Syncing your Carbs. How often or when?

It's always a good idea to begin the season on a real sharp and accurate sync.

But, there some guidelines.

Miles:

1,000 - I think there are one or two Members coming-up for this one!

7,000 - There are a handful of Members who haven't hit this milepost, yet!

13,000 - Scheduled.

19,000 - Scheduled. (Also a Manual Tensioner checkpoint -- Possible reset for Automatic Tensioners)

25,000 - My guess is that there are a bunch who are late on this one.
(This one? What about the other ones; too!!!)

31,000 - "Iron-butted" riders would have done it by now ... right???

Every 6,000 there after.

These are XJ-Lovers ... they don't need a reminder ... or even a reason. They do it for the fun of it!

 

Not that I'm trying to go against the process but...

Can someone help me to understand why syncing the carbs is so important? I mean how far out of line can they go on their own? Also, since all the carbs are connected as one unit anyway why couldn't they just be all aligned from factory and never need adjusting again?

 

Need to be the same so they all do the same amount of work. Most important for low RPM performance, but if they were way out could cause a problem across the range I suppose.

Everything moves with time. Especially when some PO thinks they are the idle or mixture screws. :lol:

 

If there's a spring-loaded screw ... it moves.

And, like MiCarl mentioned ... numb-skulls turn them thinking it will help save gas and make the bike go faster.

 

holy freakin crap, this can be the reason why my outter 2 cylinders fail to fire at idle? Someone said to snyc them but all i did was floor it and watch 4 butterfly's open up- once i break 1/4 throttle everything is smooth as glass- i gotta check this- is it as easy as turning the stop screws on the misfireing cylinders until they begin to kick in- then turn down the entire rack? The previous owner said it has always run like it currently is- the bike has 25,000 miles on it and im 90% sure all slow speed jets are clear as its a glass smooth powerband once off idle

 

No.

That's why you have to Sync the Carbs every so often.
Somebody does something like you just suggested.

You can do them really nicely by yourself.
I have posted a "How-to" using ... One and Only One Gauge.

You should try it. Getting them perfect requires a little bit of patience when you are doing a "Old School ~ One Guage Sync"

But, when you are done you are going to have:
A running-real-good bike.
Better acceleration.
Mucho better Idle.
Sweet cruising power and smooth highway riding.
Whiter teeth
Fresher breath
Better Credit
Babes all-over you.
Faster quarter mile times
and, did I mention ... babes!

 

rick you crack me up, i will search for your how to post, i just rode it again and the outer 2 carbs to kick in like a old 4 barrel carb. I will begin my search now Thanks

 

you wouldnt happen to have a link to that thread would you? I have the attantion of a kid with ADD

 

Old School Method
One Gauge Sync
The Rick Massey Show
..........................................+<>+................................

I suppose it won't be too very long before somebody comes-out with a Carb Synchronizer Tool that's all digital, solar powered, with a combined LED and numeric read-out, that will fit in your shirt pocket. Until then; columns of mercury or the handy, new, stainless steel-weighted synchronizers are the way to go.

But, for XJ-Owners, who are only going to sync-up the carbs every couple of decades ... or, for those who don't want to lay-out seventy-five to a hundred bucks (or more) for Carb Sticks or a CarbTune meter ... buying an expensive meter, or one filled with mercury just isn't practical for as often as you'd ever need to use it.

So ..., how are you going to be able to get your Carbs synchronized without buying the Sticks, or taking your bike to someone who's got sticks, or to a place that charges big-bucks to do something you'd do for yourself ... if you had the means?

! ! ! ! ! ! ! ! ! !

Easy ... Just hop in RickCoMatic's Time Machine, and come back with me, to the time before Carb Sticks; when you had to "Match-up and Sync the whole rack ... with ONE Vacuum Gauge!

The Old School Method
Single Vacuum Gauge Synchronizing of Carburetors
by: Rick Massey
Special to XJBikes.com
All rights reserved.

First, you need one vacuum gauge. (There's none better than the one sold at Sears for $19.95) and your home-made YICS tool.

You need some vacuum line. Get ten or twelve feet. You'll be making-up lines to run from each carb out to the side of the bike where you'll hook-up the Vacuum Gauge.

You need a few small, hollow, plastic-barrel vacuum line connections. (Those little things you use to plug one vacuum line into another.)

One medium-sized fuel filter; with ends that will fit the hose.

One red plastic spray tube ... like the one taped to a can of carb cleaner.

Four regular Golf Tees. (Just steal 'em from your dad's golf bag)

5-minute epoxy.

Masking tape and a "Sharpie"

OK kids ... Let's ROCK!

Prep:
Fabrication of the "Vacuum Restriction Valve." (Absolutely necessary)

Take the skinny red tube and run it through one of the hollow, plastic hose connectors.
Seal that hollow connector with epoxy; leaving a length of the red tube extended from each end.
(This fabricated little-metering device will be the all-important "Vacuum Pressure Restrictor" that will allow you to read the vacuum gauge without the extremely WILD fluctuations on the meter you'd get if you tried to get a vacuum reading without it.)

When the epoxy hardens; cut-off the extraneous ends of the red tube -- flush.

Using a short length of vac line ... attach the restrictor to one end of the medium-sized fuel filter.

