Obviously this is a bit that requires not one jot of being fucked with, apart from replacing the rod ends when they wear. I have 2 sets of throttle bodies and they have slightly different lengths. Both rods had been tampered with ,one set by me after having read "something on the net" years ago and the other by the dyno guy. The set that came with the bike have just been overhauled and I changed the rod ends with brass ones. When I set the rod length for these TBs both butterflys were fully closed and the rod length adjusted so that it slipped on its balls without moving the butterflies. The adjusting screw was set around 1/2 of its adjustment. Although I did not remove the arms that the rod connects to, when I measured them their centres appear to be identical. In hindsight I should have asked EFI (the mob that serviced the TBs) to measure them when they had them apart.
I have seen the occasional mention of the rods on forums and some folk relate to geometry and their length but don't elaborate. So are the rods purely a mechanical device linking the TBs, whose length is only governed by the requirement of both butterflys to open simultaneously without running out of adjustment at the screw ? Cheers