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it's very simple if you have removed the AI, but it's a PITA if you haven't.

You can buy one of those fancy thingamajiggers, or make your own manometer to balance them.

Look at the left in this pic, you can see my home-made manometer leaning against some old piece of furniture just behind my bike:



It's 20' of fuel line taped to a piece of cardboard, filled with Stabil, and each end of the hose is connected to the carbs.

You remove one nipple from each carb and hook the hose up to it.

Then fire up the bike and it will suck the Stabil in whichever direction that the carb has more vacuum. The amount of vacuum doesn't matter, I just marked the lines as a reference.

the adjustment screw is on top of and in front of the carbs. Look just under the tank above the carbs and give the throttle a twist, you can see the throttle cables and a small phillips head screw. some area able to reach in there and get to it, some have to remove the tank, and some can simply remove the seat and lift the rear of the tank.

It sure is easier with the rear of the tank lifted. You turn the screw either tigher or looser to adjust the balance, but VERY VERY VERY small adjustments are all it takes.

Once the carbs are balanced it will hold the Stabil in the lowest part of the U, but it will probably suck it all the way through a few times and the exhaust will smell pretty funky and smoke a lot, but it won't hurt anything.

Refill it and adjust (while it's running). It's pretty intense.

Also, see dinqua's site for more help.
 

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it is not difficult, if you don't have a manual you aught to get one. I assume the Haynes has a good description of "how too."

Basically you warm the bike up and attach the carb stix or vaccum gauges to the intake vacuum access points on the manifolds , start the bike and see where the vaccum for each cylinder reads. Adjust the screw between the carbs so that they both read the same. The lower it idles the easier it is to see the differences between the cylinders. Also as they become more properly adjusted you can idles it lower and then see better. Do this until it gets no better and it is as good as it can be.
 

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Sweat,

Thats brillaint. I have a mercury set that I have had for a very long time. If I had to make some I would have likely gone with gauges which I think would be a compromise since they are kinda bouncy. Your rig is a better idea for next to no cash.......KUDOS
 

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I've never done it yet, but I think I need to or at least check it. Two vacuum gauges are needed. I have the Triumph service manual and says.
Quote:

1) Warm engine up to normal operating temperature and adjust idle speed.
2) With the idle speed correctly set, switch off the engine.
3) Remove the rubber caps from the vacuum take off points on top of the intake adapters.
5) Start the engine and allow it to idle.
6) Open the throttle slightly a couple times then allow the engine to idle again. Note the readings obtained on the gauges whilst doing this: both gauges should give the same vacuum reading.
7) If adjustment is necessary, rotate the throttle linkage adjustment screw which is located on the inside of the left carburetor.
8) Once the carburetors are correctly synchronised, stop engine and disconnect the vacuum gauges.
9) Securely refit the rubber caps to the intake adapters.
NOTE:
Adjustment is very sensitive. Each time the screw is moved allow time for the vacuum readings to stabilise before adjusting the screw further.

The adjustment screw is on the shaft where the throttle cable attaches. It doesn't sound hard but may take some time.
 

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it wasn't my idea, I got it from this forum!

here's another pic:



it's nice for no money, but I will probably buy a mercury tool one day. The neat thing about this is it can be made for no money and there's no waiting for it to ship.
 

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if you've done it once, you'll be an expert and can adjust it in literally less than 2 minutes. It's that simple, but the first time will take some work. Really I can't stress enough to make SMALL ADJUSTMENTS TO THE SCREW.

I'm talking 1/16th turns at a time.
 

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On 2006-11-20 22:49, Loxpump wrote:

3) Remove the rubber caps from the vacuum take off points on top of the intake adapters.
5) Start the engine and allow it to idle.
Looks like you forgot to paste step 4: attach manometer to the vacuum nipples :razz: :wink:

EDIT: TJ, if you have the cash to throw at a new tool rather than make one of those neat homebrew manometers, the Morgan Carbtune II gets a lot of good write-ups:

http://www.carbtune.com/

They quote a total cost including shipping to the US of $105, so it isn't cheap by any means. Depends on whether you enjoy more the act of making one or buying a new toy.

[ This message was edited by: steviek on 2006-11-21 05:12 ]
 

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Discussion Starter #10
man, i love new toys. What about the ones on NewThruxton.com? Thanks for all the help. I was a little worried about attemting this, but now i'm feeling pretty comfortable.
TJ
 

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Its easier after the first time you do it. My son and I have been synching our xs650's and it makes them vibrate a lot less. Also, the dual throat delorto carbs on my Alfa have to be synched to prevent vibration. Havnt synched the bonny yet, only 2200 miles or so.
cliff
 

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Here's some more documentation re using the home made manometer. Maybe the directions on which way to turn the screw will be useful:

1. I tightened up all carb clamp connections (they were ok).
2. connected left side of loop to left carb/rt side to right. I used the vacuum ports closest to the cyl head.
3. Set idle at 1000-1100rpm

On startup - the right carb/fluid column exhibited the most vacuum, the Stabil rose 7-8" higher in right column, with corresponding drop in left column... it is a differential measurement.

4. Barely turned screw clockwise (tightening) and it raised the right column further (with corresponding drop in left column).

5. Then turned counterclockwise (looser), which raised left column, and lowered the right column (too much)

6. A slight tweak back toward clockwise brought the two columns level with each other.

Each time I tweaked the screw, I slowly revved the engine up to approx 3500rpm, then let it drop. and gave the columns a few moments to settle out.

Just to check and see if there was any appreciable difference using the ports furthest away from the cyl head, I replugged the ports I initially used, and ran the process hooked to ports furthest away from the cyl head. Results were, naturally, the same .... vacuum is vacuum.

So - if the fluid is high (or being sucked out) the right column, turn the screw counterclockwise (looser).

If fluid is high or being sucked out the left column, turn the screw clockwise (tighter).

NOTE - total movement of the screw required to balance carbs is less than an eight of a turn total, in most cases much less.
 

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I used ATF and it works fine. I also used a yardstick (about 1.25" wide) to attach the tubing to. Works fine and cost about $3.00 (I already had the yardstick). I put a plastic bottle cap at the bottom of the yardstick to keep the tubing from kinking. No need to buy a mercury or other fancy manometer - use the $$ for more exciting things (pipes, NARK, etc.).
 

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There is great info on how to build and use one if you search under keyword manometer on this site...use stabil and hang the thing from the rafters to give more lee way....use clear tubing about 1/4 inch or 3/16 that you can get at the big box hardware stores..... really makes the bike purr... :cool:
 

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stabil works, ATF does too, the cool thing about stabil is it is meant to be burned in your motor...

ATF? not so much, but I guess it won't hurt anything as little as you'll be running through it.

Stabil comes in a handy little bottle too. The worst part is sucking it through the hose. That's right! Stick one end in the Stabil bottle and suck on the other...tastes bad!
 

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On 2006-11-20 22:44, vertwrks wrote:

...If I had to make some I would have likely gone with gauges which I think would be a compromise since they are kinda bouncy.
Since I already have vacuum gauges, I tried that approach. They are more than kinda bouncy. They bounce so badly that the readings are useless and the gauges get badly hammered. They could be made to work with plenums and orifices but why bother?
 

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The one for $40 works just fine. It can do up to four cylinders, if needed.

You can gently rev the engine and see where it settles without having the mercury go in the carbs. Just do it gently and not full throttle. Even if the the mercury got in the carbs a bit, just ride around for a few blocks and it will burn it up.

Just don't ride and breath the fumes at the same time. That was a joke.
 
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