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Old 08-08-2012, 06:08 PM   #1
One Less Harley OP
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Hanging Idle on R80 G/S

When my bike is warmed up when closing the throttle, the bike just doesn't drop down to idle very quick, it hesitates for about 3-5 seconds then will idle. Cables aren't sticky, and I've pulled the carbs and double checked for throttle shaft freedom of movement, no stickiness what so ever. Also checked butterflies (readjusted one) for center to carb bore, all appears fine.......so is this an indication of stuck ignition advance weights or something else.
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One Less Harley screwed with this post 08-08-2012 at 06:37 PM
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Old 08-08-2012, 06:20 PM   #2
supershaft
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It can be. Although most every one advised to check them here on the net mostly for an old service bulletin that came out decades ago, I rarely ever see them stuck. Nine out of ten times it is a combo of idle speed adjustment and the mixture screw adjustment. The other one time is leaking carb spigots. Roughly speaking, of course.
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Old 08-08-2012, 07:07 PM   #3
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Richard, I had similar symptoms with the ST. Hanging idle especially coming off the hwy, cleaned and greased the weights, it would behave properly for another 100miles, bought a rebuilt can from Rick just for kicks. Never have had it hang since. ('08)
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Old 08-08-2012, 07:55 PM   #4
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I've read to go richer on the Needle Jet ,but since it is an idle problem wouldn't it make since to go larger on the Idle Jet???

1st check for air leaks, then possibly go to the next size larger Main Jet as I have 135's in there right now. Needle clip 2nd from top. Might be running a little lean. I've been having preignition issues for a while so this may be a symptom of running lean (?).

Main Jet 135 (150 stock, 130 stock for 1981)
Idle Jet 45 (45 stock for 1981,40 for 83-86)
needle Jet 266 (stock) , needle has about 15,000 miles
Needle clip 2nd from top (3rd stock)
Needle 46-241 (46-251 for 1981)


BTW-I'm very confidant that the idle mixture and sync are dead on. A hair rich on the idle screw to prevent off throttle hesitation.

Don't want to blame the bean can just yet.
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One Less Harley screwed with this post 08-10-2012 at 07:20 PM
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Old 08-08-2012, 10:39 PM   #5
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Was the bean can under water? Full of mud? They do stick but very rarely. Some people say they stick all the time because they are selling aftermarket ignitions with the exact same hall effects sensor that the bean can has. 99% of the time a bean can goes bad, it's the hall effect sensor. Since the aftermarket ignitions use the exact same technology, they trump up the mechanical advance failing. Ausherman has a "fool proof" method of diagnosing a stuck advance and it is anything but . . . . I am not saying they never stick. Anything is possible. I have worked on a lot of airheads and been around a lot of dealerships since the can first came out and I have been looking hard for sticking advances since that bulletin warning about sticking advances first came out around '85 (?). I almost never see it.

It has nothing to do with your mains. Your mains are already too rich. Later on they leaned the mains to 135's. They run better, make more power and get better mileage with 135's.

They run like crap with the jet needle on the 4th position. It richens the midrange way too much. What you might actually need richer (you will probably only hear here from me) are 268 needle jets. But still, that will hardly effect your fast idle.

You don't need richer idle jets either.

Now to what it is usually. How are you sure the mixture screw is dead on? That has me suspicious right there. Do you mean half way between the stumbling points for each carb? If so, richen them up a bit from there. Were your stumbling points, for instance, 12 hours apart on one carb and six hours apart one the other? Richen the one up one hour and the other 30 minutes so to speak.

If your bike idles fine cold with the choke off or even close to it, your idle speed is too high. Lower it a bit.

Air leaks? Check the spigots when the engine is good and hot and fast idling. If brake cleaner effects engine speed, you have a leak there.

