Review Carburetor Sync Gauges - Are They Accurate?

[@jsandidge1]

I have the same gauges and have always calibrated them the same way you've shown. I've used them to synch the carbs on my GS850 and GS750. Both bikes run extremely well. Those gauges are perfectly adequate for the job, and are a great value. I would recommend them to anyone who has a multi-carb bike.

[@cyrielgaemers]

Just bought them! 👍👍👍👏

[@shanec4441]

Same here, I use this same sync kit. I calibrate the gauges to match each other as shown in this video but I calibrate at 10-11 “ H2O vacuum not zero pressure

[@craigjohnson3603]

Good video, I went to a tech school and have the same set as you and set them the same way. In class we had aircraft mechanics that insisted on the $1200.00 digital gauges but didn't work on all engines so I am happy with them. They work great on my old V65 Magna, Bmw, outboards, anything I try. A tool is only as good as the operator!

[@UrbanMonkTV]

Thanks for watching! V65 Magna...What a gem! We drooled over those as kids. I even mention it in my book. I agree with your sentiment regarding tools and operators.

[@MaartenBakker]

The answer I needed, including a simple demo. Good work!

[@UrbanMonkTV]

Thanks for watching!

[@Pete-from-Tn]

If you don't have the vacuum pump like yours, I have the same one. You can hook each gauge up to the same carb on the bike. And get the reading on one, then the next until you have tested all 4 on the same carb plug. Plus if yours can't be adjusted. Just note the difference between each gauge. Be it 1 lb or 4 lbs of vacuum. Then you can add or subtract to make all 4 the same.

[@UrbanMonkTV]

All good points! Thanks!

[@markhorton7013]

Nice, clear and informative. I do have a set of vacuum gauges and also calibrate them before use which gives me peace of mind. Thx for sharing I'm sure this information will help a lot of people venturing into the world of Throttle body/Carb - Syncing/Balancing.

[@UrbanMonkTV]

Thanks for watching!

[@salta5859]

Thx, for once it is NOT a lengthy video. Perfect. Very informative. Greatly appreciated.

[@UrbanMonkTV]

Thanks for watching!

[@markgardner8786]

Many thanks for your video. I bought a set of these last week and wasn't sure if I had bought rubbish. Thanks to you I can sync my sv650 carbs with confidence. Thanks Mark

[@UrbanMonkTV]

I'm jealous you own an SV650. I want one. Glad my video was a help. Thanks for watching!

[@stewartsmotorcycles.315]

That was a great video with plenty of good information. Those cheap vacuum gauges have been around for years, and are very hit & miss as to their accuracy in relation to each other. It appears that you had a good set. Luckily I still have mercury gauges. I remember years ago a customer bought a set of those gauges because he fancied doing his own carb sync. He had a Yamaha XJ900, and I balanced the carbs using his gauges, and without stopping the engine I swopped each cylinder to my mercury gauges one at a time. There was a 9cm difference. Obviously it ran much better when I balanced it using the mercury gauges. I did exactly what you did and linked all the gauges together using T pieces and tubing, then applied my vacuum pump and adjusted the gauges until the needles all read pretty much the same. We balanced his bike using them, and again swopped over to my mercury gauges. There was a discrepancy of roughly 20mm across the 4 cylinder which is pretty damn close. For as you quite rightly say a minor difference won't be noticeable. So these cheap gauge sets can be accurate enough, and I suppose if one didn't have a vacuum pump one could use one cylinder of the engine to adjust the gauges in relation to each other, but it would be a bit of a 'faff' as we say over here. All the best.

[@UrbanMonkTV]

Thanks for watching and sharing your insights.

[@motorradguy184]

It's funny I just bought a set of gauges to do sync work with and decided to test and see how close they were to each other, and I did the test with my mightyvac just as you did. Great video, thanks!

[@UrbanMonkTV]

Thanks for watching!

[@nickigilbert7295]

I'm on my daughter's KZbin account. The actual guage reading is not the main issue. The main issue is if all 4 guages read the same with the same vacuum applied. I would get some vacuum fittings so I could hook up all 4 quages together. Then apply vacuum the the vacuum line. If all 4 quages read the same then they're accurate in a sense to dial in your carbs. Who cares if the actual vacuum is 13 inches but all 4 guages read 15 inches? You'll still be able to tune the carbs.

