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Cut out at high RPM

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Hi all,

I've searched, read and tried many things to try and fix this issue I am having to avoid posting a new topic but nothing I have done so far has solved my issue.

04 KLX400s with FCR carb, 3x3 mod. Bike has been running fine all season and the issue started recently and has not gone away or changed.

At high rmp the motor/revs will cut out. It does not die, and is consistent in the exact way it cuts out. In neutral in the driveway, riding down the road or trying to go over 3/4 throttle to hit a hill on the dirt the motor, the same cut out happens. Essentially anything above 3/4 throttle with any load on it the revs will pulse, going from high to down to an idle and back for as long as you keep the throttle open. Does it the same way at the same time every time.

I have had the carb off multiple times, replaced all jets and needle, cleaned thoroughly every time, tried a variety of jetting over the entire spectrum, float level in spec and nothing I do to the carb has any effect on it what so ever. I've tried with no side covers, all covers, tape over 3x3, really just doing anything I could to try and effect the issue and none of that has made a difference at all. The carb has about 1000 miles on it.
After searching the web and chatting with locals I was thinking the issue had to be electrical. I read a couple threads that sounded similar and replacing the stator fixed their issues, so I did this yesterday, and no change.

Now I'm looking for recommendations on what way to go. I still think it could be electrical, the three DRZ's I've had have never had electrical issues so this is a first on this bike for me. I am going to triple check for an air leak again, but nothing has been apparent to me. 

Thanks for any tips!

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2 hours ago, 1hp said:

have you checked the strainer on petcock inside tank?

Thanks 1hp, yes I have had the petcock out and tried different fuel. Fuel flows into the carb freely.

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Dang I was reading it and it sounded familiar and a new stator fixed it for me (last spring) I'm having similar issues again, and really hoping it's not another stator (although I do have an year warranty). It does sound electrical though.

On electrosport's website, they have a electrical problem solving flow chart. I need to apply it to my bike.

I would also follow all your ones and make sure there aren't any exposed wires or loose connections.

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There is a throttle position sensor, and this is factored into the ignition I believe. Anyway, I would start the trouble shooting by checking the sensor and associated wiring. 

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There is a throttle position sensor, and this is factored into the ignition I believe. Anyway, I would start the trouble shooting by checking the sensor and associated wiring. 
Any tips on how to do that?

I've heard of people just disconnecting it, so maybe I'll try that

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Try it but I doubt it helps. The tps advance isn't much to cause running issues which is why most people use aftermarket carbs with no tps. Have you rtired replacing the plug?
 
 
That was the first thing I tried :(

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Sure  does sound like a stator problem, but mine did those same symptoms at about 4-5 k  rpm in neutral, in gear, under load or no load.

the only way I confirmed the stator was with timing light and scope on coil primary wire, when the problem happened the timing jumped all over the place.  What kind of stator did you put in, used, new, brand? I would still suspect stator.

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Sure  does sound like a stator problem, but mine did those same symptoms at about 4-5 k  rpm in neutral, in gear, under load or no load.
the only way I confirmed the stator was with timing light and scope on coil primary wire, when the problem happened the timing jumped all over the place.  What kind of stator did you put in, used, new, brand? I would still suspect stator.
I used a new electrosport stator. It has an year warranty that's up in the spring, so I need to run through their troubleshooting guide.

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14 hours ago, Juney said:
14 hours ago, bucket list said:
Sure  does sound like a stator problem, but mine did those same symptoms at about 4-5 k  rpm in neutral, in gear, under load or no load.
the only way I confirmed the stator was with timing light and scope on coil primary wire, when the problem happened the timing jumped all over the place.  What kind of stator did you put in, used, new, brand? I would still suspect stator.

Read more  

I used a new electrosport stator. It has an year warranty that's up in the spring, so I need to run through their troubleshooting guide.

I was addressing  the original poster, put troubleshooting these stator's can sometimes be difficult. Mine passed all the volt and ohm tests, but I know the ignition timing went for a crap when bike started to buck and fart. I still think a visual is a good test, if it looks burnt and crispy, lose it.

