Vacuum Advance Tube

[Poeman]

Can anyone tell me or point me to where I can find out about where the vacuum advance tube goes to from the case on the left side of my bike? I had been running with it just vented to air, but I don't think that is correct. Is a diagram available somewhere?

[Snow]

It connects to the nipple on the #2 carb - make sure you connect to to the brass looking nipple on the carb body and not the carb holders. Running it disconnected allows more air to enter the carb. You will probably notice an increase in mpg and performance when you hook it up correctly as you are running on base advance only.

[Poeman]

Hey thanks a lot, Snow!!! That is what I was thinking, but I was not sure at all. I really appreciate your help!!!

[Igotit4free]

Well poeman, I checked your bike and the number two carb already has a hose on it that goes to the little square valve "thingy"(sorry guys) that looks like it provides even distribution the carbs from the petcock. Maybe there is supposed to be a splitter of some sort on there. Does anyone have a drawing of the proper placement for the fuel lines and vacuum lines?

[underdog57]

remove the hose from the carb and put it on the carb boot(holder)
someone misplaced that ....
the thingy is the octopuss ...
the vacuum advance goes to #2 carb as stated by itself no t...

Bob

[Igotit4free]

Well........we went to Auto zone and bought a vacuum "t". We cut the hose between the number two carb and the octopus and hooked up those two with the hose from the vacuum advance line. it now appears that there is a much better response to cracking the throttle and it even runs much better at idle wh3en cold. Before this was hooked up I had made a small adjustment to the Idle screw on te bottom bar of the carbs. I don't know if Po had to readjust it again as I was gone when he hooked it up. He did tell me that all appears to be great though. We'll see what happens next though.

[Igotit4free]

Hey Poeman, chime in here and let us all know how the bike ran on the way home. I'm sure everyone would love to see some pictures of this thing too. I think the guys would love to see what 15 hours with 4-5 guys in a garage over the winter can do to a bike that was left for dead more than 15 years ago.

[pggg]

No 2 carb to vacuum timing unit is metered thru a tiny 0.5mm hole for smoother vacuum timing operation, the carb boot nipple is a 3mm hole, lot wider and too abrupt for the best vac timing performance, but good for the vacuum fuel taps

[Igotit4free]

hummm......well...........it works a heck of a lot better than before but I would love to know exactly what it should look like when hooked up properly. I remember seeing that someone had posted a drawing on the fuel and vacuum lines (about a year ago). I cant seem to find anything on it now though. I'm not sure when the post was either. Got anything like that?

[HobbyMan]

I don't have a diagram but I can spell it out for you. #1,3,and4 intake boot nipples are supposed to be capped. The #2 intake boot nipple plugs directly into the fuel octopus.(square thingy) The vac advance line goes from the diaphragm to the nipple sticking out from the #2 carb body on the top left side in front of the choke actuator. THat sums it up for the vac lines. One fuel line from the petcocks on each side goes to a T fitting which then plugs directly into the carbs. THe other lines from the petcocks plug into the outer fittings on the octopus. The inner fittings on the octy plug into the fuel t fitting. simple. The way the stock system is set up on the special, you can run with one petcock off if you wanted to because the octy is one valve so the left and right side joing together.

[Igotit4free]

thanks man, I'll let you know how it turns out