'09 250 Drops to 1 cylinder on highway, I'm stumped.

[atxninjette03]

Hey yall I'm a little bit stumped here and would like any ideas or suggestions. Randomly and infrequently (every 20-50 miles), only at high speeds such as on the highway, my 2009 Kawasaki Ninja 250 drops a cylinder. It runs only on one with a top speed of about 60 and when I come to a stop it usually dies. It won't start back up immediately but after a couple of minutes of sitting there (and with some choke) it briefly comes back to life for another chunk of time. I don't think it has ever lost it at less than 8k rpm and always at constant throttle. Works incredibly well and then boom, randomly down to one cyl.

Here's what I've done to try and fix it:
- Full carb cleaning and rebuild
- Leaned the bike out slightly
- Brand new spark plugs
- Checked plugs, boots, coils etc for cracks, none I could see. The connector between the coil and boots was maybe a little iffy, but everything reseated
- Swapped the left and right coils for shits and giggles

I've run out of easy things to test and try other than to just start replacing components and hoping for the best. I don't think its fuel anymore and am suspecting something electrical overheating and failing. Would love any kind of thoughts.

[atxninjette03]

Hey yall I'm a little bit stumped here and would like any ideas or suggestions. Randomly and infrequently (every 20-50 miles), only at high speeds such as on the highway, my 2009 Kawasaki Ninja 250 drops a cylinder. It runs only on one with a top speed of about 60 and when I come to a stop it usually dies. It won't start back up immediately but after a couple of minutes of sitting there (and with some choke) it briefly comes back to life for another chunk of time. I don't think it has ever lost it at less than 8k rpm and always at constant throttle. Works incredibly well and then boom, randomly down to one cyl.

Here's what I've done to try and fix it:
- Full carb cleaning and rebuild
- Leaned the bike out slightly
- Brand new spark plugs
- Checked plugs, boots, coils etc for cracks, none I could see. The connector between the coil and boots was maybe a little iffy, but everything reseated
- Swapped the left and right coils for shits and giggles

I've run out of easy things to test and try other than to just start replacing components and hoping for the best. I don't think its fuel anymore and am suspecting something electrical overheating and failing. Would love any kind of thoughts.

[Triple Jim]

When the problem happens, can you pull over and figure out which cylinder is not firing, maybe by using and IR gun type thermometer aimed at the exhaust head pipes? Or run long enough for one pipe to cool, and then spit on a finger and see which pipe doesn't go "pssss" maybe.

If you know which cylinder is having the trouble, at least you'll reduce the possible sources. Also, you'll be able swap components and know when you've found the culprit, since the cold exhaust pipe will move.

Welcome to the board, Brian!

[atxninjette03]

Originally Posted by Triple Jim

When the problem happens, can you pull over and figure out which cylinder is not firing, maybe by using and IR gun type thermometer aimed at the exhaust head pipes? Or run long enough for one pipe to cool, and then spit on a finger and see which pipe doesn't go "pssss" maybe.

If you know which cylinder is having the trouble, at least you'll reduce the possible sources. Also, you'll be able swap components and know when you've found the culprit, since the cold exhaust pipe will move.

Welcome to the board, Brian!

Unfortunately it doesn't run long on that one cylinder before dying or magically getting both back once I come to a stop. Hard to tell which one is failing. Although I CAN sustain that one cylinder for miles at speed so a temp gun on the exhaust might let me know which of the two is cooler once I pull over.

I trimmed the ignition cable between the plug boot and coil so we'll see if that helped. Time will tell and if not I'll try to identify the side and swap or replace components.

[DannoXYZ]

You can also verify coil-triggers from ignitor using solenoid light. Will verify that you've got trigger signals to coils. These new-gen ignitors have been known to drop a channel. Amazon - solenoid test light

Can simulate on-road conditions in your garage for testing too. Idle bike and let it warm up. Then hit various electronics with hair-dryer: ignition-switch (jiggle key), start/stop switch, fusebox, relays, ignition-coils, ignitor. See if something acts up when you stress it with heat. Then you won't get stranded.

