KLF300 Bayou 1995 not starting, has spark and compression

[Params_sweden]

Hi!

I got my KLF300 running again with your help a couple of months ago, at that time it was the ignition coil that had failed. It has been in use since then without issues until two weeks ago.

When the new issue showed I was going at about 10km/h and it suddenly slowed to a halt. I started it again after that with choke and I drove it 400 meters and parked. Next time it was really hard to start, and since it was low on gas I thought that was the problem. It didn't get any better with a full tank, so I assumed it was the cold weather, and adjusted the pilot slightly.

After that it I actually got it started again with full choke and some slight gas, I drove about 300 meters and then it slowed down to a halt again. After that, it hasn't started again.

The compression is 165psi. The spark has good intensity, the ATV has functioned before with the same spark "intensity"/light. I *assume* that it has gas as well, there is definitely gas on the spark plug when I remove it

I have checked the carburetor slightly, the float works, diaphragm looks ok, but I haven't disassembled it to really look for dust and such in all the small places.

My theory right now is that it might've been some dust in the gas tank that went into the system, it's just a theory

I'm thankful for all the help and pointers I can get, don't hesitate

/ Pär, Sweden

[Gwbarm]

It sounds like the main jet may be clogged or not getting enough gas, will it idle without choke.

[Mech]

Going 300 metres before conking out, and pettering slowly to a stop, makes me think it's slowly emptying the carb. I'd undo the drain screw on the bottom of the carb and watch it's flow keeps going after the bowl has emptied. If there is plenty of fuel getting to and through the carb then I'd take it off and clean it thoroughly. if there isn't a good flow I'd check it at the inlet to the carb in case it's the fuel tap/filter.

Edited November 11, 2023 by Mech

[Gwbarm]

Yeah! As Mech suggested the easiest first look would be to pull the fuel hose off the carb and make sure you are getting fuel from your tank to the carb. Nice looking Bayou i really like the color and the moose, very nice green. Most greens are like kind of blah but yours really snaps.

[Params_sweden]

I have gone through the carb after watching a rebuild video for the KLF300 '95 (link below), no issues there as far as I can tell, looked clean and well functioning. However, when I checked the spark again it appeared MUCH more erratic and weak, and it didn't spark at all for many engine revs. battery is charged and has good voltage.

My next step is to test the ignition coil like @Mech instructed in my previous post, and see if it gives spark on the bench.

Yeah it really looks good, both the shape, build and color 🤩 Kawasaki did some great choices with this exact revision of the Bayou! The moose is the cherry on top, it's actually the decals that Kawasaki chose for it which is funny since Sweden is well known for it's mooses

Rebuild video: https://www.youtube.com/watch?v=BJVXOJGK1XY

[Gwbarm]

Just watched you carb video, very good video, its a Kei Hin very similar to the one im working on for my Suzuki. Spark related, check connections very well make sure you have a good ground and check coil resistances with the service manual specs as a guide. I dont think its the CDI from your description, pick up coil maybe ,but you can check to see if you have proper resistance fairly easily, but it still could be trash around the coil, you could also check to see if its putting out the correct voltage.

[Mech]

Did you try the spark using the pull start ? I don't remember the previous post but if I suggested testing it on the bench then I presume it's a 12v ignition coil and so if the starter is drawing too much power or the battery is weak it might have a weak/intermittent spark when cranking. That though shouldn't cause it to die once it's going and driving.

You didn't say you'd checked the fuel is coming out of the drain screw at a good rate... I still suspect from your initial description of the symptoms that it's a fuel related problem.

If the spark is getting intermittent while you are driving it I'd expect the bike to start behaving differently than if the fuel's running out in the bowl.. When they start running short of fuel the power generally starts to fade away fairly smoothly, but if the spark is starting to get intermittent I'd expect it to start having a definite miss-fire and perhaps some back-firing out the exhaust, If it looses spark entirely then the bike will come to a sudden stop, but running our of fuel they generally keep trying to run till it's all gone and they will often recover if you back off the throttle a little.

 

[Gwbarm]

How did you check it for spark

[Mech]

It's always worth trying a new plug too..  Cheap, and if it's not the cause it's good to have a known good one for future diagnosis sitting on the shelf..

[Params_sweden]

I've checked the ignition coil (IC) resistances, both within spec but a bit on the lower end. I've compared with the measurements from when the IC was new, and both primary and secondary are about 10%-20% lower now.

I also did a quick spark test on a bench (by the instructions in my other post), with just the coil, battery and spark plug, and the spark is very weak compared to a couple of months ago when I last did it. The spark plug is new, that was the first thing I tried changing before doing anything else the other week I ordered an ignition coil earlier today, cost 30EUR, hopefully it will arrive this week.

I remember that the old ignition coil also acted in a similar way, it made super weak sparks, it had resistance although it was out of spec. Maybe some electric component is damaging the coils. I'll try to wait until the new IC arrives, and hope it's within spec (it's a lottery with these..), before jumping to conclusions.

