Q: Missing Sportster
Tom Manley, Ogden, UT

My bike is an‘03 Sporty, with some 35,000 miles. I’ve never had any trouble with the bike, until I took it out for a ride last week. It’s been sitting in a warm shed all winter. I kept the tank full, and a battery tender hooked up, to keep the battery alive. I’ve done the same thing every year since I bought it, with no problems. All of a sudden, my bike started missing right off idle. It pops every once in a while, just to keep me awake. Can you shed any light on my problem? I had a couple of shops look at it, and both told me it sounded like carburetion or electrical. Any suggestion will be greatly appreciated. I don’t understand how the bike can just change the way it’s running, while being in storage.

A: Hey Tom, you’ve got a problem that has been around since the invention of the carburetor and gasoline. If I’m understanding your description, and for sure there may be more than one issue to deal with— but with the problems that have come through the shop, the bottom line has always been corrosion— some kind of chemical reaction to sitting still and not moving. It happens in the gas tank, to electrical connections, rubber lines, tires, all kinds of stuff. Don’t get me wrong— I’m not suggesting your tires are the problem. It’s just that all parts can have some kind of reaction, when not in motion.

When I get a bike in with a problem like yours, the first thing I do is check for air leaks around the intake manifold. Next, the carburetor comes apart for a complete cleaning. Usually, in about 3 months, the gas in the tank starts to lose some of it’s potency, and starts turning to a thick gel. This gel gums up the passages in the carb. Depending on which jet is affected, the bike just goes lean, causing your motor to run hotter than normal, color your pipes blue, and miss or skip a beat every once in a while. The gel I’m talking about is just old gas, so it comes out easy enough. It stops your carburetor from metering the correct mixture, but once you’ve got it clean, it should revert right back to the way it ran before. If it doesn’t, then move to the electrical system. Usually, correction isn’t a problem with the newer bikes, but I’ve had a few. There’s lots of connectors, and each one houses at least 4 pins connecting the circuits together. These connector pins can become loose, from vibration, wear, and corrosion. The connection can be intermittent, and fail only sometimes. A good way to start in checking out the electrical, is to check all the ground connections you can find. Make sure they’re all very clean, not corroded, and tight. Try wiggling and pulling on the wiring harness, while the bike is running. Make sure your battery is being charged at the proper rate, and that it’s putting out it’s full potential. After you find the problem, and I’m sure you will, coat all connections once clean, with a good quality electrical protectant.

Run a couple of tanks of fuel with fuel injection cleaner in them. This should clean out all that’s part of the fuel system. Put fuel stabilizer in the tank, and get new gas for your bike ASAP, after the storage period. Keep a new battery charged and ready to go. You’ll eliminate your problems next year.

Q: Where did the gas go?
Internet

You wrote an article about a lady who left her bike sitting, with the gas on. She left it all last winter. When she tried to start it for the first time, she discovered it wouldn’t start because she was out of fuel. My question is— where did the gas go? It can’t flow out of the tank without the motor running. So, where did it go?

A: Sorry about the delay in answering your question. You didn’t leave a name for me to call you by. And, when I started to answer your question, I couldn’t find your E mail for reference. But , here’s what I remember about the problem.

The lady you referred to, lived in Montana, and rode a Dyna, I think. She had made a few modifications to her bike, but mostly it was stock. She said if she left the gas on after riding, when she came out to ride it again, there would be a gas spot under the bike. My reply was, she must have had a sticking float seat needle, and the carburetor was over flowing. I also assumed that her petcock was not functioning— or it had been changed to a non- vacuum type. Both of these would, if left on, allow gas to keep flowing, and if the needle was open, it wouldn’t stop. This would mean the gas would run through the needle, and over flow onto the ground, until it was all gone. OR: It might also overflow into the crankcase. I had this one happen about a year ago. We found his crankcase full of raw gas. It got there when the float needle stuck open, when he left his bike parked for a few hours. The thing I’ll always remember about that bike was, it still ran.

Q: Still Popping Fat Boy
Bill and Sue, Portland OR

I recently had a Power Commander installed on my 08 Fat Boy. I had the bike tuned at a tuning center I won’t mention. It does seem to run better, but still pops when I let off the gas. It also has a spot just off idle where it hesitates, or stumbles, when I blip the throttle. I told the Dyno operator about both problems, and he assured me they would be taken care of. Well, they aren’t, and my front exhaust pipe is bright yellow after the tuning session. They told me this was common with my kind of exhaust, with connectors to each pipe. What do you say?

A: Hey Bill and Sue, you’ve got a great bike. Your troubles can be cured. Here’s what I know about the popping. It can be stopped, if everything on your bike is installed correctly— meaning the exhaust. From what you said is happening, it may be your pipes are leaking at the connection joint— the one that connects the two together. These connections usually have a slip fitting, that can, and does leak on most bikes. When this happens it’s just about impossible to stop the deceleration pop.

Another telltale sign, is the yellowing of the pipes. If it’s close to the leaking joints, it will show it-self, by coloring in that area, or close to it. Your miss can be corrected with the accelerator pump feature, in your Power Commander. This feature isn’t used a lot, maybe because it uses more fuel. But, it will cure the stumble problem, if the problem is fuel injection related. What I mean is, your exhaust can cause the same kind of problem in the power band. This can’t be covered up with fuel. Some of the after-market pipes have a dip or flat spot in their power band. It shows up as a miss, or hiccup. My suggestion is to go back to the Dyno shop, and tell them your problem. Ask if they will unplug the Power Commander to see if the miss is still there. If the miss still shows up, after being remapped for the Power Commander, you can bet it’s an exhaust related thing. The only way to cure it, if that’s the case, is with more or less back pressure. Also, try to find better clamps and sealing rings for your connections. Stopping the exhaust leak will cure lots of ills.

One last thing: Each exhaust manufacturer has their own grade of chrome on their pipes. This has a lot to do with how well they’ll hold up to heat. Some will color at the slightest sign of heat. When a bike is performing at it’s best for extended periods, the heat will show it self usually where the transition from small to larger starts. Lots of heat here, when making HP. A good dyno room has at least 2 high powered fans to keep it all cool. But, when you combine poor quality chrome with a high heat charge, there’s a very good chance you’ll end up with color on your pipes. The only ones that don’t, are ceramic coated, double wall construction, or just super efficient, with super high quality chrome—usually reflected by the price of the pipes.

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