I have a 2006 Ultra with 4700 miles, 103 HD build. Recently it has begun to sputter and stumble at about 1100 to 2000 rpm. I put some seafoam in it yesterday.....1 oz per gallon. Also changed the plug wire and plugs. I noted that the bike also still has 8 degree injectors, so I called the dealer where I bought it. He said it was out of warranty...well yeah...but that maybe he could get them replaced thru the EPA thing. Since the bulletin on the injectors had no end date on it Im hoping they will do it. Any other suggestions? Above 2000 rpm it runs very very well.

 

With only 4700 miles on it. the first thing that I'd try is some serious Injector cleaner. The bike has had a lot of garage time and the gas may have plugged the injectors at one time or another. I'm not bashing Sea Foam, it works very well to maintain your fuel system, but sometimes you have to do a much heavier cleaning. Most automotive stores carry injector cleaner and I don't care which brand that you use, but you should at least give it a try.

 

Agree with cochon. 4700 miles is not many for a scoot that is 5 years old. Prolly some old gas that smells like turpintine, or at some point the gas got stale and created deposits in the fuel system.

One ounce of Seafoam per gallon is a maintenance ratio to prevent the fuel from going stale. Read the can again, one can treats 8-25 gallons. I dumped a whole can in my 5 gallon tank on many occasions when leaving for a ride that will use all the gas/Seafoam mixture in short order. Personally, I use Seafoam when the ride is gonna be a sustained high speed run on the super slab. I will downshift and gag it with full throttle when I have the opportunity to force as much fuel through the injectors as possible.


Does Seafoam really work? Hellifiknow! But, with the 61K+ miles on my scoot I have never had a fuel related running issue...

 

How old is your battery? If it runs better at higher RPM's you could have a low battery or one going bad and at low RPM's there isn't enough voltage to give you a good spark.

 

Are you throwing any codes? Here are some suspects:

1. Bad TPS (throttle-position sensor)
2. In-tank leak causing low fuel pressure
3. Bad plug or plug wire
4. Bad injector, connector, or wire at the connector
5. Bad coil

I just went through this, but mine started over a year earlier and was intermittent, sometimes going away for months at a time. I changed plugs, plug wires, changed brands of gas, replaced everything except the pump inside the tank, and finally changed the TPS. The problem was the TPS, and the last two weeks it got much worse and started throwing P0122 codes. I've had no problems since replacing it, and that's been almost two months.

I would change the TPS first, as it is only $31 and fairly easy to change, but there are no guarantees! The in-tank hoses, pressure regulator, etc. isn't so easy to deal with and is an expensive proposition, so I would not do this first. Just my 2¢ based on lots of research to find my problem. One guy on HTT had the same symptoms as me and his problem turned out to be an in-tank leak. I also had a leak but but changing parts ($275) didn't fix my problem.

Misfiring like you're experiencing is very hard to diagnose unless you have some codes to guide you.

 

If it was that low I don't think he'd be able to start it. OTOH if it is a loose cable or bad cell that shows up only intermittently, that could cause misfiring. Again, my 2¢.

 

I live in snow area so every winter I dump about double the fuel stabulizer in the tank and then run it for 2-3 minutes every six weeks to keep any gas from varishing up in my injectors has worked on last 2 bikes I had , no problems at all I think I did see some kind of bulletin in injector recall in here a while ago

 

I agree, I don't know at what voltage they won't start. I recently had a friend go out for a ride and everything was fine. Stopped and started a couple times then his bike starts to misfire and gets to a gas station thinking he has bad gas, then bike wouldn't start. They called and I suggested the battery but they thought otherwise since the radio would play, checked all fuses and everything was fine. It turned out to be the battery. Just another place to check.

 

Thanks for the replies. Battery is good, connections are good. No codes at all. The bike was my brothers and as you can see......it was not driven much. when he passed away he left it to me since we bought ours together. Anyway...it has had this sputter/stumble and its getting worse. Also, I installed new plugs, plug wires and k&n air filter. No improvement. Only thing I could think of was the injectors since mine went bad and caused the same problems. I had put about 500 miles on it since I got it..........could have been bad gas, but it is getting worse. Maybe th cleaner will improve it or it will throw a code or something, lol. Thanks again!

 

HD should replace the injectors. I had some problems with my 06 right after I bought it. And the dealer was going to replace the inj. For free, under the service buliton, but found out they were allready replaced. If your gummed up the new inj. Will fix that.

Mine was just stalling @ idle, and if I revved it it would keep running I cleaned my IAC and all is good.