[@UrbanMonkTV]

Thanks for watching. I have done exactly what you describe in the video and completely agree.

[@RATsnak3]

That is literally the entire point of this exact video buddy…

[@VFR-Owl]

I have the same vacuum set to use on my VFR800, it's fuel injected but need the starter valves setting. Number 1 cylinder is the reference so 2, 3 and 4 are adjusted in relation to that. I calibrated my set by noting no. 1 reading with the engine running and then set up gauges 2,3 and 4 by connecting to cylinder 1, one at a time and adjusted as per the video.

[@UrbanMonkTV]

Thanks for sharing that here with others. You never know who you will help with an experience like that. And thanks for watching!

[@exeterrider]

Thanks for clearing that up

[@UrbanMonkTV]

Thanks for watching!

[@shanec4441]

It’s best to calibrate to match the gauges at say 10”H2O vacuum not zero. Bikes typically pull 10-12” vacuum and it is best to be most accurate at that vacuum pressure.

[@UrbanMonkTV]

That's a good point. I'm happy you shared it here for the benefit of others. Thanks for watching!

[@fastboy8315]

thanks for the tips....i bought yesterday this sync kit .....

[@UrbanMonkTV]

Thanks for watching!

[@pistre14]

Thank you for explanation for plastick valves :) my gauges are dancing and I didn't know why :) thank you soo much !

[@UrbanMonkTV]

Happy to help! Thank you for watching.

[@44lespumas]

This was very interesting. I didn't realize you should check the calibration on the gauges before starting. So I did. Could see where I had gone wrong. Yesterday I synced the 4 carbs on my 1000RX perfectly. Great help from this video as from others I've looked at.

[@UrbanMonkTV]

Thanks for watching! Glad it was helpful!

[@passoapassoevoluindo6838]

What are the vacuum measurement sizes? What measurement scale does it use?

[@freddieastaire6312]

Awesome content, brief yet informative 👍 you just earned a subscriber!

[@UrbanMonkTV]

Thank you!

[@MrLeeflemwell]

I'm looking at these gauges. Good information. Thanks

[@UrbanMonkTV]

Thanks for watching! I have a discount code and link for Alpha Moto on my website. They sell the ones I have. No expectations.

[@edwardallan197]

Thank you Urban Monk!

[@UrbanMonkTV]

Thank you for watching!

[@TheSilentStar]

Thanks for doing this cleanly, concisely and thoroughly. Great video Thumbs up!

[@UrbanMonkTV]

Thanks for watching!

[@evonpaige8873]

I liked to second that. I am just learning about how to service and evaluate Carbs, your explanation on this tool is one of the best I've seen on KZbin; even 11 months after the posting of this video. SMH

[@timkis64]

i have an high quality gauge (single) from the 80s.then using the same cheap set you have there.they are within a half inch of vaccum of each other when i compared them.thats good enough for me.just NEVER drop them.

[@UrbanMonkTV]

Great info for others here. Thanks for sharing!

[@passoapassoevoluindo6838]

What are the vacuum measurement sizes? What measurement scale does it use?

[@UrbanMonkTV]

First, thanks for watching. I'm not sure I understand exactly what you're asking. Are you asking about the hole and thread pitch to the connections that go into the intake boots? Or simply the diameter of the nipples that the hoses connect to?

[@passoapassoevoluindo6838]

@UrbanMonkTV Vacuum is measured in pressure units such as pascals (Pa) and torricelli (Torr). One torr is equal to the displacement of one millimeter of mercury (mmHg) in a pressure gauge. Some digital vacuum gauges can measure in multiple units such as: inHg, Torr, psi, mbar, mTorr, Pa, micron, kpa. Which of these does it measure?

[@UrbanMonkTV]

@@passoapassoevoluindo6838 Ah! Mine are graduated in mm and/or inches of mercury.

[@tombair1401]

I have the same set acurate enough smmothed out the idle but not as much as the mecury ones

[@UrbanMonkTV]

@@tombair1401 Thanks for watching!

