Carburetor Adjusting: Idle Drop Procedure

In this video I wanted to go over one super important carburetor adjusting technique we call the Idle Drop procedure. This type of adjustment is one I would consider to be the final touch or "tune" you need to put on the carb to REALLY dial it in.
This type of adjustment really works wonders for those of you who throw on common bolt on upgrades like exhaust, hi-flow air filters and more. Many people think that re-jetting is always required when you change those type of parts out but you would be surprised at how well this works!
Carburetor tuning is quickly becoming a lost art but I hope this helps to shed some light on the topic and helps you dial in your motorcycles carb!
Enjoy!
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[@marksullivan9179]

I have no idea who would thumbs down this video, all of Cody‘s videos how been very Informative and he’s a great mechanic what can you say good job Cody keep up the good work

[@Synthstain]

Their idle adjustment screw was probably at 4 turns out and it fell out. Then they felt personally attacked by Cody

[@patgraeme775]

Or they were looking for a simple answer to a simple question, not 19:00 minutes of talking for a 90 second explanation?

[@joewee]

7:20 is where the procedure actually starts if you want to skip the informational intro

[@JeremyBorumComposer]

Yes! Skip the first 7:20 for sure. That's where the video actually starts. Helpful though, thank you.

[@dylan51racing]

10 minutes in he actually explains what you’re looking for

[@MrMrsregor]

thank you !

[@Mcvanderospickersen]

I just dropped you $50...because YOU ROCK! Your videos are excellent and they save me a pile of money. I'd rather give it to you than some shop I don't trust. Go Honda!

[@waynegacyii9010]

Fighting idle drop myself after changing pilot jets, great explanation.

[@saatanakettu7514]

Damn dude i bought my first Honda motorcycle like a week ago and you have been really big help already. Thanks!

[@marckublicki3153]

Thank you, I learned a lot from this video. As a hobbyist, I enjoy learning as much as possible. Again, thank you for a very instructional video.

[@jacobgriffin2636]

This video is the sole reason my honda shadow is now tuned correctly after a stage 3 rejet and intake upgrade. Thank you.

[@flatbmw4784]

This video helped me tune my Grom with a 212cc big bore race engine. Thanks for sharing your knowledge. VB represent!

[@doyle873]

Thanks for posting the link for the straight slot adjuster tool, Cody!

[@akbarhussain1767]

Hi there Cody,thank you again for an Excellent tuition about carburetor tuning, (Idle Drop Procedure) Excellently Explained, thank you friend 😊😊😊

[@garyconstant4234]

You’ve saved the day again Cody 👍 I’ve got a virago 535 that needs the fuel/air mixture adjusting where someone before me has basically played with them and now the back cylinder is too rich as it’s blowing a bit of black smoke out from letting too much fuel in. Do you do a video of a twin cylinder bike. I watched your one doing the four cylinder tune up as I done my zephyr after watching it. Keep up these awesome videos fellas as they are absolutely awesome. Greetings from England

[@reubentan4737]

Thanks so much! Best explanation on procedural steps. My Honda CG 125 running too lean( blueing of pipes). Now I know how to tune the old school carb!

[@normanbonnette295]

In January of 2022 I purchased a 2007 Honda Reflex and since that time I have been attempting to get it to run a bit better. I've installed a B face off a Big Ruckus and Dr. Pulley sliders. These helped the Flex drop the dreaded lag and gave it much better performance, however I couldn't get the lag from my throttle. I would twist the thing and it would just stay, as I let her back it would pick up and go. I bought a additional tack tried every suggestion in the service manual, read every bit of information I could find on the web to no avail. Today I found this sight by accident watched it three times, went out to the garage and gave it a try. I installed a new Denso plug, let her warm up, put this procedure into practice buttoned up the doors and took her out on a 60 mile test run. Finally, it's perfect, no crap, perfect. It will now run 82 MPH cruise all day at 70, not hesitate to climb a hill, and smoothly clime from a dead stop to 50 without skipping a beat. My deepest appreciation, I have subscribed and will continue to look for those elusive answers Cody.

[@Oldtimerider]

You have a great way of explaining things! Thanks much.

