How to Balance Motorcycle Carbs

I am going to show you how to mahe $5 motorcycle carburetor synchronizer, and see how well it works at balancing a set of motorcycle carbs on a 1980 Honda CM400.

[@cri8tor]

Over six-years old and still totally relevant. Cheers

[@mcdonaldchris86]

Thanks bro!!! You just saved me 70 bucks, and gave me a good reason to pickup a 12 pack.

[@DrLelantos]

Just in case you break 10 of the bottles trying to make it right ;]

[@brf001]

You continue to amaze me with your clear understanding of mechanical devices and your ability to simplify them for those who don't. Good work!

[@mikelachance2058]

I just synched my carbs on my 1980 Honda CX500. I'd never done it before and was nervous about it. Used your method and they synched up perfectly. Thanks for posting.

[@adrianc4712]

cool! i have a 1978 cx500 and was also kind of nervous about this but after seeing your comment i will try this this weekend

[@aaronraynor8785]

good to hear I'm not the only one that's nervous. ill try this on the weekend.

[@danielkenway2413]

Did the tubes fit right into the sync port or did you need an adapter? I have 1980cm400a so what worked for you I'm assuming will work for me lol

[@scottjones5455]

I too have a 1980 cx500. It's about to turn 20k miles. The original owner must have kept it in the garage because it is in top shape. The guy I bought it from was the second owner. He knew nothing about maintenance and had just had the valves adjusted and carbs rebuilt so I'm probably good to go for a while, but when it starts running rough, I'll know what to do. Great video.

[@alextupou4992]

Brilliant! CW and CCW.... rubber stops in the freezer. ...heard the sound difference. ..excellent video man.

[@rikdol]

Omg thanks!! I know it’s an older video but for any 2 carb setups this is pure gold. Was fiddling around with a hose filled partly with oil. Watching the levels rise to fast oil in engine aargh. This will make it much clearer!

[@Bwalt1]

You did a good job at explaining, btw the level difference in each bottle does not matter as long as if It does not move.

[@lmdetect]

Exactly.

[@ELCLAVE300]

I did this and one bottle goes completely empty.

[@SprintSt955i]

THANK YOU SO VERY MUCH I was about to give up I bought myself one of these four gauge synchronisation meters, you could either choose wildly bouncing gauges or no movement at all as well as way too low readings. Out of desperation I used google and stumbled across your video. Recreated your tool and what should I say: IT’S LIKE HEAVEN works like a charm costs nearly nothing very hard to mess up ❤

[@nightsongs]

For someone who is new to motorcycles, and likes a visual representation of the effects actions have other than a needle on a gauge this is awesome!

[@lynxonwatch]

Thanks a lot, just built my sync tool following your idea, and it worked great. Honda Transalp XL650V now purring like a big cat...too bad it's winter time here ;).

[@joebananas4741]

Great idea, seems more accurate than the commercial balancers. I don't drink so I will have to find some bottles from somewhere.

[@osmoregulatoryorgan]

That's probably one of the better setups I've seen on YT. Nice one.

[@paulbarnett5818]

awesome video, I have done a similar thing, but I used auto transmission fluid as it is an oil and if for any reason it got pulled into the bike it would be okay, oil good...water bad, I also found that the auto trans fluid was less jumpy in the container and showed more accuracy than water. used very successfully on a '96 XV1100S Virago. Paul.

[@boomerguy9935]

I just sync'd my dual carbs on my 1988 Honda Shadow VT600 VLX using your procedure and manufacturing instructions for the homemade manometer. It worked great! One suggestion: Don't overthink the CW vs CCW thing about the adjusting screw. Just watch the tiny bubbles in the crossover tube (I used red ATF instead of water) and you can see the direction of flow. This is much quicker than waiting for the level to change in the bottles. Also, my screwdriver had to be in a vertical position, pointing downward from where the gas tank was attached ( had to remove the tank which turned out to be a good thing because I discovered a leaking petcock) which put weight on the adjusting screw, so I removed the screwdriver after each adjustment. I also "blipped" the throttle a few times throughout the adjustment. Total time of actual adjustment was less than 10 minutes. I don't know if it made a difference but I reinstalled the air filter housing after installing the brass adapter tubes and clear plastic fuel lines (5mm ID) for the adjustment.

