vacuum lines to intake manifold

[jeffro1954]

I'll probably feel dumb for asking this. when I synchronize the carbs using a small gas tank so it's easier to get to the screws the vacuum lines that normally plug into the gas tank fuel cock are hanging loose. Idles just fine, gauges look good. put the tank back on, hook up the vacuum lines, start it up and now my idle speed is up about 1,000 rpm from where it was set. Is my fuel cock plugged up? I cleaned it and it looked fine. If I put my fingers over the tip of them when the bike is running the idle speed increases about 1,000 rpm just like when I plug them into the fuel cock.
The bike also still doesn't snap back to idle when releasing the grip. sprayed carb cleaner around the intakes so I know I don't have an air leak. Haven't checked the ignition advance.
bike is a 1978 XS1100. all standard. I just know someone will recognize this right away. Thanks guys.

[cywelchjr]

When your syncronizing the carbs, the lines that normally plug into the petcocks should be in use for the sync gauges to do the syncing with. If not your doing something wrong and messing everything up and you need to start over.

The same ports used to run the vacuum ports on the petcocks are the ones used to sync the carbs, which is why there are 4 of them, if your doing them with a single gauge, you need to plug the ones that are not in use while the gauge in not on them, they should NEVER be open to atmosphere.

[bikerphil]

Just a guess, but I'd say your throttle cable is being disturbed somehow when the fuel tank is put back on the bike, causing the RPM's to rise.

[jeffro1954]

using 4 gauges so all intake vacuums are in use. after I disconnect the gauges and put the plugs on the outside 2 carbs and the #2 and #3 line to the gas tank are just hanging there bike idles fine. If i plug the ends with my fingers (gas tank off) the idle goes up. when I put the tank on and plug them into the tank rpms go up.

[DGXSER]

I have to wonder if you do not have a vacuum leak in the lines your hooking to #2 and #3 when you synch. As it seems the idel and all is set up perfect for having a vacuum leak on #2 and #3.

[jeffro1954]

maybe I need to check my hose connections on the gauges closer or the gauges themselves for a leak. I know those tubes are meant to suck the diaphram in the pet cock open for gas to flow to the carbs when the little lever is pointed down.

[cywelchjr]

That's what the signs point to. Which also means that the sync is way way off. Try adjusting the idle speed with all the ports blocked off, then hook up the gauges. If the idle changes at all, there is a leak in the hoses for the gauges or in the gauges themselves. I'm close to 100% sure it's one or the other, it's just a question of which, and I'm hoping it's the lines cause that's easy to fix, cause if it's the gauges it means replacing them. If their the ones with the brass restrictors and the plastic valves in the lines, I found that the brass things that screw into the barbs on the carb manifolds didn't seal so I threw them away and just push the hoses onto the fitting and use the valve to restrict it down for them to work.

Of course, I also found the hoses are crap, they have cracked since I last used them so I have to go down and by new ones before I sync again, but I'll buy good quality hose myself this time (part of the diff between the expensive set and cheap is the quality of the fittings and the hose they use, they seem to use the exact same gauges, they just don't bother to calibrate them for you on the cheap ones, you have to do that yourself).

[jeffro1954]

they are cheap gauges with plastic valves. You're right though if a gauge or line is not air tight the carb synch is way off which would explain the weird idle. get what you pay for right?

[cywelchjr]

Those gauges are fine, just go down and spend about $4 on vacuum line at the auto parts store and replace the line and they should work fine, just make sure it's the line and not the gauges first (the lines are the most likely source though).

I've got what are probably the same set and they can work just fine, it's really just the rubber line that's crap, so just go get some good stuff, it's not like it costs that much.

[petejw]

jat,
if ur using the 4 vac guages they need to be callibrated to each other
so they're reading the same, this can be done using a miti vac
or connecting them up 2 an inlet barb and having all 4 of them reading the
same.

[DGXSER]

or connecting them up 2 an inlet barb and having all 4 of them reading the
same.

Just to be clear, what Pete is saying is hook them up one gage at a time to the same inlet barb.

[jeffro1954]

planned to try that tomorrow, best way to get them to read the same. I do have a miti vac I can try. speaking of miti vac, that tool was invaluable bleeding brakes.

[DGXSER]

If it were me, I'd go with the mity vac method. Alot better certainty that your reading a consistant vacuum level to calibrate the gages against..

[DiverRay]

When you get the hose, pick up some vacuum "T" fittings. I use the mity vac to check each pair, and then the pairs together with just one "T". If you buy three, you can check them all at once. I'm just cheap.....

[jeffro1954]

Ok DGXSER using the Miti vac worked really really easy to calibrate the gauges. they weren't off by much so I don't think that's going to solve my isse with the vacuum tubes hanging loose it idles fine but when plugged into the tank idle goes up 1,000. umm tackle that tomorrow. Goldwing needs a new water pump so that's today's job.