring when I took it out there's an o-ring and a washer unburn underneath it so if I was to screw it in here there's gonna be a nice seal the other thing to note I'll recap is notice that this fuel screw this is a fuel screw because it close to the engine side that's how we know that and then if it was towards the air filter side it would be an air screw and it would have that blunt end just like this so in a nutshell the range is half a turn out from lightly seated to three and a half turns out from lightly seated if I have this set a half a turn then that means that you know I'm resisting this the fuel so that means the fuel is we've got way too much fuel because I'm I'm really cranked in almost all the way in I need to go one size smaller on our pilot jet here's our pilot jet and that's an and that is the number 34 these normally going to step increments so that's it the next size is going to be a 36 so I can go a little bit larger or a little bit smaller so when somebody says reject your carburetor that's what that means this is the pilot or idle jet you can reget it by going a little bit less fuel well that does is changes the diameter of this tiny little hole and the opposite effect if I back this out to three and a half turns I'm pretty much maxing out the fuel which means I need to go a little bit larger on this pilot jet and this is a transition from basically 1,000 rpm to 4,000 rpm 3000rpm there's kind of a range there so here's our main jet this is going to be for 3000 rpm and above and I'm screwing it into the emulsion tube you notice there is a number right on the top of that that's because that's the size of that jet that's what that is you got the pilot jet it's idling on the pilot jet you've got the main jet that's 3000 rpm and above and the transition to help a smooth transition from the pilot jet to the main jet is gonna be this needle and here's our choke you're gonna see these this is an automatic one if you notice there's a plug so basically when you first start it your choke is going to open up that air it's just gonna open this needle up basically it's gonna pull it back and allow more air in remember that circuit from up here going back down to your pilot and basically it's gonna what the colder the engine is the more fuel it's gonna need so that's the reason why you have a choke you always want to make sure this is really clean whenever you clean your carburetor if you need to and then you remember what the needle and seat is this is like the flapper valve and a toilet that's the needle the seat is fixed in the carburetor here and then here's our float to adjust the float you're gonna move this pin here up or down generally you do not want to do that don't do that unless you know for sure needs to just be adjusted then there's a hinge or a pin that slides through then you've got your diaphragm make sure there's no rips and then remember your needle gets dropped down through just like that and then you have the little cap so the spring could ride right on top of it and then spring and then dropping it down back into your carburetor you gotta line that up and there's always gonna be like a little spot for the diaphragm so that it fits in there perfectly and then you've got the cap you want to make so dang sure that once this is on there say I've screwed this down already this needle and diaphragm see how slow that goes didn't even hear it if I take this off there is no suction at all and it'll just flop I don't have a spring in there but that's you want to make sure that you don't pinch this in any way when you install it so here's our carburetor I kind of have it facing like same way it's a little bit different than in the illustration so based on how far we open up our throttle we've got zero which would be an idle all the way up to you know quarter throttle half 3/4 and full throttle let me show you so if you're on if you're on the pilot jet just hear this one at an idle you're gonna be at the thickest part of the cone it's running a 100% on that pilot system which consists of the pilot jet that I showed you as you give it gas like half throttle you're on that jet kneel basically that that diaphragm here that's the transition from pilot then you got the diaphragm or needle jet all the way up to main jet these are the three circuits that you're really going to be focusing on there are some other things on here but I'm not going confuse you all of your jetting and your tuning is gonna be basically this pilot and that's going to be your needle that's the transition all the way up to main jet if you need if you have problems in any of these areas you can refer back to this diagram it makes things really really easy I know I know this gets confusing but you can always go back and and watch the video again if you don't understand but let's talk about AFR ranges AFR means air fuel ratio this is the modern way to tune a carburetor you notice here this is a sensor it's called a wideband o2 sensor what this does is this screws into your exhaust system and this sense sensor will sniff your exhaust and spit out a number which will come out on this gauge which range from basically this is your range you're going to go this is your operating range for running so as as your bike is running this gauge is going to show a number stoical is chemically ideal this is like if you have a car from the factory or a motorcycle or whatever this is going to be set normally to 14.7 that's good way it's going to run perfect across the board now if you were at more like eleven point five which is more fuel you're gonna run even better like that's for performance so when you send like your ECU out or have somebody read yet for performance there their number is anywhere from eleven point five to thirteen point three for performance now if you're just want fuel economy then you're gonna be like sixteen point five now this number as you ride you're gonna adjust your carburetor on all of the circuits that I talked to you about so that that number is right where you want it to be based on what your interest is performance economy or just chemically ideal alright now that you know what AFR ranges are I can explain rich condition and lean condition rich means too much fuel lean is not enough fuel so if anybody refers to those terms now you know what they mean lean or rich a rich condition if you go to give it a bunch of gas that smells like fuel right out the exhaust it's really lethargic and it's it's just not it's not going you just blow it's gonna be rich symptoms city pipe or if you pull your spark plug out and look at the tip it's gonna be really black and city and it's gonna really smell like feel you could even smell the spark plug it's gonna be that's a rich condition now lean your engine is gonna be really hot if you have a temperature gauge gonna be hotter than normal you're going to get detonation or pinging you could look that up online to get a sound you'll hear the detonation the pinging in the engine and then you're just gonna get a lot of hesitation like didn't as you give it gas so those are the kind of the two the biggest way to tell is you'll just pull that plug it'll be really black and that'll be a rich condition and if it's really white then you're a lean condition I didn't go over everything I went over the basics I don't want to confuse you guys a lot just you can totally get by with what I just taught you and you're going to want to pick up a nice little jet kit come with a bunch of different jets so you can tune that carburetor because you've got to deal with the main jet circuit the pilot jet circuit and then you can move that needle around to for the transition and remember if you have a rough idle you can always adjust that air fuel screw there is a sneaky sneaky little trick I could show you if you don't want to do a jet kit then you can always do a jet drill kit you these are hobby drills a bunch of them are missing but see I can drill out one of the Jets and then if it go too big then I could solder the jet closed and drill it out again it's a little way to be a little bit more precise than jetting or if you're limited on jets thought I'd throw that in there all right you guys well that in a nutshell is carburetor tuning I do have a really good write-up that I did on the website I'll post it down in the description it'll help you even more especially for high altitude jetting like say if you're at sea level of Californian you come to Colorado you're gonna want to reject your carburetor so go ahead and head over there give this video a thumbs up I appreciate you guys watching and we'll see in the next video [Music]

Channel: Rolling Wrench

Views: 47,348

Keywords: how does a carburetor work, how carburetor works, scooter carburetor, how does a carburetor work on a 2 stroke, scooter carburetor cleaning, carburetor tuning 4 stroke, carburetor tuning 2 stroke, automotive, how it works, carburetor, how do carburetors work, carbs, how do carbs work, carburetors explained, carbs explained, vs, fuel injection, air fuel mix, carburetor tuning, how carbs work, how carburetors work, engine tuning, carb tuning, afr ratio, jets, jetting, fix

Id: Q9Gh80q8D-s

Length: 24min 21sec (1461 seconds)

Published: Sun Mar 17 2019