"Stumped"
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
"Potato, potato" is good..."bumdunbumdunbumdun" sounds like it needs a 45 slow jet... but try taking the idle screw out completely and looking at the tip of it....is it nice and sharp?
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,070
Likes: 2,115
From: Ohio
I reread your post and saw you replaced the voes
but onto something else.
I just recently went through running on one cylinder at an idle below 1000 rpms after setting over the winter and was a failing coil.
You have a new coil by your first post but need to determine if electrical or mechanical problem is present, I figured out my problem by pulling a plug wire off while running in the problem area and noticed that spark would only jump about 1/4" on one of the wires but matched the other wire when revved up alittle so that might be a hillbilly troubleshooting test needed to determine which direction.
Electrical failures seem to be the common failures after setting for a lengthy time but strange mechanical things can happen like lifters not staying pumped up at an idle but need to find a direction to follow, my coil was 8 months old and new mass produced electrcal products can fail out of the box
Something else to check is your charging system, you might be dropping below voltage required to fire the coil at an idle and comes up with rpm's, possible regulator failure, the hillbilly plug wire test will show this also or a VOM to be fancy.
I had my ear to the monitor trying to determine the difference in the 2 sounds you were describing but couldn't pick out a constant pattern of a possible failure. LOL!
but onto something else. I just recently went through running on one cylinder at an idle below 1000 rpms after setting over the winter and was a failing coil.
You have a new coil by your first post but need to determine if electrical or mechanical problem is present, I figured out my problem by pulling a plug wire off while running in the problem area and noticed that spark would only jump about 1/4" on one of the wires but matched the other wire when revved up alittle so that might be a hillbilly troubleshooting test needed to determine which direction.
Electrical failures seem to be the common failures after setting for a lengthy time but strange mechanical things can happen like lifters not staying pumped up at an idle but need to find a direction to follow, my coil was 8 months old and new mass produced electrcal products can fail out of the box
Something else to check is your charging system, you might be dropping below voltage required to fire the coil at an idle and comes up with rpm's, possible regulator failure, the hillbilly plug wire test will show this also or a VOM to be fancy.
I had my ear to the monitor trying to determine the difference in the 2 sounds you were describing but couldn't pick out a constant pattern of a possible failure. LOL!
Last edited by 1997bagger; Apr 24, 2011 at 09:34 AM.
Thread Starter
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Cruiser
Joined: Nov 2008
Posts: 139
Likes: 0
From: Beaver, OK. (No mans land)
I will try the hillbilly wire check LOL! As you mentioned charging system I have'nt thought about that. I did give it a new rotor, stator and regulator last summer seams to charge good but at low rpm volts on the gauge drops but have'nt checked with volt meter, I will look into that. Thanks for lending your ear 
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
I will try the hillbilly wire check LOL! As you mentioned charging system I have'nt thought about that. I did give it a new rotor, stator and regulator last summer seams to charge good but at low rpm volts on the gauge drops but have'nt checked with volt meter, I will look into that. Thanks for lending your ear
You need better than 11.6 - 11.8 volts at idle to keep it running sweet.
Thread Starter
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Cruiser
Joined: Nov 2008
Posts: 139
Likes: 0
From: Beaver, OK. (No mans land)
Was able to spend a little time with the old girl today and checked my voltage and had 12.5 volt @ 1000 rpm jumps to 13.2 @ 2000 rpm and 12.3 @ bat with all off seams to me plenty of juice. Both primary wires had good spark hillbilly check it would jump a good half inch and run alone on either cylinder although it ran alot better on the front then the rear. I have pulled the carb ( AGAIN ) going through it with a fine tooth comb. While I have it off I sealed the carb port of the intake and put 3 psi of pressure in the intake and soaped the connections to the cylinders, In good shape there sealed up tight. So see what I find with the carb.
Road Master
Joined: May 2009
Posts: 817
Likes: 1
From: N.E. Ohio
12.3 volts at the battery seems low. Especially if the battery is new. My battery is 3 years old and it stays around 12.8 sitting overnight. I will check my output tomorrow ,but I think I get 13 or so at 1000 rpms. I did a rotor and regulator last summer. 32 amp. I would check your regulator and stator output while your checking things.
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
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Outstanding HDF Member
Joined: Jun 2007
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From: Bellville, Tx
Have you started it up and idled it til it gets the "bumdum" sound , then put your hand near the exhaust tips to see if both cyl are firing. If both cyl are puffing then what you descibe is the classic "potato potato" sound of a good idling Harley. My Evo idles at 650
Can't address the enrichener anamoly, can only think there is abstruction or leak in the
enrichening circuit. A restricted flow would allow fuel to collect over time giving a startup boost but would not provide the flow necessary to sustain fuel delivery to the carb, so it would drop back to idle when the gas ran out. My best guess.
Can't address the enrichener anamoly, can only think there is abstruction or leak in the
enrichening circuit. A restricted flow would allow fuel to collect over time giving a startup boost but would not provide the flow necessary to sustain fuel delivery to the carb, so it would drop back to idle when the gas ran out. My best guess.
Road Master
Joined: Apr 2009
Posts: 1,123
Likes: 43
From: NJ
PT,
I am following this with great interest because mine does pretty much the same thing, rear does not run as smooth as the front. I have been through the thing top to bottom and back again.
If you hold you hand over each exhaust, does the rear ond seem to fire-fire-and then give a strong poof..? (best I can describe..)
Thanks
D
I am following this with great interest because mine does pretty much the same thing, rear does not run as smooth as the front. I have been through the thing top to bottom and back again.
If you hold you hand over each exhaust, does the rear ond seem to fire-fire-and then give a strong poof..? (best I can describe..)
Thanks
D