(Now you have a restrictor attached to the fuel filter. You just made what you NEED to get the needle on the vacuum gauge "Quieted-down" enough to get an accurate reading without the meter being so wildly fluctuating as to be useless. You have Baffled-Restricted-Regulation and this softens the harsh, impossible-to-read fluctuation, the indicator would have, without it.)

Hook-up and Sync:

The rest is by the book.
YICS tool inserted.
Four Vacuum lines run from the Carb Intakes over to where it will be convenient for you to connect these four lines up to Vacuum Gauge ... each marked with a little tape label for one through four. Stick the golf tees in the ends of these lines ... and get ready to sync the carbs.

Attach your "Old School - Baffled Restrictor" to the vacuum line coming from Number - 3 with the red tubed restricted end plugged into the vac line coming off the engine.

Plug the Vacuum Gauge into the Fuel Filter end. You're officially restricted and baffled for testing ...

So, let's do it!

Run the bike and get the vacuum reading of Number 3 (Three) ... to check for good vacuum on three and to observe how the needle of the gauge is still going to MODERATELY "Vibrate" as it measures engine vacuum.

Sneak the rev's up to 14 > 16-hundred rpm's and the fluctuation will become rapid enough for you to read the vacuum that the hole is pulling.

Mark the gauge face with a short strip of masking tape and mark the tape with a check-mark. Don't let the tape strips block you from seeing the vacuum gauge needle during the sync.

Authors Note:
It's a good idea to practice pulling a golf tee out and covering the hose with your thumb. This will keep the engine from stumbling and possibly stalling.

Checks and adjustments:

Read the Vacuum being pulled by Number 2. Mark maximum vacuum drawn by 2 with line of tape.

Get your magic fingers ready to do the "Carb-Shuffle!"

Pull-out the baffle and block the vacuum with your thumb until you can insert the golf tee you have ready between your lips or behind your ear.

Measure the vacuum being drawn by Number 1. If the max vacuum being drawn by Number 1 is NOT the same as you have MARKED for Number 2 --ADJUST the SYNC SCREW on Number 1 ... until the Vacuum drawn by ONE is the SAME as the Vacuum drawn by TWO!

Two down ... two to go! But, here's where it gets tricky.

Plug-in to Number 4. Set the Vacuum drawn by Number 4 -- to -- the BASE Vacuum you measured for Number 3. (Actually check 3 again ... adjust 4 to match 3 -- because 3 is the Base Vacuum Port, has NO sync screw adjustment, and usually has the petcock vacuum hose connected to it.)

At this point you start TWEAKING. From here until the rack's in-sync ... it's all down hill!

The engine should be sounding pretty darn good; right about here. But, we need to finish it off!

Just hook-up to Number 2, now ... and bring the vacuum being drawn on Number 2 -- UP or DOWN to match the value of Number 3.

They'll be no need to adjust Number 1. Number 1 is connected to Number 2 and goes right along for the ride when you sync Number 2 to Number 3 ... and you ...

HEAR the results of synchronizing all four of your carbs with only one vacuum gauge.
Let what I have outlined, here, be your guide ... but, don't be afraid to get creative with where to have the golf tees ready to pop-in the lines!

When you wrap-it-up ... the One - through - Four ... Final Measurement should be all right on the same value -- right across the board.
Yes? DONE!
No? Tweak until you nail it!

Can you believe that we used to have to do it this way? Compared to the MotionPro Carb Sticks -- It's like being in Bedrock ... spending a little time with Fred and Barney doin' a little Stone Age Tweaking'!

You folks are great.
The quiz is whenever you try it.

That's our report for this evening ...
This is Katie Kouric ...
For CBS News; thank-you;
and, good night.

-30-

 

What would be an indication that they needed syncing, or is there a way to test to see if they are out of sync?

 

my xj600 misfires on the outside 2 carbs as the throttle plate is not snyced with the inner 2 carbs, it takes about quarter throttle before all cylinders fire

 

Test for sync is by putting vacuum gauge on the nipples on the intake manifolds and taking a reading.

Idling difficulties (racing idle either always or when hot, rough running) are an indicator you might have a problem with sync.

 

And all this time I thought syncing my carbs meant balancing out fat and protein intake. Now I find it involves hooking up nipples to vacuum gauges. Man this is an exciting forum!!!!! Woohoo.
Where'd ya post the pittchers?

BTW Rick, you're showing off some long past history there...
-30-

You've been there and done ain't cha?

 

I don't feel old when I'm wrenching and tuning.

 

Vacuum lines run $5 for 3 feet at AutoZone. Would aquarium air tubing work? $0.29/ft is more my style.

Also, is there a specific guage to pick up? I bought some Craftsman guage, but I don't know if there are range requirements or +/- pressure makes a difference.

Finally, I assume the pressure reading on the guage and the level in the tubing should direclty correlate?

Sorry for the newb questions, I enjoy this kind of stuff, but have no one to keep me from detonating my bike..

 

-30-
???
I'm not recognizing the reference.
I'm still missing Dan Rather.

 

Aquarium line might present a problem. I don't know.
We're working with Vacuum, here, not lightly moving air or fluid.

The Craftsman is a perfect choice.
Best of BOTH worlds.
Vacuum & Pressure.

(A "Dry Erase Marker" lets you mark the face of the Guage)

 

I use the cheapy vinyl or whatever tubing from Home Depot. Worked for me. Could it have been better with real vac. tubing? I dunno, but this worked pretty well.