How To: Make a 2 bottle synch tool

Everyone needs a sync tool to get the bike performing at its best. I have put together this post to assist all in this needed component for making your XJ alll that it can be & not spend a fortune doing it. Hope it helps.

What you need:
1. 2 bottles - I used 8oz glass baby bottles with oz measurements on them.
Purchased at Kmart for $5.95 + tax. You get 3 bottles which is good if
you break one.

2. 2 rubber plugs - bottle opening is 1 1/8"ID so narrow end of plugs need to be 1". Purchased at Lowe's $2 plus

3. Clear tubing - Approx 15', I used 1/8"ID tubing, it was tight fit on carbs
but worked fine. You may want to use 3/16"ID instead.
Purchased at Tractor Supply $3ea plus for 2 10' coils.

4. 1 quart of automatic transmission fluid - ATF


How you put it all together:
1. Drill 2 holes in each plug. Holes size based on OD of tubing used. Mine was 3/16"OD so I used a 3/16" drill bit. Make sure holes do not join or go thru the side of plugs.

2. Cut a length of tubing - Mine is approx 22" long - this will be the syphon tube between bottles that fluid will pass thru to equalize vac in each bottle. Push each end of tube thru one of the holes in each plug - put plugs in bottles & push tubing thru till end is touching bottom in each bottle.
Turn each plug so this tube is on the inside of the setup.

3. Cut 2 more lengths of tubing - I used 5' for each - Push one end of tube thru remaining hole in plug - push tubing thru till end is sticking out of plug. Do same with other tube in remaining plug. These are the lines you will connect to the vac fittings on your carbs for syncing. You may want longer or shorter lines depending on your needs - MO long is better.

4. Pull plugs from bottles, put 3oz of ATF in each bottle - put plugs back in & happy syncing.

5. Rack setup is in was stolen from the guest bathroom, just removed soap & lotion bottles.

Setup works great & is very accurate.

If anyone has questions ask away.

 

lol

that looks like a hooka

 

A hooka for carbs Flash.

 

Nice explanation greg, I love the rack, makes it look very professional!

 

Well, that has to be one of the niftiest tricks I've seen... Definitely going to give this a whirl! Thanks for the tip.

 

Ace, just had to sweet talk the wife out of the soap/loation rack from the guest bathroom.

DianCecht, your welcome. If The ATF gets sucked into your carbs it won't mess anything up. The bottles are graduated so you can see what level each bottle is at. It works really good.

 

greg, I just made one of your rigs, and it works great. I couldn't get rubber stoppers, so I got two bathroom-sink plugs, and used the ring that holds the baby bottle nipple on to hold down on the sink plugs, makes a nice tight seal.

 

Ace, good idea on the sink plugs. They were probably cheaper than the rubber stoppers. Glad you like the setup, I know it worked great for me.
Gregg

 

<--- Sync Noob.

So once built, you sync left two cylinders together, then right two, then both pairs? Correct? (only seen this done with carb stick w/ 4 lines that's why I ask)

 

dpawl, synch #4 to #3 (#3 is not adjustable on xj's) Synch #1 To #2, then syunch #2 to #3. You should be running like the wind after you done.

 

Im going to make this tool, but... what are you looking for while syncing? This is my first time doing this. Are you trying to get the fluid to stop flowing? A little instruction on how to synch would be great for this thread. Thanks, Lou

 

#3 is the "master" carb with the idle, essentially #4 carb adjusts to #3 independently of 1 and 2.
The bottles are hooked to 3 and 4, and you tweak until the levels are the same, but there may be a little back-and-forth even when they are perfect.
Then, connect 1 and 2 up, plug off 3 and 4.sync them together, then sync 2 and 3. As you adjust #2, #1 follows along, as it's connected to #2.
Problem is, if they were all way off, #3 and #4 will be off a little now, so you have to do it all over again, and , as you tweak-in your Pilot screws, the sync changes slightly.

Which is why I built the 4 tube set-up.
I can tweak the 4 Pilots and the 3 sync screws in any order and any amount without shutting down the bike.

