The MYSTERIES of CARBURETOR tuning EXPLAINED!

[@randytolle6706]

70 Datsun Pickup had a glass plate cover for the float bowl with a float level line. I thought that was so cool.

[@classiccycleconnection9334]

‘72 Datsun 510 Sedan. Thinking about that carb still gets me frustrated.

[@drgallup]

I spent the first 35 years of my motorcycling career tuning and trying to hop up bikes with carbs. Meanwhile, I had spent 30 years of my professional engineering career designing port fuel injectors. I was so happy to get my first fuel injected bike, a 2016 Triumph 1050 Speed Triple. With the push of a key I could remap the fuel delivery, ignition timing, correct the speedometer and a host of other things. Bliss. I don't miss carbs at all and if I'm feeling nostalgic I still have carbureted lawn mowers, leaf blowers, chain saws and outboard motors demanding my attention.

[@tieredlabsllc5728]

I remember well the carb hassle on inline 4s, airheads, etc, and how great EFI was at relieving that pain. Much as I was done with carbs in the 90s, these days I am really enjoying my carbed Harleys. Single carb; so simple, so easy to access. I can tune them with my eyes closed. F the EPA/Euro and their insanely lean factory EFI.

[@hughjanus3378]

Ha haah. This comment rings a bell with me. I have updated an old engine control system to full computer control. Professional Engineer as well and I was astounded at the capacity of the modern systems. Everything is controllable. The poor old Engineers had to work around problems with vacuum systems and solenoid valves and clunky measuring instruments and so on…. did a commendable job….but if they were offered a modern programmable microprocessor to do the hard work…..they would grab it with both hands and you’d never get it back !!!😂😂

[@rupertbollywood1190]

MORE Kev Cameron. There's never enough Kev Cameron. More gold nuggets of actual information per minute than any other motorcycle KZbin guy. You're lucky he doesn't ditch CW and start his own channel.

[@josephreisinger33]

Had a nabor who, as a kid, raced Go-Karts and 45 years ago taught me how to tune carbs. Thank you, gentlemen. 4 bringing me back to the 70s. Tuning was a pain in the ass but when you get it right, you feel like a KING AMONG MEER MEN.

[@dougrobinson8602]

As Kevin said, the needle height adjustment is pretty coarse. You can shim the needle to get half or even quarter step adjustment. I did that on my Polaris triple snowmobile, and the results were well worth it. It was a bit sensitive to altitude and temperature, but when you were in the sweet spot, it was pure joy.

[@nickrider5220]

Love carbs because I'm old and have learned how to tune them ! I like to do all my sevicing and tuning, I don't have the means to work on the complicated electronically controlled systems on recent bikes. Great content again guys 🍻

[@blipco5]

Bingo, and generally speaking, once you find the sweet spot you never have to monkey around with them again outside of buying quality gas.

[@danmanthe9335]

Want to help me jet mine after moving?!

[@danmanthe9335]

Want to help me rejet mine after moving up in elevation?!

[@ClassicTrialsChannel]

My 45 years old Beamish Suzuki 250 trials bikes carb is set up beautifully. She sounds so crisp and people are always commenting how nice she sounds on the pipe . I had my first bike aged 13 and I'm now 62. Ive only ever had bikes with carbs.

[@mountainmandale1587]

I love geeking out on subjects like this.

[@billdennis2993]

Thanks CW for excellent relevant content and production of your video. You mentioned support of MC carburetors. I would like to mention the FCR Kehien carburetor which is still utilized on many single cylinder DS and off road competition models from 90's to mid 2010's. Kehien, Sudco and all have not made available the mid body orings and seals which would require replacement with a new carb for $1ks which is avoided by the great people @ All balls racing have produced and marketed a $20 kit to return these carbs to produce IMHO the most precise metering device known to man. YMMV Stay Healthy and keep up the great work. Long Live PW's 4360s.

[@TheDuckofDoom.]

