Please bear with me here as I feel I need to lay the ground work and history.

I bought the bike new in 03. It now has a little over 42K miles on it. Two years ago, for reliability ONLY, I had the chain cam drives replaced with a S&S gear drive set. At that time that was all I did because that is all I coud afford to do right then. I knew that the new cams would benefit from a better flowing exhaust and breather but it would have to wait.

It ran just fine, no problems. The following summer the factory exhaust finally died a horrible death. So with the need of a new exhaust anyway, I purchased a set of Vance & Hines Straight Shots. I also had a K&N breather kit installed and they re-jetted the carb.

It ran OK for a while but has for the last 6 to 8 months run like crap. It misses, spits and pops A LOT. If you are between 3K and 3.5K RPM, it is unrideable. When you close the throttle when approaching a stop, it back fires out the tail pipes like a shot gun.

The real problem is that it is a very intermittant problem. It doesn't always do this and I have yet to identify the common thread. I use good gas from a station that is always busy so as to get fresh gas. The bike never sits long enough for the gas to go "stale".

At first it seemed to be a "lean" issue because pulling out on the choak or enrichener would smooth things out. First investigation found the intake seals cut. This seemed to be a real good explanation but it only ran really good for a couple of days then back running like crap.

I took the bike back to the shop where all the work was done and they were really scratching their heads. (A very reputable independent shop which is a factory authorized Harley warranty shop with a good reputation with the Harley owners in the area).

Inspection of the spark plugs indicated a perfect mixture. Going on the fact that pulling the enrichener seemed to help, he re-jetted again with a little larger jets. (sorry I can't tell you the size of the jets he put in.) Again when I left the shop, it ran great but within a day or so, again running like crap.

The shop owner says he thinks given the fact that it is very intermittant, it could be ignition related and thinks we should try a new ignition module.

In order to try less expensive fixes, I purchased a new set of Screaming Eagle plug wires today. I compared the resistance of the old wires to the new ones. The old ones had much higher resistance than the new ones so I had hoped I had found the problem, but alas, no such luck.

The shop has tried to check for fault codes but there are none. I can give you the specs on the cams installed if you want, but I think I have dragged this out long enough. Any help or direction any of you can give would be GREATLY appreciated.

 

Sounds like an ignition problem since it seams to happen in a specific RPM range. I would clean all the connections to start with a good cleaner and put it back together. Inspect the plugs for cracks or replace them. Is the idle OK? Doubt you have an airleak but t for it with some carb cleaner.

 

Sounds very simular to my buddies problem, his after market ignition was bad. To help figure that out he hooked a timing light up and reved the motor up and you could see the timing light blinking irratically. We compared it a good bike and you could really see a differance

 

If you have access to a coil , try that, coils can act weird sometimes.did you check the coil as per the manual.

 

well if adding fuel aleviates the problem, how can that be ignition? things to check...your seals again. Stock seals seem susseptible to easy leaking with ethanol. Use S&S intake seals. thicker, different rubber, better sealing. Next thing to check is float level, and you could have a problem with the needle/vacuum. Another possibility, the fuel filter is dirty. I would perhaps try a different shop if the wrenches can't figure it out where you went. if they added fuel(with rejet), fixed it , then it started again...I think the best place to look is at the manifold seals again.

 

Yes, the idle is fine. I'll check the connections to the module and the coil pack today. The spark plugs were replaced last week and I replaced the plug wires yesterday. Thanks for the input.

 

That's a thought. I have a very good timing light that hasn't seen uses much since all my cars have the computers that control it and you really can't adjust it anyway. Guess it is time to dust it off. Thanks.

 

I don't have access to a spare coil today but I can look in the manual to see how to check it. I'll give that a try as well. Thanks.

 

Well that has always been a question in the back of my mind. But If the intake seals were leaking, how would that account for the intermittant nature of the problem. Besides they replaced those seals two weeks ago, and yes the ones that were on it were torn pretty bad. The fuel filter and carb were both checked last week when he rejetted it. There was no sediment in the bowl. He didn't say anything about float level.

Right now I think I will take a look at the ignition suggestions first as they will be the easiest, (not discounting your input as I certainly do appreciate it), but it just seems to me that a fuel problem would result in a more consistant problem rather than intermittant. And while he did find the torn intake seals, replacing them and rejetting has not fixed it.

 

Thanks to all so far who have responded. I'll take a look at everything you all have suggested and post what I find. Thanks again. For everybody else, keep those cards and letters comming in. I will take any suggestion. If any of you remember the movie War Games where the kid hacked NORAD's supercomputer, in one scene the General in charge said "Hell, I'd pi$$ on a spark plug right now if I thought it would help". I am starting to get that feeling right now.