The MYSTERIES of CARBURETOR tuning EXPLAINED!

Why even mess with carburetors? Because it's fun and carbs are actually pretty simple, elegant devices of great flexibility. Technical Editor Kevin Cameron has seen his share of carburetors and spent a whole lot of time thinking about how they work. Editor-in-Chief Mark Hoyer recently got a 1995 Ducati 900SS running again with a pair of factory Mikunis. It can be done! Listen now to find out how.
Read Kevin Cameron's detailed carburetor tuning story: www.cycleworld.com/story/bike...
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[@randytolle6706]

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

[@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.

[@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.

[@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.

[@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.

[@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.

[@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?!

[@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.

[@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

[@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.

[@hillarylevenworth8824]

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

[@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.

[@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.

[@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.

[@johnhooper8057]

Hollow ground gunsmith screw drivers work excellent for jets!

[@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

[@mountainmandale1587]

I love geeking out on subjects like this.

[@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.

[@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 !

[@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.

[@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

[@seller559]

Great video 👍

[@user-jn3hm4fx7p]

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

[@markbrown-us4xe]

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

[@hokogan]

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

[@lesmontgomery6498]

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

[@alanwarner8489]

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

[@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

[@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

[@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.

[@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.

[@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.

[@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.

[@RandallSoong-pp7ih]

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

[@dereksmith5019]

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

[@70sport37]

I remember Yamaha big gas annalyzers that nobody used .

[@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

[@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.

[@DrSmile81]

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

[@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…..

[@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.

[@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.

[@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. 🫵😁

[@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

[@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.

[@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