Surging and backfiring

[Troll]

Make sure you ground one of the plug connectors...and be sure you disconnect the wires on the same side of the engine, they are on 1 coil, the other side is on the other coil. Yeah, I used to like Milwaukee, but it sure has changed...

[wayne]

I know those roads well,your gone along time and everything has gotten so over populated you wouldn't believe it was the same place.i've rode to Wis. 3 different times and once your out of Milwaukee it was really nice place.I'm going to try disconnecting the plug wires as you suggested and give it a try.Your right about it running well before so something had to happen and I'll get back to you.Didn't know they came with the steel braided wires but I'm learning,thanks again Wayne

[Troll]

They come with stainless braided wires. 12,000 miles is nothing at all for these bikes. I have over 100,000 on mine, and the Cobra Peace Pipe, with a wide open K&N intake, and no addon fuel processor.  A dual plug system will fool you into thinking there are some other things wrong. You want to try to isolate the problem as quickly as possible. With the setup you have, why do you think it suddenly went too lean? These is no reason for that. A 15 year old ignition system is probably more to be concerned about. The banging in the exhaust tells me that there are secondary ignitions happening to light off unburned fuel. Here's the tricky part. You have to determine what subsystem is messed up. The 1500 will run just fine on only one set of plugs. You should disconnect the plugs on one side, and figure out how to ground one of the plug connectors. If you just disconnect it, the voltage build up in the coil will have no where to go. See how it runs on just 2 plugs. If it runs badly, misses, or does what you have described, then reconnect the first set of plugs and disconnect the other set, grounding out one of the plug wires. See how it runs, then. I had dual plugs on my '78 SuperGlide, and I fouled out one of them coming back from a trip to Wyoming...Didn't miss, but it just didn't run right...Every once in a while that plug would fire and the exhaust would pop. I lived off Burr Rd, near Larkfield and Jericho...moved out in '73.

[wayne]

Forgot to add that the bike has 12,000 mi

[wayne]

Thanks for your help Troll, I hate to be a pain in the butt.I will check the spark plug wires again but I don't believe that is the problem as they have been changed at some point to the stainless steel type.I am thinking about the Cobra fuel processor FI2000 and a KN air filter and hope it will cure this problem as it doesn't feel like a  a miss in the ignition system and more like a fuel problem as in running to lean. with that said I will recheck the wires and coils again. I live off Pulaski road in KP,nice to here your from Commack and thanks again for the help.

[Troll]

I know this is going to be a PITA, but you need to examine several things. A cracked coil tower will cause this, as will a bad/leaking insulator to one of the plugs. May not be the wire, itself, but the connections. A 1500 has 2 plugs per cylinder, each fired by a separate coil. The system has been around for over 100 years, so it's not something new. If one of the plugs/wires/coils has a problem it will affect both cylinders. I don't have time, right now to get into how analog waste spark works, but if you short, say #1 right side plug wire to ground, it will also kill #2 r/s plug. You will have to pull the tank to access the coils and their connections. ANY white/light grey residue on the connections indicates a spark leak. This is a common problem with lots of cars.   How many miles? Where in King's Park? I'm originally from Commack!

[wayne]

The surging is as you described like being in a rocking chair when I hold the throttle steady and as it surges it back fires through the exhaust not the intake but when I give it more throttle it will take right off with no problem and there is no popping from the intake.The bike still has all its pollution pieces intact and I'm not sure they could cause this problem if something went bad.With that said it ran great for the 2,000 mi. I used it before it started doing this.

[Troll]

I know what you wrote, but there are two distinct kinds of "backfiring" that people lump into one category. An actual backfire occurs when unburned fuel ignites in the exhaust and the sound is much like that of a shotgun. Sometimes this happens as series of pops and bangs usually on decel, and is normally caused by air getting into the exhaust system and helping to ignite unburned fuel in the exhaust that would normally just be expelled. A pop back through the intake, causing a noise and small explosion in the air box is the other type. Exhaust pop is caused 99.9% of the time bu an ignition problem, the other type by a lean, unburnable fuel mixture. Whatcha got? Surging is another one of those problems that is often hard to describe. Most common surges are caused by a lean fuel mixture, and feels like you are in a rocking chair, or perhaps riding into a headwind.

[wayne]

Hello,been a member for awhile but haven't posted anything till now.I enjoy everyones input and I could use some help.I have a 2002 1500 drifter which I bought about a year ago and have enjoyed riding so much that I sold my Harley.It has about 12,000 miles on it which I have put on about 2,000 miles.Bike ran great till I got home from a recent trip and it started surging and backfiring when I hold a steady throttle.It idles fine and you can run it through the gears hard and it doesn't miss a beat but if I'm riding at a steady MPH and steady RPM it surges and backfires.I have changed the plugs which were a nice tan color,air filter is clean, spark plug wires are all good,I changed the exhaust gaskets just to make sure they were not the problem. Bike has Cobra exhaust with no after market computer.I have added Seafoam to the gas but the problem still exists.Bike is immaculate and been well taken care of and ran excellent for the 2,000 mi I put on it,would appreciate any help as i'm out of ideas.