High idle after carb clean

[Guest]

I realize this may seem like I'm trying to cut corners. My true intention is to gain a bit of direction on what to do first since I don't get much time to work on my bike.

I recently cleaned my carbs following the guides on Bikecliff's website. I did the full dip and replaced all the o-rings with new ones from Robert Barr. I did the bench sync with a paperclip to get all of the butterfly valves even. The intake boots and the airbox boots are good (soft pliable rubber). I got the bike started (barely). It started with the choke on a quarter to half and was at low RPMs, about 1000-2000. Within a minute I had the choke off and it quickly revved up to 4000 RPMs. And the idle screw doesn't do anything. The pilot needles are set to 2.5 turns out and the idle screw was set to 3 turns in (or whatever the guide said to set it at). I do not own anything to vacuum sync the carbs (going to buy it soon). My plan is to get the idle ok then take it to a shop to get the carbs balanced.

Now my question is; What do I go after first to get the idle under control?

• Is an air leak the cause?
• Should I adjust the pilot needles first?
• Should I check throttle cable tension or choke cable tension? If so, how?

I was planning to do the highest idle adjustment but since the RPMs are so high and the idle screw does nothing I don't know if I can.

http://members.dslextreme.com/users/bikecliff/images/highest_rpm_plug_chop.html

[tom203]

Disturbing the boots (by pulling carbs out) might make it hard to get seal. But first check that the throttles are actually resting on idle stop screw (the gizmo with knurled knob). Hard to see, probably have to remove tank, unless you have small hands like me and can feel that the stop screw is making contact and doing its job.
Also make sure that "choke" lever is not holding the choke bar on carbs open a tiny bit .

I'd say that you have 1: throttle plates open too much or 2: choke not closed all the way or 3: airleak in carb boot area


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[DimitriT]

I wouldn't worry too much about the idle until you've hooked up the sync tool and made some adjustments there. You can try reducing the idle to 1500 to 2000 RPM with the idle adjustment knob behind the carbs. That should get you in the ballpark so you can do the vacuum sync.

[tkent02]

You can try reducing the idle to 1500 to 2000 RPM with the idle adjustment knob behind the carbs.

He said the idle adjustment knob wasn't having any effect, which probably means the throttle cable is too tight or routed incorrectly.

[Garagemahal]

I know I am late jumping in but you may have what is called "Hanging idle." If it happens after the bike has warmed up that is likely the culprit. Open the pilot screws up a bit.
Symptoms are usually hard starting and then increased idle as the bike warms up - especially after opening the throttle a bit.

[Nessism]

Did you replace these O-rings?