Author Topic: Erratic Idle  (Read 2168 times)

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Offline coffee_brake

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Erratic Idle
« on: July 03, 2008, 11:52:00 pm »
In my understanding, an erratic idle should be from an intake leak. My '05 has in increasingly erratic idle, to the point that it has shut off on decel a few times, not what you want to happen approaching a turn or in heavy traffic.  This '05 (bought in early '06) is a daily rider and has been since new, it will turn 30k this coming week, and I have faithfully synched the carbs at every recommended service interval. They are never more than a tiny, tiny bit off. I know that an intake leak can be detected by spraying something flammable near the carbs while it's running. When I do this with carb cleaner, I get absolutely no reaction, no revs increase at all.  My lines all look good and healthy, I have never removed the carbs, never (thank goodness) had to mess around the fuel system at all, until now.  I keep the idle setting right around 1000 RPM but now it's jumping around 100 or more to either side of that. Doesn't matter if the bike is hot or cold.    Anybody got any idea what's going on with my idle? The shut-offs are kinda disturbing and I'd sure appreciate anything you folks have to offer...  
Jenn in "Chaahlston, y'all...."

Offline 2linby

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Erratic Idle
« Reply #1 on: July 04, 2008, 12:38:00 am »
Does it run erractically only at idle???  Does it do this with a full tank of gas? Half? empty?    Could be a venting issue but as always.....    Check the cheap stuff first!    These things usually are fuel related, but it can be electrical too. Also mechanical and sometimes spiritual....... even cosmic!  Hey Its happended to me!   :eg:    Try running the bike on reserve and or prime to see if you experience the same issues. If you run it on prime just make sure you return the petcock to the run position when you stop. Otherwise you run the risk of having fuel flowing into the carbs and eventually into the cylinder heads. Not a good thing to have happen when you start the bike the bnext day. Hydrolock anyone???.  If you do not experience the erractic idle then I'd say you have to replace the petcock.    But also check the following too.    Make sure all the vacuum lines from the carbs are secure. 1&4 tee'd to the reed valve thingy (technical talk) #2 to the petcock and #3 capped off    Do you have a in-line fuel filter?  If so replace it and make sure the hose is not kinked in any freaking way.    Open and drain the float bowls place clear tubes over the nipples to a catch tank then place the petcock on prime and to see if you have adequate fuel flow from all carbs. This might also clear any crap (technical again sorry) from the carb and bowls.    Make sure the petcock is clean.    Make sure all the plug boots are completely pressed tight over the plugs.     Make sure the coil wires are attached properly and they are not frayed etc. Intermittent grounding coil wires suck.      Best of luck and please let us kow what you find out.    AKA "2linby" That's 2-lin-by folks!  Northwest Area Director  COG #5539  AMA #927779  IBA #15034  Team Oregon MC Instructor    http://community.webshots.com/user/2linby  http://tinyurl.com/njas8 (IBA BunBurner Gold Trip)  http://tinyurl.com/lwelx (Alaska trip)      
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Offline Paulie

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Erratic Idle
« Reply #2 on: July 04, 2008, 12:05:00 pm »
this slacker sez: throttle cable slack!  ;)  01 Conc, Mijami Floriduh  Over the Pond 06: http://tinyurl.com/2vk9o2 route map: http://tinyurl.com/4p7pmd  

Offline S Smith

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Erratic Idle
« Reply #3 on: July 04, 2008, 04:00:00 pm »
Try using a good quality fuel system cleaner like Chevron Techron.  Maybe one or more idle jets have a bit of gunk in them.      --  Steve Smith, #3184  COG Northest Area Director  (somewhere in south central CT)    If you're not living on the edge, you're taking up too much space.  
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Offline Bill Hookman

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Erratic Idle
« Reply #4 on: July 04, 2008, 08:24:00 pm »
The shutting off on decel is probably due to the idle set too low.  It should be set at 1100, not 1000.  Mine will shutoff on decel with the idle set at 1000.    Bill Hookman  Columbus, OH  COG #6893, Ohio AAD    The twistier and hillier the road, the bigger the smile.
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Offline Greg M.

