’09 KLX250S, Digital dash, Bone stock engine, 4,700 ft above sea level.

My idle readings bounce all over the place. Doesn’t seem to matter if it’s hot or cold – the RPM (according to the digital tach) is always bouncing plus or minus 1 or 2 tick marks (250-500 RPM?). The manual says to set idle at 1300-1600 RPM (if I remember correctly). I can’t get it to stay within that window. I was thinking it might be inaccuracies in the digital tach, but the engine (sounds) seem to follow the tach readout.

Anyone else have this problem?

 

Generally this is a jetting issue and especially at the air/fuel screw. You said "bone stock", and to me that means you haven't removed the cover of the air/fuel screw to richen the idle a bit. To clarify, have you adjusted the air/fuel screw?

 

See if it changes as you turn the bars also in that case it's the cable hanging somewhere.

 

Not an issue with the cables binding... and, no, I have not done any jetting adjustments (yet). The adjustment screw still has the metal cap on it.

I haven't messed with it yet because it runs relatively well at the altitude I live at (high altitude = richer), compared to all the problems I read that other people have starting it and keeping it running at lower altitudes.

 

If it "runs relatively well", I'm curious why you're asking for a possible solution. The wide majority of the problems you mention that are often covered here are jetting issues. Either someone has a bike they haven't jetted or someone has a bike they're trying to jet but perhaps don't know how to get it done properly. Except maybe in the case of someone living at a relatively high altitude all the time, frankly I don't see how anyone can ride, or at least enjoy riding, one of these KLX "S" models in the stock jetting condition. These bikes are lean. No, they're not lean...they are stupidly and ridiculously lean. I've ridden a bone stock '06 and '09 model, and they are hideously anemic...and I'm not comparing them to a ZX1400 or such. I can't see how anyone can ride one of these bikes without some jetting tweaks.

rgoers, most of the noise and complaints you hear are from people about starting and running issues who need to drill the starter jet and/or rejet their bikes, and/or get their ongoing jetting attempts dialed in properly. Those of us who have dialed in the fuel needs of our bikes are happily motoring along with big smiles on our faces. If you want a smooth idle, you're going to have to tweak that air/fuel screw...unless you have a more serious issue occurring.

 

As I noted in my original post - I *AM* at high altitude. 4700 feet is the lowest it gets around here... I can easily be at 11000 feet on a half-hour ride. My complaint was the idle bouncing. It seems like it's going to stall when I stop at a light (though it hasn't done so yet). It's hard to set idle to spec when it's jumping all over the place.

So, I really had 2 questions: 1) Is the digital tach reading RPM correctly, and 2) what to do about the bouncing idle. TNC seems to have answered the "what to do about it" part. I'm still left wondering if it is *really* idling plus or minus 500 RPM.

Yes, I have to get in there and do some tweaking - no doubt about that. The reason it's "okay" for now is because I'm still healing up a broken collar bone from my last off-road adventure. It will be a few more weeks before I'll be able to go nuts off-road again.

 

Can you feel it idling erratically? If so, then I'd believe the tach. If not, I wouldn't believe the tach. That much difference is easy to feel. I will say that float bowl errors, as well as vacuum leaks, can cause an erratic idle.

 

Yes, it seems to stumble at idle... hard to believe it's 500 RPM though, but it probably is. This is where an analog gauge would be much preferred.

Anyway, it looks like I need to fiddle with (at least) the idle air mixture screw to get it right.

 

Your gauge may be dead-on with the fluctuation. I have a digital guage in the Vapor instrument panel on mine, and it's right on the money. If you're hearing a corresponding idle fluctuation, it's probably the real deal.

 

just know from experience check your spark plug make sure its tight mine was a little loose like a thread caused a lean condition same idle issues