Carb sync gauge.

[ken]

Is there much of a difference between the vacume gauges and the mecury type gauges?

[mrich12000]

Yes the Gage set seem to bounce more..

 

I just bought a new Morgan 4 carb tune, still in shipping. Can't wait for this to arrive.

Goggle the Morgan Carb tune , very good website, checkout out..

[V7Goose]

Obviously there is a huge difference in design - the mercury stix can spill or break easily, and the mercury can even get sucked into the engine, where the vacuum gauges are practically indestructible. Both measure actual vacuum quite accurately, unlike the Carbtune that measures just the amount of air being pulled around a rattling metal rod.

 

The vacuum gauges come with plastic valves that are placed in-line with each gauge to adjust the amount of needle bounce - you should set them so that the needle just slightly wiggles. If you turn them all the way down so the needle does not wiggle at all, you won't know for sure that they aren't closed a little too far and, therefore, showing incorrect vacuum reading.

 

The reason any vacuum measuring tool will show a large bounce at idle is that the vacuum is only present during the intake stroke, which is just 25% of the time on a four cycle engine. The slower the RPM, the worse the bounce because there is so much time between each intake stroke. You control the bounce by restricting the vacuum line so that only a very small amount of vacuum in the gauge can bleed off between intake strokes, but there is a very fine line between enough restriction and a tad too much, which doesn't let the gauge read the full vacuum. While the little plastic valves work well enough, you will find brass valves with screw knobs much easier to find just the right point. You can find those at some hardware stores in the plumbing section, or look at some internet aquarium supply outlets (I'll try to find a link and edit this post).

 

Update on brass valves - it seems that quality in-line brass aquarium valves with a knob for precision adjustment are a thing of history. The only thing I can find now are valves with a 1/8" NPT on one port designed to screw into a manifold. See the item labeled "Brass Valve" here:

http://www.fosterandsmithaquatics.com/product/prod_display.cfm?pcatid=8165

 

That kind of brass valve will work fine, but you will also need an adaptor to screw onto the 1/8" NPT side that will let you use it with a vacuum hose. You can find that at any hardware store. You do NOT want a lever valve - they are very difficult to get adjusted correctly in this application.

 

Goose

Edited October 18, 2010 by V7Goose

[Condor]

Both measure actual vacuum quite accurately, unlike the Carbtune that measures just the amount of air being pulled around a rattling metal rod.

 

 

Hmmm. I use the CarbTune and haven't experienced a rattle. I'd send yours back if they're that bad.....

[V7Goose]

Hmmm. I use the CarbTune and haven't experienced a rattle. I'd send yours back if they're that bad.....

Nothing to send back - I would not own such a poor tool!

 

But they all rattle - even yours. They have to - that is a specific design feature. And it is even referenced in the instructions; although, I don't think they actually use that word.

 

But in whatever words they choose, the instructions specifically tell you that if you cannot see the rods rattling in the plastic tubes, then you cannot trust the reading.

Goose

[uechi kid]

A couple of months ago I bought a dial carb sync tool. Works great and is less expensive than the Morgan.

By the way, thanks for the advise V7Goose.

http://cgi.ebay.com/ebaymotors/EMGO-Carburetor-Synchronizer-/230538549941?pt=Motorcycles_Parts_Accessories&hash=item35ad2b1ab5

[Condor]

Nothing to send back - I would not own such a poor tool!

 

But they all rattle - even yours. They have to - that is a specific design feature. And it is even referenced in the instructions; although, I don't think they actually use that word.

 

But in whatever words they choose, the instructions specifically tell you that if you cannot see the rods rattling in the plastic tubes, then you cannot trust the reading.

Goose

 

So, correect me if I'm wrong here, but what you're saying is that you've never owned one, maybe only used one once or twice, but feel experienced enough to critique the CarbTune?? And that since their webpage uses the term 'rattle', that it means the rods are a sloppy fit in the tubes, and not maybe their expression for the up and down pulsing of the rods?? I also need to find your website reference to 'rattle'. I just searched most of the pages that might have a reference to rattle and couldn't find a thing?? I did find reference to smooth rod operation, and machined fit.

[V7Goose]

So, correect me if I'm wrong here, but what you're saying is that you've never owned one, maybe only used one once or twice, but feel experienced enough to critique the CarbTune?? And that since their webpage uses the term 'rattle', that it means the rods are a sloppy fit in the tubes, and not maybe their expression for the up and down pulsing of the rods?? I also need to find your website reference to 'rattle'. I just searched most of the pages that might have a reference to rattle and couldn't find a thing?? I did find reference to smooth rod operation, and machined fit.

You are wrong in most aspects of this statement other that what you may or may not have seen with your own eyes.