[@genecurl6284]

Glad I found your video. The vacuum tester Kawasaki recommends is $1,322.00 and I only paid $1000.00 for my bike, so. . . .

[@fasteddieskustoms]

Your a genius man. I wish you nothing but luck and prosperity in the future .

[@SprayIgniteBoom]

that is freaking ingenuous!!! You are why this platform exists. Sharing useful simple daily tips. Good job!!!🖖👌🍫

[@costelconstantin978]

Made it two days ago on my Silverwing 2001. ! Huge deference! Thanks buddy!

[@danjaynes2137]

Thank you for the clear and thorough demonstration. Great video.

[@Terkee]

Best sync vid on KZbin and I have watch a lot of them.

[@grreeknick]

Your videos are the antithesis to the stupidity of youtube comments. Brilliant!

[@bobs2440]

Great video and synch tool. Others may have said this, but the relative heights do not matter with the tool you created, only that they no longer move fluid between the two bottles.

[@chukaz]

Just did my own tool for my V star 650 and it worked great, thanks for the video.

[@BasicPoke]

Thumbs up for the carb sync animation at the end. Thanks for the video.

[@filmfreaken]

Thank you alot for this video, it helped me create this tool from scratch and i've synced carbs on multiple bikes with this!

[@pauls28]

Great Video! I need to sync my Yamaha Super T carbs, lost some power last year on a red line and I think this is the issue from what I've read in the forums. Defiantly a thumbs up on this one!

[@alexandergardner2396]

Paul spisak Hey Paul, Is that on the old 750 Super T or the new 1200?

[@Lonnie-bb5ok]

This is an excellent vid, and very ingenious, cost effective, thank you 👍

[@HowardNChauncey]

I love the way you broke it down.

[@heartfang21]

looking for a way to synch my carbs on the same bike you have! haha! so this was fantastically informative. Thanks!

[@liferider2089]

A good monometer set up because of clear hoses to carbs NOT connected directly to carbs (just to top of bottles) so liquid doesn't get sucked into engine.Nice one ;)

[@sandrisb1985]

Sound distinction was huge!!!

[@TriniRogue]

Lmao @ actually throwing em in the freezer take a thumbs up just for that.

[@hotdogdog4740]

“Fish tank tubing” ichiban moto would be proud

[@davidthompson103]

Great job, doing this on the weekend 👍

[@malcolmhodgson7540]

What a superb result.

[@bjamesW32]

You mention at the beginning that you don't care for the gauge manometer because the needle keeps jumping around at idle. I wonder if you could simply use a damper in-line? Perhaps something as small as one of the bottles you are using for the fluid manometer or a bit larger? Ultra easy to try anyway. Just a two port rubber plug to stop the bottle and the air volume inside smooths erratic pressure/vacuum changes without altering the mean pressure/vacuum, kind of on the order of an anti-knock riser in plumbing.

[@roman_verenich]

Amazingly! Greetings from Belarus HighFive!!!

[@crash5868]

I like the freezer tactic. I have got four carbs to do on my Kawasaki 550 zephyr but I'm sure I can figure out the build.

[@ddubrall]

best one I've seen yet!

[@snatr]

That is cool. I gotta try this! Was thinking about using a light oil instead because if you watch @7:00 when you rev the engine, you'll actually see water vapor form in the bottles. Although a little water vapor in the engine is no big deal. And btw, did you know you can actually boil the water off with enough vacuum. Science 😉

[@nevek20]

I didn't mangle my hand via my bike but i did mangle my hand and my surgeon was talking about how hands are the hardest to put back together properly and in conversation we got onto the topic of Bikes and common injuries and hands are common as you put your hands out infront of you to save yourself.

[@AuMechanic]

Vac gauges are plenty accurate enough, all you are lacking is a small air tap found on fish tank air pumps which needs to be closed down so that the vac gauge just stops pulsating. One for each gauge.

[@cheesymcbuttkins6323]

Great video and well edited. This seems to work and I will definitely be referring it to some friends

[@reido2000]

Gonna try this out on my 82 Suzuki gs400 this weekend. Thanks.

