CV 1 and 2 carbs wont sync.

[GS1100E]

The nr 1 and nr 2 carbs wont sync. All 4 carbs have been cleaned and bench sync. The nr 3 and nr 4 carbs pull 20 inches of vacuum while the 1 and 2 carb only pull 5 inches. I do not have the long vacumm vent hoses attached to either side, should I? The bike is an 81 GS1100E with vance and hines 4/1 and stock airbox. I installed the DJ stage 1 kit and drilled all the slides. I am at my wits end. Any advice is greatly appreciated. I did spray some water around the intake and carb boots but did not detect a vacuum leak. Thanks for your help.

[Big T]

Well, unless you have a leak in your vacuum line for your gauge, you have either:

1. Low compression
2. Blocked passages in the carbs
3. Leaks in the intake boots

So, tell us more. Have you adjusted your valves? Done a compression test? How old are your intake boots? The O rings?

The intake boots themselves can leak once they're old enough.

[GS1100E]

All the parts are original except the DJ kit stuff. I have had the carbs off, this is the 5th time, and each time I check the intake boots, o-rings inside the boots and the air filter boots themselves. I don't see any cracks and all the rubber still seems plyable. The bike only has 4800 miles on it. I have not adjusted the valves or checked the compression because I rode the bike when I first bought it and since I installed the DJ kit and header, this is kicking my butt. Everyone's help is truly appreciated.

[renobruce]

So when you turn the synch adjuster screws on #1 and #2 nothing happens? They should all be synched to #3.

[liloaty]

I'm having the exact same problem with my 80 GS1100e. 1 3 and 4 all pull 20-25 inches of vacuum and 2 is stuck at an embarrassing 5-8. This is after I checked all the boots, went through the carbs, adjusted the valve clearance...I can't find anything.

[GS1100E]

I pulled the carb assembly back off and just cleaned the 1 and 2 carbs since 3 and 4 vacuum was good and sync together. I cleaned the carbs with spray cleaner, blew out all the orifices and blow dried everything with compressed air. The nbr 1 carb sync screw had the plate opened up farther than the other carbs so bench adjusted it as the other carbs. Put the assembly back on the bike, fired it up and all 4 carbs are now equal at 8 inches of vacuum. Thanks everyone for you advice.