CARBURETOR TUNING: How it Work?

How Carburetor Adjustment works inside 2-Stroke Carburetor.
Uniquely explained like never before, this video will give you a firm understanding of how this system works on a two stroke carburetor.
Two-stroke carburetor fuel adjusters play a crucial role in controlling the air-fuel mixture to optimize the engine's performance. These adjusters are typically in the form of screws, often labeled as the L (low-speed) and H (high-speed) screws. Here's how they work within the carburetor:
Low-Speed (L) Screw: The low-speed screw controls the air-fuel mixture at idle and low engine speeds. When you turn this screw clockwise (inward), it reduces the flow of fuel, making the mixture leaner. Turning it counterclockwise (outward) increases the fuel flow, making the mixture richer. By adjusting the low-speed screw, you can ensure that the engine idles smoothly and doesn't stall.
High-Speed (H) Screw: The high-speed screw regulates the air-fuel mixture during high-speed operation. Clockwise adjustments lean out the mixture, while counterclockwise adjustments richen it. Proper adjustment of the high-speed screw ensures that the engine runs efficiently and delivers maximum power when needed.
The way these adjusters work is by changing the amount of fuel that can flow through the carburetor jets. Clockwise turns restrict the flow, while counterclockwise turns allow more fuel to pass. This, in turn, alters the ratio of air to fuel, affecting the engine's performance. Proper adjustment of these screws is essential to ensure the engine runs smoothly, avoids damage from running too lean, and doesn't waste fuel by running too rich.
Adjusting these screws can be a bit of a trial-and-error process, and it's typically done while the engine is running. It's important to follow the manufacturer's guidelines and ensure that the adjustments are made carefully to avoid engine damage or inefficiency.
Images in this video are Created and Copyrighted to Craig Kirkman of The Repair Specialist Channel and no reproduction of this content is granted.
Many thanks indeed
Craig Kirkman (Owner and Creator of the 'The Repair Specialist' Channel and it's copyrighted content)
Website: www.therepairspecialistonline...
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#TwoStrokeCarburetor #FuelAdjusters #EngineTuning #CarburetorAdjustment #AirFuelMixture #ChainsawMaintenance #SmallEnginePerformance #HighSpeedScrew #LowSpeedScrew #FuelAdjustment #OptimizeEngine #PowerfulPerformance #CarburetorSynchronization #EngineEfficiency #FuelMixtureControl #TuningCarburetors #MaximizePower #OptimalPerformance #ChainsawRepair #SmallEngineExpertise

[@TheRepairSpecialist]

Hi guys I just wanted to Introduce to you my other Channel "Kirkman's Academy" - which i'm just getting started. It's a go-to channel for simple explanations for hard to grasp subjects such as physics, maths and chemistry etc. Here is the link: www.youtube.com/@kirkmansacademy/videos . Thank you so much for looking, and if these topics interest you then I hope to see you the there. Many thanks indeed. Craig 😊👍

[@brusselstv9213]

This fella is the best explainer I've seen ever. He doesn't get lost talking about himself or how many beers it's going to take you to fix your problem, he just gets on with the explanation, with superb graphics. That's what we need when we have a problem with our implements, because let's face it, generally we're not in a very good mood about the issues, and we don't need a joker. This fella is EXCELLENT.

[@TheRepairSpecialist]

Im so gald you found it useful, i really apreciate comments like this they make my day :) -Craig

[@rodwaller7214]

I'm 65 and have " known" about rich and lean carb adjustments since I was 12 but never really understood them until now. Thank you for taking the time to create the excellent graphics!

[@TheRepairSpecialist]

Thank you so much! I'm happy to hear that the images I made helped you understand the ideas of rich and lean carb changes. After all these years, I'm delighted I could help you comprehend these adjustments because they have a big impact on the effectiveness and performance of engines. It's never too late to learn more about subjects that have long piqued our interest. Thank you for your kind comments about the graphics; I'm delighted they helped you understand the ideas. We appreciate you sharing your experience, and please get in touch if you have any further questions or require clarification on any other subjects. I'm here to help you along the road because learning is a lifelong adventure. Craig

[@dulcamarabuffo]

This is the best and clearest explanation that I have yet to hear on the net. Regards from Weimar, Germany.

[@carlmaro]

Of All the videos I've watched, my chainsaw runs Excellent for the first time in months. Thank you !!

