1500fi with a random stumble

[828Dino]

I'm new to these Kawasaki's, but love everything about my 01 Nomad. Everything except a random stumble or miss. It happens sporadically and at any speed or rpm. It also affects start up, almost like a timing issue would. So I replaced the pickup coils, the ignition coils, the plugs, and it has a new battery. A self check of the ECU shows no error codes.
I would really appreciate any help.

[ringadingh]

I had the same problem with mine a few years ago, it was a loose coil wire under the gas tank. I squeezed the connector with pliers and it fixed the problem for me.
Also check the wiring harness at the rear cylinder on the left side of the bike, just below the tank, sometimes it can wear the wiring there.

[recumbentbob]

The first thing I would do is get some carb cleaner and a tooth brush and clean the throttle body and both sides of the butterfly. Clean them real good until they look like new.

[DragonLady58]

For anyone new to these bikes, since most folks just ride the hell outta theirs, before they sell them or trade them in....its best to do a good, basic maintenance tuneup. Thats the fluids, filters, look at your hoses good, and yes, clean the throttlebody as RB suggested. Look things over good as ringadingh suggested also.
Treat you newly acquired ride just like a new bike thats right as its maint. checkup.....
Me, myself, the first thing I do is oil and filter change, change all the fluids, filters, and I also install iridium plugs....
Establishing a good base line for your bike will aid in your taking care of it....
And do not add any motor oil that has friction modifiers in it, it will screw up your wet clutch. Use only motorcycle rated oils....
If the bike is stock configuration, you might wanna consider a decrapification. These bikes run super lean from the factory, so, a exhaust, EFI controller, and a air intake might cure your problem if its a lean stumble, like the old early HDs. They were so lean they'd pop back thru the intake....
As for stumbling....this could be coil, throttlebody, spark plug, fuel related....
I would start as they suggested, but I would also add fresh fuel, along with some seafoam. I would install iridium plugs. Also, if the engines in good shape, wick it up and bounce it off the rev limiter a few times to help decarbon the heads and valves. Lugging these big engines will soot/carbon them up pretty good. Make sure your goat belly is clear and not congested or clogged....
Performance wise, dynatek coils will make a big enough difference you can feel it....
These bike accumulate alot of miles, anything over 60K deserves new coils....

[Peg]

All good suggestions, and here's a couple of other things to think about - that I can recall have been the cause of similar issues in the past...

If it has a fuel tuner, the connections (particularly the earth) or the tuner itself may have a fault, you could bypass it to check that. And if it has a "speedo-healer" type device fitted, that has also been known to sometimes be the cause of an intermittent fault.

[MAS Tequila]

I’ll go a little further with the SeaFoam.

Don’t just add it to the tank.

With the air cleaner off, put it directly into the throttle body.

Keep pouring until it almost dies.

Do this a few times.

You’ll be surprised at the difference.

[DaPreacha]

I have the 1700 Nomad and had a random stumble or hiccup which was progressively getting worse. Found some suggestions on this site and another Vulcan site to check for vacuum leak around the throttle body and intake. That is exactly what was wrong with mine. It was due to bad engineering on Kawi's side. Took a few hours labor and really improved my performance!