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Erratic Idle
« Reply #5 on: July 06, 2008, 03:22:00 pm »
This slacker sez... turn the idle up 100 rpm. Worked for me!!     When I had the idle set at 1000... and the bike was cold... and I was going downhill... it would sometimes die during decel... like, I'd be in 2nd or 3rd, pull in the clutch as I was slowing down, and it would die.. then I would pop the clutch (the bike was still rolling) and it would start... I'd keep it running by just feathering the throttle a little.    So, I finally turned up the idle, just a very little... and it doesn't happen any more.    Anyway, like Bob P. says... try the cheap (easy) stuff first.      
« Last Edit: July 06, 2008, 03:43:00 pm by Greg M. »
Greg M.  Newcastle, Wa.103

Offline coffee_brake

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Erratic Idle
« Reply #6 on: July 06, 2008, 10:58:00 pm »
OK thanks everybody. This idle problem is at all tank levels, I'm sure it's not a petcock/fuel feed issue. I don't think the plug wires are bad on such a new bike...only 29k of careful maintenance, is there a way to test them?  Paulie are you saying I should tighten up the throttle cables? They have the right amount of play according to the Clymers and I lubed them well after this idle thing started, they are still in spec and it made no difference.   This trouble is only at idle and decel, not at speed.    I will put the idle up to 1100 tomorrow and see what it does.    If I spray carb cleaner around the caps on the carbs, should the idle increase if that's where the problem is?    Again, thank ya'll for the input...  
Jenn in "Chaahlston, y'all...."

Offline Paulie

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Erratic Idle
« Reply #7 on: July 07, 2008, 06:01:00 am »
Nope Jenn, if the play is hokay leave it be. I'm gonna guess that bumpin the idle adj will git r dun.    Like Steve sed, I give the ol dawg a treat of 20oz Techron & she usually responds with better mpg. But always has idled raspy n ruff. No worries.  01 Conc, Mijami Floriduh  Over the Pond 06: http://tinyurl.com/2vk9o2 route map: http://tinyurl.com/4p7pmd  

Offline Eddie-FL

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Erratic Idle
« Reply #8 on: July 07, 2008, 07:42:00 pm »
Jen,  Try draining the carb bowls if you haven't already. I had a similar problem and found some very fine grit in the fuel. Even with a fuel filter. Costs nothing and may help.    Eddie  AMA# 686667 COG# 7073 CDA# 0136  
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Offline coffee_brake

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Erratic Idle
« Reply #9 on: July 08, 2008, 11:26:00 am »
Now she is idling MUCH better at 1100-1200, sounds better, accelerates smoother from the line, and no issues with sudden shut-offs.     Wow, I sure like these cheap easy fixes!    Just for giggles I'll drain the float bowls on this next carb synch, just see what's in there. I need to install that fuel filter anyway, been putting it off too long.    Thanks! That was easy!  
Jenn in "Chaahlston, y'all...."

Offline smithr1

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Erratic Idle
« Reply #10 on: July 08, 2008, 12:58:00 pm »
Yep I usually set mine just above "Dunt sound right"  ----------------------------------  I will answer any question.  It is up to you to figure out if I should have.    <p align="left">My Photos<br
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Offline Gene W

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Erratic Idle
« Reply #11 on: July 15, 2008, 04:23:00 pm »
The plug wire are subject to popping off of the plugs for no good reason.  I think that sometimes exposure to water from washing or riding in the rain may cause it but at any rate, they just pop off. Number one seems to be most likely to do it.    Once the plug wire cap has popped off of the plug it is still sitting on top of it making a connection that varies from pretty poor to pretty good.  This has little to do with the quality or frequency of maintenance.    Raise the rear of the gas tank and put a 2 X 4 block on edge under the back end of the tank to hold it up. Check each plug wire by pulling it off of the plug and push it back on until it snaps into place. You can feel it when it goes on correctly.    While the tank is up look for any kinks in the fuel line or vacuum lines that are off of their nipples as mentioned earlier.    I would raise the idle to 1100 as previously suggested.  I have had the same experience as the others at 1000 rpm.    The plug wire thing happens a lot so it's always a good place to start.    Gene        
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Offline coffee_brake

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Erratic Idle
« Reply #12 on: July 16, 2008, 01:50:00 pm »
Thanks Gene, the first time I had a plug wire not "doing right," it was on my car and I was sure I'd blown the engine. Now, like you said, I always make very sure the caps are on good and snug.   Running at 1100-1200 has the idle issue all fixed now, it's running great! (except for the camshaft noise)  
Jenn in "Chaahlston, y'all...."