[@WV591]

whole lotta work goes into this man's films to impart knowledge. appreciative TU + sub

[@rudorc]

Just found this channel. And I am so glad it exists. This is another great explanation and it helped me adjust the carb on my ice auger. It’s now running like new!!!

[@USMC-Sniper-0137]

My carbaretta is freshly rebuilt and my carbaretta works perfectly. I love my carbaretta!

[@TheRepairSpecialist]

Brilliant. Well Done! Thank you for sharing. Craig

[@dondavidson4061]

Wow! Finally a video that shows you not only how, but most importantly why carburetors function. Thank you so much. You've made my day!

[@Canoe571]

Very clear and helpful. I will recommend your video to friends who keep asking me to adjust their equipment, saying they cannot figure out what's going on. This should be clear enough for anyone. Thank you, and please keep posting your helpful information.

[@anotherone9460]

Thoroughly explained. Great diagram. Really illustrates what goes on. thank you!

[@brucethompson3762]

I'm in awe of your knowledge and explanations.....You've helped me tremendously. Thanks.

[@OfficialELTB]

Realised the L screw had undone and was causing bog down and stalling. Wound it in and out 1 turn. Boom! Brand new! Awesome. Thanks

[@TheRepairSpecialist]

Brilliant. I'm pleased you found the issue. Thank you for your awesome feedback. Craig

[@cjcampbell4799]

damn bravo! now I have a better understanding of how my carb works and how to hopefully fix this issue on hand

[@tomzeedee]

Thank you..i finally have found a proper explanation of how this works

[@markbutler9046]

That video was excellent! I've been wondering how they do that for years and you just made it so simple start the motor full throttle ..adjust the high at full throttle. Go to idel. Adjust the low. When they sound perfect you're good to go!! Thanks 😊

[@TheRepairSpecialist]

Thank you, Im glad it could helpp :D -Craig

[@grahamrobson998]

Please keep doing your videos they are so HELPFUL. Great Job. Thank you

[@tas0989]

Great vid, simply explained dispelling some myths I was told, thanks

[@Jessealonso4392]

Thank You so much I appreciate it really really really helpful for my goped scooter

[@Painkiler99]

great tutorial I'd call it. With knowing build of 2T carburetor and this video here I know everything which I need to get to work on my chainsaw to make it work properly :D

[@bobbelsekwol]

Just genius. Thanks for your time to put this on KZbin.

[@588158]

Well done! You have no peer when explaining the operation of small engines and carburetors; excellent organisation of your lessons as well as easy to understand detailed illustrations. I'll call you Professor.

[@scottmagoon2984]

Thank you so much for doing this. Extremely helpful and I appreciate the effort you put into this and the explanation. Thank you!!!

[@TheRepairSpecialist]

Thanks so much. Its comments like yours that keep me motivated to continue making videos. Craig

[@brianb5779]

As usual, excellent information and so gratefull for your incredible teaching and knowledge and excellent presentation. I have helped myself and many people from learning from you.

[@jondavidmcnabb]

PHD expert level explanation! Bravo sir!

[@andileigh33]

Simple and to the point Great explanation Thanks

[@soccerrefeducation]

you are good, thank you, you have helped me.

[@jimschiltz5343]

Awesome, as usual, Craig!

[@Kup0p0]

After searching ALL DAY through youtube videos of guys turning screws and saying nothing, trying to get my blower’s carburetor calibrated. This vid told me everything i needed to know and more, thank you so much!

[@TheRepairSpecialist]

Thank you so much, Im so glad this helped :D -Craig

[@pabloenriquegorga4222]

thanks for the video and the explanation

[@pascalennis9123]

Thanks a lot .yesterday i was blindly turning these screws,now i know how to do it right

[@jasonoconnor5228]

Excellent!

[@williamsmithers9490]

Very helpful, got it in just one try.... after dozens of times before your video...... Dat guy good THANKS!

[@mr.derekbresolin9167]

Well done!!!

[@dazalenko4250]

Thank you for taking the time and effort to make this clear informative video, you are a legend sir..from Australia much appreciated.

[@knnproductions8269]

thank you for sharing the knowledge.

[@christopherhoff3724]

Needed a refresher and this was perfect. Thanks!

[@balzak2132]

Thank you for the very basic and simple instructions. Worked perfectly 👌 Many Thanks from Detroit .

[@TheRepairSpecialist]

You're welcome!

[@danielwood6930]

Great explanation!!!!!

[@emersoncampbell2661]

Thanks for thar pertinent information.