The carb on my airplane allows me to lean or enrich during flight to match local temperature and altitude, with a simple knob that changes the height of a jet needle. Not exactly the jet/needle setup on a bike but similar concept. Though power changes don't need to be super snappy. Fine tuning the mixture can be done either by prop RPM (power)if using a fixed pitch prop, exhaust gas temperture sensors, or just listening to the engine. Max rich for low altitude takeoff and climb, max RPM for high altitude takeoff (slightly rich of peak EGT); and for cruise adjust to the lean side lean side of peak EGT or lean until rough running then enrichen just until smooth.

[@hillarylevenworth8824]

As usual, when you two editors team up, technical gold!

[@vintagetrikesandquads4012]

I love the simplicity of my carbureted dirt bikes and quads. They are so easy and inexpensive to rejet. I also have some fuel injected machines, and remapping them requires an new ecu like the Vortex, computer program, etc. It's a real pain--and expensive.

[@dogpaw775]

talking about Amal carb's[ don't be afraid of 'tuning' cutaway height between two stock cutaway sizes. If on full throttle you put on the choke and speed picks up; you need a karger main. If at top chat you ease the throttle slightly and the motor feels smoother and is pulling still, smaller main is needed. Guess discussion of the Wal Philips fuel injector was outside the scope of this vid' ;D

[@LBrawn]

i hand grind old screwdrivers too, especially if they still have good handles. You can buy the screwdriver Mark made, it is called a cabinet tip (made for fitting into holes the same diameter as the head.

[@deanmsimpson]

Thank-you for sharing that information 👍

[@btrader3625]

Its nice that this guy has taken time away from his band the Black Keys to play word smith. Keep up the great work.

[@Sladep123]

You guys are both full of great knowledge, humility and have a great way of making it feel like we are part of the conversation. Always enjoy and learning and being entertained as well. Thanks and looking forward to all the future episodes.

[@flexjay87]

I got my first Honda mini bike in 1971, and i am still riding a much newer Honda, but with 4 Carbs. I have found that i love the performance of Constant Velocity Carbs. I store my bikes with fuel stabilizer, and really never have a problem with post Winter start up.

[@wheelie63]

have read columns by these men for years , but have never heard them speak, so this was extra interesting.........i discovered the use of guitar strings to clean jets years ago, cool to hear that Mark also does this. thx guys.

[@guyhayes5288]

Sudco folded probably 3 days before he gave them a shout out. RIP Sudco, thanks for your many years of flat slide joys.

[@cycleworld]

We were bummed to hear the news, for sure. Such a great, knowledgeable supplier of quality parts.

[@lesmontgomery6498]

I have found that the low speed screw is upstream of the discharge it is usually an air screw. Righty richy lefty leany. If downstream usually fuel screw right leany etc. Just finishing up a set of Kehins 76 cb 400 f. All screws damaged jis mark. Widest change I made T M 400 Suzuki Dr gordon Blair pipe QUB design 7500 rpm. Had to reduce by 4 full mains throttle became a rheostat would out start most 750 s on a flat track

[@ORflycaster]

Thank you gentlemen for another enjoyable hour of education. Seeing a new video release is a highlight of my week. I appreciate the link to Kevin’s article because I just pulled the four carb assembly off my Royal Star for cleaning and rebuild kits. I’ve never disassembled a carburetor before, so this will be learning to swim at the deep end of the pool.

[@gregsidel3557]

I want to thank you guys for the video and I am one of those guys that has two or three cards of jets your video is very informing thank you

[@wdhewson]

I have great respect for the modern Japanese carburetor. With correct valve timing, valve clearances, correct ignition timing, and correct carb set up, my Japanese Fours have spark plugs as consistent as my port fuel injected Honda and Toyota cars. And the bikes are air cooled versus the thermostated liquid cooling of the cars.

[@lesmontgomery6498]

Some old small Hondas had fixed pilot jets. I used to heat them with a micro torch so chemical cleaner would work

[@copperaudio9664]

JIS with a set of Vessel Ball Grip Penetration Drivers is heaven. And they have a #2 impact as well.

[@micyclesport]

This is a great topic, thank you Mark and Kevin, you guys rock! I enjoy my carbureted toys and love getting the tune dialed in so satisfying!! A lot of the newer FI bikes I've ridden feel quite snappy compared to there carb'd versions

[@deanmsimpson]

Thst was excellent! Thank-you 👍. A wealth of knowledge. Fascinating and very useful. Thank-you.

