AussieCheech, you are correct in that the performance of a fully modded Lidless KLX ( Performance header and slipon + MCM + Lidless CVK setup ) will usually put a BB kit far down the list, or off the list, for future mods..

However, just know that such a well modded KLX will instantly gain over %30 more TRQ (up to %40 more) , and approximately %15 more HP.. AND, is the only "next level" mod available that provides a drastic power increase for your bike (once you've done the MCM and put on a full exhaust system).

 

_250s, sorry don't know the size jets they put in at the shop. I asked but got some BS about the mechanics won't say as they have some chart or something that they perfected to get the right combo for the particular pipe... Like it was interlectural property or something. Anyway, if I need to change jets I will just pull the carby myself to find their special secret BS. Though don't plan on doing that any time soon as it is not lean or rich. Looks like they did get it right. As per my signature, I went for an FMF powercore 4.

xster till the mods so far, I was sure I was going to move up to possibly a 331 when my warranty runs out, but for the trails and fire tracks around Brisbane, I am finding 3/4 throttle is about all I am using. So the MCM and extra low down torque will hopefully satisfy the inevitable 'can never have too much power' quest. About the only thing left I may do is play around with the carby. Haven't looked into it much yet, but seems there may be a few things to do with needles and settings. I ride with my son and he has a WR450, and he is only using half the power of the bike. The little KLX is often faster being lighter and able to use more of it's power.

 

It's been a while and I just wanted to update this thread. I have not done the cam chain tensioner yet. I did do the planned oil change successfully.

Other news: I'm still having trouble with this ****ing idle situation. I tightened the hose clamps down to where they are almost touching. I turned the idle up a little bit. About 1800 rpm. And adjusted the mixture screw around the new setting. The bike was fine for a little. Then I noticed in a parking lot that occasionally I couldnt shift out of neutral if I held the clutch in. So I loosened up the clutch cable a bit. After that I had stalling issues. If I'm in low rpm regardless of what gear I'm i . Then pull the clutch the idles drop and the bike dies. If I'm in moderate rpm and pull the clutch the rpms surge about 2k and then the idles drop and the bike dies.. I do have an aftermarket handlebar and an aftermarket clutch. Again pointing to the possibility that the previous owner fought the same issue.

At this point I'm extremely frustrated and considering taking it to a shop. Only reason I haven't is because I dont have money to throw at it rn. I'm starting to think I have as clutch problem not an idle problem.

 

Test...
1 Does the idle change when you pulll in the clutch while in neutral?
2 Does the idle change when you kick into gear?
If 1 doesn't change and 2 does, yes your clutch is the problem.
As far as I have ever heard, pulling in the clutch should not change the idle. Another possiblity is that the clutch cable is somehow in a bind with the throttle cable/linkage.

 

I will test this and respond with results.

 

1 and 2 did not cause change in idle. I did notice some surging in idle about 100 - 200 rpm at random. Also noticed I have some motor oil coming down from the area around the carb where the mixture screw housing is located. Possibly getting kicked back from the area around the boot that clamps to the carb.

What does this mean?

 

A 100-200 gpm variation in idle sounds normal to me.
You shouldn't have motor oil around the carb. The crankcase breather vents to the airbox. Check in the airbox for oil. If you're getting an abundance of oil in the airbox, that could be a problem.

 

*Progress update*

The oil in the airbox was a result of me overfilling it when I did the oil change. I also discovered some fuel around the hose that goes from the fuel tank to the carb. I'm going to replace it soon. I did also replace the spark plug which was a perfect example of oil fouling. I was unable to make any other determination because it was too far gone to highlight any other issues with fuel mixture.

Still have not done the cam chain tensioner. I wanted to get the other issues ironed out first.

As far as the idle issue as a whole: I set my clutch pretty loose and reset my idle mixture screw starting at 0 turns out. The bike liked 2.5 turns out. The only way I can get around the idle issue of the bike dying when I pull the clutch without downshifting from low rpm is to turn the idle speed to about 2k-22k rpm. It's just the only way. Otherwise when going low rpm (3500 and under) to straight up pulling the clutch will just kill the rpms and cause the bike die.

I know downshifting is best practice but it shouldn't kill the bike either way. I can get around the issue by just revving my rpm a little before I pull the clutch and it idles fine when I pull the clutch in..

I used to think I had an issue where the bike would rev a little bit when I pulled the clutch and then idle rpm would drop and it would die. But I have since decided this was due to me over revving before clutch so as not to kill the bike and have since just been mindful of it. I do have slight stuttering at 1/4 throttle and below but hardly noticable. I'm currently considering going a step up in the pilot jet but as of rn have no real interest in actually testing it out.

Anyway. Not sure what any of this means and I'm sure I could maybe be a little turn one way or another to get the fine tuning better but I dont know which way that would be at this point and I have a running (and pretty forgiving imo) setting currently that wont allow me to kill the bike unintentionally.

Also if you just Google klx250s dies when clutch or dies when idle it seems like this is an unresolved issue for many people with the 09. From now on I'll probably just be riding it and not messing with much unless I have to.

Thanks all for the input/ suggestions.

 

IIRC, there was a battery grounding issue with '09 which seemed to be tied to the bike sputtering. I don't recall the fix; you'll have to search back on it. Small chance, but maybe this could be an issue.

 

Interesting. Thanks