[@williamramsey4431]

Thank you sir!!!! Cheap and appears to work.

[@PeterHall-qt8er]

OK Good Video, great piece of kit, but how did you adjust the screw between the carbs. I have the same carbs as the video but the screw and locknut are 'buried' between the carbs and I can hardly get near either of them to make an adjustment with engine running. It must be simpler?

[@Watupm]

moving the H at the end was cool lol XD

[@michaelwilliams4974]

Great video man

[@atsernov]

Your balance job was dead on man. With this system you're not looking for the level to be the same, that part is irrelevant because all this setup does is show you a vacuum difference. You know the carbs are synched when the levels stop changing.

[@ctsteve1967]

and all you had to do is change one carb

[@benjaminwest2281]

Thank you Forrest. Very good video. I like how you had an old motorbike also. Have you done this under a load, also? Say 2200- 2500 rpm, to adjust the cable lenghths? Ok, take care, Benjamin

[@nivlacker101]

didn't even know such a thing existed thanks

[@herbmorris2762]

Well done video. Thanks. I'm going to give it a try!

[@SwedenAirhead]

This was fun! I´m propably make one to! Thanks!

[@abelbabel8484]

Good info, well presented. Have a thumb

[@Zkkr429]

Great video, I will be making me one of these bottle indicators!

[@alexteo2738]

Thanks for cheap and good idea!!! ;)

[@csselement]

It seems one could do a fair job merely by sound. Thoughts?

[@KK-mx2di]

Thank for knowledge ❤❤❤

[@Nicolas-xg6pg]

Great video! Really useful! Thanks!

[@MarcoBiscarini1]

Great video man! Hope this works for my bike.

[@combinbain]

Nice video! I can't get one point: can I make this calibration even without cleaning the carburators first? I mean, I have my bike in here in her side stand, can I just try out your method or I need to do anything else first?

[@ricardomunoz2010]

Awesome tutorial

[@paulb4777]

I'd like to use the same method on a set of SU HD6 Carbs but I don't know where to connect the two synchronization tube's. Could it be to either the overflow or the suction pipe?? - Great video by the way 10/10

[@mattcero1]

Great DIY video guy! Who could not like this video!? Rev the motorcycle to around 4k rpm and sync' there or a reasonable cruising RPM. Syncing at idle isn't relevant as the engine spends most of it's time at cruising RPM's.

[@andersw2274]

Can you do this for 4 carbs? Same but to more? Or do you sync 2 carbs and then two?

[@2369chico]

That's cool . well done .thanks for sharing.

[@howtocreatesculptures6713]

Thank you for making such a cool video , have fun on your bike and keep a watch out for idiots in vehicles that are not paying attention to bikers, be safe , smile and pat yourself on the back for a great simple easy to listen to and learn video . your a great guy ! Oh yes i will be making one of these synchro tools as soon as i polish off a couple brewskies lol... gulp gulp, and yes the fish in the fish tank are eyeballing me now hardcore, they know im about to rob the fish hoses lol, just kidding haha

[@ЕлизаветаМеньшова-л2н]

🤣🤣👍🔥

[@korzbro35]

Man, simplicity of your idea is awesome! Thanks for sharing this. Out of curiosity, is it possible to make this for 2+ carbs?

[@vertonmccaulou5]

Just have to start at one end and do 2 at a time

[@deadguy237]

bike sound real nice man. enjoy in and very funny out tro

[@twistedmetal701]

Thankx man. Very informative

[@Maruti_motoshop]

Brother, if you set the air screw of the throttle, then the rpm will also change?? 

[@Zaiyetz]

The boat man, let's see the boat!!

[@viliusbivainis7883]

Great video! Thanks

[@knd266]

stupid question I guess but where did you get the rubber stoppers? Hobby Lobby or something?

[@michaelwilson8461]

My biggest question is how the hell did you get the lime slices out of the bottles? lol

[@MarkLoweLowebrau]

Good job!

[@rupturemetal5471]

I’m going to try this. I tried the other method where they get a yard stick, 2 stroke oil, a 4 meter clear hose. That oil was jumping all over the place, fixed nothing.

