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I have a 2007 Harley Davidson Road King. Yesterday morning I decided to replace my headers as the original pipes cracked at the Y-Connection in the rear cylinder port. I got Cobra True Duals at a very good price. Installation went smooth. Unplugged O2 Sensor plugs and removed headers completely with Sensors attached. Removed Front plug and installed in Front pipe & Rear plug to Rear pipe. Added new header gaskets. Followed Cobras installation instructions. All sealed correctly and everything plugged in accordingly. Went on a 15 minute ride and everything was great. Later in the afternoon, the wife and I went around the block and the bike was losing throttle response and was sputtering nearly shutting off. This morning I tried running it with air cleaner, took it off thinking maybe filter was plugged, no luck. Tried with gas cap open thinking the vent may not be working, no luck. Have double checked exhaust ports for leaks, checked O2 Sensor connectors, checked spark plug wires, checked breather bolts on air cleaner, no luck. I have tried changing tunes on it ant still has same problem. I just fueled up the tank yesterday morning before exhaust installation, but other than the exhaust nothing else has changed.
I do not have any trouble codes displayed on my speedometer or FP4 app.
Generally, when my bike is running well, I change something, and it starts running badly, I don't try anything except things directly impacted by the new installation / repair. It's easy to start trying everything we can think of, but the root cause is usually close to the repaired area. Look at the exhaust, any wiring close to the repaired area, especially anything that could have melted on the pipes (since it took a short time to show up). Check throttle body wiring, crank sensor is unlikely, but could it have been bumped while trying to get to those pesky front studs? If the battery / maxi fuse was removed, could something else in that area have become bumped?
If the battery terminals were loosensed, check them. They cause all kinds of issues. If the fuel tank was removed, disconnect and reconnect the QD. If the cavity behind the rear jug was messed with, check the coil ends of the plug wires.
Last edited by Ultra103; Jul 24, 2024 at 04:35 PM.
Generally, when my bike is running well, I change something, and it starts running badly, I don't try anything except things directly impacted by the new installation / repair. It's easy to start trying everything we can think of, but the root cause is usually close to the repaired area. Look at the exhaust, any wiring close to the repaired area, especially anything that could have melted on the pipes (since it took a short time to show up). Check throttle body wiring, crank sensor is unlikely, but could it have been bumped while trying to get to those pesky front studs? If the battery / maxi fuse was removed, could something else in that area have become bumped?
If the battery terminals were loosensed, check them. They cause all kinds of issues. If the fuel tank was removed, disconnect and reconnect the QD. If the cavity behind the rear jug was messed with, check the coil ends of the plug wires.
Thank you for the thorough response and different ideas to try next. I have bought two new Feuling O2 sensors from a local shop. The original ones were bad from previous owner running bike ver lean (bought motorcycle used and been fixing as I go). I have siphoned the gasoline from the tank and will try adding new fuel. I will be checking TPS and cleaning/lubing throttle cables next. So far with new O2 Sensors issue still persists.
Gotta make sure that you get nothing on those O2 sensors such as anti seize or oil/grease. The best thing is to not touch the probe portion. Did you try switching the leads?
So I went over the stuff I did on the bike. Checked O2 Sensors (after replacing with new Fueling Sensors) & made sure they were tight. Made sure headers were tightened and secured. Checked TPS, checked any other plug near the headers. Checked battery terminals and anything that could have been disconnected. Nothing obvious to the eye. Although as I was fiddling thru the bike I noticed the evap vent line had crumbled and fell. Its the line that connects to the black canister under battery. It also melted a bit from its proximity to the rear pipe. From my understanding this is just for venting. I doubt it will be my issue but can anyone put their input on this? Im planning on dropping it off at the mechanic. Cant seem to figure out the problem
Found this YouTube short. Its exactly what my bike is doing and obviously bogging down while throttle open. Hope this helps better understand my problem
Sold a bike that did that very stutter but only while riding it. Priced it low and told the new owner what all I had replaced trying to solve it. Good luck.
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