[@madcat4563]

Was abit difficult to understand for a newbie, byt the practical example made it crysral clear. Thank yoy so much, your videos have been a huge help.

[@radekfedyk4588]

Thanks for that. Will be doing my carbs tomorrow using this procedure. It will be fun as it’s a Magna VF500 with 4 carbs. Thanks again!

[@BenjaminCrooks]

I'm an aircraft mechanic and your advice helped to tune a 1994 Kawasaki ZX11 with 4 carburetors, thanks again. Very valuable information!!!

[@lewistibbitts3894]

Does this process work the same as a single carburetor? I mean do you do one at a time or turn each one the same each time?

[@SoapyHB]

Excellent video. Thanks for that. You have a very good teaching technique. Much appreciated.

[@sharonsharon2604]

One if the few best instructors on KZbin in his field!

[@roberttosa2560]

Excellent video. Really helpful. Thanks Cody.

[@ryanred5724]

Wait...I just realized that is the procedure explained in my Honda's shop manual, but it is explained much more vaguely than in this video so thank you for clarifying things out

[@laynetravis]

Finally!i found a video to understand how to adjust my carb

[@jarrodfarley905]

Thanks man well informed easy to understand

[@user-ot1dv6ri4f]

You do all the good things

[@adallen3]

Happy New Year Cody! Man your tips and advice are always top notch. I love the technical explanation. Thank You my friend.

[@TheMotorcycleMD]

Thanks man! That is super encouraging to hear 🤗

[@mfc392]

Great video... thanks Cody.

[@WheelsofSteal]

Cody!! Great video but what did you do with the idle screw now. Turn it back up afterwards? Thanks.

[@darrengann7777]

Dude thank you for the video. I think you and Giovanni Ribisi sound alot alike and I'm a big fan of his too

[@BardoReyes]

Genius man!!! Thank you for the help

[@MotoMango]

Anything to avoid rejetting! xD Nice work mate.

[@shees221]

Dude your awesome. Explained it pretty well. 👍

[@baazigaj9125]

Good stuff Cody..cheers

[@zrkn1]

Excellent info and explanation. Thank You

[@TheMotorcycleMD]

Thanks man!

[@sydneybaumgartner9801]

Thanks ! going to try this on my KLR

[@joeblow3939]

Cody, Would liked to have heard it return back to idle after you did the adjustment. 👍👍

[@jayrenner211]

I am about to get a free 1986 Radian - sight unseen. I am sure I will be doing this procedure soon. Thanks for the video.

[@leeclynes4712]

I have a zephry 550 b and I would like to say thanks for this as living in the highlands/Scotland the air going into my bike can be a pest as it’s different air pressure sometimes I have found so al give it a try cheers

[@iDSMB1]

nice and clean tutorial.thx

[@stealhty1]

Hi, Honda CB400// bog down on acceleration ,left side spark plug was getting black, I did your adjusment and closed the idle screw 1/2 turn ,and the bike now runs like a charm

[@tebarker92]

Really enjoying your videos. As said below a video of this procedure on a V twin would be really helpful as it’s confusing to know on how to make the adjustments to one cylinder when there’s another cylinder beating in the background.

[@koricaDHNajbrziStakor]

imagine quad carbs

[@DavoMelendez]

good explanation

[@How2Wrench]

I'm only 8 min in and NICE WORK BUD!

[@kurtteixeira]

Sub’d . Great info

[@edwardmalfroid946]

Great job!

[@TheMotorcycleMD]

Thanks man!

[@jessy6464]

Was also wondering how its done on a 4 carb like my v30 magna! I removed the baffles and would like to try this to see if i can get it at a sweet spot!

[@rashellyohn5128]

I just shot you a request for this very vid. oh another of your vids. Thank you for your brain power. She is my best friend and now she sings...

[@tamusbaby]

fkn GREAT vid!!! Thank You !!!!!! Exactly what I needed !!!

[@hotdogdog4740]

First off I love your videos, you’re pretty unrivaled as far as raw knowledge and understanding of these bikes on KZbin. I’m actually building a 1972 cb350, with the stock keihin carbs. I’m at the near end of the build but having difficulty with the carb tuning, any suggestions on jet sizes? The stock idle jet is #35, main is #68, secondary is #105. I just switched over to k&n pod filters btw and upgraded to a #35 idle, #75 main and 115 secondary. Haven’t tried starting her up yet as I’m in Michigan and it’s currently pretty cold out but I’ll give her a kick soon.