[@mikeyrogers8518]

Basic but just what I needed to know,, I believe I was half way right thanks geeza

[@AdventuresandLifestyle]

Brilliant - explains what i'm doing wrong! My machine actually tells me to turn full in then back off H by 3/4 of a turn and L by 1 whole turn. Why did i not get it? Not reading it carefully enough. Your video has out me right. 👍👍👍👊

[@mehrzadrashidkhani3250]

Thank you Sir for sharing your wisdom

[@alanwmann]

Excellent demo, thank you.

[@deniseandmarkfirestine7443]

Very good video straight to the point!

[@jeffreysizer1391]

Best information I have found on here /THANKS, now to try and reset my hedge trimmer

[@TheRepairSpecialist]

Wow thanks for the brilliant feedback. Its comments like yours that really give me the motivation to continue to make more content. Thanks again. Craig

[@jsurges1]

Thanks, Great Explanation!

[@PikeyPirate23]

You keep saying this is a very basic explanation. But I say bravo 👏🏽 I think this is a GREAT explanation for 2 stroke carb tuning. Probably one of the best I've seen. We always take carbs back to factory settings to get a base level and tweek. But i think your explanation for taking both screws out a full turn then tweeking high and low rev screws from there is a great start, especially for beginners. excellent video, thanks for posting.

[@TheRepairSpecialist]

Wow. That is some great feedback. Thank you for your comment. I really appreciate it. Craig 👍

[@markmywords1955]

Great explanation thanks

[@OomptzMusic]

Amazing. Thanks so much

[@MrGG3008]

superb , very helpful

[@robinbebbington7063]

Just the information I needed thanks

[@normanchong5796]

Thanks boss...gud sharing of knowledge...

[@jaxxonbalboa3243]

Very good video. Thanks for your effort!

[@TheRepairSpecialist]

Thank you. I appreciate your nice feedback. Craig

[@logman6656]

Thank you

[@regalbowman3143]

Well explained

[@trevorvairy1504]

To easy thanks for the knowledge

[@hedisoman]

Clear and precise

[@TheRepairSpecialist]

Thank you so much for the nice feedback. I really appreciate it. Craig

[@Raritan7]

Hi Craig, Thanks for the excellent videos. I put on a NEW carb on my Ryobi Trimmer, everything seems to be in order but the engine smokes heavy and does not idle, runs well for a few seconds, if I prime it well before starting, otherwise it would run only if I keep the accelerator trigger pulled. I have bought 2 new carbs which are listed as compatible with my Ryobi 725 R but I cannot make it work. Have adjusted the L and H screws step wise, maxed out on RPM adjuster screw but it behaved the same with both new carbs. Working on it for several weeks, very frustrated now. Any guidance will be appreciated.

[@chrismots6479]

I have an rc boat that is powered by a 26cc 2 stroke engine. I have quite some problems with the acceleration and top speed. The rpm screw is tuned in so i think i need to work in those 2 screws. Thanks for posting the video!

[@johnwagner8465]

Great video...thank you..very informative

[@georgepoirier9014]

Good explanation.

[@brockfiger]

Thank you so much

[@charliecrowe6606]

Made the mirky clear. Thanks

[@carstanje]

Best carb HL explanation ever! Thanks!

[@TheRepairSpecialist]

Thank you so much for your nice feedback. It's comments like yours that motivate me to continue making these videos. Craig 😀👍

[@CrystalliteKK]

Thank you very much for clearing the H and L screw concepts. I just needed to know if EGT can be used to determine weather the mixture is right?

[@china1013]

You're amazing. Subbed!!!

[@blksheepdogtonyg.6453]

You need more subscribers and likes your a repair specialist genius 👍👍👍👍👀

[@peterfletcher8411]

This is exactly what I was needing to learn. Thankyou so much for this video. Very well explained.

[@TheRepairSpecialist]

Thank you for your feedback I really appreciate it. Craig 👍

[@kashmirdhirkot7877]

Well explains.

[@vaninec]

this a best video Thanks!

[@jerrid19]

Great work. Thank you

[@TheRepairSpecialist]

Thank you so much for the nice feedback. I really appreciate it. Craig

[@rameshpram1444]

Thank you brother

[@TheRepairSpecialist]

Thank you for your feedback I really appreciate it. Craig 👍

[@Jim-ie6uf]

Excellent

[@TheRepairSpecialist]

jim st. Thank you for your comment. 👍

[@g.m_styling3571]

Great vid!! Just waiting for my air filter to dry and ill be trying this!

