I've had a few people email me looking for some insight on setting up Syncro shifters. I don't claim to be all knowing on the subject, but I have had some success based on info I've read, as well as a couple of tricks I've picked up.
First things first. The first thing you MUST do is consult the tables provided by Campagnolo with regards to what combinations of freewheel, chain, dérailleur and shift collar work together. Yes -- the different colors of collars can be hard to find. In some ways, I'd suggest selecting your derailleur, freewheel and chain based on the collars you have access to. Some substitutions will work better than others, but unless you have lots of time and lots of spares, stick with something that Campy published as working. It can be hard enough setting up Syncro with the correct equipment.
One tip I read that seems to help comes courtesy of a usenet post by Andrew Muzi over at Yellow Jersey. He advocates artificially wearing the teeth of the shifter notched insert, using a buffing wheel. I used a dremel with a little bit of buffing compound, which also works. The goal is to take some of the square edges off the teeth of the collar. This eliminates some of the harsh edges you'll encounter when shifting, and make the whole system a little more tolerant of imperfect shifts. The above shows a slightly worn blue insert. Might be hard to see in the picture, but the tops of the notches begin to round slightly when they wear. The goal is to simulate repeated shifting, and eliminate any break in time for the shifter.
There are also some who advocate using a floating upper pulley -- similar to the kind you'd find in a modern derailleur. The bearing units tend to be more precise, and indexing systems can benefit from a little wobble as they're shifting. It provides a little overshift, to get the chain up on the next cog, and then lets it sort of float back to the appropriate location. Personally, I haven't had to resort to this, but it may make the system a little less finicky.
If your derailleur doesn't have a barrel adjuster, it should. Some Syncro shifter sets came with one, and once Syncro continued, derailleurs came with them. You need this for the fine-trim on your derailleur. The Campy supplied one is shown above, but you can cobble one together from your parts box.
One thing I've never read anywhere, but really seems to have a positive effect, is tightening the indexing lever more than you'd think. If you're used to modern indexing systems, you know the tension on the lever really has no impact on the quality of shifting. The tension isn't really all that adjustable. On the Syncro, however, having it snugged down further than you think seems to improve shifting accuracy immeasurably. If you hear a discreet 'click' when you shift, make them tighter! Mine make more of a thump sound when shifting...If you're used to friction levers, you will not end up tightening the indexing lever enough. Don't strip anything, but don't be shy either. I think this is related to the 2 springs not providing support for the insert when not tightened down (hence the eventual move to a much much better 3 spring version post-95). Just be careful -- I've seen cracked inserts before.
Use modern derailleur cables. They don't have as much stretch in them, and that seems to be a good thing. The use of linear cable housing may also be a wise thing, although I have to admit -- I'm using spiral housing successfully.
My setup works beautifully, if I do say so myself. I do *not* have to overshift, which was a common complaint with these. I think the wearing of the collar, in conjuction with the tight indexing lever makes all the difference. Curious about my setup? I use a Croce d'Aune derailleur, Regina Oro freewheel, CX chain and the yellow collar with Syncro 2 levers.
Here's a gratuitous picture -- a pile of NOS Syncro II's. Its all part of my effort to corner the market in obsolete, inferior technology.