Hi all,

I'd first like to thank everyone for the incredible resource and help this site has been over the past couple years, but I've come upon a problem I just can't figure out. Hopefully I don't get too long winded, but I want to describe things the best I can.

Starting about a month back I noticed my bike would "hesitate" or "stutter" cruising down the highway at 80 or so. It would also backfire a bit as it stuttered. I was on a long trip and checked fluids, etc. when I filled up next and everything seemed good. So I sort of chalked it up to bad gas. The problem went away for a bit and then appeared again every once and awhile, usually only while cruising 65 - 70 or so down the highway. Never an issue just cruising around town. Now this past weekend it started this again, but much more often and at various times. Yesterday it was doing it quite a bit. Usually when on the throttle. It seems to happen more in the upper rpm's. I don't have a tach so I'm not sure exactly where. I continued driving home at 60 and for the most part it was good, but would still hesitate now and then. Often times taking off it seemed ok until I really got on the gas. Then it would stutter and backfire, but continue to keep moving down the road. Now when idling in the garage the motor seems louder, but that could be my head playing tricks with me.

To me it seems like a fuel problem (running too lean?), but what do I know?

Details of the bike are... 2004 Fatboy, K&N filter, D&D Fatcat exhaust, power commander III usb. Other than that it is pretty much stock.

Before I take it in the shop I'd like to have an idea of what it might be. Any thoughts or suggestions on what to check would be greatly appreciated. I'm not a mechanic obviously, but I can handle some of the simplier task.

Any ideas? If you need more info, don't hesitate to ask. Thanks in advance!

 

Might want to check for an intake leak. Sounds like you might be sucking some air at the intake flange causing a lean pop (back fire) at higher RPM's. could be loose flange bolts or throttle body. Or is it carborated?

 

You might want to pull your fuel filter out and see if it is dirty............How many miles do you have on it?

 

Thanks for the help so far guys. I certainly appreciate it! The bike has about 22,000 miles on it. I added the D&D exhaust, PC III, and a new K&N about 7,000 miles ago (May '08). It hasn't sat for more than two days without riding since April. Bike was running with zero issues before this started. Let me know if any other questions come up. Thanks again...

 

You should check your fuel filter as suggested. My experience with your symptoms is that something electrical is the problem. It could be something as simple as a loose/dirty connection at the battery or its ground to the frame (somebody on this site just had that problem) or a short in the ignition wiring as I did. It was a pain to find. Certain rpm created a vibration that was just right for making the wiring for my ignition shake and it rubbed through the insulation under a clamp for that wiring. It could not be seen until I pulled the clamp off and checked the wires under it. It was essentially turning off my ignition for a fraction of a second by shorting to ground and then restore the ignition which would make the bike buck and let loose a HUGE backfire mostly out on the freeway...but it was rpm/vibration related.
If it ain't any of those things it still could be a bad connection at a connector or other wiring that could interrupt the electrical to your ignition system. I hate intermittent electrical problems, they are hard to locate. Come to think of it, any intermittent problem can be hard to find.
Good luck, man.

 

Well, I gave up and finally took it in the shop. I did do all the checks y'all mentioned and everything seemed good. Frustrated to no end I broke down and took it to a reputable shop in the area. As soon as I started describing the problem he asked where I got the map for my power commander. I told him I d/l from their website. From then on he insisted that was the problem. Since he's the expert (30 years of building bikes and motors) I had no choice but to believe him. So I left him the bike to have it tuned. Of course I couldn't just stop there, I figured hell, it's in the shop, lets do something with it. I figured with the mileage and the long history of cam tensioner problems on the vtwins it might be a good idea to switch it out with a gear drive kit and while I'm in there, put in a mild cam. Thankfully I did this. The old tensioners were in pretty bad shape. Anyway, I had him do this work and tune the bike. WOW, what a difference that made! I've only been able to put about 300 miles on it since, but so far, so good. The problem hasnt appeared again. And with the newly installed parts, it jumps quicker on the trottle and runs smoother than ever. His theory on the hesitation problems came down to this (apparently he's seen it often). The maps posted on power commanders website are generally ok as a start. He said Harley tends to change more than they let on from year to year on models of bikes. Usually subtle changes within the motor, but none the less have an effect. This along with my new exhaust getting more and more burned in most likely caused my hesitation issues.

Anyway, I thought I'd let you know how things came out. Can't wait to get some more miles on it, but it hasn't appeared again. Plus, I it's a tad more snappy now.

 

I had the same problem with my 2004. Replaced intake gaskets. And it still had the issue my mechanic found that one of the hoses from my fuel pump had a hole in it. fixed it and it's back to running great