ST1300 has a miss at lower RPM under load.

[Dinkie Diesel]

Looking for some help with diagnosis. My 2006 1300 has 58,000 miles on it. I replaced the original plugs with NGK Iridiums before I left on my long trip out west. About the second day my bike developed a low rpm intermittent miss. It runs great on the highway. No fuel mileage problems. It was idling perfect but in the last day or so it has begun to idle rough at times. I tried putting the original plugs back in. That made no difference.

I have a CCS-100 installed. The current air filter has over 30,000 on it. I feel confident it is spark related the way it acts. When it is acting up the rider behind me can smell it. As soon as it reaches 2800-3000 rpm it hits on all cylinders and runs great.

Does anyone know if the spark plug wires are wire core or carbon core? Wondering if it could be arcing over to ground.

Would a leaking diaphram in the CC cause this behavior? The cruise control works but not like it should. Seems very sluggish or at least more sluggish than it used to.

Any help, comments would be greatly appreciated. I'd like to have some ideas before I pull off the plastic to have a looksee. One member is offering his help this weekend but I hate to bother him when he should be out having fun, not working on a bike.

Thanks

 

[Nevada]

Sounds like it may be a bad plug wire.

 

[RCS]

Sounds like it may be a bad plug wire.

Or bad spark plug connection.

 

[Mellow]

I just don't see it as a plug wire myself, I've accidentally pulled the wire out of the boot before and was going to order a replacement and you can only buy the wires or the boot separately, not connected to each other. There's a barb in the boot that catches the wire and makes a connection. I supposed it's possible it was pulled out and when pushed back in missed the barb?

The low-rpm thing has me thinking possibly a fuel pump as mine was doing a low rpm dance before I replaced it but it was just a very minor surging/missing. That was around the 50k mark.

I'd try running some seafoam through a few tanks and see if that helps, I like the simple solutions the best.

I remember the 1st and only time I changed plugs on my 1800, I cracked one and didn't know it.. 'til I had to pass but on lower rpms it was fine, not the same thing here but something to consider. We can pull the plugs at NatSTOC and take a look at them.

 

[SteveST1300]

My vote would be fuel pump as well. I think GeorgeGeorge just replace one on his bike he got it at an auto parts store, I don't remember which one.

 

[BakerBoy]

Jeff, is it worse at higher elevation or when the bike is hotter?

I'll bring a coil/plug wire set with me (they're small) and you can take it home with you to use in troubleshooting.

 

[RCS]

Hmmm...fuel pump...interesting. Maybe. I haven't had to deal with mine yet at 38,000. I'll stay tuned.

 

[dduelin]

One or more starter valves are sticking in the cold or rich position. It only affects idle and off-idle performance. The cylinder(s) affected runs an over-rich mixture at low rpms causing misfires and the smell.

 

[Booger Man]

Hey ACL used bags of ice on the gas tank :.

 

[Mellow]

Hmmm...fuel pump...interesting. Maybe. I haven't had to deal with mine yet at 38,000. I'll stay tuned.

Yeah, mine was fine at the upper rpms... but would just idle w/surge and I tried a new coil on each side and messed w/plugs and wires, never replace the wires.. after I replaced the fuel pump it seems to have gone away. Not sure that's the issue here but a fuel pump problem can show up in different ways.

We could probably replace one at the campground but that's something I'd rather do at home in a control environment. The bike is running so it's not an emergency situation.

 

[racer1735]

My '04 acted in a similar manner just before the original battery took a crap. Replaced the batter and its ran smoothly ever since.

 

[Dinkie Diesel]

Happy to report the problem was a pin hole in the spark plug boot. Arc jumping to head.

 

[Adam Tran]

Happy to report the problem was a pin hole in the spark plug boot. Arc jumping to head.

How did you discover the pin hole, if you'd help me with a similar problem. Thank you.

 

[mjc506]

Not sure you'll get a reply from the OP from a decade ago..

Apart from physically inspecting the cables and boots (tricky while still fitted to the bike) you could take a look while the bike's running in a dark environment/night time. Arcing will show up quite clearly!

 

[Adam Tran]

Not sure you'll get a reply from the OP from a decade ago..

Apart from physically inspecting the cables and boots (tricky while still fitted to the bike) you could take a look while the bike's running in a dark environment/night time. Arcing will show up quite clearly!

Glad to hear back from... you. Thanks for the tips. Will inspect as you suggested.

 

[Andrew Shadow]

How did you discover the pin hole, if you'd help me with a similar problem. Thank you.

In addition to a dark area, using a spray bottle spray the ignition wires with water while the engine is running. The water will make it much easier for the spark to jump where there is a break in the insulation making it much easier to see/find.

 

[Adam Tran]

In addition to a dark area, using a spray bottle spray the ignition wires with water while the engine is running. The water will make it much easier for the spark to jump where there is a break in the insulation making it much easier to see/find.

Yeah... can't hide then. Thank you.

 

[Dinkie Diesel]

How did you discover the pin hole, if you'd help me with a similar problem. Thank you.

If I remember correctly, it was a matter of hearing the spark jump. Of course it was intermittent making it that much harder to find.

 

[jfheath]

Turn the lights off? That trick only works at night time though.