[@arvincharlesatega5660]

Deserving to be subscribed, thanks

[@jotarokujo6729]

I’m going to try this on my 89 gs500 ! Hope it works

[@sinisakragulj104]

thank you! very helpful!

[@ugotgankked]

I tried a different set up and got water sucked into the carbs. Now the bike won't start! How do I get the bike to start again (it's a 2009 ninja 500r)? Going to use this method in my next attempt, thanks for the vid :)

[@elstupidos3863]

nice video ! what did you take to conect the tubes to the cylinder ?

[@JohnSmith-qt7pw]

DUDE. I get carb- lexia every time I do this bloody job, so frustrating. I'm going to label each side CW and CCW straightaway before I do it again. That's brilliant.

[@jeanpaulbouchard8763]

dont forget to label which carb each is for, or you may end up backwards. (i.e. CW - Right Carb)

[@JohnSmith-qt7pw]

Again with the brilliance. Do you do taxes?

[@AuMechanic]

Don't put liquids near the intake, if the liquid accidentally gets suck into the intake it will cause some hydraulic locking that can bend a rod.

[@ugotgankked]

what can I do if water gets sucked in?

[@konr4d]

brilliant

[@Zakamooza]

can you bypass the bottles and just hook the tubes directly in the carb vacum ports ?

[@Pertamax7-HD]

ok sir

[@Docv400]

Actual level in the bottles doesn't matter. If there is no movement (in the levels), then the Carbs (or Throttle Bodies on EFI Bikes) are perfectly balanced.

[@GrandeTacos]

Im convinced you’re tom green

[@1971wildwill]

Good tutorial if you want to save some coin, I have 4 carbs to sync so will soon be building my little kit..great video.

[@shotgunsmurf5740]

i built one similar to this except i used longer tubing with no bottles and put connectors at the bottom and zip tied them to the board i was using i used blue 2 stroke oil i picked up at the garage near my house worked perfect the throttle response was alot cleaner and the idle is alot smoother

[@Vjiovino]

How would you make this for a 4 cylinder bike ??

[@modikee56inchkeegandafterw13]

how you make for 4 cylinder? so what if i sync left 2 carbs first then right 2 carbs later and then only middle 2 like that with same 2 bottles like you did?

[@scrinja]

That would work as the first two carbs are then balanced and set with one another do the same on three and four and finaly balance two and three to sync them all....Bit of a faff about though just make a linked four bottle setup would be my advice...... good video upload though by Forrest

[@Metroidam11]

Thought the "h" at the end was a nice touch. Are you pursuing a major in college right now? And if so, what major?

[@ClintsTractor]

In the beginning of the video he said he got the bottle idea from other people, as for the carburetor adjustments and what not, I would assume he got them from the FSM. (Factory Service Manual)

[@W3BZSL1NG3R]

I have a 72 cb 750 4 into one long tube header kerker pipe love my bike

[@MegaChevy65]

Nice. Where do you get rubber plugs though?

[@CandiiBanks]

Haha you're a legend, great watch!

[@dustinram89]

How did you connect the plastic tubes to the intake manifold screw holes? It looked like you had them taped up pretty good. I'm assuming it's necessary to get a tight seal at those ports. Thanks!

[@danielkenway2413]

Dustin Waite looking to get the same answer. Did you ever get one?

[@jansmisek9987]

If your port has M6 or bigger diameter, you can make an adapter using brake fluid bleading screw, you just cut off the end of the screw. Unfortutately my bike has M5 diameter and those are not to be found in my country. Lathe will have to solve it.

[@SpecThompsonTV]

Great tip.

[@TonicEnergy]

Hey Trenaman, I own an '01 suzuki Gs500 naked, and i've been noticing that i'm feeling a gradual decrease over time in power delivery & responsiveness from the engine. It feels sluggish and very dull. So i've been thinking about cleaning my carbs thoroughly. It is required to sync the carbs AFTER they have been cleaned and re-installed? Thanks bud! :)

[@OrigCocaColaMan]

I own a 2006 gs500F and Yes, you need to Sync them after any work has been done to them, including even if you've just replaced plugs and wires. :)