pickup's vacuum line

[randy]

Actually it is what is called "ported vacume". The oraface in the carb bore is behind the butterfly valve (air box side) so that there is NO vacume until the butterfly(throttle) is opened slightly.

Well, actually, ACTUALLY, it is 'ported vacuum', but it's FULL vacuum at idle. When the butterfly opens, LESS vacuum is applied to the advance mechanism. The spring in the vacuum pot then rotates the baseplate to retard. Watch it in action, start the bike and you'll see the advance mechanism pull in full up advanced. Crack the throttle and it will retard.

At least that's the way it's designed to work, and should, unless changes have been made

[XSokieSPECIAL]

The vacuum port on the carb body has a snubber or smaller orifice in it to dampen those back and forth movements you saw when it was hooked up to the carb boot. With the motor running and the cover off you should see the plate rotate with changes in throttle

Actually it is what is called "ported vacume". The oraface in the carb bore is behind the butterfly valve (air box side) so that there is NO vacume until the butterfly(throttle) is opened slightly.

So, at idle the vacume advance machanism should NOT move. It should start moving as the throttle is opened. If it doesn't move when hooked to the #2 carb port it's possible the port is plugged, or you just have a bad diaphragm. I had to replace mine when I got my bike.

Just disconnect the hose from the engine end and suck on the hose and see if the advance mechanism moves. If it does then see if it will hold vacume.

[wingnut]

The vacuum port on the carb body has a snubber or smaller orifice in it to dampen those back and forth movements you saw when it was hooked up to the carb boot. With the motor running and the cover off you should see the plate rotate with changes in throttle

[oldyam80sg]

Don't hook it up wrong.If you do you will never quiet the noise and movement.

[CatatonicBug]

and confirming what i've been told the vacuum from the pickups goes on the carb body and the vacuum for the gas octopus goes on the same carb boot

Here's a picture of what it would look like. The hose from the pickup attaches to the carb body, and the fuel vacuum attatches to the vacuum connection closest to the engine (rubber caps should be on the same connectors for all 3 other carbs).

[79XS11F]

the plate chatters, should it always turn?
hooking it up what i was told to be the right way it doesnt move.

If it is bouncing back and forth all the time then it is likely that you have the hose hooked up to the vacuum nipple on the carb mounting boot. It should be hooked up to the carb. There should be a brass tube on the front left hand side of carb # 2 to receive that hose. As stated it will only move when additional throttle is added. There are specs as to when and how much it should move. Check your manual.
Rob

[XSokieSPECIAL]

the plate chatters, should it always turn?
hooking it up what i was told to be the right way it doesnt move.

When it's hooked to the CARB itself like it's supposed to be. I should only move when you open the throttle.

[Eddie Gravy]

the plate chatters, should it always turn?
hooking it up what i was told to be the right way it doesnt move.

[dbeardslee]

They're supposed to stay firmly mounted to the ATU plate, but the entire assembly will move as the vacuum advances. There is also a gap that needs to be set between the rotor and the pickup coils. Stock gap is .7mm, but setting them slightly closer may work better. I've got mine set at .56mm, which works well. If they're chattering you might want to insure they aren't making actual contact with the rotor.

[Eddie Gravy]

do the pick up's for the coils suppose to 1/4 turn and chatter while the crankshaft spins?

i had hooked up the vacuum line to the carb boot and it chatter something awful. so much i thought it was my cams or a piston knocking. i hook it up to the instructed carb #2 and they dont move at all.

are the pickups suppose to rock or stay in one place? and confirming what i've been told the vacuum from the pickups goes on the carb body and the vacuum for the gas octopus goes on the same carb boot