[@gam0t0]

Thanks great vid, so did you bring the idle back up a bit after the procedure or leave it way down in the 500-600 range for normal riding

[@CoolKillkennyCat]

Hey mate, great content as usual. Just wondering what I should start looking at if I can set my bike up to idle fine and the after it gets warm the idle sits high either indefinitely or for a good 30 seconds before returning to normal?

[@MOTOPILOT6]

Having this issue after changing the throttle tube on my Africa Twin and had to loosen the adjuster at the carb to get the cables into the new tube. Throttle is 95% good but returns slow. And it sticks when I turn the bars at all. Hoping your fix does the trick.

[@sleezymechanic]

Hey man! I cleaned the carbs on my vt1100 and it seems to run great already! But when fine tuning I hardly get an idle raise when I turn the fuel screws counterclockwise. Do you think I should put one size higher jets? Or maybe just the pilot jet? It seems to run really good at 60.

[@gester236]

Hi Cody, can you perform the idle drop procedure on an inline 4?

[@taledarkside]

that is an important thing to remember is the changes don't happen right away love to see goldwing repair videos, like the 1500 in the back

[@petev.9357]

Hey Cody, hope you see this. I know video is old. Would LOVE to see this on your 750 Nighthawk. Pilot screw clearance HAS to be tightest on this bike with carbs in place.

[@willethridge5202]

The BEST!!!!

[@norbertogonzalez534]

perfect thanks

[@Isaa5500]

Guys I hope you can help!! I have a 2001 Yamaha FZS 1000 and the start-up on the choke is really difficult it cuts out 3 to 4 times I have to Revit up really high in order for the idle to continue running otherwise it stalls four to five times. When I initially start with the choke the idling is 3000 and slowly decreases and then stalls after 30 seconds of running !! The Choke plunger works perfectly. Any idea why this is happening thanks

[@OFFICIALxGAMER]

Good stuff man. Just got my 78 cb750 running and driving. Set timing. Still has old points after sitting for years.. I rebuilt the carbs. Running air pods and 128 main jets. It's kinda hard to start. And hesitates at low rpms mid range is great. I did not rebuild the accelerator pump. Kit did not come with it. Any help would be great. Thanks.

[@Bh-dq3pd]

I was wondering if you could help me. My kz440 starts then dies immediately. I cleaned the carbs and still

[@zacharyryan_art]

Thanks for the videos man! First time doing any of this stuff and working with a Yamaha XJ500. Took it all apart cleaned the carbs, put some bigger mains, (cuz of pods), and finally got it started today for a bit, but needed to have the choke open, and think I flooded it cuz it wouldn't start after about the 4th time I shut off and started it. Also it was slowly getting back to idle like you said that was doing. Too lean? One last thing... Was wanting to subscribe to your website, but I know it's mostly for Honda stuff, is it worth it if I'm working with stuff other than hondas?

[@VOLVOb18ft]

I have rebuilt the carb for a suzuki gt125. I set the float to spec, set idle air screw to spec (one turn from fully closed) but my issue is that the engine does not idle at all. It keeps dying unless i stay above 1500 rpm. How am I supposed to set Idle since I have to keep engine runing high? Any idea?

[@jake_break9185]

so Cody, what do i do if my sweet spot is only maybe half a turn out, and one carb idles up with mix screw all the way in. what do i need to replace or adjust?

[@dustinanderson7285]

Much cool, much class, great videos.

[@gester236]

Can we have an Idle procedure drop on inline 4?

[@lordofbasement]

I would love to see if you do the idle drop procedure on a GL1500. Because i have a GL1500 and struggle a little bit. Two carbs which are bad to get to. Mine runs perfekt after i cleaned the carbs (Idle circuit was clogged) but i setted the mixture screws to the position which honda recommends (i think 2 5/8). She reacts to throttle inputs perfect and gets to idle immediately but on coldstarts with choke she is sewing if i adjust the choke to about 1500rpm. What can i do against that behaviour?

