Carbs/Runaway Idle

[geneborg]

1980 XS11 SG
PODS and No Octy
'79 SF Carbs with new Pilot Screws/Idle Mixture Screws
Butterflys set via Bread Tie method and the carbs disassembled and cleaned.
I am having a runaway idle problem with the bike.
Plastic Floats set at 22mm and I have had the pilot screws from 1 1/4 out to 4 turns. Three of the old pilot screws were broken off in the holes when I got the carbs and I am sure the holes are now slightly larger as a result of removing the old tips. I also have small fuel filters and Toro shutoff valves in the direct fuel lines. The left fuel valve going to #s 3 & 4 carb and the right side going to #s 1 & 2 carbs. I do notice that inorder to get all 4 cylinders to fire that the fuel must be on OR #s 1 & 2 will not fire with what is in the carb bowls.
The bikes starts right up but shortly thereafter the idle will increase dramatically or "runaway" and I immediately shut off the engine. What causes runaway idle????
Any ideas please---
gene borg in the Tampa Bay Area of FL

[CatatonicBug]

Did you push the choke in? If I leave the choke pulled out, the idle starts to run away. As soon as I push the choke in, it drops back to normal.

After the bread-tie thing, did you do a proper sync? The bread-tie is just a starting point. You do have to properly sync them. Also, you say the mixture screw holes might be enlarged? That shouldn't matter if you tune them, since you can still block off the hole with the new screw if you want to. Don't rely on "turn them X turns out". You have to properly adjust them for each carb. No two carbs are exactly alike, and even 1/64 of a turn makes a difference.

[DGXSER]

1980 XS11 SG
PODS and No Octy
'79 SF Carbs with new Pilot Screws/Idle Mixture Screws
Butterflys set via Bread Tie method and the carbs disassembled and cleaned.
I am having a runaway idle problem with the bike.
Plastic Floats set at 22mm and I have had the pilot screws from 1 1/4 out to 4 turns. Three of the old pilot screws were broken off in the holes when I got the carbs and I am sure the holes are now slightly larger as a result of removing the old tips. I also have small fuel filters and Toro shutoff valves in the direct fuel lines. The left fuel valve going to #s 3 & 4 carb and the right side going to #s 1 & 2 carbs. I do notice that inorder to get all 4 cylinders to fire that the fuel must be on OR #s 1 & 2 will not fire with what is in the carb bowls.
The bikes starts right up but shortly thereafter the idle will increase dramatically or "runaway" and I immediately shut off the engine. What causes runaway idle????
Any ideas please---
gene borg in the Tampa Bay Area of FL

First, your float height is way high for the early carbs. I have not worked on them, but even with the plastic floats, I believe they should still be set to factory of 25.5mm Even on the later model carbs, they should be 23mm.

As to the runaway idle, after your float height is set better, as the idle increases, lower it with the idle set screw (not the mixing screw) until the bike is warmed up really well, then set the idle to about 1100 rpm. Now see how it starts up for you. Should need some choke.

Yes, bread tie is just a good starting point for the synch IMO.

[TomRodgers]

also check to make sure that your throttle cable protector (little silver metal collar at the end of the cable.....where it hooks to the carbs...not the tablet shaped thing that gets fished ito the carb bracket but the metal sleeve that actually goes OVER the end of the black cable) is seated properly. its worth looking at...1/4" of cable there is quite a few RPM's worth of adjustment...on mine it was the difference from 1300 rpms to about 6000 rpms....