 

Lou, your looking for the fluid leve in each bottle to be the same. If one bottle is higher the carb attached to that bottle is pulling more vac. Once you have the levels the same in each bottle, move to the other set of carbs. Hope that helps.
Gregg

 

I'm definatly gonna have to try this. I'm not gonna have my nieghbors Elec sync forever!
Question though! Where do you attach your vac Line for your petcock during the syncing of 1 and 2 and two and three. My Vac Line is connected to #2

 

SL, just attach it to any of the other vac fittings. The fuel valve doesn't care where the vac comes from as long asa it is getting vac.
Gregg

 

Either that or just set the petcock to PRI.

 

Brilliant! Didnt even think about that. Pri got me in trouble once so I'm tryin to steer away from it lol!

 

So I'm sync my carbs right now and have a question so I'm perfectly clear: I see a few people above mention the fluid should the same in both bottles BUT I'm thinkin it just needs to be Not Moving. whadayathink?

 

awsome, i've got tons of baby bottles laying around. the wife loves when i spend money on stuff for the bike, well maybe not but i do anyways. lol

 

DOLLAR each at dollar store/family dollar

 

I would think it would need to be level. The fluid is subjected to the pressure difference and gravity in a manometer, thus if the pressure is not equal then the difference in pressure is enough to "lift" a certain mass of fluid. Steady just means a good reading. http://en.wikipedia.org/wiki/Manometer#Liquid_column

When I set this up, it took the fluid a long time to go from one bottle to the other, so the result was that I kept waaaay over correcting. Am I right in assuming that the ATF does not have an immediate response?

 

here's something i've been pondering. i like the 2 bottle synch because if built correctly, it guarantees no cylinder will suck up all the ATF. but i also like the board/hoses synch because it allows you to see all 4 cylinders at once.

question: do you think a 4 bottle synch could be made by connecting 2 2-bottle synchs together? keeping in mind to only fill them just under 1/4 full instead of 1/2.

 

I think a four bottle synch tool would work. I was just thinking about trying to make a 4 carb sync tool with a fifth common source bottle, but I think just plugging two together would be alot easier.

 

I too made one of these bad boys but my connecting tubes were longer and i placed them on a board like the real sync setup. i thought it worked sweet .pics will follow .thanks to all those before me that came up with the thoughts and designs


cheers john

 

Level in bottle does not have to be same. The vacuum each cylinder is what cause the fluid to move from one bottle to the other. More vacuum creates less pressure in the bottle. This will cause fluid to move from one bottle to the other. If the vacuum is equal the fluid will not move between bottles regardless of its level. The only thing to remember is the fluid has to cover the hose that is connecting two bottles. If not it will not work. One thing to watch out for is a very small leak in the stopper will mess up readings. I have used this many times and like it but if your stoppers dont seal good it can be frustrating.

 

Well this is what my 4 bottle set up looks like. and it works well bike goes like never before.sorry its in my gallery

 

The level in the bottle does have to be the same to have equal vac pressure. If the fluid is connected, in order for the fluid to have a different height, there has to be a force "holding" it up. That force is a difference in pressure. Try this experiment . Take your sync tool, primed (with fluid in the connecting tube), but with the tubes exposed to the atmosphere. Make sure the fluid in the level bottle is equal. Now raise one of the bottles by putting a 2x4 underneath it. You won't see the fluid flow immediately (because of the viscosity of the fluid, the weight of the fluid, and the size of the connecting tubes), but leave it for a while and the fluid will end up being at the same level, because they are exposed to the same pressure.

 

Hey johnboy_28, I noticed your 4 bottle sync tool <here> didn't connect bottles 1-2 to 3-4. This means that 1-2 aren't going to be synced relative to 3-4 (this is the middle sync screw, the final step). I wonder if all you would have to do to that set-up is cut the two connecting tubes, then attach them to a cross tube. That way, all four bottle could share the fluid.

If you don't try it, I will soon.

 

lets say you got a 4 bottle setup, the motor is hot with a fan on it, the idles not to good because the sync is still off
now 1 is going down, 2 is going up, 3 is going up, 4 is going down, what screw do you turn first ? quick, the #2 is getting full and 4 is almost empty
and you still have to get on the screw of choice and turn it the right way
and if you get lucky and get on the right screw and turn it the right way the idle shoots up to 2500 and you've got to turn it down while the other bottles empty and maybe suck liquid in the intake
why not keep life simple and use 2 bottles

 

Hi again

just one query but why do 1/2 & 3/4 bottles have to be connected if they are all pulling the same vacum they should all come up the tube at the same time true?which would show that they are all equal .if you are getting full flow from bottle to bottle then this would mean there is an air leak in one of the bottles right ? but you are not trying to measure flow but vacum which is what i thought my set up achieved for me . but first off i bench synced my cards first which would mean that they are fairly acurate any wayand wouldnt be going up and down that much . will try to post video on you tube or something of the like and you can see it in action.

