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Discussion Starter #1
Hey guys,

I've got an 04 KLR 250 that has had an intermittent problem since I bought it, and I need some troubleshooting help.

When I first bought the bike, the throttle response was terrible. Any quick grab of the throttle and the bike wouldn't respond and would just start to die. I thought it might have been a carburetor issue, so I cleaned the carb and adjusted the idle mixture screw. Things improved slightly, but then I had two circumstances where I was riding along and the thing just died on me in the middle of traffic. Both times it was warmed up when this happened. It finally came back to life after kicking it for a couple minutes, and afterward there was no sign of anything wrong with it.

A month or so later, I was riding on the highway on a cooler evening for about 30 miles with no problems, and then it started sputtering like it was running out of gas (but there was plenty in the tank). I pulled over and it shut off. I could start it after that, and it idled fine, but when I tried to rev it up to 4k+ rpms, it would rev intermittently and then die, and continue this sputtering/surging pattern until I closed the throttle. The bike would still function but it would start to die if I went much above 3k or 4k rpm. The next day I started it up and it was acting similar to the night before, but not quite as bad, and then after about 5 minutes
of riding the problem disappeared completely and I was able to ride it the remaining 50 miles to my house without issue.

I increased the main jet a couple of sizes and this had a fairly profound effect on the throttle response - the acceleration wasn't super strong but there was no longer hesitation. I thought I had fixed the problem until the other day I was riding it (low on fuel, on the reserve tank) and it started to die on me going up a hill. I was able to kick it back to life and then by the time I got to the parking lot at the top of the hill it died
again. I came back to it a couple hours later thinking it was just having one of its "episodes," but no matter what I did with the choke or the throttle position, no amount of kicking the starter produced even the slightest cough. I rolled it home, and even on the steep downhill parts where I was going plenty fast for a long bump start, I got nothing. Also noteworthy was the fact that I was having a lot of difficulty with shifting on the ride home without the engine on (not sure if that is significant). It took me about 5 minutes to get it into neutral and the shifting felt extremely harsh, like something was wrong with the mechanism. Then somehow that shifting problem resolved itself. When I finally got home, I was able to start it (having done nothing differently), although when I applied throttle it would die on me.

Any ideas on what this might be? I've cleaned the carb multiple times and it's never appeared dirty, although there was some buildup in the main jet but I replaced that. I've changed all of the fuel lines and the fuel filter multiple times. I've also changed the spark plug. I'm starting to look into the electrical system to see if it might be something with one of the coils, but after removing the ignition coil, I couldn't figure out which two points to measure the resistance between for the primary and secondary windings - the coil was different from all of the examples I could find online. Any suggestions would be extremely helpful.
 

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I suspect that the interior passageways of your carburetor are not as clean as they need to be.

Have you paid special attention to the 3 little low speed outlet holes under the bottom edge of the throttle plate? They get their fuel from the pilot jet.

Have you cleaned the air holes in the emulsion tube which the main jet screws into?

How far apart have you had your carburetor? Maybe this link to a link will help,

http://www.klrforum.com/how-tos-tech-guides/45258-care-feeding-cvk40.html

The KLR250 carb is very similar to the larger carb.
 

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I'd recommend:

http://www.klrforum.com/how-tos-tech-guides/19026-carb-overhaul.html

The INTERMITTENT nature of the problem(s) remains daunting. Ignition possibilities are manifold; for example, safety switch wiring problems can cause havoc . . . an intermittent short or open circuit can disrupt things. Checking the wiring and connections might be in order; corrosion can certainly attack a bike that old.

Assume you have the KLR250 Supplement, and the KLR600 factory Service Manuals; a usable wiring diagram ought to be in there. Ignition coil resistance is the same both ways; I think ignition coil secondary winding continuity is center contact to ground, or to one of the primary winding terminals; problem doesn't sound ignition coil-related to me.

Good luck; KLR250s forever!
 