[atxninjette03]

Originally Posted by DannoXYZ

You can also verify coil-triggers from ignitor using solenoid light. Will verify that you've got trigger signals to coils. These new-gen ignitors have been known to drop a channel. Amazon - solenoid test light

Can simulate on-road conditions in your garage for testing too. Idle bike and let it warm up. Then hit various electronics with hair-dryer: ignition-switch (jiggle key), start/stop switch, fusebox, relays, ignition-coils, ignitor. See if something acts up when you stress it with heat. Then you won't get stranded.

triggers, signals!?? That sounds like something those fancy schmancy fuel injected motor vehicles with computers use. Not here sir. We use the venturi effect in this household.

[DannoXYZ]

heh, heh.. ignition is fully electronic. Ignitor uses bumps on flywheel to set off spark. Trigger wire at each coil should show signal like this. High full-time with occasional drops to ground to dump coil and fire sparks. Won't show up with test-light because pulses are too short. Solenoid lights have duration-extending circuitry so bulb stays lit long enough for human eyes to see. It always seem to be the left channel that goes out for some reason. Maybe sharing signal with tach may have something to do with it.



Definitely not fuel-related as carbs don't gum up suddenly, then clear themselves while you sit on side of road.

[Triple Jim]

Originally Posted by DannoXYZ

Definitely not fuel-related as carbs don't gum up suddenly, then clear themselves while you sit on side of road.

But there are fuel-related things that could cause these symptoms... like a clogged tank vent.

[atxninjette03]

Originally Posted by Triple Jim

But there are fuel-related things that could cause these symptoms... like a clogged tank vent.

I thought it was that at first but I ruled it out completely. I looked at the entirety of the ignition assembly and noticed my left boot connection was REALLY corroded on the metal terminal. Seems to still get power through but maybe with enough heat and RPMs it's failing there. The right one was super shiny and clean.

The connection seems to reestablish briefly (about 1 second at a time) if I cruise on a single cylinder, and comes back quickly after starting. It happened again today and when I got it started on one cylinder, I revved it a couple times and the second one magically came back.

Gonna see if I can clean that terminal or just outright replace it

[atxninjette03]

This is the connection I was talking about. Any thoughts on if this could be the failure point? Or how to clean it

[DannoXYZ]

Try some Deoxit contact cleaner:
https://www.amazon.com/DeoxITLiquid-...dp/B0015A5AAY/

Can convert to COPS to save some weight and clean ignition-system a bit.

Also try opening gas-cap next time it dies to see if tank-vent is clogged. If that relieves built-up vacuum, blow out vent tube and do tank-cap mod.

[InvisiBill]

Kawasaki ZX Ignition Coil Pack/ coil over plugs (CoPs) modification
Zx coil over plugs

Don't expect any measurable performance gains, but it gets rid of problematic spark plug wires, and cleans things up a bit.

[CZroe]

Originally Posted by Triple Jim

But there are fuel-related things that could cause these symptoms... like a clogged tank vent.

I definitely had similar behavior where it would run on one cylinder and then die. Usually happened when the tank rapidly cooled either by riding off after it had been parked hot (engine warms tank) or because it started raining. I obviously couldn’t just open the tank in the rain but I eventually realized that was all it took to get back on the road.

[atxninjette03]

Well as much as I'd hate to admit it. It was the fuel filter. I replaced it with a new, slightly larger one and the problems have seemingly gone away completely. I'll post if it still fails but I doubt it will.

It must've been at the perfect restricted fuel flow where at a certain tank level the pressure wasn't enough to overcome the filter or something and it choked one of the cylinders dry. At 2 gallons left it would barely go above 6k and when I filled it up it fixed it, so I replaced the filter after that.

A month's worth of headaches and a $6 fix

[Triple Jim]

I'm glad you found the trouble. I had the stock filter at the carb inlet cause trouble too. Without my realizing it, it slowly got more and more restricted until it got to the "perfect" point you said. I now run a pleated paper filter in the line.