It doesn't spark at all when I crank like crazy

There's a good flow of fuel when I unscrew the carb drain, and I also checked the float and the little spring assisted needle when it was disassembled. I could've missed something of course, but the spark situation really feels similar to last time.

[Mech]

Ok.. Well if the new coil cures the problem you'd better try to figure why it's killing the coils.

I'll have to go have another read of the manual..

[davefrombc]

I've mentioned this in other threads,  but  a  handy tool is an  inline spark tester.  Sometimes a spark test in free air ( spark  plug out of the cylinder) will show a spark, but it will fail  under compression.

[Gwbarm]

Params i would have done exactly what you did , bench test with battery and spark plug, weak, order new coil, last time i ordered one it took 3 aftermarket coils before i got one with the correct specs, but as Mech suggested we need to figure out whats killing your coil. Maybe check voltage at the coil when running see if it changes.

[Gwbarm]

The Moose is interesting,I didnt know that was a Kawasaki decal, never seen one with a Moose here. Maybe only in Sweden.

[Params_sweden]

Hi guys, took some time to get the coil, because I ordered it to an old address of mine. I installed the other day, and guess what, it fired right up! It was the coil once again. The new coil is a bit below spec on the secondary, but gives a good visible spark.

I will test the "broken" coil again today because when I removed it I noticed that the cable going to the spark plug was a bit loose, just to make sure.

@Gwbarm I think you're right about the moose, I did a bit of searching and couldn't find pictures of other Bayous (1994) with the moose! Surely, the moose must've greatly increased sales in Sweden

Anyway, a theory of mine, the coil is mounted around 10cm from the cylinder where it might get a lot of heat, especially since the engine is often running too hot. Could that be causing the issue?

[Params_sweden]

I cleaned the original carb in a ultrasonic bath and rebuilt it as well by the way! I used the float, float needle, pilot jet needle and diaphragm from the china carb. The original carb makes SO MUCH DIFFERENCE, the engine works very well now. With the China carb it made a lot of backfiring, always had to warm it up with choke and stuff like that. We have about -5c outside, and she firing right up without issue.

I have compared the original and china carb, everything really looks exactly the same! It must be some of the internal "drillings" that makes a lot of difference, jets and everything are exactly the same.

Very happy

[Gwbarm]

Glad to hear you got it going coil is an easy fix  hope this one lasts longer than the last one, never tried using parts from aftermarket carb didn’t really trust that they were exact enough for OEM carb , but it worked for you, good work!

[Mech]

Glad to hear it's going well now.

The coil shouldn't get too hot with 100mm clearance from the head. The spark plug caps on them are sometimes resistor caps, and sometimes not, and the resistor caps can fail. The caps resistance is sometimes included in the secondary resistance figure, and sometimes not. Some they say to remove the cap and measure the lead and coil only. And, even when the coil resistances are right, they can have an internal short that only shows up at thousands of volts. And for that matter, the rubber boots on the plug or coil can get a short burnt across it sometimes. I'm a fan of coating the leap, cap and boots with vaseline.. Hopefully this new one will go for years now..

Good work on/with the carb. Those parts you swapped are all adjustable so can't really be wrong, except perhaps the taper and diameter of the idle mixture needle, and threads which are sometimes different, but those are visible differences. I always opt for an original carb too.

 

[Params_sweden]

@Gwbarm Thanks! I thought so as well, but this carb copy is most definitely produced from the original blueprints, all of the parts are interchangeable as in I actually took the bottom half from the copy and mounted it on the original, perfect fit (original had the drain screw totally stuck). I guess most copies aren't that exact

@Mech Thanks! I guess we will just use the ATV and see if this happens again 40 hours down the line... Hopefully it lasts 🙏 Yeah I was lucky that the carb copy was an exact replica, but obviously something really important is differing between them.

Well, another problem solved, ATV running better than ever, thanks for your input once again everyone!

[Mech]

Every part of a carb is designed and tuned to work with all the other bits as a whole, and for a specific bike, and they get tuned differently for climate, altitude, fuel type, and, the sort of power band the engine it's made to fit. They will happily sell us a carb that's the same, and runs ok, but that's really made to be on some twin cam, high compression, high revving road bike with a wide flat power-band, and although we can coax them through the flat spots or overcome the over rich at low revs that the slow old quad does, it's never really satisfactory,

I do as you did if the idle mixture screw can't be got out, or the body is really worn, and get some after market to use as a base to swap all the old brass and rubber bit's into. And that doesn't always work I might warn people.. sometimes the air jets can't be removed from the air-cleaner side even though they appear to be exact copies, and the threads are sometimes different.. the jet threads as well as the idle mixture screw threads.  You were lucky Params.. Glad it worked for you.

Edited November 27, 2023 by Mech