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Discussion Starter #4
Thanks for the responses guys. I'm going to take the carb out in the morning and do another thorough cleaning, paying special attention to the ports referred to by pdwestman and the ones in the video. I've had the carb apart pretty far - I've removed the main diaphragm and the float and the rubber needle attached to the float, as well as the main and pilot jets, and the main jet holder. I sprayed the main jet holder with carb cleaner; there was definitely some corrosion on the holder and around those air holes, as well as in the main jet itself, but maybe I need to get at it more thoroughly with some fine wire to scrape off the buildup. Also, in the video, he shows the removal of the needle jet from above the main jet holder - maybe mine is just stuck in there (I'll find out soon enough), but I don't recall ever having handled or seen that part. How would the carb's performance be affected if that part were not installed? I can't imagine it'd be good, but I also don't see it having an intermittent impact on the performance.
@Damocles - on the ignition coil, I only see three points where I could attach a multimeter to measure resistance. 1). ground, 2). the terminal that the spark plug wire screws into, and 3). the metal tab that a wire from the harness is clipped onto. Which of these three points are you referring to as the "center contact," and the "primary winding terminals?" And when checking resistance values for the coil, should I include that spark plug wire and have it connected to the coil, or should I be measuring from the point at which the plug wire would screw into the coil?
Also, would you happen to know what the resistance of the spark plug wire should be? Mine is about 5k ohms, but I couldn't find a suggested value for it in the manual.
 

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Damocles - on the ignition coil, I only see three points where I could attach a multimeter to measure resistance. 1). ground, 2). the terminal that the spark plug wire screws into, and 3). the metal tab that a wire from the harness is clipped onto. Which of these three points are you referring to as the "center contact," and the "primary winding terminals?"
I consider 2) as the "center contact;" the primary coil resistance can be checked between 1) and 3).

The spark plug wire is not included in ignition coil resistance tests.

Don't know what the spark plug wire resistance is; if you get a healthy spark across your spark plug electrodes when you ground the base, chance are the srark plug wire is o.k.

Again, your symptoms don't suggest a defective ignition coil to me, but . . . some have noticed strangely varying behavior from ignition coils hot and cold.

SUBSTITUTING components may be a worthwhile diagnostic testing procedure, if you can find some known good parts to borrow for substitution.
 

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The spark plug wire may or may not be replaceable separately. If it is replaceable it will Un-screw from the coil body, like the spark plug cap un-screws from the wire.

Spark plug wire by itself would have near full continuity.
Spark plug cap near 5 K ohms.
Secondary terminal to steel body core, 3.2-4.8 K ohms. Add these 3 together near 8-10 K ohms.

Primary terminal to steel body core, .17-.25 ohms.
 

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The spark plug wire may or may not be replaceable separately. If it is replaceable it will Un-screw from the coil body, like the spark plug cap un-screws from the wire.

Spark plug wire by itself would have near full continuity.
Spark plug cap near 5 K ohms.
Secondary terminal to steel body core, 3.2-4.8 K ohms. Add these 3 together near 8-10 K ohms.

Primary terminal to steel body core, .17-.25 ohms.
Just verifying: These figures for the KLR250? May be the same as for the Generation 1 KLR650; changed for Generation 2 KLR650s.
 

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Ignition coil specs are identical to KL600A1, B1,B2 & all KL650-A,B,C. From OEM SM 99924-1051-15.

Exciter coil also KL600-650 spec.
Pickup coil also KL600-650 spec.
 

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Discussion Starter #9
This morning I took the carb apart and inspected the entire thing, but there was nothing to be cleaned. The jets and the jet holder for the main jet were virtually spotless. I inspected the little holes beneath the throttle plate but they appeared clear. And I did indeed find the needle jet installed.

I checked the inside of the gas tank for gunk and didn’t find any. But in doing so, I was inspecting the venting system and noticed the flow to be somewhat obstructed. I’m not sure how it’s supposed to be, but when I blew into the air vent tube at the bottom of the tank (the one that is piped up into the tank cap), there was a fair amount of resistance. Not impossible to blow through it, but it did require some effort – is that normal? I took apart the gas tank cap, and just blowing through the venting channel in the gas cap, there was a fair amount of resistance – is that normal? I know there’s some sort of a one-way valve in the tank cap but I would expect air to be able to flow through there pretty easily.

When I checked the spark plug wire, it had almost no resistance, and the plug cap itself had around 5k ohms, so that checks out. However, for the ignition coil, when I measured between the piece that attaches to the spark plug wire and ground, it was around 4k ohms, but when I measured between ground and the other contact that goes to the wiring harness (what I believe pdwestman is calling the primary terminal), I couldn’t get a reading less than 1 ohm – you think that might be problematic? I’m not sure how much it’d have to be off by to cause concern.
 