 

True, I have never owned one - thankfully I didn't need one so I did not get sucked in by all the people who seem to think they are great. But I have used at least four different individual Carbtune Pro tools to sync well over 50 Royal Stars, plus a few other bikes. And one of those was brand new in box that a friend brought to me to show him how to use. That particular one came from the manufacturer with the four tubes NOT reading the same vacuum (out of calibration), and it is exactly why I know that the manufacturer says it CANNOT be calibrated, as well as the rest of what they said in the instructions.

 

BTW - despite their claim that the tool could not be calibrated and their attempt to physically prevent it from being done, I was able to fix that defective tool so that the disappointed purchaser could at least use it.

 

All four of those tools showed the same major faults, even the brand new one. First and foremost, the rods STICK in the tubes, and they stick A LOT. The only way you can get a reading that is close to accurate is to constantly tap on the tubes, causing the stuck rods to begin vibrating (rattling) again, at which time they will jump up or down to the proper reading until they stick again. The other fault that I consider major is that the tool must be held perfectly vertical or it won't read properly at all.

 

So yes, I DO feel experienced enough, both with this tool and all the other types of sync tools, to accurately criticize it. In fact, I suspect I have a lot more experience with it than you or the majority of other owners.

 

I never gave a "website reference to 'rattle'." In fact, I never claimed to have seen Morgan use that specific word at all. I did say that the rods rattled, because they in fact do. And I did say that they had to rattle because the design requires it, no matter what term the manufacturer uses to describe it. I do find Morgan's use of the term "smooth rod operation" to be somewhere between a sick joke and deceitful dishonest lies to sucker potential customers. But that is just my opinion.

 

And no, rattling is not an expression of the up and down puling of the rods; it is specifically a side-to-side rattle or vibration that is caused by the air rushing around the rod in the plastic tube. If the rod is not rattling like this, then it must, by design, be stuck. A "rattle" is both a type of motion and an audible sound (although everything that rattles does not have to sound like a rattle). Nevertheless, if you were to put a steady vacuum on your tool in the shop in an attempt to check the calibration, the audible rattle of the rods would be very obvious.

 

Finally, I will note that in both this and several older threads on the same subject, I have posted not just my opinion on the tools, but very specific observations and technical explanations so that you or any other possibly interested readers can actually understand what causes me to have those specific opinions and then decide for themselves instead of just having to guess whose opinion they might want to blindly follow.

Goose

Edited October 18, 2010 by V7Goose

[ken]

Sooooooooooo........... Is the vacume dial type ok for our bikes???????? http://cgi.ebay.com/ebaymotors/EMGO-...item35ad2b1ab5

[V7Goose]

Sooooooooooo........... Is the vacume dial type ok for our bikes???????? http://cgi.ebay.com/ebaymotors/EMGO-...item35ad2b1ab5

Any sync tool will work just as well on our bikes as it does on any other bike.

 

The dial gauges are my preferred type of sync tool for any bike. They are reasonably priced, rugged, and accurate.

Goose

[ken]

Any sync tool will work just as well on our bikes as it does on any other bike.

 

The dial gauges are my preferred type of sync tool for any bike. They are reasonably priced, rugged, and accurate.

Goose

 

Great!! Thats what I was looking for. I see them on ebay for around 50 bucks or less.

[Condor]

Finally, I will note that in both this and several older threads on the same subject, I have posted not just my opinion on the tools, but very specific observations and technical explanations so that you or any other possibly interested readers can actually understand what causes me to have those specific opinions and then decide for themselves instead of just having to guess whose opinion they might want to blindly follow.

Goose

 

I find your criticism curious in that there are so many users of the CarbTune world wide who are perfectly satisfied with it's performance, but your opinion seems to always be 'anti' to the norm. I guess you're just smarter than the rest of us...

Edited October 19, 2010 by Condor

[Freebird]

I can actually see both sides of this issue. I own the Carbtune and have used it for many years. I am 100% confident in the job that it does. I also agree with Kent though that they are NOT without their faults. I have indeed found that the rods can stick and require tapping on the tubes to make sure that they are moving freely. I have found though that if you remove them from time to time and clean them that they rarely stick. I have checked mine by hooking each to the same port and found them to be accurate if clean and the tubes held vertically. I have NOT found that they have to be held perfectly vertical but they have to be pretty close to vertical.

 

I do actually think that the dial type vacuum gauges are a better choice. I will continue to use my Carbtune but if I found myself in the market for a new tool for doing this job, I would probably go with the dial gauges.

[KiteSquid]

ANY mechanical measuring device can go out of calibration.

 

With a gauge type you have four gauges so you have four mechanisms.

 

The Mercury type cannot go out of calibration, but there are the above mentioned toxicity issues.

 

 

I personally have a set of Mercury sticks......

 

 

 

Oh and you may want to read the thread at THIS link

Edited October 19, 2010 by KiteSquid

[LilBeaver]

I'm not trying to split hairs or be a smart alec or anything, I am purely curious about two points that I hear repeated a lot when comparing the Morgan CarbTune to the dial-type gauges.

