Carb sync tool

[Rein]

So I was searching for one and came across this homemade one:

http://www.vfrdiscussion.com/forum/lofiversion/index.php/t16200.html

Now, would this work for our bikes? You just need the vacuum to be equal, right, not at any specific measurement. I have all the parts for this already, just wondering if it would work.

 

[Guest]

That should work & yes, all you are really doing is comparing the vacuum between cylinders, not setting them to any pre-established vacuum level.

For the CV carbs, you want cylinders 1 & 4 to be equal, with cylinders 2 & 3 also equal to each other, but just a tad lower than 1 & 4 (maybe 2-3 mm less).

However, the best bet is to just buy a carb sync tool, the best one out there is (IMHO) is:

http://www.carbtune.com/

 

[KiwiGS]

That should work & yes, all you are really doing is comparing the vacuum between cylinders, not setting them to any pre-established vacuum level.

For the CV carbs, you want cylinders 1 & 4 to be equal, with cylinders 2 & 3 also equal to each other, but just a tad lower than 1 & 4 (maybe 2-3 mm less).

However, the best bet is to just buy a carb sync tool, the best one out there is (IMHO) is:

http://www.carbtune.com/

Yes it will work, just remeber water/oil are alot lighter than merc so you will need a much bigger gauge like between 13 and 14 times longer.
If you have a header that doesnt have a crossover then I think you want all 4 at the same vacuum, I may be wrong but that is what have done.
Cheers

 

[Steve]

Yes it will work, just remeber water/oil are alot lighter than merc so you will need a much bigger gauge like between 13 and 14 times longer.

Not sure about the exact length necessary, but did you notice in the link to that homemade item that the tubes were SEVEN FEET LONG??

There have been many versions of homemade manometers shown on this board, ranging from the one linked above to a single gauge with an aquarium manifold to switch between the cylinders. In the opinion of many here, you really need something that allows you to see the vacuum level for all four cylinders at the same time. The vacuum levels are so inter-related, if you change just one adjustment, it affects ALL of them. If you do this with only one gauge, you will be busy for a LONG time trying to get them all to match.

.

 

[1948man]

If you get the Carbtune for 4 cylinders, I assume that could do double duty syncing a V twin no problem. You would just use 2 tubes, right?

 

[Steve]

Correct. I have not used a Carbtune, but I have used other multi-cylinder units.
With some, you might have to plug the other two inlets, with others, you can leave them open.

By the way, you can use it unless the V-twin in question is a Harley. They only have one carb, so there's nothing to sync.

.

 

[rustybronco]

If you do this with only one gauge, you will be busy for a LONG time trying to get them all to match.

5-10 mins with VM's. 15-20 mins with CV's.

EDIT ***if the bench synch was close to begin with***

 

[earlfor]

If you get the Carbtune for 4 cylinders, I assume that could do double duty syncing a V twin no problem. You would just use 2 tubes, right?

Yes, just connect the carbtune to however many cylinders you have. It will even work if you only have one cylinder. LOL

Earl

 

[earlfor]

Forget trying to synch a 4 cylinder engine with a single vacuum gauge. It can be done, sort of, but it can NOT be done accurately. Any adjustment on one carb will change the values on the other three, so you would always be adjusting in the blind and guessing as to what the values had changed to on the three you will not be able to see.

Earl

 

[Speedo]

earlfor-thx for the laugh. I needed that today. Sometimes i wish I only had one cylinder; and sometimes it FEELS like I only have one left:-k

Once again, listen to the guys below. Especially Steve and Earlfor. You need a synch tool to look at all 4 at same time to do this right. Don't mess around.

I bought a "Carb-Stix" mercury synch-er 20 yrs ago, have moved 7 or 8 times since, and the thing has survived and still works just fine. I also made a temp gas tank out of a coffee can w/gas line hose "gooped" into a drilled hole in can to keep bike running w/o gas tank on there while synching....and believe it or not, that too has lasted 20 years

I am intriqued by some other posts i am reading that say there is a mano sold now that you can use to test while actually riding.

 

[Rein]

I was just curious, what's the difference between this and the mercury one from motion pro? Other than the obvious (liquid, size, etc). how about the emgo with the vacuum gauges?

Don't the mercury ones (motion pro) operate on the same principle, although jus tmore elegant? Or are they all separate reservoirs of fluid?