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I was addressing  the original poster, put troubleshooting these stator's can sometimes be difficult. Mine passed all the volt and ohm tests, but I know the ignition timing went for a crap when bike started to buck and fart. I still think a visual is a good test, if it looks burnt and crispy, lose it.
Good advice, and relatively easy to do. I will probably do that myself after I test a few more things with the ole multimeter

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On 11/5/2018 at 5:09 PM, bucket list said:

Sure  does sound like a stator problem, but mine did those same symptoms at about 4-5 k  rpm in neutral, in gear, under load or no load.

the only way I confirmed the stator was with timing light and scope on coil primary wire, when the problem happened the timing jumped all over the place.  What kind of stator did you put in, used, new, brand? I would still suspect stator.

Thanks for all the comments everyone.
I replaced my stator with an OEM unit. Install was easy but did not fix the issue.
Tps unplugged.
This bike is starting to get to me! My other two DRZ's were rock solid, always performed perfect. This one can't seem to do 1000km without needing something replaced or repaired. 

I will go over everything closely again, check all grounds ect. I just took it up and down the road for a minute, runs great at lower rpm. The same issue remains at higher rpm. I will post up my findings.
 

 

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Thanks for all the comments everyone.
I replaced my stator with an OEM unit. Install was easy but did not fix the issue.
Tps unplugged.
This bike is starting to get to me! My other two DRZ's were rock solid, always performed perfect. This one can't seem to do 1000km without needing something replaced or repaired. 
I will go over everything closely again, check all grounds ect. I just took it up and down the road for a minute, runs great at lower rpm. The same issue remains at higher rpm. I will post up my findings.
 
 
Have you tried swapping in a different CDI? I'm thinking that may be the issue on mine.

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If I don't get it figured out this weekend I will grab a cdi from a new DRZ from my local dealer next week and try that out. 👍

Here are some photos of my cams this morning. Something seems off to me. There are 15 pins between the arrows but the other lines don't line up with the cylinder head. 
Can someone confirm from these photos if my timing is off or if something doesn't look correct?

Thanks!!

20181117_120746.jpg

20181117_120713.jpg

20181117_120728.jpg

20181117_120521.jpg

20181117_120454.jpg

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If I don't get it figured out this weekend I will grab a cdi from a new DRZ from my local dealer next week and try that out. 
Here are some photos of my cams this morning. Something seems off to me. There are 15 pins between the arrows but the other lines don't line up with the cylinder head. 
Can someone confirm from these photos if my timing is off or if something doesn't look correct?
Thanks!!
20181117_120746.jpg.41df0bb66ee2e4e1a5184f3f4af8f685.jpg
20181117_120713.thumb.jpg.5e4cb68a1010cfd04b8e61682338f97f.jpg
20181117_120728.thumb.jpg.bb324f51eb2237b2bbca844f95f6dac9.jpg
20181117_120521.jpg.a9ac0911a526e10fabcb30f769594e58.jpg
20181117_120454.jpg.0b4517e5ca5e557d355846f538f7c7fd.jpg
You're off 1 tooth. Need to rotate both cams counter clockwise
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You're off 1 tooth. Need to rotate both cams counter clockwise
Thanks for the quick response Ohio! I'll do that this afternoon. Problem solved? Hope so!

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Remember it's easy as 1, 2 3.

At TDC the right arrow on the exhaust cam marked 1 should be level with the case surface.

Arrow 2 on the exhaust points to the 1st pin in the count.

Arrow 3 on the intake points up to the 15th pins. Every other arrow doesn't really matter.

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That does look like both cams are advanced one tooth each. I would be confirming that TDC mark is accurate with the piston AT TDC. Best way is with a degree wheel on the crank and a bump stop through the spark plug hole. Mark down the degree's at the bumpstop from both directions of rotations and cut the total # of degree's in half, that should be your true TDC and your T mark on the crank should be perfectly lined up. That would eliminate the possibility that the flywheel has moved on the crank. Then put the cams where they should be. If they then seen slightly retarded the chain could be stretched. How's the tensioner ?

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