Carbs are giving me fits.

[Spookysxs11]

I have a 1979 xs 1100 special i have gone threw the carbs and sinked them and adjusted them. The bike runs good my issue is now it won't idle initially ( seems too low and acts like it wants to stall) but after you have been riding it the idle will hang around 2500 for a while then eventually come down. I had the bike idling fine before i sinked the carbs but now the carbs are sinked and the thing is giving me fits. what to do i have also adjusted the pilot screws to 1 turn thinking that it was to rich at idle. the book calls for 1 1/4 turns out. anyone with any ideas

[natemoen]

Hanging idle usually means to lean.

[DGXSER]

Three things I can think of will cause the hanging idle, well maybe four.

1 Need to synch carbs, which you said has been done, but if you tuned the mixtures since, you will want to repeat the synch.

2 Vacuum leak, if you have a vac leak around the throttle plates or the intake boots it can cause a hnging idle, but that would not go away.

3 Lean mixture like Nate mentioned, and what you stated as to mixture screw settings may well be the cause.

4 Would be the dreaded sticking throttle cable.

Hope that helps you some.

[Rasputin]

The initial idle and the hanging idle point me in the direction that DGXSER has said as well as Nate. Personally I would be inclined to look at the mixture screws first in this situation.

[Spookysxs11]

Thanks for the advice

I will try the idle screws i never would have guessed. I will post the results and let you know thanks again.

[petejw]

jat, did u use vac guages 2 do the carb sync? If so did u calibrate the guages?

[Spookysxs11]

i zeroed out the guages before i used them . the first time i did the sink the darn thing had a flutter before 2200 rpm's but it would idle fine.... Now it runs great no flutter but this idle thing. is just odd

[greatnw]

I like DGSXER's list. Mine did the same thing. The carb boots were horribly bad. Didn't show up until it warmed up. Can't remember what I sprayed to find them, but when the idle ran up it was pretty obvious. Plus, like most here, I found the book settings on the mixture screw was way too lean.
Keep at it.You'll get it.

[cywelchjr]

I like DGSXER's list. Mine did the same thing. The carb boots were horribly bad. Didn't show up until it warmed up. Can't remember what I sprayed to find them, but when the idle ran up it was pretty obvious. Plus, like most here, I found the book settings on the mixture screw was way too lean.
Keep at it.You'll get it.

The "book" setting on the mixture screws is nothing more than the place to start adjusting from, not the place to run them at. You need somewhere to start adjusting from when starting with an unknown carb setup, and that's what the "book" setting is. You need to use one of the several methods for determining the correct setting for the idle mixture screw for EACH cylinder as part of the sync process. If you don't do this, you have not REALLY done a sync, you have only done PART of one.

[petejw]

i zeroed out the guages before i used them . the first time i did the sink the darn thing had a flutter before 2200 rpm's but it would idle fine.... Now it runs great no flutter but this idle thing. is just odd

Zeroing the guages isnt calibrating them unfortunately, u need a vaccuum source, a mity vac works well if u have 1 or i use the engine, whilst the engine is running use the same inlet barb and connect 1 hose at a time to the same barb and note the readings on each guage adjust accordingly, once adjusted the guages wont neccesarily show zero when disconnected. Calibrate ur guages, give it another sync and hopefully that will solve ur problem.

[Spookysxs11]

not sure what to do??

I adjusted the screws out 1 1/2 turns and still the same thing although it is better. should i continue to adjust out untill it is good ?? the carb boots last time i checked are not leaking. I will check again tomorow. let me know any other ideas. do you think it is mechanical??

[cywelchjr]

I adjusted the screws out 1 1/2 turns and still the same thing although it is better. should i continue to adjust out untill it is good ?? the carb boots last time i checked are not leaking. I will check again tomorow. let me know any other ideas. do you think it is mechanical??

As I mentioned, the book setting is just a starting point. The proper way to set the idle mixture is to adjust the idle mixture on each carb for the highest idle speed, then turn the screw in till the idle speed just starts to drop again. You do this for each carb, and once this is done the idle mixture should be pretty close to right where it should be. If you need to go more than about 4 turns out, you may need to go up a size on your idle jets or you might have clogged idle passages. But it's very important to do a proper idle mixture adjustment, the bike will exhibit strange running characteristics until you do.

[DGXSER]

First thing to rule out is the vacuum leak. Take soem carb cleaner or WD40 or starting fluid, or even an unlit propane torch. whatever the source, move it around each carb and inlet boot listenign to the engine as it idles. If the idle jumps when you hit a certain spot, there is your vacuum leak. If you have a vacuum leak, everything else is futile really.

[melbxs]

I found that the Colortune was the secret to getting the idle just right.

There are plenty of folk on this site who swear by it. I bought mine simply because so many raved about the difference it made to performing what is quite a tricky task.

http://www.xs11.com/xs11-info/tech-tips/maintenance/carburators/70-colortuning-carburetors.html

[Woof]

[QUOTE=melbxs;337665]I found that the Colortune was the secret to getting the idle just right.

There are plenty of folk on this site who swear by it. I bought mine simply because so many raved about the difference it made to performing what is quite a tricky task.

These videos on Colortuning are pretty interesting think I will give this a try

http://www.youtube.com/watch?v=5BU-5FhX_Qc&feature=related

http://www.youtube.com/watch?v=cy_yaAOKjA8&feature=related

http://www.youtube.com/watch?v=6hFUvQ4gaPc

http://www.youtube.com/watch?v=USb3M-MQYXU