 

1&2 can be sync'ed at a different overall level and still look exactly the same, and level with 3&4. But then you would just hook 3 to 2 and plug off 1 and 4 and set the final sync.

Now THIS JUST IN !!
A new sync tool so simple, even Schooter could use it !

*Get a BB from a BB gun
*use some of that clear tube to construct a horizontal, shallow bend.
*make 2 RickCoMatic union restrictor baffle things

The idea is the BB settles to the middle-bottom of the one foot shallow bend, (looks like a wide smile) and a vacuum imbalance pulls the BB left or right. The BB stops at the union-restrictor. This device would allow a "rough" running sync without a $25 gauge, or sucking water into an engine, or trying to quickly figure out a bottle sync.

After that, a 2 bottle sync will nail it. Wlhile I enthusiastically promote a 4 tube Manometer (because they are so cool to use) I think the first timers to syncing should just use the very large loop method with the restrictor in the water itself. So, the BB device could go in the bottom first, then water.

I should draw this. . .

(oxygen mask tubing and connectors work well for the top of the system)

 

Polock is right about the practical issues for what i suggested. The reason not connecting the bottles doesn't balance 1-2 to 3-4 is because you aren't measuring "vacuum" persay, but instead measuring a difference in pressure between two intakes. The 1-2 bottles could pull the same vacuum and be level, and 3-4 could do the same, but that doesn't mean that 1-3 or 2-4 (or 1-4 or 2-3) would pull the same vacuum. Remeber, this tool measures a difference in pressure, not the actual pressure.

 

Thanks guys
that shot my theory out the window

 

Hey no worries, you still only have to connect it twice each time you balance

 

don't give up yet guy, if the three hoses that connect the bottles to each other had valves in them, by closing the right valve it becomes a 2 bottle setup then when it's all setup and done, open them all and it's a 4 bottle again and very impressive
now if you put a different color water in each bottle.................

 

I think the "Bottle-type" Sync Tools have a Flaw you need to overcome.

The Mercury reservoir on my "CarbTune Carb Sticks" is a COMMON Volume of Heavy Metal feeding all four tubes.
The Vacuum draws-up Mercury from a Single source.

I think these Bottle systems need that Common element too.

I bought the set of Carb Sticks back when I was doing four or five bikes a season.
If I was only concerned with getting my own Bike accurately synced; I'd Hook-up 4 Vacuum Lines to an Aquarium Air Valve Set-up with a Restrictor element to soften the fluctuations and use a single Vacuum Gauge and shoot for accuracy.

 

if two containers of H2O are connected with a hose they are a common source

 

What are the units on the carb sticks? Because the specific gravity of ATF is 0.875 (this is a quick google number) and the specific gravity of mercury is 13.6. This means that the two bottle tool is 15 times more sensitive than the mercury sticks, but I'm sure the area of the reservoir is greater than the tubes, making the sticks more sensitive.

Lets do some math:
Given that the bottles are about 6 inches high (15cm), the pressure difference that can be measured is 15cm*density_of_ATF*g which is about 1.28 kPa or 9.6 mmHg or 0.38 inHg. Another quick google search showed that combustion engines pull between 18-22 inHg (61-75 kPa) vacuum. This means that the range being measured could be assumed to be 4 inHg or 14 kPa . So the main problem with this tool in my opinion, is that it cannot accommodate the range that the manifold vacuum can be. To accommodate a range of 14 kPa, we need to make the two bottle sync tool about 1.6 m tall. I guess this is why the viscosity is a good thing, slowing the readings down. If it just jumped to a stead reading, you'd lose fluid too fast. I'm not quite ready to tune, but when I am, I might try different diameter tubes for connecting the fluid to get a better response. I think the tube I have now is too small.

 

"If two containers of water are connected by a hose at the top ... they are two SEPARATE containers of water connected by a hose ...