[@RabbitInAHumanWoild]

This is a wonderful introduction to carb tuning and I thank both of you very much. I currently have a Honda 305 Superhawk (CB77) that has just seen a long rebuilding process and should be on the road soon. I have a lot of experience with road bikes but none with racing bikes so some of the jargon, which I assume to be racing jargon, is unknown to me and as a result I am sure I have missed some important information. For example, what does "riding the needle" mean? I don't think this presentation is intended for specialists but it misses some us who are merely knowledgeable and have gaps in our knowledge that racing tuning specialists would have. Some subtitles or explanations in the dialogue would be very helpful. Thanks again.

[@LBrawn]

outstanding channel guys,,,especially the 2 stroke topics.

[@paulblouin6955]

You mentioned G50 Matchless. 1973 IOM. Peter Williams G50 splits betwen two Suzuki 500 twins in 500 Premier. 40s vs 70s. Pretty cool beans.

[@basilwatson1]

Today, on my Royal enfield ( points ignition/carb) Today, I was at the DGR ride and forgot to turn the ignition off Zero battery bike still started first kick still got me through the day Try that with an ECU that need 12v If you want a lambo fine ! but even if I leave my bike for years, I can flick the bowl off and clean in less than 5 min !

[@greetsromo841]

Thanks Guys . Keep up the good work.

[@thekrutchinator]

Very good educators!

[@johnhooper8057]

Hollow ground gunsmith screw drivers work excellent for jets!

[@TomStratis]

Great stuff. As much as I thought Iknew ( forgot) I learned something today. Japanese industrial standard ! Who knew. How many " Phillips" screws have I destroyed on my many Japanese motorcycles I owned over the years. I'M EMBARRASSED

[@rotarolla1]

If you can't get a stubborn screw out use a quality pair of side cutters, the extra torque from gripping the outside of the screw will usually get it loose.

[@paulblouin6955]

Ha ha. I left the petcocks open on my hot rod Atlas. Kicked it over in the morning, and it started. A 360 degree plane of gasoline sprayed out around the copper head gasket. The crank case was pretty full!

[@hokogan]

I have some impending tuning to do on an ‘87 TW200 and an ‘82 XV920R, so this was timely.

[@whatspeedlimits]

You get the thumbs up for the JIS comment. JIS work in Phillips....Phillips don't work in JIS.

[@alanwarner8489]

Same with Posi-drive: lines between the shoulders, fits like a que ball in a snooker table.

[@collyernicholasjohn]

Thanks for your podcast guys, great information. My two cents: on Mikunis or other Japanese carb do yourself a favour and get JIS screwdrivers! Phillips heads just screw up the carbs for you and everyone else following. Oh 32:38 you just said that 😂😂😂

[@alanwarner8489]

Pothole in turn 8 was lethal when Willow Springs had an absentee owner but Cal Club and Jim Russell School didn't mind.

[@seller559]

Great video 👍

[@jfess1911]

I would appreciate a quick comment on why changing the exhaust system, especially to a lower restriction one, often affects fuel mixtures and requires changes to the carb. I only have a very vague idea that it changes the signal going to the carb. Thank you

[@paulblouin6955]

A nice valve adjustment often pulls carbs back to sinchronization

[@BlackwaterAquatics]

Do you find that opening up the airflow requires a smaller jet because the increase airflow creates a lower pressure?

[@markbrown-us4xe]

I start with paper and pen. Take notes and it's easy to go back. Air filter and plug reading.

[@888jackflash]

Currently wrestling with a bank of Bandit 1200 carbs...trying to nail down a slight gurgle off Idle when hot. I'll get it, but Yes.. Carb tuning is a mystical art

[@paulblouin6955]

XS650. Not very fast but pretty durable, my limited experience. I remember helping my buddy remove and reinstsĺ the head on a kickstart version. The elastomer carb mounts were pretty cracked.

[@daniel-vm3qn]

The two basic rules you need to understand about carburetors I did not hear are 1- the Venturi effect 2- pressure differences. You can't talk carbs before you know this two. Kevin Cameron is a "god" when it comes to moto tech, I'm surprised he didn't start with that.

