The point of the sync is to make all four have the same vacuum. It doesn't matter, for the sake of vacuum, what the value is as long as they are the same. Certainly a bike will run better with the proper mixture, but syncing the idle to match a pre-supposed "proper" vacuum level won't change the mixture setting or the jet sizes. Those things have to be done through other processes. Ega's are pretty cheap nowadays and are very accurate.
If you change the mixture which results in a lower idle setting, then the sync should be checked again.
Now having said all that, "the sync is to make all four have the same vacuum", may not necessarily be the goal we are shooting for. RonKZ650 brought up this topic a while ago. The sync will ensure each carb has the same vacuum, but that does not necessarily mean each carb has the same flow, or that each cylinder is doing the same work. If the cylinders are not pulling the same amount of air, then the same vacuum in the manifold means each cylinder is getting different amounts of fuel and is doing different amounts of work.
(Riverroad already said the comp on his cylinders were relatively equal so he is probably ok with a simple vac sync.)
If we want each cylinder to get the same mixture, then a different technique for syncing is needed. You could just visually match each throttle opening and that may get you close enough (as Ron suggested) or you could make a vacuum apparatus with manifolds to supply the same vacuum to all 4 carbs at once, then set the throttles using the sync tool. It wouldn't be hard with some PVC pipes etc.
I'm sure there are many other ways to "balance" the cylinders at idle, it's probably up to the condition of the motor to determine which method is best.
Post edited by: loudhvx, at: 2007/10/07 07:03