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Discussion Starter #11
It's been pouring rain here all day, hopefully I'll be able to check tomorrow. What would a healthy, robust spark look like in comparison to a weak spark?
 

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Good question, with no comparison experience!

I THINK I remember song lyrics, "You'll know, when it happens, you'll know; you'll know, just wait and see!"

(The subject was NOT electric spark intensity!)

I'll amend my question: "You DO have clearly visible spark, right?"

A positive answer would suggest functioning pickup coil, stator exciter coils, etc., as a minimum.
 

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With the spark plug removed from the engine and the cap unscrewed from the wire and the end of the wire near a valve cover bolt so as one will have 1/8 - 1/4 inch of air gap, one should see a Blue spark when working in dim or shaded area. A Really Good spark will jump about 3/8th inch. Working in bright sunshine you may not be able to see the spark.

Probably best to have a helper to look, while you kick.
 

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Discussion Starter #14
Well it appears to have a spark. Even in the sunshine I could see it jumping from the plug wire to the frame when I kicked it. Hard to tell if it was a "healthy" spark, but it was certainly present and would good jump a good distance (~1/4") to the frame. But who knows how a warmed up engine might affect the coil differently? Any more ideas? Any thoughts on that gas tank valve?
 

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Your spark description sounds robust enough; the petcock ("gas tank valve") rather worn-proof; you can sense compression from the kick starter . . . you only need a combustible mixture.

Starting fluid will guarantee a combustible mixture, useful for diagnosis and testing. Look up, "Carb Overhaul," on page 3 of the, "How To" forum, if you want to get that one right (your CVK34 is awfully similar in design to the CVK40).
 

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Discussion Starter #16
Could valve timing cause an intermittent issue like this? Just thinking that if the timing were off, then maybe I would be losing power if an inlet or exhaust valve was open when it wasn't supposed to be.
Also, I checked the gap on my spark plug and it was around .5 mm, when it should have been between .8 and .9 according to the manual - is that discrepancy a big deal?.
 

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Doubt your problem is valve timing.

Regardless, very easy to check. Recommend the Kawasaki KLR250 Supplement Service Manual. The companion, KLR600 Service Manual might come in handy, also; or a Clymer KLR650 Service Manual. (No type; the KLR600 (vs. KLR650) manual is "base" to the KLR250 Supplement.

A tip: TWO (2) top=dead center (TDC) piston positions exist for each complete cycle on 4-stroke cycle engines; you want the one with ALL valves CLOSED to check valve timing and adjust valve clearance.
 

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Discussion Starter #18
OK so I've been trying to check the resistances between the wires emanating from the CDI box but every time I switch between a resistance setting on the meter (e.g. 200 -> 2000, or 2000 -> 20k) I get a different reading. I just bought this meter a few days ago so I wouldn't expect it to be malfunctioning. For example, when I measure with the positive probe on the black wire connector pin and the negative probe on the white wire connector pin, the screen displays "534" on the 2000 ohm setting, then it displays "7.57" on the 20,000 ohm setting, then it displays "41.7" on the 200,000 ohm setting, and then "289" on the 2,000,000 ohm setting. At least to my knowledge, the only thing that should be changing is the location of the decimal point - correct? I was trying to compare my readings to the ones indicated in the manual, but now I have no idea what reading I'm really getting.
 

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2>>4, if you're getting a healthy spark, chances are your CDI unit is working just fine.

Never mind the resistance between terminals. The solid-state nature of the CDI leads to different readings from analog and from digital ohm-meters, men say.

At the end of the day, doesn't matter what the resistance values might register; the single index of success is: A healthy, robust SPARK!
 

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You will need to use an analog meter to measure the resistances or you will need to place the digital in the "Diode" mode.

A little bit of forward current is necessary to get consistent readings through what is essentially a bunch of diodes and transistors (which are really just a couple of diodes stuck together either head-to-head or head-to-toe.

And what Damocles said. If you have spark, look elsewhere.

Are you absolutely certain that there is no tear, pinhole, or mis-insertion or pinching of the slide diaphragm?
 
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