[@rupertbollywood1190]

I think they discussed between themselves and decided to keep it simple. Many people who are completely new but interested get stymied by carbs.

[@simonmears1726]

I brought ttr125 new hard starting pilot jet tiny opened air box fitted Yamaha factory exhaust bigger main cant adjust needle height fuel screw has brass plug bottom of carb u can drill out bit of hassle but big improvement started cold no choke it pulled like a school boy 😅

[@patrickarmitageWWW]

You didn't even mention vacuum leaks. Dirt is dirt you can see it. But you cant see a vacuum leak. My first new bike only ran on full choke roughly and didn't idle at all. The fuel idle screw did nothing at all. Until it fell out and then the engine actually idled and sounded somewhat happy. It was breathing out strong smell of gas from that idle screw opening. I replaced the whole carburetor with a new one and it runs fine. I eventually found that the original carburetor (also new), had a massive vacuum leak from rubber teat where the throttle cable enters. I just wrapped masking tape on the top and base of that rubber section. The engine ran perfectly after that. It was a You All PZ27 roundslide. A copy of the Keihin PZ26.

[@GeneCash]

It's funny... I tried adding the bookmark for the carb tuning story, and I already had it. Edit: After 30 years, I'm so happy to have fuel injection, a Power Commander, and a laptop. I never want to have to clean a brace of carbs ever again.

[@patclarke3323]

many many years ago, my Dad told me that 99% of your carb issues can be fixed with the ignition. All these years later, I have found little reason to disagree :-)

[@alanwarner8489]

Found a bad condenser would go full rich with throttle before it even started misfiring. You could see it looking down the venturi.

brilliant

[@paulblouin6955]

A Commando with a standard flyweight advancer gets worn in the slots at about 1500 to 1700 RPM. I've pulled those out and filed the notches out of the slot. I still have a Commando with points. The other has an old Boyer. The advance curve on the Boyer is so slow. Not useful. Im going to another one now. Hope it is better.

[@TheDuckofDoom.]

Now the two barrel setup on the Yamaha XT350 will make you want to set the whole thing on fire just accessing the relevent parts, let alone actually diagnosing and adjusting. Especially the last few years of production which were complying with more gov regulations both in the stock default tune and purposely hindering tunability.

[@ejgrant5191]

Sad....Timing of this broadcast....RIP Sudco USA closed in May 2024.....Jets R Us I think is a decent alternative.....The price of a PWK or FCR these days....Pretty INSANE! Carbs also add intake charge cooling giving better power.

[@keithburns5707]

As of the Fourth of July 2024 I looked them up on the Internet and they’re open right now bud check your fax again.

[@RandallSoong-pp7ih]

I know fuel injection has its advantages, but I just love ❤️ carbs

[@paolopaletti2738]

ciao,è un vero peccato non sia possibile la traduzione.

[@robertlamontweber5865]

I always used the end of a wooden match stick

[@rgmcmichael]

Dear Kevin and Mark- Question. Have a 2000 GSF1200 with Stock carbs. Bike runs great except when I pull in the clutch the RPM’s rise to 3K. I can sometime blip the throttle and the idle will go back done to 1,200. Or if I shut the bike off and then restart it it idles fine again. Any ideas? I have smaller non stock needles, second clip down and different jets compliments of Dale Walker.

[@YouCantSawSawdust]

They NEVER answer from the "comments" section.

[@simonmears1726]

When u work on bike carbies u get too know is it lean is it too Rich had air in ad fuel plug check s give u a reading rich or lean but if hills Less air will become rich wind in fuel screw if 4 stroke if 2 stroke air screw in is rich out is lean more air nothing like a well tuned carby nice and crisp no bog no hesitation a real art but fun to learn 😮

[@bren42069]

I was gonna pick up a jis screwdriver for my 40 year old Suzuki but I got to looking at it and all the screws were already mangled by a Phillips. So 🤷‍♀️ if you can't beat em join em

[@70sport37]

I remember Yamaha big gas annalyzers that nobody used .

