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Carb Syncing: How to Fine Tune Your Carburetors

TheMotorcycleMD

951,515 views

I apologize for the audio, vocal mic kicked the bucket!
Learn the proper methods to accurately adjust your carburetors synchronization. Head over to the blog and dive a little deeper as I break down and explain Honda's different carb setups as well as some tips and tricks to make the job easier.

Here is the Carb Sync Set identical to the one I use
http://amzn.to/2gXVvX0
Carb sync special adjusting tool
http://amzn.to/2gXJAbG
Spare Gas feeder
http://amzn.to/2hiwBlV

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20 Comments

@TheMotorcycleMD Creator 4 years ago (edited) Pinned

►► Here is my step by step Twin Carb Cleaning tutorial - https://www.themotorcyclemd.com/inline-four-product-options

@Dsolo325 6 years ago

One thing i learned. Before you connect all four gauges to different carbs you should connect all gauges to one carb to make sure they are reading the same vacuume. they can be off and you'll have to compensate on your adjuster.

@walterswartz3406 6 years ago

I sure like this kid... He's as thorough as it gets. Once you see a video of his, you rarely have questions.

@rootbeercouch 8 years ago

This video taught me more about carb syn in three minutes than hours of other videos. Thank you

@richardwillson101 5 months ago

Its a 9 year old video, but THANK YOU, it was VERY informative and interesting.

@coppermine64 9 years ago

Probably the best tutorial on CV carb synching on Youtube. Top man.

@BadgerScrub 6 years ago

I know you posted this a while ago, but I hope you see this message anyways.

Recently I bought my first street bike. I've only ever had dirt bikes before now, so I've never been familiar with anything but one cylinder. I noticed very bad gas mileage after riding my bike around for a couple of weeks. I took off the carb rack, cleaned everything out, and adjusted the throttle plates. I had no idea what syncing the carbs were until now, after I've already put everything back together. It's such a relief that I did something right, granted without the perfect tools, and adjusted something for the better. Now in hindsight, because I actually know what syncing is, thanks to you, I'm so glad that I adjusted those plates, because they were MILES off a proper setting.

Thanks you again so much.

@TPTTEESSIDEPatTestingServi-c9s 3 weeks ago

I like the idea of keeping the bikes grommets in your ears, now I will never lose one, :) , 9 year old video yet the video explains the basics, clear and concise

@K-so8gx 9 years ago

Your not wasting my time with the extra information its great!.
Like the way you go about your work. "I like to get em perfect".

@cavscout62 5 years ago (edited)

I’ve been using CARBSTIX Mercury gauges for many many years and I love ‘em. BTW on these Japanese bikes those screws that appear to be Phillips head screws are NOT! They are JIS screws, Japanese Industrial Standard which is why everyone strips them out using Phillips head screwdrivers. Excellent work BTW and I believe I’m going to get a set of those sync gauges, you’ve convinced my 60 year old self!🤘🏼

@GrievenceCapitolist 4 years ago (edited)

I just picked up a guage set from a guy retiring from boat motor wrenching . It's got about 6 different sets of vac needles all labeled 25 bucks . The carbs you rebuilt for my 78 cb750ss are doing great . Awesome job ! . You said I should sinc them . 2k miles later I will thanks to this video . It's almost riding weather bro , let's GO. Thanks again .

@PorkBarrel. 9 years ago

I'm working on a Yamaha 50HP outboard engine with 4 carbs. This video really helps more than motorcycles! Thank you.

@jenpsakiscousin4589 7 years ago

Depending on how the carb vacuum layout is you can have 2 banks of 2 carbs instead of 1 master carb. Keihin FCR's are like this. Carb 1and2 are tied together and 3and4 are ties to gether. With port linking the 2 banks of 2 together. You make 1&2 the same, 3 & 4 the same then bring both pairs together with the center spring screw.

@1FastKawboy 1 year ago

Not saying anything bad here, but in actuality, not only can you have vibration over time, but every cylinder breathes slightly differently. Compression is usually different, more so on a higher mileage bike. Compression will change over time. Synchronization helps put all the carbs on the same playing field. You can " bench synchronize" using some kind of feeler gages and set them all the same. And guess what? They will still be off to some degree from one another. That is why the vacuum is so important. Over time, many factors can come into play, and vacuum gages are how to set them so that each cylinder gets what it wants. So yes! Good advice in this video!

@allanbrowne111 3 years ago

Mate, absolutely brilliant video. The comparison between vacuum and mercury was interesting, and a full description of why and how was invaluable, I am now a subscriber.

@johnnyappleseed7798 9 years ago

If you calibrate the gauges to each other they will have more accuracy. All you need is a syringe and 4 port manifold to create a common vacuum, then use the calibration screws on the affected gauge. Best to pull the vacuum to the normal operating value during cal-in your case around 20 cm/hg. The cheap Emgo gauges have a cal screw under the glass. If the gauges don't have adjustments then note which are off or mark the bezel for error correction. You also need to dial or damp more bounce out of all the gauges.

@iamthefatstig 6 years ago (edited)

What a find! Yes its from 2016 but this is the cool thing about YT. I've been working on bikes for 30 years now and this is, by far, the clearest explanation yet. I've got this to do, just rebuilt the carbies on my 1985 GS850, she starts, idles with a fart and a pop but isn't pulling much above 3000rpm. Carbs were bench synced only so I'd expect nothing less than dog rough! You're a gold mine, if only to confirm what we know (or thought we did!) Love you man.

@benp6361 2 years ago

what I learned how you easily set the sync without gauges is:
remove the carb-bay from your bike
take the smallest drill you can (one that is not grimy nor with burrs) get mark one side of the shaft with a Edding(or whatever permanent marker you can get) for repeatability of the position
for the next step: BE GENTLE! using force might damage your carb fataly
open the butterfly by turning the RPM screw in, so that the drill will juuust fit between the "Master"-butterfly and the carb-body with the mark facing up (make notes for the turns on the RPM screw)
repeat with the "Slave"-butterflies so that the drill will juuust fit underneath those
close the RPM screw back to normal by screwing it out
insert the carb back into your bike and take a ride to warm up the engine
adjust the idle to spec RPM

@revdrshad 5 years ago

You have a real easy way about you which is thorough and complete. Keep up the good videos.

@JustinSugita 8 years ago

I love this video. You went over how the carbs work, how to fix it, and what are things to know.
How you explain things, in order and what to watch out for is awesome.
You answered questions i didn't even know i had, and things like the base carb, never knew existed. But that makes sense.
Awesome video, Instant sub. Keep doing what your doing.