Hey guys, looking for idea's here that focus mainly on the electrical components on the bike. I've exhausted all other options and there's a few tells that seem to indicate that this is an electrical problem. I know you'll all have a gut feeling that it's a jetting/needle issue but please read below in full before replying. EDIT: It seems to be a fueling issue after all, but I'm running smaller jets that I should for the elevation to resolve the symptom and the top end is very lean.

Symptom:
Bike runs GREAT up to 4000 rpm. From 4000 - 5500 rpm the bike experiences a huge torque dip and running at WOT in higher gears at this speed will cause the bike to burp and stutter. Past 5500 rpm the bike runs better than it ever has - tons of power and accelerates happily to redline in all gears.

In short: Missing torque in mid range, misfire and sputtering under load only at mid range - regardless of jetting / needle position.

Troubleshooting:
Carb - jetting, springs, needles, inspection, cleaning - everything looks mint, nothing makes much difference.
Spark plug replaced, air-filter replaced, coil + plug wire replaced.
Plug reading is good with current set up.
Battery voltage checked.
New fuel filter, several tanks of gas used during troubleshooting. Checked Petcock and fuel lines.

To reiterate, I sincerely doubt this is a Carb issue. I've tried dialing the jetting back and running the bike with the airbox lid on much like the usual set up most riders here have - to no effect. I've cleaned and inspected the carb in every conceivable way several times. I've tried several proven set ups including the N1TC with airbox lid and appropriately sized jets - this issue persists to varying degrees no matter the carb set up and the only way to prevent it from stuttering so far has been to lean it out so much that the engine begins to lose power and the plug reads very lean - this doesn't help with the torque dip as you can imagine.

While testing the old coil I noticed after I put it back that the issue wasn't nearly as bad, which leads me to believe there's a bad connection or something. The new coil unfortunately didn't make much of a difference (although it seems slightly better around 5500 rpm power wise and won't sputter past 5000 rpm now). I'm not sure if that's due to the new coil or the fact that I disconnected some of the harness plugs and cleaned them.

Battery voltage checks out fine. Spark looks strong.

Question:
What's happening on the bike electrically around 4000 RPM that might impact the spark intensity or timing?

Has anyone heard of electrical/ignition issues that manifest themselves at specific RPM's before? Everything I can think of typically affects the entire RPM range.

Why would reinstalling the coil(s) cause a change in the severity of this issue? (removing the tank, etc etc)

Thanks in advance for any thoughts to input.


UPDATED on POST 77 https://www.kawasakiforums.com/forum...e8/#post522828

 

I'm experiencing nearly the exact same issue with my KLX. My symptoms started after doing the MCM, and after extensive troubleshooting and messing with the carburetor, are yet to be remedied. I've received some great advice from other members, however nothing has worked yet. I've all but given up on the CVK, and am now researching the TM36-68, but will be watching this thread with great interest to see what suggestions others make. I'm still convinced it's some type of carburetor issue, but at this point will consider any angle.

 

Have you done the extra grounding thing more prevalent on the '09 models?

 

Snowdrifter, Please give us some more details:

1. Did your bike run perfectly fine before MCM ?
2. Assuming the answer to #1 is "yes" - When you did the MCM, did you (alter/mod/look crosseyed at/touch with angry fingers) ANYTHING else? Anything at all?
3. Assuming the answer to #2 is no: Please detail the tests and checks that you have performed so far - in trying to solve this problem.. This is so we can compare notes to PWJM's efforts at solving the issue..

This made a difference on PWJM's bike: Remove the coil, look at it lovingly, clean all its' connections, reinstall and see if the problem changes in any way.

BTW, don't be myopic about this issue being carb related. Open up to other possibilities - this appears to be "new ground" we are exploring..

 

Here's a link to a thread showing the extra ground modification, apparently done by some Kawasaki shops for similar situations. There is another, but the gist is there. I did it on mine when I had a small surge, but mine was a lean carb.

 

The problem that the grounding mod seems aimed at is the occasional misfire at higher RPM's.. Right?

His bike is basically unrideable - Stumbling all over itself between 4-5.5K (When the problem was at its' worse. Removing and reinstalling the coil has had a big effect - almost curing it..)

 

Here's an updated description after a long ride while trying to maintain that RPM at various road speeds:

I agree that I should attempt the grounding mod next(thanks for sharing the link). I had avoided it until now because most of the people describing it made it sound like it was higher RPM misfires. I DO get those from time to time under WOT acceleration runs, but nothing like what's happening in the lower RPMS. Given Snap's input about the MCM possibly coming into play and knowing that the MCM moves the powerband down, perhaps I've effectively shifted the range at which the symptoms of the grounding mod come into play also? It may be worth reverting the MCM.

Furthermore, I also took the bike for a short ride with the R/R unplugged and it exhibited the same issue as before with no change. I'm unsure if unplugging the R/R is an effective way to troubleshoot that issue though - one would assume it would be unless my understanding of that particular grounding problem has less to do with the rectifier and more to do with the harness.

Appreciate the input thus far boys. Keep it coming!

 

Have you changed or taken apart the spark plug wire?
I have had good luck with rebuilding the wire to fix unsolvable issues on a few bikes.
Sort of the same advice as cleaning and removing the coil.
Lots of vibes from a single...things come apart.

 

Thanks Max,

The coil on the 2009+ bikes are all-in-one with the plug caps, so I've effectively changed that out as well.

 

Try a new plug & gap it.