High idle issues

[Piets8]

i have a 1984 suzuki GS550L that's idling around 4k RPM, thinking i might have an issue with either my throttle or my choke.

If i throttle up, my RPM will spike, then dip below 2k RPM, struggle for a bit, then climb back up to 4RPM


Any suggestions on what the issue might be?
(also sorry if this is in the wrong section)



Other note worthy things
-Carbs have been "professionally" cleaned
-jets are clean and clog free
-seals seem to be fully intact
-everything that should be lubed is lubed
-occasionally has some issues starting


Thanks.

[Homie]

Did you do anything to the engine/carbs prior to this problem occuring (i.e. remove and reinstall the carbs, etc..)? Assuming that you didn't, I would check the following:

a. Ensure that the throttle stop on the carb cable bellcrank is actually seated against the idle speed thumb screw. If it isn't you have something holding the carb slides partially open. Check the throttle cable adjustment, carb linkage, etc.

b. If the throttle stop on the carb cable bellcrank is seated on the idle speed thumb screw you most likely have a vacuum leak. The most obvious place for one are the carb boots. Make sure the boots are properly sealed to the head and the carbs.

[mike_of_bbg]

Hello and welcome. What you have is going to be a carb/intake issue, so yes the Electrical/Ignition section is the wrong place.

Are you leaving the choke on? RPMs will easily rise to 3-4k on choke.

However, it sounds more like you have air leaks. An 84 550 has those siamese dual carbs, but I'm not sure where issues can arise on those. On most of the earlier models there are o-rings which seal between the boots and the head. Also the boots themselves can deteriorate and leak air.

Make sure that everything on the intake side is sealed up tight.

"Professionally cleaned"? As some say, professionals get paid to do something, it doesn't mean they're good at it. If you clean the carbs yourself, you'll know the job is done right.

"Hanging idle" is a good term to search on the forums.