"bench syncing" the carbs is used to get it close enough to start the bike for further tuning. Eventually you'll need to buy or borrow a set of gauges to do it right. Even the slightest adjustments to an already synched set of carbs can change the way it runs. To answer your question, you'll need something like some pieces of 14 or 12ga solid wire that you will be using to set the gap at the bottom of the slides and get them as uniformally set as possible. 14 or 12 gauge wire should be stripped of insulation before you use it, and you place a piece of it in each carb under the slides and adjust the nut on the top of each carb until they all match, then lock down the jam nut. Be careful you don't twist anything when you loosen or tighten the nuts.
