klx140 stalling problem

Tmax6x6
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Menifee, CA US
Hello all, hoping someone can give me some insight into this annoying problem with my niece's klx140.
The bike if fairly new and 100% stock and ran fine untill my nephew started doing wheelies with it, (this shouldn't have had any effect that I can see) and it will not stay running.

The symptoms

First issue I ran into was a fully dead battery, I mean less than 2v, so I changed that and the bike would start but would not idle.

Pulled the car and gave it a cleaning. The only thing I found was the pilot was clogged as is typical. Checked all passages and everything is good and clear.

Put it back together and it fired up instantly with the first blip of the starter.

Here is where the problem is. The bike will idle fine although a bit cold blooded and will hesitate if touching the throttle when not warmed up, once warm it is fine. Im going to chalk this to emission standards with the bike being at 100%stock settings.
I go to give it a ride up the driveway and it will take off fine BUT after a second or 2 of motion it will cut out like someone hit the kill switch (kind of like doing a plug chop on a 2 stroke but at slow speed) then it will pick back up with a wiggle of the throttle and take off, then cut out, then take off, and so on. I can get it to sometimes to stay running by having enough speed and full throttle, then I can keep it going but once I slow down it'll start with the on/off issue again. When it stalls its a 50/50 that it starts back up instantly or it will just crank. If I let it sit a few seconds it will always start then.

When starting and idling the bike up right it will idle for as long as you let it with a solid steady idle, But if i lean the bike over a bit it will stall 80% of the time.

I am thinking this is a fuel issue so i have pulled the carb and checked the float, it moves free and functions fine. I have tried lowering the float level and raising the float but issue persists.

I then checked the fuel/air mix screw and with the special D tool (stupid emissions crap) adjusted the mix a bit, but no luck exactly the same.

Electrical issue maybe? This bike doesn't have a tip over sensor does it?

I have never had it kind of problem on any bike ive worked on and I think im decently competent with the mechanics of motorcycles.

Anyone have any idea of where to check next?

Thanks.
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Paw Paw 271
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Benton, LA US
3/22/2021 7:32am
Check the ignition coils OHMs readings. If incorrect it will break down when warmed up and thus will die and not run until it cools off.

Paw PAw
Tmax6x6
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Menifee, CA US
3/28/2021 3:37pm
I got to spend some time this weekend to dig into it again.

I have ruled out any fuel/carb issues as I swapped carbs with a friends stock 140 carb and same issue, so that leaves spark.

I check the coil like Paw Paw suggested, and while the secondary coil ( terminal to plug cap ) seemed fine at 12.5 k ohm, the primary (terminal to ground) was hard to pick up with my meter where it would start at .5 or .4 then read 0. It could just be my meter as its not a high quality one but idk.

I also did a quick check by shorting the plug boot to the cylinder head with a screwdriver and it has good spark, BUT when it stalls I pulled the cap and checked it and no spark. Give it a sec or two then spark again. I tested this about 5 time and I could get it to happen every time.

So, intermittent spark. The next logical step is to pull the side cover off and check the stater. The ignition coil could also be bad with the hard to read primary but again that could be my meter not picking it up.
Any idea of any other ways to check the ignition coil before spending $$ replacing parts as kawasaki is quite proud of their oem parts prices.
Paw Paw 271
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Location
Benton, LA US
3/28/2021 5:44pm Edited Date/Time 3/28/2021 5:45pm
Check your coil mounting surfaces for dirt, paint and rust. Those will cause issues.
Primary side seems to be a bit low. The secondary side seems a bit high and thus could also be an issue.
Try removing the plug cap, cutting 1/4" off the wire and the replacing the plug cap/ See if this helps the reading ( like under 10) and see if it helps with the running. Also check for a bright Blue spark at the plug. If it is anything other than Bright Blue you still have coil issues. In most cases you will find that the coils don't fail much and the biggest problem is with the mount and the wire connection.
You may also want to look into setting the float level in the carb after doing a complete carb tear down and doing a good carb soak cleaning.

Paw Paw
3/28/2021 7:22pm
I worked on one of these with a similar problem. I cleaned out the kill switch real good with brake cleaner and compressed air. No more problem.

The Shop

Tmax6x6
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Joined
4/25/2020
Location
Menifee, CA US
3/28/2021 7:37pm
Paw Paw, I cut back the plug wire and redid the cap, no change to resistance still at 12.5-12.8 K ohm. Scotch brite'd all the mounting surfaces real good and got the primary to about .004 to .003 ohm but still still drifts down to 0 after a few seconds on the meter.
The spark is nice and blue and has a good audible snap but no dice, still the same problem.

Garagedog, I'll pull the kill switch apart and give it a real deep clean and see what that does.
Paw Paw 271
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Benton, LA US
3/29/2021 10:37am
Those OHM readings are too low on the primary side and will cause the coil to fail and thus loose spark. At the same time the secondary side readings look a bit high to me ans this too will cause the spark to fail under pressure.

Paw Paw
Tmax6x6
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Location
Menifee, CA US
3/29/2021 12:10pm
I agree that the coil readings are low and it should be replaced, HOWEVER, I blasted the kill switch / starter switch on the handlebar with contact cleaner like garagedog said, and it made a massive difference. It still not fixed as it still looses power and tries to stall out but I can actually catch it with the clutch and get it to relight with just a bit of throttle. But it is actually "rideable" to where I can get it up and down the driveway without it trying to buck me off with the stalling/starting nonsense.

The killswitch looked spotless inside and the little pcb with the led on it had no visible signs of corrosion so it may just be a faulty switch as that is exactly what it feels like when it stalls out, like your flipping the switch while on the gas moving then flipping it back to catch it self.

Ill talk to my sister and see if they want to spend the $$$ on replacing the switch and coil together as motosport wants about $80 for each.

Of the 3 kawasakis I have owned over the years(kx450f, klx110, klr650) all 3 has electrical gremlins in various forms, and all were related to the kill switch or headlight switches so who knows.

Ill see about swapping the parts out and report back when that happens.

Thanks Paw Paw and garagedog for the help and insight.
1
Tmax6x6
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Location
Menifee, CA US
4/16/2021 12:12pm
I wanted to give an up date on the bike.
I got the parts in and installed. I did the coil first and no luck, it still had the stalling problem although it start and run much cleaner than before so im sure the old coil was weak at least.

Then I swapped on the new hand switch and boom instant start and no stalling. I actually runs like new now with no hiccups or anything.

This makes 4 for 4 of kawasaki control switches that have failed for me for whatever reason, makes no difference as im sure its a fluke and ive never had mechanical faults with any kawi ive had so eh.

Thanks to paw paw and garagedog for pointing me in the direction with this thing.
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