[@brianb5779]

Is there any chance you happen to know what the hole size is on a 06 honda crf50f for the pilot jet? Forums are all over the place on hole size..if i were to guess i wana say .012" but guessing doesnt help. Thank you if you could respond..

[@cri8tor]

Know this tutorial goes over the basics and its well done, but please consider a follow up tutorial on syncing a set of duel carbs such as the ones on a Honda Shadow 750. Had to remove welch plugs to expose my needle screws. No bueno. Cheers

[@screamfingers]

Ive got an honda mc22 beautiful 250cc inline 4 screamer from the 90s. I believe it has a fuel screw and its at 1.5 turns out. Is this acceptable? Thanks for your videos they are a big help.

[@peterpoggi]

I see you have a VTX1300 in the background. I'm tuning my 2005 1300C after replacing a bad petcock. Does my A/F mix screw work the same way as the one you demonstrated? Meaning, turning it in reduces fuel, turning it out increases fuel?

[@darktimefreak1678]

Is that the same on in line four ?! i have a bandit and the idle is like lower than normal .. it's dropping probably the fuel air is too rich ?! should i do same while the bike is running and warmed up ?!

[@dalt7666]

So when you finished. Did you turn the idle screw back in, to its original idle speed?

[@drewdrew1000]

Very informative thanks. Do you have any experience with a Gunson colortune? It’s a clear spark plug, that you can view the colour of the combustion flame with and adjust accordingly

[@ouch2925]

The get in the hole part destroyed me. I love this guy lmao

[@foxyeee]

I'm new to carbs and am working with dual carbs freshly cleaned. When working with dual carbs do you just do this procedure to both carbs one at a time? Or do I work them both at the same time?

[@mdgardner70]

My 2004 250 Ninja runs great, but decelerating to a stop doesn’t want to maintain idle. Honestly can’t remember the last time I cleaned the carbs, but it hasn’t been driven much in the past several years. I did store it with shitty fuel that had separated but got the tank and carbs drained and good fuel back in. Think there is some varnish still in the carbs?

[@cheesquilin962]

Would synchronizing ur carbs take care of this? Is this procedure done before is after a sync? I got a 82 xj650, not a mechanic. Great informative videos, thx.

[@uziXwraith]

you can use a strong centerpunch to knock that welsh plug out sometimes if you angle the center punch a bit... some cheap china aftermarket carbs have welsh plus so flimsy you can dig the soft metal welsh plug with a screwdriver or hook

[@MarKeMu125]

Does anyone know if loctite blue is any good for these adjuster screws?

[@starfighter2952]

Will engine gradually getting hotter affect making adjustments if you take too long while doing drop?

[@minxita]

Hi, great video. Actually educating :) Thank you. Could you explain about the 4 carbs, as it should be done all at the time the same no matter what? I do get a lot of backfire, and low and high rpms just dont work properly at all. Thank you

[@nathanielmcauslan9377]

Do each one independently

[@brynbull6942]

After you found the sweet spot did u turn the idle screw bk up to normal idle

[@jaystrappa]

I was thinking the same thing 😂 🤔

[@charlies6546]

i got a 03 honda shadow with golf cart mufflers, did the baffle delete and installed stg 1 needle set, for some reason the pilot needles are not same size, does this mean i have to set air/fuel mix screws independently from each other?

[@TheMotorcycleMD]

I would set them the same.

[@703Bugeye]

i cant get my honda shadow to stop popping at idle and deceleration with open exhaust and stacks im also in va and ive tried every jet combination from 42/142 (bike wont even run) to 50/150 (bike is running pig rich)

[@lamontcleveland482]

Can u do a video on a 86 Honda Shadow VT700C carburetors

[@joserantocb750]

Hey Cody, Happy new year bro, looj, I have a question, when you close "turn in" the air mixture screw are you leaning the mixture? thanks buddy.

[@TheMotorcycleMD]

Yes! Exactly!

[@joserantocb750]

Ok, thanks

[@quadflopper1012]

Does anyone know if there are any main and pilot fuel jets from other carb manufacturers (ie: Mikuni, Keihin, ect.) that can be substituted for use in the Hitachi HSC 32 CV carbs used on the 80-82 Yamaha XJ650?