How about the Emgo vacuum gauge type ones on z1?
Or are they just vacuum gauges that are separate from each other, IE one gauge for each carb? cause I have a load of hose and vacuum gauges from my past air compressors.

 

[outlawfox13]

I have seen that design on the net before, but I like one that I found on this site, let me look for the link, will edit when I find it.

Edit: http://www.thegsresources.com/_forum/showthread.php?t=140793&highlight=homemade+manometer&page=3

 

[Nessism]

Vacuum gauges will work as long as you calibrate them first by hooking each gauge up to the same vacuum source one at a time and making sure they all read the same value.

Regarding that Motion Pro model, they switched from mercury to some other fluid very similar to ethylene glycol a few years ago and the change hasn't been a good one in terms of functionality for the unit.

Although I have never used one I'd just drop the money and get a Carb Tune since the feedback has been almost 100% positive from people that have owned and used them.

 

[Baatfam]

Regarding that Motion Pro model, they switched from mercury to some other fluid very similar to ethylene glycol a few years ago and the change hasn't been a good one in terms of functionality for the unit.

Although I have never used one I'd just drop the money and get a Carb Tune since the feedback has been almost 100% positive from people that have owned and used them.

To be fair to the Motion Pro folks, I got one of the new ones, with the blue fluid, last year and used it on my 1100E...seemed to work fine.
I still purchased a Carb Tune this year because they are suppose to be so much better and rechecked the 1100E with it.
No changed needed. It was still right on from the Motion Pro.

I will say the Morgan Carb Tune was easier to use, although the connection things are nowhere near as nice as the Motion Pro ones....

 

[Guest]

To be fair to the Motion Pro folks, I got one of the new ones, with the blue fluid, last year and used it on my 1100E...seemed to work fine.
I still purchased a Carb Tune this year because they are suppose to be so much better and rechecked the 1100E with it.
No changed needed. It was still right on from the Motion Pro.

I will say the Morgan Carb Tune was easier to use, although the connection things are nowhere near as nice as the Motion Pro ones....

I also have BOTH the "new" Motion Pro & the Carb Tune tools - they both work well, but as you say, the Carb Tune is easier to use. A couple other advantages of the Carb Tune:

- Since it doesn't use fluid, there's nothing to accidently suck into the engine when over-rev'ing, or sync'ing at elevated RPM's.

- No need to "standardize" the fluid heights between each column, with every set of carbs - the rods are already calibrated, & they never change.

 

[Nessism]

I also have BOTH the "new" Motion Pro & the Carb Tune tools - they both work well, but as you say, the Carb Tune is easier to use. A couple other advantages of the Carb Tune:

- Since it doesn't use fluid, there's nothing to accidently suck into the engine when over-rev'ing, or sync'ing at elevated RPM's.

- No need to "standardize" the fluid heights between each column, with every set of carbs - the rods are already calibrated, & they never change.

Hey Mike,
There is no calibration with the old mercury type type. How do you "standardize" the new type Motion Pro unit with the blue fluid?

Regarding the Carb Tune, one guy here said the unit needs to be calibrated to one vacuum source so was that bad info?

 

[Guest]

Hey Mike,
There is no calibration with the old mercury type type. How do you "standardize" the new type Motion Pro unit with the blue fluid?

Regarding the Carb Tune, one guy here said the unit needs to be calibrated to one vacuum source so was that bad info?

The Blue Motion-Pro unit has to be standardized every time by attaching the hoses one-at-time to the same carb vacuum - then use the adjustment screw at the bottom of each column to raise/lower the fluid heights so they all start at the same level/value...

The Carb Tune has no adjustments to tweak (at least none you're supposed to mess with) because the weights of each rod have already been balanced from the manufacturer.

 

[Don-lo]

With mercury stix, the pool of liquid is vented, so the vacuum is raising the weight of the liquid (and mercury is very heavy, so it is the most stable). With this vf forum tool, there is no venting. Since liquids do not compress, how do the lines move? The plastic hoses themselves are collapsing, allowing the fluid to move upward. It's a neat idea, since it will be automatically leveling. I don't see how it can draw the fluid up to the engine unless a leak occurs in a bottom tee, or they use extremely thin tubing. The setup should be self dampening too, so the restrictors shouldn't be needed (lol, they seem to think the restrictors will keep fluid out of the motor)