Join Date: Jun 2017
Location: Denver CO
Model: GL1500 Aspencade 1980 GL1100 STD Vetter
I wouldn't want to try to sync a 4 cylinder wing with a single gauge, at minimum you will want another. Especially since adjusting sync on one carb will affect the vacuum reading on the carb you are syncing it to (plus all others).
On the 1100's carb #3 is the base carb, all others sync to it. I suspect the 1200 has the same sync order.
First thing you'd want to do is get a reading on #3 and #1 carbs then swap the two gauges to compare readings (this checks the gauges themselves). On the 1100 you would sync #1 to #3, then #4 to #3, then #2 to #4, then re-check #4 to #3 and #1 to #3 settings. "Wash-rinse-repeat" if the #4 to #3 and #1 to #3 settings have changed, it might take a couple rounds to get them all lined up. Follow the sync sequence for the 1200 though, it may be similar but different.
With a single gauge that would be an awful lot of hose swapping, and you will still need at least two (and better to get 4) vacuum port nipples, and something to cap or otherwise plug a nipple that doesn't have a gauge connected.
1972 CL-350 (1980-1988) sold
1978 Suzuki GS-550 (1985-2005) sold
1977 GL1000 (2002-2006) sold
1980 GL1100 STD Vetter (2005-)
1993 GL1500 Aspencade (2017-)
1983 Trav-Lite Camper (2010-)