Well, it turned out to be a cracked sleeve (long story, and not Bill's fault. Advanced Sleeve f***ed up big time). I figured that was the cause of the symptoms and it made sense. That would explain why it was running like it had water in the gas, right?

So, since the top end was being rebuilt again, I went ahead and switched over to the Mikuni carb at the same time. Seemed to make sense. Why not just upgrade?

Alas, I am still having the exact same issues. Won't hold idle after it gets warm. Gets more and more erratic, first surging, then dropping, and then finally dying. Exactly like before, but no cracked sleeve this time (not that I can tell yet, anyway. Coolant levels still seem fine, but I'm less than 20 miles into it this time).

Here's a video of a cold start up till the first 10 minutes of idle. If I had let the camera go longer (ran out of memory), you would have seen the bike stall itself. If i had gone for a ride, it would have been very obvious. It happens within seconds of pulling the clutch in to coast to a stop. Nice backfiring on shifting and decel, too. *headscratch*
KLX Idle Problems - YouTube

 

I could see the headlight flicker in the vid. Does it also flicker at higher rpms?

Shooting in the dark here, but have you reviewed this thread? https://www.kawasakiforums.com/forum...y-speed-34470/
Your idle problem sounds different from these, but perhaps there is a correlation since you said it may be electrical.

 

I have not noticed that, but I have noticed that the engine acts funny between 5k-6k RPM in every gear. I know that's a common problem with the SF, but with no solution.

UPDATE: I have just discovered that if I have the a/f screwed in all the way, it will idle a bit longer and slightly steadier. If I try to back it back out (lean it out) even just 1/8th of a turn, it will die IMMEDIATELY. Now I am beginning to think it is not electrical. *headscratch* Still, I will test all the electrical components, because we all know what happens when we assume things...

 

On the stock carb a/f screw, in=lean and out=rich. Is your new pumper carb different?
If you have the 6500 rpm surge issue, consider the fix found in the Surge thread (go towards the last pages for details).

 

I have noticed that surging issue since new, but it was never terribly noticeable. But that thread just sparked (no pun intended) a "now that you mention it.." moment. I did at one point last year have the dealer check it out, but they said all was normal and suggested rejetting, blah blah blah. I will go ahead and try that grounding technique while I'm at it. Or, rather, have the dealer do it. Seems simple enough. Not sure it will help my idling issues, though. But, I can have them test the rest of the electrical while I'm at it, since I have no equipment to do so anyway.

 

For those who want to see exactly what I'm talking about, here's a short video featuring some mechanical failure and rrrraaaggggeeeeee:

Kawasucky- Why I Hate My Motorcycle - YouTube

 

Hey Laurie,

I had the same issue back a while ago and it just turned out to be that the spark plug wire was shorting out. The previous owner must have been yanking the plug wire off without reading down and grabbing it around the base like you're supposed to do. I discovered this because the portion that goes around the plug literally came separated from the rest of the wire. I replaced it with a used one off of Ebay and all was well.

 

Fuel tank venting issue ?

Try riding with the cap open and see what happens.

 

This thread is making me second guess getting a BB 351 kit.

My 250SF has fluctuating idle, but never more than 1 bar on the LCD, and not really noticeable by ear, sounds as steady as any engine. Occasionally it'll idle a bit higher when it's HOT, not warm, but hot.. like riding at 7k+ rpm for several minutes and then coming down to idle. But once it cools for a few moments.. it idles normal again.

It's died once on me when idling at a red light, I just put a hair more idle screw on it, and it's never done it again... only bogs when I'm low on fuel, or in too high of a gear

 

Just because a few people have problems does not mean that you will. Do a search and see how many people have the 351 kit, how many miles they have on it, and how many few problems people have. From what I've seen in the last few months, most problems are self inflicted and have nothing to do with the 351 kit at all. Will some people have problems with the kit. Yes they will. Just like some people have problems with brand new cars, and other people don't. I would give it some time and do some searching and find out all the info there is on the 351 kit. I plan on making this a winter project, if I can get make some decent progress on my house remodeling.