Carb Synch Tools Accuracy

[Shuriken]

Does anyone have any opinions on the accuracy of the various carb synch tools available, including homemade tools?

I have had the Morgan Carbtune for years now, but I think it's time for a replacement or something new. If I test vacuum on of my bike's cylinders by connecting to Carbtune port #1, measure vacuum, and then move the tube to Carbtune port #2, I get different readings. As a whole, it seems all 4 are constantly off. Naturally, this makes it hard to synch a bike.

Anyone else seen this on the Carbtune? What other options do we have?

Ben

[DiverRay]

Ben,
I've used the mercury tube type sync tool for years. I've been very happy with it, and it's easy to use. Warm up engine, shut down, plug a tube into each carb, and start engine again. Check that all four tubes are sitting almost level with each other, and your done. the nice part is you can set 1&2, 3&4, and then the two pairs together with ease. It does NOT matter how much vacuum you have. All you do is set all four to the same line, and then check by rolling the throttle up to about 3,500RPMs. Don't forget, USE A FAN to keep the engine cool.

[red bandit]

You didn't say how much diff. between #1-#2. I used a homemade one for a while, fish tank 4-way valve, everytime the rpm changes the vacumm changes, can be a little PITA going back and forth. I don't like the mercury tubes because if you blipp the throttle or lay/fall them down... there goes the mercury. I like the 4 gauges, I tee'd them all together and checked/adjusted all the gauges so they all read the same before I used em. I try to get em about a half lb. or so. I don't worry to much about the #'s, as long as they idle smooth that's all I care about. Some people will say the mercury sticks are more accurate but I don't think you would be able to tell the diff.

[mro]

Have you read this thread

http://www.xs11.com/forum/showthread...r&pagenumber=1

mro

[webbcraft2150]

I to have used the mercury sticks with no complaints. I have never been able to get all four the same but real close. There are some sync tools that do not use mercury or dial type gauges. Hippie Dave had one that would fit in you pocket and used a steel ball in the tubes to dial in the carbs. Maybe he will chime in here and tell us where he got it.

[John]

The item that Hippy Dave has is a Morgan Carb Tune. He brought it with him when he attended the Meeting of the Minds last year. It used metal rods instead of mercury. I used them on WK's 81 SH, and they worked great. You could rev the engine and not worry about injesting the mercury.

[Shuriken]

I also have the Morgan Carbtune, but I'm questioning them. They don't seem to move as well as they did years ago. Weather seems to affect them as well, as they are made out of plastic and rubber peices that are affected by heat and cold.

I haven't been able to get trustworthy results out of them anymore. If you properly synch the carbs and the bike runs worse, something is up. So you go back to the guages and they indicate different readings every time.....

If liquids are more accurate, I might try them.

Lately, I've been trying to get by using only one of the rods in hopes of more consistency.

Ben

[AlanB]

Hi Guys,

Anything which works by gravity should be accurate, and not need calibrated......

I have always had issues with "Dial" type gauges, but columns are usually OK!

To check the gauges, don't try one column on different cylinders, Try each of the columns on ONE CYLINDER!....all should read the same.

AlanB

[egsols]

I use a single vac gauge hooked to an aquariam manifold with a pcv tube damper.

I really don't care about the accuracy of the gauge. I only care that I get all of the carbs to read the same.

As I understand we are trying to sync the carbs. If we use four different gauges, be they vaccum or tubes filled with fluid, we first have to make sure that the four devices are themselves synced!


My 2 cents.

[planedick]

Best one...

The Motion Pro mercury synch tool is by far the best. IMHO Some suggest that you could suck the mercury into the engine, but that only shows they don't know how to use it. On the back there is a short tube that connects to the resevoir and one of two posts on the back above the resevoir. If you look closely at those posts you will discover one has a slit down the side to let in air and the other does not. When first synching your carbs, start with the hose on the post without the slit and get them close and because there is created a vacuum in the resevoir you cannot suck the mercury into a cylinder. After you get them close you can move the tube to the post with the slit and the level of mercury will be much higher and much more sensitive so you can get them really close. When using the synch tool this way do not suddenly drop the throttle from high RPMs to idle so you don't create such high vacuum to lift the mercury over the top.

I have tried many types of synch tools and except for those costing around $500 the Motion Pro is the best for your money, around $50.

[AlanB]

Hi Guys,

Can you still buy mercury gauges over there?

I believe that they are all off the market here.

Any one feel like shipping a set over the pond?

AlanB

[79XS11F]

My own experience with "getting them all the same" is to do it with the engine HOT after a 20 or 30 min run. Make very very tiny adjustments at a time when you get them close. You may notice that just pressing downward even lightly with the screw driver will change the readings. Between adjustments give the throttle a twist and let it go so it returns to a true static position before adjusting again.
Rob

[planedick]

In some states

Some states like California don't allow the sale of them, but I got mercury refill at Cycle-Re-Cycle. Internet search will get you a list of distributers and you can probably get one to ship to you.

[Winterhawk]

I like my K&L's