Sputtering Sportster

Hey Mechanics, I have a 2004 Harley 883C with screamin eagle pipes, air filter, and I assume a rejetted carb. (I am the second owner) After the bike warms up (about 15 miles) it will hesitate, cough, sputter, and backfire when I first open the throttle like at a stop sign. It runs fine down the road and while it is still cold. Any ideas. Thanks, Chuck23

From the info you have provided, it sounds like you have a lean air/fuel condition. Is the popping from the exhaust or through the carb?

Sputtering Sporster

I believe it is from the carb. I am not very mechanical but that is my opinion and that is what it sounds like.

If you have to start working on the carb, don't worry...it's alot easier than it sounds. Especially with that CV, I had someone walk me through it and now my sportster scoots along down the road REAL well.

You should have the carb tuned by someone in your area that has a dyno AND knows how to use it. With the addition of a high flow air cleaner and mufflers, you have leaned out an all ready lean(from the factory)fuel system.
A low speed jet change and a short dyno session should cure your ills!

John

Sputtering Sporster

I had that in mind, but hesitated to take it in since the problem comes and goes. Only when it's warmed up and when I first crack the throttle. There is a Harley shop not too far from here. Guess I will bite the bullet and take it to the shop. They have a dyno so that's no problem. Thanks for the advice.

I don't want to sound like I hate Dealerships, but...check for an independent
shop that specializes in dyno work. Hourly rates are USUALLY less, plus these shops are more likely to fix the problem. It has been my experience that the dealer will tune to HD specs, which won't fix your problem.

You can get a list of tuning centers from Dyno-Jet's web site.

John

Are you running Premium gas? Could be an octane issue. But the most likely is that the carb was never retuned for the new air/pipes. Or maybe never tuned for anything........

Sputtering Sporster

Hey Red Rider, I am running 87 octane. Owners manual says that is ok. Maybe, I'll try the up graded gasoline. The bike ran fine last year. When I took it out this spring the trouble started. I think the screamin eagle air filter and pipes were done at a Harley Dealership when the first owner bought it. I would have guessed they would have rejetted and tuned. I can't find the first owners number to call and ask him. Also, I have run carb cleaner through the bike 2 times in case it got gummed up over the winter. I didn't stabelize the gas, but I started it and ran it a few times during the winter. Any more ideas from anyone before I start spending big bucks for repairs.

Runni'n Drags And A 7" Mod. Air Cleaner On My 03' . It's The Carb, Your Runni'n Lean. If It Seems To Caugh Or Like I Call It A Miss, You Need To Get The Carb Re Jetted. I've Never Fixed The Problem With Mine Because I Plan To Put A New Carb On This Winter. As Of Mine It Will Start Turn'n The Front Pipe Blue. No Matter If It's Warm Or Cold You Get The Cough. Also With That Set Up You Might Think About Putt'n Some Power Cones In For The Extra Back Presure. MY MANUAL ACTUALLY SAYS TO RUN 87 REG. EVERY TIME I GO IN FOR MY PMCP, I HAVE TO PULL MY PLUGS BECAUSE THEY WANT THE HD ONE'S IN THERE. I'VE FOUND THAT THE SPLIT FIRE WORKS GOOD WITH MY SETUP BETTER THAN HD. SO NOW I HAVE HD PLUGS FOR THE LIFE OF THE BIKE, OR ME WHITCHEVER.

If you pull out the enrichener a bit when this happens does it still do it? If it stops then you know it is a lean condition causing the issue. If not, then you can look at your plugs, wires, or coil. One or all may be breaking down when hot and under the load of starting off from a stop. Could also be your ignition module getting hot and cacking. K's, CC's would be nice to know.

If the condition did not exist last year but does after storing it for the winter or after sitting a long time, I wouldn't think jetting here. You did not alter the state of tune by changing jetting correct?

Then, we have to trouble shoot from the approach of what has changed that is causing the problem.

Water accumulates in fuel very quickly if you do not run a treatment like Stabyl. Water gets into the bowl and being heavier than fuel displaces fuel near the main jet holder. With the enrichener pulled out slightly, you add additional fuel helping to make the engine run somewhat better. Even starting the bike does not help because you now lower the the fuel level allowing for more room for vapors to form and condense. You should always store the bike with a full tank and treat with a stabilizer.

I would drain the fuel tank and bowl and refill the tank and mix in some gas treatment. A lot of gas stations have a ton of water in their underground tanks and you can pick up water while filling up. Don't forget to drain both sides and remove the cross over.

You probably will need to change your plugs as water mixed with fuel is not nice to them.

Another possibility is you developed a bad intake leak and you are basically offsetting the leak with the enrichener. Use some WD40, lightly spray the intake around the flanges and listen for a change in the RPM at idle. A sudden increase in RPM means you have a leak.

Mines an 84 and was doing the same thing. It ended up being the ignition module. (I'm having a brain cramp and can't think of the correct name of the part). The plate that the timing is set with, has electronics on it, that was bad. Man it's been a long day.