It seems like most of these problems are due to Lean conditions, right? I know in the KLR650, if raising the needle didn't fix it, or, sometimes a bigger Pilot (or turning the fuel/air screw a bit more "out") didn't fix it, a different needle off of a KLX would fix it....I understand it's thinner, so, it lets a bit more fuel in at a given throttle position.

I don't hate carb problems as much as electrical ones, I guess it's because they confound me too often. But, I hope you find your cause and can fix it easily.

 

I bought a 2009 KLX250S a few months ago with about 800 miles on it. I have the same hesitation many of you have described, and it's driving me crazy. It occurs at any stabilized power setting above about 3K RPM, and about half throttle. Took it to the dealer and paid them $90 bucks for them to tell me that the bike is working exactly like it's supposed to. I just ordered the maintenance manual so I can start investigating on my own. It's either fuel or ignition related. Is there a way to test the ignition and rule that out as far as timing, etc.? Has anyone else tried re-jetting/adjusting the stock carb with any success other than adjusting the needle? Better success with different carb?

 

Carbs get re jetted here all the time. Some bikes seem to do the misfire thing more than others. I have re jetted my stock carb then switched to a different carb and still get the occasional misfire.

I have a hand held lab scope to investigate the ignition. It will take 2 people to do the testing. One to run the scope and one to drive the bike. The trick is when the bike misfires, I need to stop the scope from recording then go back and review the screen to see if its electrical or not.

Scope is at work, maybe I can get my son to help out.

Sometimes the bike acts like its loaded up especially if I am accelerating to full throttle in a lower gear. But when I pull the plug it looks perfect.

David

 

David, I also wonder if it's electrical.



Any of you Aussie guys with the different electrics have this problem?

 

I will plug the scope into the bike later in the week.

David

 

That's just one of the reasons I'll never take a bike to a dealer. My apologies to the good mechanics that work at a dealership, as I'm sure there must be many.

 

My bike has been doing this since I picked it up from the dealer.(09 250 SF) I have brought it back 2 times and still have the same studder/ miss in 6th gear crusing between 60 and 65 mph. I've had it in to the dealer 2 times now. The first time it went in they adjusted the needle positon to richen it up some. This seemed to help a bit under heavy throttle, it didn't seem to breakdown like it did before, but the miss or studder continued at 60 to 65 mph. The second time it went in for the tank recall and more carb work, they went with a larger pilot jet and sent me on my way. The problem still persists and the breaking down under heavy throttle seemed to return as well. I have swapped fuels(87 to 91), added K100 to the tank and the problem still comes and goes. Sometimes worse than others. I also noticed it seems to act up more with a full tank of fuel as opposed to almost empty. I don't know if this means anything, but I am trying to take notice of some potential factors that could be causing the issue.
Kawasaki contacted me 2 weeks ago and was looking into the problem but I have not heard from them since. But the bike is back in the dealers hands today. They are going to contact Kawasaki and see what they recommend to resolve the issue. We will see in a day or two. I'll keep you posted.

 

best of luck maine if you get an answer please post up, my dealer has stopped looking since I wont pay them for no answers, kawi doesn't return my calls or my emails so I just keep trying new things as I can afford them. A new voltage regulator is a ways off yet, I'm still in the poor house.

I'm pretty sure it's not a lean or rich surge as so many people with some many jet set up are having the problem.

 

Thank you, I have only paid for one hours labor for the first visit and they have really treated me well so far. Haven't resolved the problem but the lead mechanic seems very interested in getting to the bottom of the problem. He has been very helpful and honest with me so far. He was going to contact Kawi himself and see what they recommend.
I didn't mention the voltage regulator to him though. It may be worth calling him tomorrow and telling him some people thoughts this is the cause. I totally understand the trying new things when the money is available. I have a few of the mods ready to do, I just want it running right before I start changing anything. Thanks for the reply and I'll post when I talk to the dealer tomorrow!

 

The poster said all they did is unhook the rectifier / regulator. I never said anywhere to replace it.

Unhook it and see if the misfire goes away. You will be running on a consatnt loss electrical system, but no big deal for a short while. I have not tried this yet.

I like to only fix what I KNOW is broken, not take pot shots. I am a mechanic, not a parts replacer. Diagnosing is what a real mechanic does. (almost) Anybody can replace parts. No kawasaki at work today, its raining. Stuck driving the ford to work. Putting the scope on the kawasaki is this weeks work.

David