I have an '02 954 that is starting to run rich for some reason, I believe. I have about 13,000 miles on the bike now. It starts kind of rough, and when it idles for a bit, it loads up, and chugs to take off. Last weekend, it even started to backfire at low rpms. As soon as you wind it up, it's fine. What could cause this? I just changed the plugs this spring. Thanks for any help.

 

have you checked any codes?

 

No, but the light is not on, indicating that that are any codes. There can be codes without the light on?

 

Sure can. It will throw a code when it gets out of range but then it gets back in the range for the code not to be up all the time. Your comp will store the codes that have been in and out of range.

 

Try raising the tank. On the fuel rail you will see a Fuel pressure regulater.There are two vaccum lines running from the regulater to the #1 and #4 cylinders.Pull the vaccum lines off and check to see if they are soaked in fuel. If the regulators diaphram were to leak thats where the fuel would go causing a rich running condition at low RPM.FI system would not be able to detect this problem..

 

What plugs did you use? Did you try to put performance plugs in, or go stock? Also, do you have any other mods done?

 

The plugs are stock. The only aftermarket part is the bolt-on pipe. I'm sure that isn't the problem though, because I've had this set up for three years now, and it just started running rich in the past couple weeks. I changed the plugs in the spring, and it was fine then.