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If one of the carbs doesn't show any movement then that means the vacuum on the other two exactly balances against that one. That's a condition I would think was hard to hit accidentally, and transitory.

The idle adjuster works directly on one of the carbs; #2, I believe. You need to use the adjustment screws to make #3 and #1 match. The manometer is measuring the differences between the three, and adjusting one will affect the readings of the others, so you have to keep that in mind. Go back and forth between 1 and 3 until you get them all about the same. If you can put a restrictor in each line the readings wil be more stable. 1/16" hole in the restrictor is plenty. The manometer is very sensitive. If you can get them within an inch or so you're fine.

Bubbles? Is there a leak in the manometer? What are you using for a fluid? If it boils under vacuum... I use ATF.
 

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I tried the home made tool and had similar results, by results I mean it pissed me off and I didn't get anywhere balancing the carbs. I spent hours taking everything off, checking boots, clamps, carb settings, filters.... I finally solved the problem by breaking that shtt tool in half and waiting for a proper tool to come in.

I even had a thread asking about why I couldnt get the carbs balanced with the home made tool.

Some people get it to work, it must be a magic bit of tubing or the perfect batch of two stroke oil. The home made tool is just as bad as the vacuum gauges, it's bounces all over the place so you guesstimate where you're balanced. I was shocked at how well and easy it was to do with the Morgan Carbtune tool (I'm not a paid spokesman) I lent to a "professional" and the guy crapped his pants.

***** back to balancing*****

The idle speed adjuster moves the 2 carb. The screws where the throttle arms interconnect moves the individual butterflies for the 1 and 3. Get your bike to idle at 1,500 rpm and start balancing there. If you have a carb way out it will suck all the fluid out of that home made tool.

I don't remember which way to turn the screws to increase or decrease but the slightest amount will make a difference. Just the pressure from your screwdriver on the head should show a difference.
 

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Turk, I sent the new Motion Pro back to the ebay seller (due to arrive tomorrow) because the thing wouldn't function ass directed. It sucked all the fluid in to #1.

I suppos eat this point, I'll go through and do another bench test and check the caps for leaks.
There is a screw on each tube that I believe your suppose to, shoot, which one is it, either open or close to keep from sucking all the fluid in. In the instructions your suppose to get the bike to normal operating temp then hook up the carb tune, 1st plug that short length of hose with the adapter that the other 3 hoses plug into into the#2 master carb, you adjust each screw on the carb tune to make it so all 3 tubes with the dyed fluid in them are running the exact same height. once you have that set then you just hook up the carb tune vaccuum hoses to the vaccuum inlets on the carbs and your good to go. if you have it hooked it up from a cold start and you use the choke, the engine is revving to high and will thus suck all that dye liquid in.
 

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The manometer measures the differences between the carbs. For this reason, you must hook all three up before you start the engine, otherwise the one you hook up first will swallow all the fluid.

If your bench sync is any good and your manometer is 5 feet tall you shouldn't have any trouble with the fluid.

The readings are more sensitive at lower RPM, for 2 reasons. First, the differences between throttle plate settings are exaggerated when the throttles are nearly closed, and second, the manifold pressure is closer to atmospheric pressure at higher throttle settings.

Remember, the goal is to get them all the same at idle. Absolute readings are irrelevant.

The Morgan Carbtune is a fine piece of kit, but I'll bet I can sync any 2, 3, or 4 cylinder bike with my manometer and get it just as good. Being part Scottish, the choice for me is clear! ;)
 

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Discussion Starter #25
If you can put a restrictor in each line the readings wil be more stable. 1/16" hole in the restrictor is plenty. The manometer is very sensitive. If you can get them within an inch or so you're fine.

Bubbles? Is there a leak in the manometer? What are you using for a fluid? If it boils under vacuum... I use ATF.
I'm using 2stroke oil for the liquid. The airline is 3/16 aquarium air line.
 

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I suppose my homemade manometer would read a little more "smoothly" with ATF or other oil as a fluid, but it works just fine for me with plain water. It is VERY sensitive! Like Rollin says, you can easily see the effect of just slight screwdriver pressure on the adjust screws. And this sensitivity means that when you first start adjusting, if you are off very much, it can be frustrating when one cylinder very quickly sucks up all its fluid.
 

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Discussion Starter #27
I suppose my homemade manometer would read a little more "smoothly" with ATF or other oil as a fluid, but it works just fine for me with plain water.
Do you get 'bounce' that causes air bubbles?
 

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My only problem with bubbles was with a couple of my fittings that were not QUITE vacuum-tight. A wrap or two of tie wire fixed that.
 

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... it works just fine for me with plain water. ... it can be frustrating when one cylinder very quickly sucks up all its fluid.
And that's why I don't use water! ;)

I don't see how you could get bubbles into the fluid other than a leaky fitting at the bottom where the tubes join. It's unlikely you're pulling enough vacuum to boil 2-stroke oil!
 

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Do you get 'bounce' that causes air bubbles?
Was wondering if the Motion Pro carbtune you had came with the little brass restrictors that you push into the vacuum lines to keep the fluid from bouncing? Also WSC I meant that you bring the engine up to operating temp, shut it down, then hook up the carbtune.
 

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Discussion Starter #31
Was wondering if the Motion Pro carbtune you had came with the little brass restrictors that you push into the vacuum lines to keep the fluid from bouncing? Also WSC I meant that you bring the engine up to operating temp, shut it down, then hook up the carbtune.
Turk...
the brass restricters were in the tubes per instruction. Bringing the engine to operating temp seems to be the methos for all sync tests, minus the bench sync.
I zip tied all of my tubes to the nipples and will get out tomorrow to give it a test. I'm out of gas at the moment.....
 

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Discussion Starter #32
A sight to behold.

Best kept under your jacket. When buying the fuel you need.

:grin2:

....mind in the gutter, today?
:)
 

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Hi interesting post. I would like to ask where do I start with the synchronising. I was told to set the idle screw at a high idle then adjust 1 and 3 to tge same tgen use tge idle adjustment to bring it down to 1000RPM is this correct. My carbs are running at 0.4 0.3 0.4. Both exhausts are smoking a bit running rich I expect. What is tge correct procedure
 
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