[@TheRepairSpecialist]

Thank you so much for the nice feedback. I really appreciate it. Craig

[@Sebi076]

Very nice explanation, thank you

[@TheRepairSpecialist]

You are welcome!

[@waynecartwright9478]

Make exact same adjustments when changing fuel mixture ratio's as the fine adjustment can matter also.....great video break down....thanks.....

[@afrikagreen6303]

thanks friend,,,

[@oscara.8176]

Tks sir.

[@TheRepairSpecialist]

Oscar A. Thank you for your comment I appreciate it thanks 👍

[@snewp90]

when i start my stihl weed eater 2 stroke it goes wide open full throttle but the trigger wire looks fine. would the carburetor settings cause this at all?

[@jlangley317]

Crude explanation and actually makes it hard to understand. For example the low speed screw should be inletting on the engine side of the butterfly. The way he has this drawn wouldn't work at all and doesn't make sense. The low speed needle works similar to the choke in that it is subject to higher vacuum when the throttle butterfly is closed. its purpose is to supply fuel to the engine to idle and the idle screw on the engine adjusts the amount of air allowed past the butterfly. Once the throttle is opened, the vacuum on the idle jet is greatly reduced and flows minimal amount of fuel as the engine switches over to run off the main/high speed jet. Idle adjustment is important because it does add a small amount of fuel to the high speed running conditions, it also plays a role in the efficiency of transitioning to the high speed jet. On small equipment i recommend starting at factory settings, reving the engine up to high speed and tuning the carb, then drop down to idle and adjust the idle jet. Once you dial in the idle jet, then rev back up to high speed and fine tune again. Once you've adjusted the high speed again allow to idle and fine tune if necessary and then test throttle response by opening the throttle quickly and verifying if you have a smooth rev or if you have a bog. If you have a bog then you will have to fine tune a bit further unit you find a place where the unit runs smooth at idle and high speed without bogging on acceleration.

[@herberttv4349]

my God so helpful thanks a lot fom Philippines

[@7Toki777]

Hi! Would you explain, what is the meaning of fuel tank pressure test? Thx! Have a nice day!

[@CS-en5xz]

So if i have a carb that floods unless the low is off, would that be a diaphragm problem? When i adjust the low out and it warms up it floods

[@tttttttt8482]

Thank you. 👍👍. Very clear explanation. Do you have any video about throttle needle adjustments ?

[@robbsmind2209]

Thanks! What if there is also an idle screw? Is there a baseline setting as well? That is, do I start with the H and L turned all the way clockwise and backed off one full turn and same with the idle screw?

[@WillBilly.]

Idle screw usually just hold the throttle a bit down using the screw, so not a part of the carb really

[@alexanderb7197]

Would this have something to do with a 2stroke cutting off when idling?

[@xx3868]

HELP- what could be causing a now and then fuel starvation?? already completely pulled apart and cleaned everything and checked idle bores using light in the bore and did all this many times and it runs and has all the power up down up down and i can adj more or less fuel with the screws so theres enough supplied by the pump. Then after 15 mins, it starves although the fuel line you can see fuel there and the pivot height i have tried around level with the casting as its a WA-110. How can it be not starving at all then starving? Carefully cleaned the needle jet bore and replaced all the parts and spring and everything. Done cars carbs before and never had one shut down after it starts. I can tell its starvation as a quick pull on the choke saves it and the plug is bone dry. Pulse hole has to be ok as the clear fuel line is full of fuel when it stops.. I notice the well lip for the 3 holes idle area where the welsh cap presses into has slight damage on the sides so could fuel be leaving there when its hot and thus the idle holes starving? have put a ton of nail polish on this and replaced with fresh cap and will try again after a day to allow dry. Originally i thought it might be the needle well sticking after carb gets hot and thus starving but thats got plenty of play and it was flooding before when the old spring was too weak so thers plenty of flow from the pump and the spark plug was soaked. so fixed that and it ran for a hour fine, no stops, but this time its back to its fuel starvation thing again?? I wonder if its the chinese kit i put in it but why would it work perfectly for a while then not?? Unless theres a hairline crack somewhere bleeding off air or fuel but why would it work for some time before failing? totally lost on this one!! either it works and flowing or not. it cant do both. compression is down but once again it runs like a rocket even with a long line and the screws are about 1-1/2 for L and up to 2-3 for H as i run a heavy line but will run on 1 H when no line so main jet is working too but that wouldnt effect bog down at idle. Something is being missed on this one. tons of fuel, up down acceleration smooth as anything then idle starvation?? and even the vent valve i checked but it ran for an hour before after i did kit so that cant be it and fuel line full so carb has fuel just starving suddenly. Very strange one this one.. Vaporisation blockage inside? after a time operating. Using only reg gas, no methanol as parts and nail polish would be dissolved. I can get it started again and maybe get it going, so woulds causing partial starvation?