[@How2Wrench]

To my knowledge, there were no substitutes but our shop would buy replacement jets from any "K&L Supply" dealer (most all Powersports shops are). Its been a few years since we had a Hitachi in so maybe someone came up with something to help with this annoying problem.

[@Joe_1971]

Hi Cody, I have an 01 Kawasaki Vulcan 500. It seems to run good, very peppy and has no problem accelerating. Only issue I have with it is when I hold a constant speed or decelerate, I get some backfire out out the right side exhaust. I have cleaned out the carbs, balanced them and like I said the bike runs good with the exception of a slight backfire out of the right exhaust. My question is when performing the idle drop test the left side carb will cause the engine to die when i turn the piolot screw all the way in and run nice when it's 2 1/2 turns out. The right side card turning the pilot screw all the way in or all the way out makes no difference to the running engine. Any idea why? I am assuming that they both should do something to the idle and not just the left hand side one/

[@tylanway5450]

The right side isn't adjusting. I think that is a signal that there is something wrong like a clog the right?

[@khell1169]

i have 2 carbs on a honda cx500 - can i pull the plug on one side... make the mixture adjustment, then do the other side? aka 1 side at a time?

[@anthonyskorner4511]

No

[@joshlujan7019]

Please do a vtx 1300 carb tune vid please man. Would greatly appreciate that genuinely

[@RSRevivals]

What are your thoughts on a colortune?

[@Halfcocked86]

Where is the screw on my 82 cb750? Please and thanks

[@RICHIE_RICH89]

I always go out till engine change in till engine change then between the two spot on everytime

[@TheMotorcycleMD]

Boom, well put! Me too!

[@thedaydreamer7972]

Hi, I have both a Intruder VS1400 and Marauder vz800,,,I have the bikes running well and synced and carbs inspected and set to spec,,,However the idle on both of these bikes is a bit off,,,AND upon bliping or reving the throttle on both bikes the idle hangs for a sec before returning to steady idle,,,from my under standing when this happens its typically a lean condition, conversely when you blip a throttle and it dips, then returns to idle its a rich condition,,,,,,,IS this issue solved by simply finding the correct mixture screw seting on both carbs? IF not do you have any other ideas for me to try? TY you have a great channel

[@Airon0727]

yes sounds like its running a little lean if its not your throttle cable getting hung up

[@sidneycowdroy4668]

Hey Cody. As always amazing video. I am based in Aus and have a vtwin. Ive learnt and fixed so much with your help. Carbies are a lost art here and i really need some help with some small questions. Is there anyway i can message u direct just to get some help man?

[@nathanielmcauslan9377]

So this doesn't have to be very accurate? My bike requires a set point of 2 turns out on all 4 jets for starting. Than it tells me to attach a more accurate tach than the one my bike comes with and adjust each on independently using that. I have all at 2 out and no access to a tach but bike fires up good and idles nice. Can I leave them where they are?

[@jameslesesne7969]

Nathaniel Melkic those are your manufacturers baseline settings for a stock bike. More tuning will be required based on elevation, aftermarket exhausts and intakes, etc. only way to know for sure is to check your spark plug

[@chrismirasyedi]

Got an 83’ Yamaha XS650 and my idle is too low. To the point where when I come to stops the bike will start to choke and proceed to stop. Would this just be an idle screw adjustment or fuel adjustment as well?

[@Airon0727]

COULD BE BOTH

[@Crazygaucho62]

Perhaps a very stupid question but ….so that screw adjust actually fuel ? The more you open the richer the mixture ? Are all carburetors the same or some adjust air ?

[@mikelyons9971]

Should I do this idle drop tune on a carb in the ambient temperature that I will be riding in?

[@Roboticdoughbull3k]

mike lyons I just went out and did the exact same procedure on my old 85 trx 125 and the temperature here is about 20 degrees with no danger of the recent 6" of snow we got yesterday melting. Anyhow it worked great even though I'm probably at the max 3.5 turns out, she definitely idles better than before only had adjusted the main screw and was super picky as to a exact sweet spot it would idle at. Seems much happier now in my experience.