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.

[@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 ;]

[@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.

[@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.

[@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?

[@cri8tor]

Over six-years old and still totally relevant. Cheers

[@Terkee]

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

[@Lonnie-bb5ok]

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

[@HowardNChauncey]

I love the way you broke it down.

[@grreeknick]

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

[@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.

[@roman_verenich]

Amazingly! Greetings from Belarus HighFive!!!

[@reido2000]

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

[@williamramsey4431]

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

[@SwedenAirhead]

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

[@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

[@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]

🤣🤣👍🔥

[@KK-mx2di]

Thank for knowledge ❤❤❤

[@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

[@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?

[@knd266]

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

[@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

[@deadguy237]

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

[@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?

[@sinisakragulj104]

thank you! very helpful!

[@AnthonyJenningsTech]

I have these carbs for my '78 CB400T II Hawk :)

[@Vjiovino]

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

[@arvincharlesatega5660]

Deserving to be subscribed, thanks

[@joelcastro4521]

What do you use to connect it to a 84 Honda shadow 700 I mean to the engine

[@Zakamooza]

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

[@MrShmoupy]

How do you know all this ? do you study it or do you just experament, ive got a very old Suzuki landie fm 50 and im trying to repair it. no luck so far.... :(

[@eliseoebarahona9486]

where did you buy the rubber plugs?

[@W3BZSL1NG3R]

That's how my dad tought me but with 4

[@mc2whls]

You shouldn't synchronize at curb idle. Usually 1600 rpm is a better choice.

[@ergner]

How can carbs air-fuel adjust?

[@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. :)

[@abk276]

Yea what kind of honda

[@2steelshells]

Thank you! Do you think carb sync only affects idle? Or will imbalance cause higher rpm issues? Or ride quality.

[@asasinw]

Hi i know it.s an old video i am trying to sync my carbs on kawasaki gpz 500 2 cylinders i get the video until i don.t get what screws to turn to level the water... i would apreciate the help

[@drood78]

maybe too late but try kzbin.info/www/bejne/g5PMemh5l7CijdE

[@antosweeney8058]

is there a chance that the water gets sucked in to the cylinder??

[@ghostboy4091]

If you're using 2 12 ounce glasses you shouldn't use more than a total of 12 ounces of you use more then it might get sucked into the carb

[@danielkenway2413]

Incase someone else has the same question, there are more ideal fluids to use just in case it gets sucked up. Can't remember which though

[@JoeyNumber0]

man i liked it when you weren't so focused on rc stuff a little bit of that a little bit of napalm and penny bombs then some misc

[@nevek20]

please for the love of god always wear gloves when riding, hands are incredibly complex to put back together if you unfortunately manage to come off and do something to them

[@TheBlarggle]

For some reason I feel like you're either a hand surgeon, or have mangled your own hand riding your bike.

[@altlandf]

Just how can you balance the worthless carbs if the bike refuses to start. Yamaha needs to be shutdown and ALL the people there need to be arrested. These bike are junk and the engineers that designed the bike need to be jailed. XJ bikes are no help. They lead people down the wrong path. Bigfritz is one of the biggest jerks out there. These bikes are nothing more than money pits.

[@atsernov]

Your incompetence doesn't make the company bad. There are millions of Yamaha's running just fine out there.

[@altlandf]

I am referring to the XJ and XS line of bikes. I have owned a 650 Special and an Exciter. The only problem with the Exciter was the starter. I got mad and banged the starter with a screwdriver and it would start. That's it. No other problems. The XJ bikes defy logic. The YICS is the problem. Building an induction system that uses a rich mixture to ignite a lean mixture is a major engineering flaw. I had a Honda Prelude that had the same system. It only lasted a couple years and it was gone as it didn't work.

[@atsernov]

altlandf It was called CVCC by Honda and was used for about 15 years, with the majority of that use between 75 and 85. The system wasn't dropped, "as it didn't work." CVCC simply became obsolete when fuel injection became affordable and reliable. It is a complex system to work with though. And beyond the scope of many techs these days let alone shade tree DIYers

[@napper1496]

atsernov yep.my R6 is15 yrs old,& still does 160mph no probs.

[@TriniRogue]

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

[@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.

[@hotdogdog4740]

“Fish tank tubing” ichiban moto would be proud

[@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. . . .

[@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!

[@alextupou4992]

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

[@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.

[@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.

[@michaelwilson8461]

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

[@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.

[@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!

[@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.

[@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 ;)

[@Pertamax7-HD]

ok sir

[@Watupm]

moving the H at the end was cool lol XD

[@costelconstantin978]

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

[@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 ❤

[@myturkishlife1777]

Corona bottles 😳😳😳🤔😁

[@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

[@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?

[@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 😉

[@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.

[@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.

[@konr4d]

brilliant

[@micko1404]

just double this for a 4 cylinder 4carb bike, simple and effective

[@SprayIgniteBoom]

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

[@altlandf]

I spent the better part of 5 hours cleaning another set because one of float things broke. I spayed carb cleaner through every hole front and back. I worked on one carb at a time. I installed the float needle and seats. I got nothing. I won't start. I makes no sense. Just how can the guy on TV that goes around finding 100 year old bikes and he doesn't have the trouble I have getting bikes going. These bikes defy all logic.

[@GrandeTacos]

Im convinced you’re tom green

[@heartfang21]

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

[@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!

[@csselement]

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

[@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!

[@chukaz]

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

[@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

[@osmoregulatoryorgan]

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

[@Maruti_motoshop]

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

[@fasteddieskustoms]

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

[@ELCLAVE300]

I tried doing this but it sucked water into my carbs..🤷

[@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

[@brianquigley7336]

Please learn the difference between pressure and vacuum.

[@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?

[@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 :)

[@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.

[@jaimegonszalez8166]

its thad why my bike dosn,t run no more then 25 mph is a 1979 kz400 and i can get it to run good :(

[@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.

[@siki7044]

Dear man.How is diameter tube?can i use 0.4mm?

[@sandrisb1985]

Sound distinction was huge!!!

[@alexteo2738]

Thanks for cheap and good idea!!! ;)

[@locustltz400]

How would thsi work for my 1981 cb750c with 4 carbs? 4 bottles? or Can I do 2 bottles at a time?

[@benjaminwest2281]

As many bottles as cylinders

[@streetlimitz89]

I gotta get my carbs cleaned first then ima try syncing them my bike has 4 tho O.O

[@danjaynes2137]

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

[@MrShmoupy]

Hey forresttrenaman my bike keeps turning off if i dont give it gas all the time when i leave it it just turns off, its a Suzuki FM 50 Landie fearly old any idea whats causing it? my english is bad sorry if you dont understand something

[@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)

[@levij6725]

How did you determine which bottle to mark clockwise and counter clockwise?

[@lmdetect]

Levi J Actually that was kind of pointless. If turning it one way doesn't slow the water rise, turn it the other way. And don't worry about getting the water levels even. The idea is to stop the transfer of water between the bottles, bringing the water movement to a dead stop. The actual water level in each bottle makes no difference.

[@ronaldmcewen5091]

to stop youre vacume gauges from bouncing use checkvalve in line a

[@BasicPoke]

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