[@user-zp4yh1ng5z]

hi i have a 26 cc engine i want to know the numbers of turns for HS and LS screws for better performance Thank you

[@geraldbasford6713]

greetings from the NAPA VALLEY CALIF GREAT VIDEO

[@JOEZEP54]

Great diagram & explanation on the carburetors function. This is a must for anyone just starting to get into small engines. Again great job. The reason I am here today is that I have a "dump find" chainsaw & while waiting for some parts I mixed up the 2 fuel mixture screws 😟 & was looking for some way to tell which is which. Any tip on this? Stay safe, Joe Z

[@TheRepairSpecialist]

Firstly, thank you for your nice feedback. Secondly, in the past I have done exactly what you have done. More than once! So, take a look at each screw. Assuming they are not noticeably different in threads and thread size to match the holes, then see if they are different lengths. If so, then bingo!! All I have done in the past is to take a torch and look down each of the screw holes on the carburetor. Doing this I have identified the deepest hole and the shallowest hole. I have then match the screw length with the hole depth. All I can say is that this has worked for me in the past, but I suppose it all depends on the type of saw you have found and whether or not the screws are designed with varying lengths. This is the only possible remedy I can give you at this point. I hope it works for you. Thanks Craig

[@JOEZEP54]

@@TheRepairSpecialist You are very welcome and thank you for getting back to me with this tip. I will let you know how it goes.

[@abdulkarim2699]

Thank you teacher...for teaching us knowledge. May the teacher be blessed by God who made this world

[@TheRepairSpecialist]

I'm really sorry but I don't understand. Thank you for taking the time to comment though. I appreciate it. Craig

[@abdulkarim2699]

@@TheRepairSpecialist I'm from Malaysia. Thank you teacher

[@SuperJiggawhat]

I have a 23 cc engine that I just purchased. I was running running a walbro 990 but it wouldn't stay idle, so I swapped it for a walbro 668 carb thinking something was wrong with the carb but I'm still having the same issues. Does anybody have any advice on what could be going wrong. I looked up all the stock settings for the needles and idle screws bit still nothing.

[@daweapon2210]

Thanks bro

[@TheRepairSpecialist]

No problem. Thanks, Craig

[@magicone9327]

You have any vid on walbro carb on 30 cc craftsman 4 stroke trimmer. I noticed the carb on the two stroke and the 4 stroke are the same except the 4 stroke has a spring used with the pump diaphram whers the two stroke doesn't use a spring. Why?

[@neilrobertgrayson]

I have learned a lot from your videos on 2 stroke carbs particularly about the pulse line fuel pump given i am used to a seperate pjmp. I realise you make a living by doing this but what would really help is a video with audio of you tuning these. It's what quantifies running right which eludes many. I am used to more cylinders and have always though my two stroke gear even new to be lumpy. Just my point of view of course.

[@TheRepairSpecialist]

Neil Grayson. First of all thank you for your comment, and yes, I agree, I will make a video showing me tuning up a two stroke (with audio). I will get round to that as soon as I have completed the project I’m currently working on. Many thanks for the inspiration 😃👍

[@neilrobertgrayson]

TheRepairSpecialist that would be excellent. As I said I am very familiar with car engine and yes I am old but your videos have taught me so much about the anatomy of 2 stroke parts. Truly enlightening and I look forward to when you have the time to make the follow on.

[@setnthahookwitstubbs297]

Very well explain!!!! Thank u i understand. Now!!!!! 😎😎😎

[@TheRepairSpecialist]

You're welcome!

[@mad2strokeguy694]

Can you fit this carburetor on a brush cutter

[@linzitazim]

Hi, what does it mean if the top end is breaking up under wide open throttle? The low end is fine and seems pretty crisp. 2 stroke rc. Thanks for uoloading the video!

[@jsimm4587]

Pretty basic video and you couldn’t explain it any better thanks !