Learning how to sync carbs

[62xs]

Ok I’m trying to sync my carbs with 1 vacuum gauge I have the manual and tried to follow it just like it said. After about an hour or more I finally figured that turning the adjustments screws out raised the vacuum. Turning them in opened the butterfly and lowered the vacuum. I fought and fought with this all afternoon get one right then the other was off. Finally I tried synchronizing #3 and then #2 Got them both at about 14 in. Then I did #1 and #4. Thing sounds pretty good. I’m going to let it cool for 30 min. and colortune the carbs and then check the sync again. So far the instructions stink I didn’t understand the actual way to start so as I was working on them I would check the pipes with my $20 laser thermo thing and the temp was all over the place from 110 to 325. I gave everything a turn or 2 out and started from scratch and used the main adjustment screw to set #3 at 14 in. Then I put the gauge on #2 (c) and synced this pair then #1 (a) and then #4 (b) All at 14in. The temp is now pretty even across the 4 running at about 225 Hope this helps some one else whose dumb like me. I’ve been turning wrenches a lot of years but understanding this just hit a block I though I’d never get past.

[DiverRay]

Finally I tried synchronizing #3 and then #2 Got them both at about 14 in. Then I did #1 and #4.

This is the WRONG! order on an XS1100!!
You NEED to sync #4 to #3, THEN #1to #2, AND THEN #2 to #3. The Idea ISN'T to set them all at 14", but to set them ALL THE SAME. It could be 18", or it could be 8".
YOU MUST HAVE A FAN TO BLOW ACROSS THE ENGINE WHILE DOING THIS!! I use a cheap 20" box fan set up on a 4X4. It will keep the engine cool while you set everything.
Hope this helps!

[Ken Talbot]

The problem with using just one vacuum gauge is you need to read the vacuum on 2 carbs at a time. The screw between carb #1 and #2 balances those two carbs to each other. As you adjust the screw, one carb changes to more closely match the other, but then the engine speed changes and the other carb changes a bit too. With only one gauge, you're just chasing your tail in circles. I'm not necessarily saying it is impossible, but it sure isn't easy with only one gauge.

[DGXSER]

This almost sounds like your trying to synch with the mixture screws??

I use one gage to synch with and feel I get pretty dang close if not right on it. I use a PVC plenum and hook my mity vac to one end, then use a tueb form the other to go to the carbs. Start with reading No1 then no 2 then adjust while on no 2 to even out the diff. then go back and forth again. Yes this takes longer than a "carb stick" of some kind or four gages. Then I move to 3 and 4 the same way. Then back and forth between 1 and 4 basically to adjust the sets together. Then go back and check all four once more. I get hem within 1/4" on my mity vac which reads about 9-10" vac.

[62xs]

Thats what I did. I'd change 1 then the other would go out of whack and it is like chasing your tail. It gets to you. I use a one way restrictor valve off of a 79 model car distributor to calm mine down. I have some from years ago it slows down the loss of vacuum and keeps the jitters out of the gauge. Using the temp gauge really helps.

[tarzan]

You wouldnt have to chase your tail if you use at least two gauges.You can adjust the screw between the carbs your working with and watch both gauges so you can get them even quickly.Using one gauge has to be an exercise in futility.lol
Rick