Adjusting Timing & Vac Advance?

[stevec5000]

While doing a tuneup I ran into a question about how to adjust the ign. timing on my '80 LG. Should timing at idle be set to F with the vac. hose connected or disconnected?
The Haynes manual says to adjust to the F mark at Idle but doesn't say anything about the vac. advance Then to check the mechanical advance they say to remove the vac hose and check for 36 deg. advance at 5200 rpms. They don't say what the advance should be at idle with the vac. hose connected vs disconnected.
The vac. advance moves it 20 degrees when the hose is connected, so if I disconnect it and set the timing to 36 deg. at 5200 rpms then connect it back the timing is set at 20 degrees at idle, not the F mark! If I adjust it to the F mark with the hose connected then at 5200 rpms it's way out around 50 degrees!
I think they left out some steps here. I checked the factory manual and they don't say what the vacuum advance should do at idle either but there is an extra paragraph saying to check the advance unit with a vac. pump and when vacuum reaches 150 mmHg the advance should be just at the end of it's travel.
I wonder if they are trying to say that the vac. advance shouldn't kick in at idle but should do something at faster speeds?

[Dragonrider]

Are you sure that you have the vacuum advance hose connected to the correct port?

It connects to a port built into the front of the # 2 carborator...NOT to the ports on the engine-to-carb boots.

[stevec5000]

Right, but I wonder why the instructions never say to disconnect it first before checking the timing at idle like they do for my car and truck?

[MartyA]

Clymers says to first - adjust to the "F" at 1,000 RPM with the vacuum hose connected, then second - check the 36 degree advance at 5,200 RPM with vacuum hose DISconnected.

[Ken Talbot]

The genuine Yamaha service manual and the Cycleserve manual also both say to check at idle, then disconnect the hose and check at 5200 rpm. Neither manual actually says the words, but if you are following the sequence, the vacuum hose has not yet been disconnected for the idle speed check.

[stevec5000]

Neither manual says anything about the hose at first so there's no way to be sure if it should be on or off. Normally it's removed for checking timing but I noticed on the 2nd XS11 carb the butterfly valve covers the hole leading to the hose at idle so it would seem the hose doesn't seem to be removed as long as the throttle is completely closed. That never seemed to work properly before though, so I think it's best to remove the hose to be sure.