[@firstielasty1162]

I have one in my shed, from the yamaha dealer I worked at for years. It mostly collected dust there, now it is holding up a stack of tires...so it has uses. I still have a cylinder of the calibration Gas. It was mostly for idle setup- I imagine it would work fine for big throttle openings, but, without a way to load the engine, it is hard to measure for the main jet, especially with CV carbs. Dynamometers weren't so common then. I'm not sure it would react fast enough to use the now common inertia dyno with it.. You used that thing after synchronization with the "YICS stick". Remember that? Maybe it was YCIS. It is not the same as "carb sticks", which I prefer analog gauges to. No mercury needed, although the mercury is interesting. ( no warnings from uptight californians needed )

[@dereksmith5019]

I never liked the carburation on the first generation XS650 . The bike always want to go slower or faster and no in-between .

[@shoominati23]

People after argue what period of cars / bikes was.. Well I say to them - NOW! Right NOW! THe availability of OEM and reproduction parts for classics has never been better, heck there are people that are making toolroom copies of classic cars and bikes if you have the scratch

[@donniebaker5984]

Carburetors are no mystery at all if you have a 6th grade level of Education in science.... But today unfortunately most no one who attended Public Schools have a sixth grade level in science. Simply because that is one of the the subject on a very long list that's not taught in school at all as I'm just now finding out since all public schools were deregulated in 1985.... That is the year President Ronald Reagan ended Public Education in the United States... When you take away the basic knowledge that science gives you you have eliminated any way possible to understand the basic knowledge and logic of how a carburetor works. Now we are in a world of electronic fuel injection. Again it is entirely based on simple facts and knowledge of grade school science. So to try to understand the difference between a carburetor and a electronic fuel injector will be impossible without any types of standard logic that goes with basic science 101.... This has to do with a large part of our federal government dumbing down Society.

[@jarikinnunen1718]

When you have CVK type carb, things are not simple. Some of them work like train toilet, but some are magic, and you not get them work.

[@tedecker3792]

A bristle from a stiff brush is much better for opening blocked jet than metal wire. But never do it ( wink)

[@Pompomgrenade]

What's significant about carburetors is all the new two stroke dirt bikes. That are a few injected... Have a short coming. If they were carbureted, they could be tuned in ways that somehow fuel injection hasn't attained.😂

[@YouCantSawSawdust]

Your comment is getting "likes", but I know you are being sarcastic, so your humour is not lost on EVERONE. 🫵😁

[@ridervfr2798]

Ethanol free gas is the only way to go. I have a 90 degree screw driver for balancing purposes.

[@EnlightenedSavage]

Ethanol free is actually hard to come by. Check out testing that is out there. Most E free fuel contains as much as 5% ethanol.

[@markpavletich747]

If only someone would produce a similar replacement o ring for the road race version of the FCR series…..

[@DrSmile81]

Best experience with carbs is always when the choke is frozen...😁🙃

[@LBrawn]

99% of carburated 2 stroke owners would ride the bike with bad jetting and still enjoy it. As they say 'ignorance is bliss. 🤫

[@Pompomgrenade]

I go ride, I come home & stuff the bike in the garage.. 3 days later at the garage smells like gas😂.... Before restarting, I turn on the fuel and tip the bike to the side until the overflow has made a puddle 😂.. poor man science.. either it starts or the idle jet is clogged... I'm still running the same jets I shoved in there in 2003😅 cheap bastards settle for good enough

[@donaldolin7219]

Carbs……no problem here. Grew up with them, tuned them. I’m not an engineer……..and I don’t have to be one to understand them.

[@cpuuk]

At least with carbs when you open the throttle fully you get max charge into the engine, which is more than can said for modern injected engines ¬_¬

[@Surestick88]

Carbs are more of an obstruction to airflow than fuel injection _if_ fuel injection is designed for power, not emissions.

[@connor3288]

It's all in the tuning. I think the electronic throttles are a big reason, they can be programmed when stock to not open the hrottle 100% in certain gears or rpm. The other thing with, at least stock, efi bikes, is how abrupt they are on/off throttle. Most of them probably cut fuel under engine braking because of the epa. Then when you gas it it has a slight jerk. Have heard it can be tuned out.

[@donaldolin7219]

F fuel injection.

[@robertcrosser5946]

I hate points they're so depressing