Carb Sync question

[DrDankNuggs]

Have a question on Carb Syncing on 82 gs650gl, Ive included picture from Suzuki manual. So it shows sync order as 2/1/4 (a/b/c as pictured) I know where those adjustment screw are located My question is related to carb 3 (base carb) am I correct in thinking that the base adjustment is done with the throttle stop then proceeding in the order. So throttle stop to get base line read then onto 2 then 1 then 4. then final adjustment to pilot screws? Thanks in advance.

 

[Steve]

Have a question on Carb Syncing on 82 gs650gl, Ive included picture from Suzuki manual. So it shows sync order as 2/1/4 (a/b/c as pictured) I know where those adjustment screw are located My question is related to carb 3 (base carb) am I correct in thinking that the base adjustment is done with the throttle stop then proceeding in the order. So throttle stop to get base line read then onto 2 then 1 then 4. then final adjustment to pilot screws? Thanks in advance.
View attachment 61022

Your understanding is pretty much spot-on. :encouragement:

Connect the gauges. Start the bike and warm it up enough so you don't need the "choke".
Use the idle adjuster under the carbs to get the idle speed to 15-1700 RPM (this helps smoothe out the pulses).
Use the sequence that you posted. Sync #2 to #3. Note that when you do that, the other levels might change a bit, too. When you have 2 and 3 balanced, adjust #1 to match. Don't worry about that "half a ball" difference shown in the factory manual. If #1 is a bit higher than 2 and three, it will sort of match the manual, but don't go over 2cm difference. That is the measure of "half a ball". Most of us just go straight across on all four. When #1 is done, move to #4. When you are done, blip the throttle a few times to make sure nothing changes.

.

 

[DrDankNuggs]

Your understanding is pretty much spot-on. :encouragement:

Connect the gauges. Start the bike and warm it up enough so you don't need the "choke".
Use the idle adjuster under the carbs to get the idle speed to 15-1700 RPM (this helps smoothe out the pulses).
Use the sequence that you posted. Sync #2 to #3. Note that when you do that, the other levels might change a bit, too. When you have 2 and 3 balanced, adjust #1 to match. Don't worry about that "half a ball" difference shown in the factory manual. If #1 is a bit higher than 2 and three, it will sort of match the manual, but don't go over 2cm difference. That is the measure of "half a ball". Most of us just go straight across on all four. When #1 is done, move to #4. When you are done, blip the throttle a few times to make sure nothing changes.

.

Thanks Steve You're a gentleman and a scholar.
I did end up going a head and replaced valve shims as I listed in the email went on with out a hitch, now every valve is within .06-.08 except ex4 which was a little tighter at .04, Also bought a extra 2.60 shim for the inevitable tightening of ex4.
Hopefully last question regarding syncing, should I put too much stock into the numbers on the gauge (see pic) they are all floating around 30 but according to gauges it should be 45-55 (normal motor) or ignore that and just be concerned with getting them synced regardless of what the cheap Chinese gauge says is normal.

 

[Steve]

Pay no attention to the actual numbers. Hopefully that is just one gauge of a set of four. :-k

If that <is> a set of four, hopefully you made a tubing manifold that will allow you to connect all four gauges to the SAME vacuum source at the same time. That will allow you to see what differences there might be between the gauges. Better-quality gauges will allow you to tweak the needle so they will all read the same. Then, when you put them on the four separate sources in the manifolds, you will know that any difference will be due to the cylinders and carbs, not any differences in the gauges.

If that is just the one gauge, don't even bother trying to sync the carbs. Wait until you have a proper set. And, for the money, the Carbtune Pro is probably cheaper than the set of four Motion Pro gauges that look like the one you posted.

It is more important that the carbs are all equal, not what the actual numbers are.

.

 

[DrDankNuggs]

lol yeah it is a set of four, I was just trying to get a closeup where the dial was legible.
I didn't have fittings to create a manifold to do them all at the same time, however I did go threw the gauges individually, hooked up a mighty vac bleeder pulled a known vacuum on the gauge and adjusted the needle to read the known vacuum. went through and calibrated each gauge individually, then went back threw a second time to confirm the gauges maintained calibration. I thought that would be good enough, but I could be wrong.

 

[Steve]

Just to be SURE, get some T fittings and some hose at Auto Zone so you can connect them all at the same time.

It just eliminates one more variable to KNOW that they are all reading the same.

Oh, ... this is not a one-time thing. You will need to do this every time you use the gauges.

.

 

[Rob S.]

Welcome to the site!

Put your year and model in your signature so we'll always know.

 

[Forden]

Does the order of sync described above (carb 3 baseline, then 2,1,4) apply to VM carbs? My '78 manual doesn't specify, though it says to start with #4 (but maybe only because it uses that one to calibrate the gauge?) then correct any of the other three not matching.
Thanks.

 

[Nessism]

VM carbs are different because each individual carb has it's own adjuster.

For CV carbs the order is to align 2 and 3 first, using the center adjuster, then align the outer carbs, 1 and 4, to the baseline established by 2-3. It doesn't matter which order between 1 or 4 since these are independent to each other.