Irratic Idle - Kawasaki KLR 650 Forum
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post #1 of 2 Old 05-13-2015, 02:06 PM Thread Starter
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UKbri's Avatar
Join Date: Aug 2013
Location: The Black Hills
Posts: 49
Irratic Idle

My girlfriends KLR 2011 is having idle problems. The idle seems to go up and down for no reason. I thought it was altitude or air temp but it doesn't seem to make a difference. One day it will be running at 2000rpm and the next day it will be 1000rpm.
Is there any common things i should be looking for, air leaks or carb issues etc?
last time i had the carb apart it looked pretty badly worn. It is on 53,000 miles now.
Thanks all
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post #2 of 2 Old 05-13-2015, 02:21 PM
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Tom Schmitz's Avatar
Join Date: Feb 2009
Location: Redondo Beach
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The symptoms you describe are a sign of erratic idle mixture, and the cause is often a vacuum leak somewhere.

I guess one obvious question is whether or not the idle mixture has ever been fiddled with. They are a bit on the lean side from the factory. If the idle mixture has not been fiddled with, fiddling with it to make it richer might cure the symptom (though not the direct cause if wear is the issue). Remove the plug over the idle mixture screw and gently seat the screw, then turn it out two turns. If it gets better, well, it's better. If it does, there is a method to get the mixture pretty much dead-on that we can talk about.

Looking at wear being the cause, you could grab an aerosol can of starting fluid (or carb cleaner, WD40, or an unlit propane torch) and spray it around the carb intake boot, around the throttle shaft, and around the boot to the head.

If there is a vacuum leak the engine's speed will change as extra combustible stuff is drawn into the intake.

Likely suspects are poorly sealed carb boots to the air box, head and the carb, cracked carb boots, or a worn throttle shaft bore.

You should also check all the vacuum lines that are coming off the intake manifold for leaks. There is one that goes to the petcock and one that goes to the AIS.

Make sure that the throttle cables are not sticky, too. Open the throttle about a quarter turn and let it gently close a few times. The throttle stop screw should firmly touch the throttle stop. Sticky cables could be the culprit, but the throttle return spring is pretty strong so this is a bit of a stretch. Do this with the engine running. When the throttle has returned, press on the back of the stop screw. The idle should not change.

Give it a shot.


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Last edited by Tom Schmitz; 05-13-2015 at 02:35 PM.
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