Plugs fouling
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Intermediate
Joined: Apr 2009
Posts: 26
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From: Greenville,PA 16125
Plugs fouling
I have a 79 xls and it has just started fouling plugs in the past month. I have gone through 4 sets so far. I was told that an S&S carb will do this as they are unreliable. I have always had them on my bikes but 1st ironhead. The motor was rebuilt to stock 1300 miles ago and is a strong runner. It seems to foul plugs while driving in town and the bike does not have a steady idle. Sometimes it will idle right and sometimes it will die. I do notice it more when it is damp out with the idle problem. I have checked the intake for leaks and there are none. The carb was put on new when the motor and tranny were redone. It has lots of power ( needs another gear in tranny though) and accelerates nice IF you roll into the throttle, If you just twist it hard the bike will sputter for a second then take off. The bike seems to run alot better when it is opened up. Any help is appreciated. Driving me crazy having to clean and change plugs all the time.
Advanced
Joined: Nov 2007
Posts: 60
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From: New Mexico
I have a super E and it's bulletproof, never let me down. If you have the B, it might be too big for a sportster. Perhaps you have a wrong jet size. I assume you mean the plugs are fuel fouled, since you had a rebuild. Well it's running rich, your pushrods need adjusting , or you got a wrong jet. Remember to make adjustments with the bike warm, and accelerator pump off. The S&S site has great instructions for all their carbs.
Road Warrior
Joined: Aug 2008
Posts: 1,306
Likes: 864
From: Sheboygan, WI
actually, the S&S B is the same size carb as a S&S E, just without the accelerator pump. That is causing your hesitation when you snap the throttle open. As far as your idling problem and fouling problem, i would first make sure the carb is clean, your inlet needle in the carb isn't damaged and the float level is set right, and you are running a good clean air filter. When you clean the carb, take the numbers off of the jets you have and post them here. When you reassemble the carb, LIGHTLY seat the idle mixture screw and back it out a turn and a half to start. Run the bike and adjust the idle until it stays running, then adjust this screw until you get the highest RPM idle, then reset idle again. here is a link to all the info you will need for the carb.
www.sscycle.com/admin/uploads/instructions/51-1006.pdf
Another thing to think of is what you have for ignition. If you say it gets worse when damp, you may have something in the ign. causing you grief.
www.sscycle.com/admin/uploads/instructions/51-1006.pdf
Another thing to think of is what you have for ignition. If you say it gets worse when damp, you may have something in the ign. causing you grief.
Last edited by d_slat; Jun 1, 2009 at 11:10 AM.
Thread Starter
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Intermediate
Joined: Apr 2009
Posts: 26
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From: Greenville,PA 16125
fouling plugs
I am going to readjust the valves tonight and check the jet sizes this weekend. It is a super E. I had a friend of mine adjust valves 500 miles ago and change jets out but he forgot which jets he put in the bike.( it was there for inspection). I switched the ignition from points to electronics. Timing is set right so I am going to try what all you have given me. Any idea what is the best fit jets for this bike. I have a feeling I am going to have change them out. A local shop here told me that the s&s carbs do not work correctly on the ironheads that you can not dial them in and they will foul plugs and wash down the cylinder walls.
Thank you all for the help you have given me.
Thank you all for the help you have given me.
IMO the guy at the local shop probably gave his best advice. But he is wrong.
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Intermediate
Joined: Apr 2009
Posts: 26
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From: Greenville,PA 16125
Thanks All
I set the carb by S& S standards. The bike ran ok but after hitting the high rpms it started backfiring and had to limp it home. I am going to have to do some work this weekend on it. I built it to ride not to look pretty under the lean to. The problem seems to be getting progressively worse with each turn out of the drive. I am going to readjust the valves tomorrow night and see if that helps any. I had to back the mix screw out 1 & 1/2 turns to get it to even idle correctly. I am starting to think this might be a timing issue instead of a carb issue. Never had a bike just start fouling plugs like this. 72 Shovel, 98 1200xlc, nor 66 xl nor 66 xl did this to me. Scratching my head wondering what the heck is going on. I will keep you posted on the next step. Thanks again all & IronMike thank you again for helping me with this scoot.
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Intermediate
Joined: Apr 2009
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From: Greenville,PA 16125
Iron mick
Sorry Mick, Brain says MICK but fingers type MIKE, Looks like the problem is spreading to humans now. Here we go lock the borders the ironheads are taking over the USA !!!!!!!
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... The bike ran ok but after hitting the high rpms it started backfiring and had to limp it home... The problem seems to be getting progressively worse with each turn out of the drive ... I had to back the mix screw out 1 & 1/2 turns to get it to even idle correctly. I am starting to think this might be a timing issue instead of a carb issue...
The problem started with running at high RPM and has gotten worse. I am wondering if this is a failing electronic ignition; or a failing ignition coil? The coil you can test; the best [only?] test for an EI is to replace it with a known good one.
I presume by back out you mean set it richer. Do you mean back the screw out from gently seated? Or back it out from where it previously ran well? I wonder if there is some crud in the carb interferring with fuel flow.
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Thread Starter
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Intermediate
Joined: Apr 2009
Posts: 26
Likes: 0
From: Greenville,PA 16125
update on bike.
After all things were tried a friend of mine recommended a local guy that specializes in IH. He checked the bike out and looked at the 3 different kinds of plugs I had (HD.Acel,Champ) All three sets of plugs were defective (go figure). Replaced the plugs with Autolites and have put 150 miles on it without an incident. He did have to adjust the carb a little bit as I had the idle a little too high. Would never have thought that would have caused this mess. Not fouling plugs yet( notice I didn't say not fouling anymore), still waiting for the other shoe to drop. I have a 500 mile trip planned for the 22 of this month on it. We will see what happens.
