Hi, I have a 2009 KLX250S that seems to run great, but I just started using it on road for my commute. I'm brand new at on road riding, and only a year into motorbikes at all (started dirt biking last year with my kids).

So, when I'm riding at around 100km/hr, and I am basically just maintaining my speed (give or take), I have started noticing that the bike isn't smooth all the time. Once every few seconds it feels like I'm tapping the brake briefly. It's like the motor is skipping. It's not just running smoothly or consistently while I hold the throttle open.

I can tell because the bike does a slight dip every time, and the noise changes, and I tilt slightly forward as if I'm engine braking. It's very brief, but it's quiet frequent, but the time frame is not consistent. It could be ten seconds apart, or 1 or 2 seconds apart.

I am pretty sure it doesn't happen until the bike has been running for 5-10 minutes and is nicely warmed up. I also don't notice it as much on acceleration.

I can't find anything online about this. I've had the following suggestions from friends:
-fuel not getting to the motor consistently.
-maybe the chain is skipping (it looks good to me, and I'm pretty mechanical, but otherwise I don't know how to check this).

I have some other thoughts but really I would like someone more knowledgeable to weigh in.

I have been doing regular maintenance like chain lubing and oil changes.

Thanks for your time.

 

Chain only skips if teeth are worn to nubs, so I think that's probably out.

Junk ->


The good, the bad, and the ugly...





My first thought is the possibility the carb passages and jets need cleaned if it sat for several months without being run. Residue of dried gas turns to crud and can partially or fully clog the jets. One other is if the carb has never been jetted richer, the 250 runs very lean. One way to tell is if you are running along and when it starts "missing", reach down under the left side and pull the choke out. If the skipping is lighter or gone that is a sign that the jetting is lean. The choke is not a true choke, it is an enrichening circuit and will add a slight amount more gas making the mix a bit richer.

Here is a site that will definitely give you a lot of information on the KLX250s. Both my brother and I have our bikes jetted per the instructions and it was virtually plug and play. D Pippin's KLX250 site - click here

The jetting is done with Keihin parts from Kawasaki. Others have done the Dyno Jet kit. I know the former works by experience, but I know others have done the Dyno Jet kit and the information can probably be found here in a search.

 

It might be intermittent power to the spark plug. That could make the symptoms you described. Also a low fuel level in the carb bowl might do the same thing where the engine would stop running briefly until more fuel entered the bowl.

 

Having the same issue and started chasing the electrical side with a new ignition coil and boot. Comes in tomorrow.

I thought it was the fuel system since it felt like it wasn’t getting enough fuel intermittently, but the lines and carb are 100% good.

it happens only once the bikes hot which makes me think it could be the coil. Will post back once I get the new part.

 

Interesting... be watching to see what the situation is.

 

When the bike exhibits the symptom and slows down, does adding more throttle have any change?
Ignition is usually an on-off while carb problems tend to be gradual or only in specific conditions.

 

When I add throttle the symptoms still continue. The symptoms are present anywhere from one quarter throttle to wide open throttle.

I just discovered recently the symptoms are only present when the bike is hot, which leads me to believe it could be a coil issue. Still waiting on coil in the mail as soon as I get it, I’m going to test it out.

 

Hey all, I had tried cleaning out my carb (lost a jet, had to pay to get it repaired), but the issue with stuttering remained.

Then was searching for some other thing and found a separate thread with the solution for this (at least for my generation of KLX250, which is a 2009.

I don't know how to link other threads, but the title of the thread you want is:

Surge at 6500 rpm at highway speed

The solution is splicing into the black/yellow wire (a ground) on the plug with the plastic boot down near the starter. Run it over to the motor ground point. That's it. Tried it and it worked. No more skip/stutter at high speeds (or any other speed for that matter).

Sounds like a very common issue, even from factory, for this generation of KLX. Scroll down and find the guy who posted pics, and then follow from there and you'll see the most important sections.

Took me about an hour, mainly because I had to dig to find the right parts for soldering the wire. Runs perfectly now, SO happy about it. Thanks for your suggestions!

 

Was super confident this was going to fix the problem. Grounded the black/yellow wire on engine. Problem still persists irregularly.

On the test drive I was so fed up I unplugged the rectifier completely and the problem went away 100%.

Went home, ordered a new rectifier. I didn’t go OEM but did do the ricks rectifier.

Put the new rectifier in and same exact thing happened. Stutter irregularly while 40+mph-ish

Ran the bike without the new one plugged in at all and problem went away 100%. Bike idled better. Ran through all gears and rpms perfectly.

im stumped now. Only bad thing is I touched every wire on this bike when I built it. It’s kind of a custom KLX build. I could have messed up something along the way as I built the bike ~7 years ago.

I’ve now got it ripped apart and checking grounds and continuity across wire sections, everything seems good so far.

Pics for fun. Anyone have any ideas


Pigtail off the yellow/black to engine ground

Connected

Just put the bill blue pumper carb on it to try and fix the issue too LOL. Didn’t fix it but def feels like a different bike now. Way more grunt down low.


It looks like a rats nest but it was all bound and neater before I started taking off all the wire wrap.

 

I did also get a new coil, love wasting money and throwing parts at stuff!!!

new coils on now, but I just don’t think that’s the issue after unplugging the rectifier and the bike running perfectly.

still checking if I can find any bad connection or ground anywhere