[@augustharlacher5660]

Thanks for the info. on the gauges Brother!👍👍👍😎

[@UrbanMonkTV]

You're welcome. Thanks for watching!

[@sebastiancantarelli6594]

Great video sir. Very useful with solid information. Congrats.

[@UrbanMonkTV]

Glad you liked it!

[@gustavogode]

Thank you!

[@UrbanMonkTV]

Thank you for watching!

[@richardjohnson3463]

They work for me!

[@timbarnett3898]

Question: on this sync test, should all vaccume hoses be exactly same length!

[@UrbanMonkTV]

@@timbarnett3898 No need for the tube lengths to be the same. Under the configuration I show in this video, all the space within all 4 tubes is essentially 1 space. The vacuum within a space is the same everywhere in that space. Thanks again for watching.

[@timbarnett3898]

Can you plug 1 guage an get a reading. Then connect all 3 other guages to same known cylinder carburetor to check consistency to all gusges?!

[@UrbanMonkTV]

@@timbarnett3898 Thanks for watching! Yes, but there's not really a need to "check consistency" since each gauge can be calibrated to match the others. Calibrating would be a little more difficult using the one-at-a-time model you suggest, but it could be done.

[@kruno49]

great video tutorial, find very useful info !!

[@UrbanMonkTV]

Kind words...thanks!

[@SMBBM92]

Excellent video, thank you ever so much sir!

[@UrbanMonkTV]

Thank you for watching!

[@grabir01]

A bench sync works well. No cheap gauges needed.

[@UrbanMonkTV]

Thanks for watching. Not sure how I missed your comment for this long. Wasn't showing up in my feed for some reason. Anyway...Agree on bench sync, but of course one needs to go through the trouble of removing the carbs from the motorcycle to do that. Some folks aren't inclined to.

[@cjeremie]

have you compared the vacuum ones to those with an electronic reading? which would you say would have a better accuracy?

[@UrbanMonkTV]

Thanks for watching. I've never used an electronic gauge set so I couldn't comment with any authority. What I will say is the vacuum are proven to be accurate enough to do the job effectively. If price matters, perhaps they are the best solution for many people.

[@davidupton3186]

Great video. Intelligent and to the point. Thanks for uploading 👍

[@UrbanMonkTV]

Thank you for watching!

[@timbarnett3898]

I have exact gauge qn this is my question, how accurate are these cheap gauges? I have 88' GW i want to carb sync? Thanks!

[@UrbanMonkTV]

@@timbarnett3898 If calibrated to each other they are very accurate.

[@datsdylan007]

Do you need liquid gauges? Won’t these just break with a high cc v twin bike?

[@UrbanMonkTV]

@@datsdylan007 My v-twin is 1000 cc, so I've not personally tested above that, but no issues with my 1000. Thanks for watching!

[@fstarockaburns425]

hi - just hooked the same gauge set up but the needles are nuts- what switches are those? im thinking of grabbing 4 shut off valves from the gardening section, will that work?

[@UrbanMonkTV]

Thanks for watching. I wish they wouldn't sell these things without the little adjustment valves. As you found out, they jump around too much to of any use. You may be able to find something in the gardening section that'll work. Just can't be an "on/off" valve. Needs to let a small amount of air through. You might also find something to pinch the rubber hoses that is adjustable.

[@erik_dk842]

​@@UrbanMonkTVit suggest using a drilled through plug mimicking a main jet

[@spidergorrilla7964]

Can I still use this method if I have accidentally tried to move the needles back by hand???

[@UrbanMonkTV]

Hmm. That's a good question. I'd guess if you didn't feel you had "hit the stops" of the internal mechanism while attempting to adjust by hand, in theory there shouldn't be any damage internally so adjusting the proper method should still work. Thanks for watching!

[@spidergorrilla7964]

@Urban Monk TV thanks for the advice 🙏

[@steverives3060]

Great intro music!

[@UrbanMonkTV]

Thanks. I actually co-wrote and recorded it with friends many years ago (1995).

[@TheCalvinSkinner]

Extremely helpful!

[@UrbanMonkTV]

Thanks for watching!