 

1) So what is the difference between a rod that vibrates (rattles) and a dial gauge with a fluctuating needle?

 

2) While there is not some way to adjust where the rods go to on a CarbTune, since all these tools are designed to do is measure a relative pressure - the actual calibration of the instrument is irrelevant. What we care about is the precision of each column (ie. the reproducibility of a particular reading upon successive measurements between the columns). With a dial type gauge you can simply adjust the 'zero point' or where the needle goes at a particular measurement. If you choose to and have the appropriate equipment I suppose you could actually do a real calibration on them too to arrive at an accurate reading, if you are so inclined or care. With the CarbTune, what one can do is simply hook each individual column up to the same port on the carb (or some other type of standardized measurement device) and then note for each column where the rod resides/what the reading is. Now you have a single source and a reading on four different columns and now one can easily extrapolate appropriately to adjust as necessary. To be more complete, you could repeat this at a variety of pressures (or just hook it up to the other ports on the carbs) and repeat the consistency check.

Since all we use the carbtune for is measuring the relative pressure at each port, provided one checks the consistency of each rod's reading, I don't understand why this tool is such problem.

 

For what it is worth, I borrowed a CarbTune from a fellow member here a while back and I did this consistency check. I repeated the measurement twice per rod on each port on my carbs. My results were surprisingly good I found that overall the rods all consistently read within 1/2 unit of each other (I don't remember what the full scale is on the carbtune) but that was close enough for me.

[V7Goose]

I'm not trying to split hairs or be a smart alec or anything, I am purely curious about two points that I hear repeated a lot when comparing the Morgan CarbTune to the dial-type gauges.

 

1) So what is the difference between a rod that vibrates (rattles) and a dial gauge with a fluctuating needle?

 

2) While there is not some way to adjust where the rods go to on a CarbTune, since all these tools are designed to do is measure a relative pressure - the actual calibration of the instrument is irrelevant. What we care about is the precision of each column (ie. the reproducibility of a particular reading upon successive measurements between the columns). With a dial type gauge you can simply adjust the 'zero point' or where the needle goes at a particular measurement. If you choose to and have the appropriate equipment I suppose you could actually do a real calibration on them too to arrive at an accurate reading, if you are so inclined or care. With the CarbTune, what one can do is simply hook each individual column up to the same port on the carb (or some other type of standardized measurement device) and then note for each column where the rod resides/what the reading is. Now you have a single source and a reading on four different columns and now one can easily extrapolate appropriately to adjust as necessary. To be more complete, you could repeat this at a variety of pressures (or just hook it up to the other ports on the carbs) and repeat the consistency check.

Since all we use the carbtune for is measuring the relative pressure at each port, provided one checks the consistency of each rod's reading, I don't understand why this tool is such problem.

 

For what it is worth, I borrowed a CarbTune from a fellow member here a while back and I did this consistency check. I repeated the measurement twice per rod on each port on my carbs. My results were surprisingly good I found that overall the rods all consistently read within 1/2 unit of each other (I don't remember what the full scale is on the carbtune) but that was close enough for me.

Well Sir, the answer to #1 lies in the fact that the two tools function on TOTALLY different operating principles. The mechanical gauge actually measures vacuum, while the rattling rods only measure air flow, which is simply an approximation of vacuum. The distinction is quite simple: if you put a vacuum pump on the mechanical gauge and draw a static vacuum, the gauge will hold that vacuum indefinitely until the line is removed from the input. The rattling rod system will not hold any reading whatsoever. The rod is only raised in the tube so long as some source continues to suck air through the tube.

 

For the purpose of synchronizing carburetors, the distinction is not too important, except for one thing. Since air and contaminates are constantly being sucked through the tube and around that rattling rod, it gets dirty constantly, which ABSOLUTELY MUST change the reading and contributes to the major problem of sticking. Furthermore, even when new and clean, the rod often gets stuck against the side of the tube so that all the air rushes around one side (that is why holding the tool vertical is so important). When this happens, the position of the rod does not register small changes of air flow at all. Your ONLY indication that it is not stuck is to constantly look for the rattle, and even then I don't trust it!

 

So to sum up the answer to #1, all tools that read vacuum will pulse between intake strokes on a slow-turning engine. On the rattling rod, that is shown by up and down movement, not the vibration or rattle that is required to even allow the rod to move at all. The air-flow through the instrument that requires the rod to rattle just to be able to move is a unique and very poor design principle.

 

#2 - the inability to adjust the rod position to calibrate the tool is a HUGE MAJOR flaw for the rattling rod tool. I don't care if you think it is important for the tool to accurately show 11" of mercury or not, it is CRITICAL that all four rods or gauges show the identical vacuum when connected to a single vacuum source. This might even be more important for some people with the rattling rods, since the "goal" is to get all the rods to line up perfectly.

