80 Shovelhead stutter
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Joined: Jul 2019
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From: SLC
80 Shovelhead stutter
Hey guys,
I bought a 1980 80" FXS about 2 weeks ago from a guy in town, he's owned it since 1997 and had the top end rebuilt a few years ago. The bike had been sitting for atleast a year only being started a few times in the last year. The bike is super clean and I have been enjoying riding it!
I have noticed however, that sometimes this bike likes to stutter on throttle acceleration. Sometimes it doesn't happen on my rides and sometimes it does. Sometimes it corrects itself quickly and other times it doesn't. I caught it on video this morning on my ride to work. Here you an hear what it is doing:
It seems to be idling fine but when I hit the throttle it will stutter/not be smooth and I wont get much power. It's alot more obvious when I am riding it on the road. My tach also goes crazy when it's happening. It doesn't work very well period but it somewhat shows an accurate reading. When this is happening it almost shows it redlining (when it's not). I am going to start with a super e carb rebuild and go from there. I just thought i'd ask and share the video if anyone else has any other ideas. Seems to be happening a bit more than every once in awhile now as it happened to me yesterday and this morning.
This is my first big twin and I look forward to many miles on it, finally graduating from evo sportsters so I have a lot to learn! :-) Thanks!
I bought a 1980 80" FXS about 2 weeks ago from a guy in town, he's owned it since 1997 and had the top end rebuilt a few years ago. The bike had been sitting for atleast a year only being started a few times in the last year. The bike is super clean and I have been enjoying riding it!
I have noticed however, that sometimes this bike likes to stutter on throttle acceleration. Sometimes it doesn't happen on my rides and sometimes it does. Sometimes it corrects itself quickly and other times it doesn't. I caught it on video this morning on my ride to work. Here you an hear what it is doing:
It seems to be idling fine but when I hit the throttle it will stutter/not be smooth and I wont get much power. It's alot more obvious when I am riding it on the road. My tach also goes crazy when it's happening. It doesn't work very well period but it somewhat shows an accurate reading. When this is happening it almost shows it redlining (when it's not). I am going to start with a super e carb rebuild and go from there. I just thought i'd ask and share the video if anyone else has any other ideas. Seems to be happening a bit more than every once in awhile now as it happened to me yesterday and this morning.
This is my first big twin and I look forward to many miles on it, finally graduating from evo sportsters so I have a lot to learn! :-) Thanks!
Last edited by james69; Jul 30, 2019 at 08:43 AM.
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From: Texas! Ya mean there's someplace else?
If the tach always goes nuts when this happens, look for something electrical. Ignition switch, kill switch, coil, even a loose battery connection. That said, going thru the carb after sitting for a year isn't a bad idea.
I can't really tell what you mean listening to the video. Looked like you were sitting still and the engine was trying to quit. Is the engine warmed up in the video? Enrichener working properly?
I can't really tell what you mean listening to the video. Looked like you were sitting still and the engine was trying to quit. Is the engine warmed up in the video? Enrichener working properly?
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From: SLC
Thanks for that information, I will be sure to give all of those a good look over. The stutter is alot more apparent while I am riding. It was so bad that I had to pull off the freeway (where i took the video) I keep trying to catch it on video while riding but its tough :-)
The bike wont die, it will idle just fine it's just on acceleration like a quarter/half throttle it will stutter and the bike becomes jerky. I try to open it up more and it will stutter worse and I wont have really any power almost like a misfire..not sure? The bike was warmed up and my enrichener is working just fine. Again this is my first shovel and I am used to evos. Thanks so much for your help!
The bike wont die, it will idle just fine it's just on acceleration like a quarter/half throttle it will stutter and the bike becomes jerky. I try to open it up more and it will stutter worse and I wont have really any power almost like a misfire..not sure? The bike was warmed up and my enrichener is working just fine. Again this is my first shovel and I am used to evos. Thanks so much for your help!
Last edited by james69; Jul 30, 2019 at 09:14 AM.
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From: USA
A carb rebuild is a good place to start....clean out your jets. Also, did you try adjusting your accelerator pump? Check for intake leak too while you are at it.
Here is a good video on basic set up.
Here is a good video on basic set up.
Last edited by hscic; Jul 30, 2019 at 11:06 AM.
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From: SLC
thanks hscic, I appreciate the video. I also have the super e manual (as well as the factory manual) that the previous owner gave to me. I ordered a rebuild kit and will be going through it when it comes in! Hopefully that's the cause of my issue. I might replace the petcock and fuel line as well. I have no adjusted anything on the carb yet.. when I rebuild I will set it back to factory default per the s&s video/manual and tune from there.
I have read that shovels are really prone to intake leaks. I will check that out!
I have read that shovels are really prone to intake leaks. I will check that out!
Last edited by james69; Jul 30, 2019 at 11:29 AM.
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From: SLC
Good to know hscic. It has only ever happened when the bike warms up too, never right off the bat. I am thinking in getting something like this: https://www.lowbrowcustoms.com/tite-...sportster.html
It's a bit more expensive but if it prevents intake leaks well like the reviews suggest then i'm all for it.
It's a bit more expensive but if it prevents intake leaks well like the reviews suggest then i'm all for it.
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From: la la land jerzey
intake leak is always suspect in any running issue even if you just re did it - yes they are that sensitive
I would add you could want to check if the compensator sprocket is actually tight - when its not it slides causing a shutter BUT your explaining a shutter and mine can be way different
I would add you could want to check if the compensator sprocket is actually tight - when its not it slides causing a shutter BUT your explaining a shutter and mine can be way different
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From: australia
if the carby wasnt drained before storage. id say its a blocked jet. im surprised it started at all. id start there first if it was running fine before storage
Last edited by john lee; Jul 30, 2019 at 06:19 PM.