There are other things that can cause fast idle but it is super rare in my experience. Check the timing and make sure it is on the S mark as well as the Z mark. Sometimes it isn't a sticking advance but rather the timing itself. Lots of times bean cans won't time idle and fast idle at the same time since new. That can be adjusted out by bending the weight stop tabs. Good luck! Maybe it IS a sticking advance but surely this advice can help somebody out there because it holds true ALL the time!

supershaft screwed with this post 08-08-2012 at 11:02 PM
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Old 08-08-2012, 10:43 PM   #6
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Quote:
Originally Posted by One Less Harley View Post
When my bike is warmed up when closing the throttle, the bike just doesn't drop down to idle very quick, it hesitates for about 3-5 seconds then will idle. Cables aren't sticky, and I've pulled the carbs and double checked for throttle shaft freedom of movement, no stickiness what so ever. Also checked butterflies (readjusted one) for center to carb bore, all appears fine.......so is this an indication of stuck ignition advance weights or something else.

Yes sticking advance weights.
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Old 08-09-2012, 12:39 AM   #7
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Quote:
Originally Posted by One Less Harley View Post
When my bike is warmed up when closing the throttle, the bike just doesn't drop down to idle very quick, it hesitates for about 3-5 seconds then will idle. Cables aren't sticky, and I've pulled the carbs and double checked for throttle shaft freedom of movement, no stickiness what so ever. Also checked butterflies (readjusted one) for center to carb bore, all appears fine.......so is this an indication of stuck ignition advance weights or something else.
Did you check the valve settings already? Had the problem many times on bikes with leaking or to tight valves !
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Old 08-09-2012, 06:07 AM   #8
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I'll do a valve check while it's cold 1st. Half way between stumble point on the AF mixture screws, bike doesn't stumble when slightly cracking the throttle, like it had one time before. I'll richen the AF mixture a wee bit.

Bike needs choke when cold and is a little hard to start when cold.

P/n for the 268 ( P/N 13 11 1 260971)
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One Less Harley screwed with this post 08-09-2012 at 07:11 AM
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Old 08-09-2012, 06:08 AM   #9
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Quote:
Originally Posted by bulldust View Post
yes sticking advance weights.
+1
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Old 08-09-2012, 07:55 AM   #10
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Stuck advance weights are probably the more common problem, but I had the same thing once and it was caused by a loose butterfly plate. When the throttle was open it would move off center and when I let off the throttle it would not close all the way, but after a few seconds the vibration of the engine would allow it to migrate back into place and close all the way. Likewise a couple chops of the throttle would center it up again. Looking through the carb it looked well centered in the bore, and in every way just fine until I opened the butterfly a bit and felt that it was wiggly. My first instinct was also advance weights which I lubed the hell out of with no effect. Strangely enough, the engine didn't sound wildly out of balance. It ran pretty smoothly, even when idling at 2000 rpm.
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Old 08-09-2012, 09:15 AM   #11
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It's your advance in the bean can. There are those that stick a little bit now and those that will start to stick not to far in the future
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Old 08-09-2012, 09:17 AM   #12
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As others have mentioned the idle does tapper off when letting the clutch drag.

Did the valve adjustment, exhaust were a little tight. Doubled checked the carb jets and the main jet was a 135...which makes since as the bike has been very slow to warm up and have experienced that before with the 135's.

I'll take it for a ride, but it's cool out today and will take some time to warmup fully. If it still hesitates the 142 mj or 145's are going in.

Butterflies where double check for centering and tightness previously.

I may and try to source out the 268 needle jet and possibly the other needle that's listed for the R80's.

I want to make sure it's not the carbs, before looking into the bean can. If it winds up being the bean can then I'll probably buy Ricks and save the old one as back up. I did lube it a while back though.
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One Less Harley screwed with this post 08-09-2012 at 09:27 AM
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Old 08-09-2012, 09:37 AM   #13
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Did you check that the choke's are fully returning and not hanging up a bit as well... just try and depress them fully down with a finger to see if there is any play
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your bike is suitably dirty. Well done.
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Old 08-09-2012, 09:43 AM   #14
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Did you check that the choke's are fully returning and not hanging up a bit as well... just try and depress them fully down with a finger to see if there is any play
+1, also try increasing the free play in the throttle cables at the carb end.
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Old 08-09-2012, 10:01 AM   #15
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cables are slack
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