[@Mark-sq8mh]

is the internal diameter of the adapters to attach to the port, important? I have 4 adapeters of the same type, but due to manufacturing imperfections, its internal diameter is not the same in all 4. I can appreciate this fact by blowing inside with mouth; some are more "free" than the others.. thanks.

[@UrbanMonkTV]

Thanks for watching. So tell me if I understand correctly...When you say "adapters," are you referring to the small plastic valves and, if so, are you saying the hoses don't hold tight around the nipples on all the valves in a uniformly tight manner?

[@Mark-sq8mh]

@@UrbanMonkTV thank fo reply, no I mean with "adapters" the small brass pipes with the thread to be screwed in in the carburator port

[@UrbanMonkTV]

@@Mark-sq8mh Ah! What I'll say there is that even if the threads are a little loose (caveat, only a little loose), once the vacuum of the engine running is in effect, it should pull them snug against o-rings and "seal." Whereas blowing would have the opposite effect. One could start the engine and then lightly fiddle with loose ones to see if it results in any change in the corresponding gauge. If not, you're probably fine.

[@bikerrealengo]

Man...mine are new(sincro tool kit) but come without valve and bouncing like crazy 😒 lost my mony..its. Imppsible to use...thanks for the advise 👍

[@UrbanMonkTV]

I wish some sellers wouldn't sell them like that. As you stated, they're unusable without. Thanks for watching.

[@erik_dk842]

You can put something like a main jet into each tube to get the same effect. Or a plug which you drill out

[@kymnewman3518]

physics is always accurate

[@untonyto]

Great video thanks

[@UrbanMonkTV]

Thank you for watching!

[@thenoobrider8462]

How to test gauges if you don’t have vacuum tool

[@UrbanMonkTV]

I believe Harbor Freight sells one for around $20, so not too bad, but if you don't want to do the, you could do a similar network of hoses off any vacuum source, including one of your carbs if your engine is running. Thanks for watching!

[@thenoobrider8462]

@@UrbanMonkTV thank you very much for your help

[@HighMileageOffroad]

Where can I get a set of those plastic inline valves?

[@UrbanMonkTV]

I've been asked that before and went searching only to be stumped. My best guess then and now is eBay. My advice for those who don't already own a set is to be sure to buy gauges that include them. I wish sellers wouldn't sell them without. It's like selling one chopstick. Sorry. Thanks for watching.

[@sawneybean9611]

Plastic valves can be found in pet stores in the fish tank section along with tubing

[@erik_dk842]

​@@UrbanMonkTVI'm fine tuning my repetitive comment. Ideally you'd want an identical calibrated restriction in each tube, for instance a main jet, or plugs drilled with the same size drill

[@UrbanMonkTV]

@@erik_dk842 Would love it if you post here about how your approach works out as it could be very useful to others who read this thread. As I have mentioned before, it frustrates me that sellers sell these things without the limiting valves and I assume they sell a lot that way so your solution may have value to many. Thanks!

[@frankieoneeye6217]

Make sure the tubes are not dry rote.

[@UrbanMonkTV]

Good point. Thanks for adding.

[@bluehazeboy]

Top job, best wishes to you & your wife♥️

[@UrbanMonkTV]

Thanks! She's hanging in there right now. We're grateful for every day she doesn't need to do dialysis. Hopefully transplant beats the need for that. 🙏

[@armahisham]

what are the call the small tiny valve at tube hose sir?

[@UrbanMonkTV]

Thank you for watching. The small valves stabilize the vacuum pressures so that the needles on the gauges don't jump up and down with every reciprocation of the engine. Helps you read the results. I have other videos showing how I use them on an actual motorcycle.

[@Michael-rh7ie]

I think your after a name for the valves- They are called needle valves or even stop valves they restrict or if closed completely stop the flow of air through the hose.

[@Godsblessings1111]

Can you get them in 6 vs 4? Thanks. ✌

[@UrbanMonkTV]

Thanks for watching. I'm personally not aware of any banks of 6 gauges, but there are 4s & 2s. One of each could easily be joined and calibrated in sync.