 

Of course it is 'possible' to just know that maybe the 2nd rod always reads 3/4" low, and the 4th rod always reads 1/4" high, then remember this and adjust the carbs to reflect such an out of calibration reading, but that is fraught with errors. And just because it would be possible, why in the world would you want to be forced to do that? Far better to just perform a simple bench calibration so that all the gauges read the same vacuum and then just use the tool as it is intended.

 

Finally, I do care a LOT about having an accurate reading of the vacuum on each gauge. It does not need to be laboratory type accurate, of course, but I want to be able to rely on what I measure. First, the standard for carburetor synchronization on this machine is to have no more than .4" Hg between any two carbs (that is the relative measurement you mention), but it is also important to know that the specification for this engine is to pull 280mm or 11" Hg at idle. Here is something that puzzled me for a couple of years - not all of these bike will pull 11" at idle, even when they seem to run well.

 

After working on a number of them with really fouled up carbs I now have the answer to this conundrum, but it raises even more questions about actually getting a good "sync". If the pilot jets are partially clogged, the idle adjustment will have to open the slides more just to maintain the idle RPM by sucking some fuel through the main jets, and this is exactly what causes a lower vacuum reading. Since the idle adjustments affects all four carbs together, even one clogged pilot jet will affect the vacuum readings on all four cylinders. While you can still get a proper carb sync in this situation (the vacuum is only a function of the engine condition, valve timing and intake restriction), the bike will obviously not run as well or as smoothly. A bike will almost certainly have some continued popping on deceleration, and I think it also explains whey some bikes will not hold the same sync at 3,000 RPM as they do at 1,000 RPM. I used to just scratch my head, but not worry about a bike that would not pull over 10" Hg while I was syncing it - but now I think it is real indication of carburetor problems.

 

But back to the main subject of your questions and the general tone of this entire thread - I'll sum up my thoughts on the Morgan Carbtune Pro. I have never said this tool cannot be used effectively, or even trusted. In fact, I have used it effectively on well over 50 different bikes. But I do find it a HUGE PIA to use, and unlike Freebird, I am never 100% confident with it - after constant tapping and re-checking I am reasonably confident that a bike has a good sync, but I wouldn't say 100% since the problems with the tool are always nagging at me. And it is because of the problems I find with this tool that I think it is a very poor tool - IMHO it would be overpriced at even $10.

 

In contrast, I find either mercury stix or dial gauges simple to use and they do give me 100% confidence. For those of you who have different opinions - great. I'm happy for you. Enjoy your tool of choice, but if you are going to recommend it to someone else, try to actually give them some real reasons why you like it.

Goose

Edited October 19, 2010 by V7Goose

[KiteSquid]

I'm not trying to split hairs or be a smart alec or anything, I am purely curious about two points that I hear repeated a lot when comparing the Morgan CarbTune to the dial-type gauges.

 

1) So what is the difference between a rod that vibrates (rattles) and a dial gauge with a fluctuating needle?

 

2) While there is not some way to adjust where the rods go to on a CarbTune, since all these tools are designed to do is measure a relative pressure - the actual calibration of the instrument is irrelevant. What we care about is the precision of each column (ie. the reproducibility of a particular reading upon successive measurements between the columns). With a dial type gauge you can simply adjust the 'zero point' or where the needle goes at a particular measurement. If you choose to and have the appropriate equipment I suppose you could actually do a real calibration on them too to arrive at an accurate reading, if you are so inclined or care. With the CarbTune, what one can do is simply hook each individual column up to the same port on the carb (or some other type of standardized measurement device) and then note for each column where the rod resides/what the reading is. Now you have a single source and a reading on four different columns and now one can easily extrapolate appropriately to adjust as necessary. To be more complete, you could repeat this at a variety of pressures (or just hook it up to the other ports on the carbs) and repeat the consistency check.

Since all we use the carbtune for is measuring the relative pressure at each port, provided one checks the consistency of each rod's reading, I don't understand why this tool is such problem.

 

For what it is worth, I borrowed a CarbTune from a fellow member here a while back and I did this consistency check. I repeated the measurement twice per rod on each port on my carbs. My results were surprisingly good I found that overall the rods all consistently read within 1/2 unit of each other (I don't remember what the full scale is on the carbtune) but that was close enough for me.

 

 

For me the Morgan Carb Tune would be easier to use than a set of gauges as the indicators are in line and it is easier to see if they are relatively in line with each other.

 

On the gauge type you have to "read" four dials that are spaced across a board.

 

 

HOWEVER I own a set of Mercury carb sticks that will NEVER go out of calibration. but this is a moot point for me as I no longer own a four cylinder engine that has separate butterfly's... so it just hangs on the wall like my soroban, slip-stick and HP 67.