Homemade synchronizer worked great for me, but has a few quirks. As fluid is drawn up one side, you turn screw to balance carbs. That's fine, except when they are balanced, fluid is still not even in tubes. So, turn screw the other way to draw it back down, back and forth like that a little at a time til perfect. Or, kill engine every time and wait for fluid to settle back down evenly. I used 25' of tubing so drawing it into carbs wasn't a problem. Plenty of time to kill it if they were way off.
Also, don't forget to elevate idle a little while synchronizing.