UNLESS ... the two containers are connected AT THEIR BOTTOM, such that GRAVITY will keep the LEVEL of the fluid in the two at EQUAL HEIGHT to display LEVEL

Without the BOTTOMS connected for the Level to be affected by a pressure change ...

The only thing that can happen is for the hoses to collapse.

 

manbot, 1/4 id hose , 2 snapple bottles and no leaks, your good to go

Rick, are you really ready to tell anyone who might read this that a two bottle sync setup doesn't work ?

 

Rick, the reason that you can consider the 2 bottles to share a reservoir is because the fluid is close to being incompressible. If the connecting tube is full of fluid, gravity does keep the level of fluid the same due to a siphoning effect. It kinda works like a toilet, once the fluid seals around the tube, all the fluid involved is going to be "flushed" to the other side, until the forces (i.e. air and hydro-static pressures) balance out, or there is no more fluid (and then it gets sucked into the engine.

Polock, I built mine and used it once, but the response was slow and I tended to over correct. The slow response is due to the amount of fluid it takes to change the height is too large due to the area of the bottle compared to the area of the connecting tube.

 

http://www.xjbikes.com/Forums/viewtopic ... art=0.html

Here's a working 4 baby bottle sync tool- - that works.
Water finds it's own level. . . the Romans figured that out.
I will start a new thread for my BB sync tool, that I built today.
Yes, it works, and I compared it to the 4 tube Manometer.
What am I doing in FAQ Suggestions anyway????????

 

YEAH! That's what I'm talking about...but I'm thinking about the four tube manometer for greater range.

 

I know.
I've engaged in this discussion before.

My opinion is that FOUR Bottle sources reduces accuracy.

I'd prefer to see someone Insert FOUR Hoses into One Common Bottle and Seal the Hoses tight.
Have a pinhole to break Vacuum.
A Fluid medium thick enough to respond to the Manifold Vacuum

Hook-up the Bike and see how that works.

 

4 bottles might reduce the response rate (dynamics), but not the accuracy. As long as there are no leaks, when you get a steady reading (statics), the forces have to balance out.

I'm also not sure that a 4 tube tool should have a pinhole to break vacuum. According to my calculations, you would need an 8.5 m tall column of ATF to compare the manifold vacuum to atmosphere (a 0.6 m column of mercury is sufficient). Otherwise, you'd be guaranteed to suck fluid into the engine. I think the bottle should be full and sealed and the hoses filled with fluid half way up their length (maybe 1m tall tubes for a range of 8.5 kPa) such that the tubes exchange fluid. Since we aren't ever trying to meet a vacuum spec, only compare the vacuum at each of the carbs, I don't think comparing the vacuum to atmosphere helps.

 

The underlying message from all these Posts is: Simplify.
Elaborately plumbed 4-Bottle manometers do not respond well enough to be accurate.
Using anything other than Mercury means the device cannot be compact.
The Fluid does not respond well enough to minor changes in vacuum.
The NEED to SEE a visual display of the four separate manifolds at the same level over-rules the accuracy that can be obtained without all the plumbing, bottles and fuss.

If you can overcome the compulsion to simultaneously view fluid levels all at the same height ...
The bottles
the fluids
the muss and fuss ...

can be eliminated by recording and adjusting the carbs to be in sync ... independently ... saving the time it takes to construct the 4 Bottle device ... and be done with it!

 

The sync adjustment from the Haynes book is basically as follows: Start by syncronizing one and two with the left side adjuster for the best balance you can get. Do the same for three and four using the right side adjuster. Now balance the pairs. This is done by adjusting the center screw balancing one and two to number three.
They are using four vacuum gauges with dampers. Since one and two are balanced you should be able to balance two to three. (No mention of four on the pairs balance. XJ650 & 750 Fours book 738 p.127)

 

I find it useful to install a valve or put a small c-clamp on the vacuum line. close it all the way and crack it open just a hair. This reduces any fluttering in the reading. I've been able to get really good syncs using an off the shelf vacuum gage this way. It's a "what I had laying around" replacement for the drop in beads that come with some store bought rigs.

 

Be sure to use the glass bottles, I tried the plastic version and they collapsed after a few minutes.

Also, I was able to slice off part of the stopper I bought and then use the bottle cap to tighten it and get a great seal.

 

if you sitting on the bike whick carb would be number 1...Is it all the way left or right..maybe other???