[@Godsblessings1111]

@@UrbanMonkTV Thank you! Great video by the way! ✌

[@ropeyzkittlez9703]

to bw honest you dont even really need to sychronize them just set the air screws to the same, what the manual says, usually 2-1/4 turns and set the throttle so they all open equally at the same time, most the time the throttle never needs to be adjusted, just air and idle screws

[@UrbanMonkTV]

Thanks for watching.

[@Buddycoop1]

I was going to buy these but the Amazon reviews are 50% negative... Don't want to risk it yet.

[@UrbanMonkTV]

Thanks for watching! The question to ask is whether the reviews are written by people who possess a complete understanding of what they're reviewing. Just because the Internet gives us all a voice, doesn't mean we all carry that responsibility equally. That goes for me too. Consider the source.

[@Buddycoop1]

Very good point.@@UrbanMonkTV

[@bhunter8476]

Look forward to the actual synch!!

[@UrbanMonkTV]

Waiting for fuel reservoir to arrive. Struggling with a shoddy Ebay seller. 😔

[@bhunter8476]

@@UrbanMonkTV I actually just put a stage3 Jet kit on mine yesterday and raised the needle height. Im sure the carbs will need to be synched right?

[@UrbanMonkTV]

@@bhunter8476 Nice! Yes, you should check vacuum synchronization after changes like those. 👍🙂

[@bhunter8476]

@@UrbanMonkTV ok 10/4 thnx UM!!

[@bhunter8476]

@@UrbanMonkTV quick question, do our bikes have a "welch" screw on the carb? Drill to get to or exposed? Thnx!!

[@starlightsims9229]

Not for nothing but the title is, "are they accurate?" You have shown that they are clearly in sync, but you haven't shown if they show te accurate level of vacuum. Are they registering the same vacuum as shown on the Mitey Vac?!

[@UrbanMonkTV]

Perhaps I should have titled this "Are they accurate enough to get your bike running nicely." That was the scope of this experiment. I don't have need to know whether they are indicating an accurately beyond that.

[@oldjarhead386]

I played this game. Get a digital unit. No games. Sync in a just a few minutes with no games. You’ll never get factory specs with cheap analog gauges.

[@UrbanMonkTV]

@@oldjarhead386 Thanks for watching.

[@harryohanson]

Take em and toss em! Then go get em again toss em again! There is a perfectly good reason for them to be cheap. Also may I point out that the little valves are not also equal. Found that out hard way. Bottom line, don’t bother! More moving things are nothing but more things to go wrong! Hydraulics doesn’t lie!

[@UrbanMonkTV]

Thanks for watching. Perhaps others who read these comments could benefit from learning more about the issues you encountered with the stabilizing valves on each line. I agree those require some attention to ensure one isn't constricting fluid flow unevenly. Some "feel" required there but not anything too mysterious. Also I should say that I never meant to position these as a superior choice to a hydraulic gauge set. I just believe the evidence shows they are accurate enough for the task of syncing most motorcycles when calibrated properly.

[@mortenleinan]

why are everybody putting on that annoying music, cant watch this :(

[@UrbanMonkTV]

It may be you simply don't like the particular music I happened to pick for this video or you may have a condition called musical anhedonia, which is an inability to enjoy music. Affects 3-5% of people. Thanks for attempting to watch.

[@steveireson2145]

All the comments are theese are based on the fact you have enough of a brain to syncronise them to a single vaccum source and not to reley on them straight out of the box.! if you have the mentality to sync carbs you shold not assume they are perfect as none are and they will be all you need to do a great job!!!

[@UrbanMonkTV]

Thanks for watching! Agree, best practice in any science is to calibrate your measurement instrument before making observations.

[@marzinjedi6437]

Cheep almost always is cheep ! And nothing else !

[@UrbanMonkTV]

This is always an interesting perspective to me. If you define "cheap" as it is commonly understood...it means "worth more than its cost" as an adjective and simply "inexpensive" as an adverb. There's no element of inadequacy inherent to the term. I've purchased inadequate items for various prices in the past as well as purchased adequate items for various prices. I see them as exclusive of one another. Thanks for watching!

[@douglasalexander4348]

Will an expensive and gold plated gauge do the job any better ? No. So expensive doesn’t mean better and cheap worse.