Hi guys,

I've got a problem with my 2010 KLX250S; It keeps stalling on idle! Now I'm sure it's something to do with the carb, I'm just a matter of finding out what.

The strange thing is, it doesn't kind of... Die out. It seems to idle okay, then bang, she just shuts off. Also, it seems that I have to give a slight bit of throttle when starting without the choke.

Bike has ~15,000Km (9,000 miles) on the clock. It's an Australian version (I believe the carb is slightly different?).

I've played with the mixture screw a bit. Like I said though, seems to idle okay usually. Side note - How the hell do you get to the thing without virtually removing the carb?!

Took the carb off and cleaned it out. No difference.

MODS! It has an FMF pipe and the airbox cover removed. I've also installed a Dynojet kit, which included a larger main jet (can't remember what I put in exactly), a new slide spring and needle.

I haven't changed the pilot jet! I've heard going to a #48 can make a huge difference in starting. Maybe this would help?

Plug is relatively new.

The only other thing I haven't even looked at is the float height. Maybe it's set too low running out of fuel, or something? Thoughts?

I can upload a video if that will help.


Any ideas would be greatly appreciated. Thanks in advance!

 

You can check the float level pretty easily by attaching a piece of clear tubing to the bowl drain on the bottom of the carb and looping up the open end so that it's above the carb. Open the drain screw and the fuel level can be seen when you place the hose against the carb housing-make sure that the bike is level so that you get an accurate reading.

 

Okay, I might give that a go. It should read level with where the float bowl meets the carb housing, right?

Thanks

 

Dynojet stage 2 says stock airbox snorkel removed. Not remove lid, try putting the lid on with snorkel removed. You should have the DJ128 installed, look in your DJ kit and see what jet is missing. That should be what is in your bike. Also did you put the washers on top of the needle as per the intructions.

 

I'll chuck the lid on and see if that does anything. Correct, DJ128. Yes, I put the washers on.

The thing is though, it was running fine for a couple months after I installed the kit. Also, none of those things should really affect the idle much, should they?

 

You are right, the DJ kit should not effect idle. Maybe you need to soak the carb to really clean out the pilot jet passages in the carb. Also remove the pilot jet when you clean the carb and be sure to blast carb cleaner using the straw into the tiny holes at the mouth of the carb. You should see it spray out the tiny holes on the other side of the butterfly.

 

Have you checked valve clearance and/or cam chain adjustment?

 

The manual states that the level should be .5mm above the mating surface for the bowl/carb body. It gives you a tolerance of +/- 1.0mm so you could use fuel level as a tuning aid if jets are not readily available-a lower level will lean out the mixture and a raised level will richen the mixture across the board.

 

^This

Tight valves should also make it difficult to start.

 

Hey again guys, sorry I haven't had a chance to reply.

Got it sorted! Checked the fuel level in the bowl. It was filling a good 15mm above spec! Needless to say, this was the culprit. Couldn't figure out how to measure the float level properly, so I just winged it. Got it spot on. Eventually...

Chucked her back on the bike (my favorite part!), and it was definitely running better, but still not quite right.

Played with the mixture screw, and found the sweet spot at 4.5 turns out. WOW! Didn't know she could run so well! Starts easier that I could have imagined. Obviously I need a larger pilot jet, but I'm not too fussed about that at the moment. I suspected this was the case for a while.

Thanks to everyone for your help and suggestions. Until Next time!...