Tb synch

[Travis]

Does anyone know why tb sync is done at idle? The cylinders change vacuum throughout the rpm range, so wouldn't it make more sense to set it at anticipated rpm? Or cruising range? Who cares if it's a little lopey at idle. Only reason I can think is, Yamaha wants it set this way because at idle is where a customer would notice.

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[tominca]

All you are adjusting is the opening of the butterfly over the throttle body. Anything above idle and that opening is lots larger. Fred's unauthorized TB Sync actually closes down the throttle body screws, then minimally reopens them to produce an equal vacuum. Once synced at idle, they should open evenly as you increase throttle. That's my primitive understanding. If Fred pops in, he should have a book to write about it.

[raYzerman]

The air flow you are adjusting is essentially a vacuum air flow. It is less effective at higher rpms, but is more easily adjustable at idle, then verified at higher rpm. You are not adjusting butterfly openings unless you choose to attempt that, which is the "Unauthorized" procedure of actually tweaking the butterfly openings. On a Gen3, there are no butterfly adjustments.