'09 KLX250sf. I will preface with the fact that I am no mechanic.

Bike ran out of gas last week long before it really should have based on miles and when I last filled up. Attributed it to being new and breaking it in. Rode it to work this morning and at a stoplight close to the office smell gas. Look down and see that the nipple on the very bottom of the carb is just dripping away. Nothing connected to this nipple. Pull in to the office parking lot, shut off the fuel and it of course stops.

Sure looks like a tube belongs on this nipple on the bottom of the carb but don't see any tubes nearby that are not already connected to something.

Any help greatly appreciated, thanks!

 

That sounds like the carb bowl drain, there is a allen head bolt on mine that is probably loose. and there should be a tube on it so it dumps out under the bike.

 

x2.

If it is a little allen head bolt that has a spring between the carb and head bolt it is most definetly the drain for the carb bowl. I usually drain mine out when I leave it sit over winter. There should be a little black tube that is routed with the rest of the carb vent/tank vents right near the rear shock. Sounds like you may have lost your tube!

 

Here is a pic. The allen screw is there and is not loose. When running the leak is not a slow drip but a fast drip, kind of like a coffee maker. It drips a lot on the engine case and puddles on the ground. I should add that I started with a full tank this morning and after only about 12 miles was down to almost half a tank.
Is it as simple as adjusting the screw to a slow drip/no drip?

 

You have one of a few issues going on there all of which involve fuel rising in the float bowl above the excess fuel level "standpipe".

You could have a float needle that is stuck in a position that is not completely shutting off the fuel flow at the needle and seat. A piece of grit or debris can get between the the "point" of the needle and where it bottoms out in the "seat" to shut off fuel flow. This would require removing the float bowl for access to cleaning the needle and seat with carb cleaner spray or compressed air and flushing the fuel line all the way down to the needle seat location with the float and needle completely removed. The needle could also be worn to a point where it will not completely shut off the fuel flow in the seat. Replacement of the needle is required.

You could also have a stuck float that is "hanging up" on its pivot shaft with some fuel varnish residue. You'd need to remove the float and pivot pin and clean the whole area with carb cleaner spray.

You could also have too high a float level which is allowing fuel to overflow into the high fuel level standpipe in the bowl and is then flowing out that nipple on the bottom of the fuel bowl. To fix it you have to adjust the small "tang" on the float where it contacts the "non-pointy" end of the needle and pushes it into the seat. You're effectively lowering the float a tiny bit into the float bowl much like the float in a toilet tank to keep the fuel level at the recommended fuel level so it doesn't rise above the standpipe. Using the float level measurement where you measure the actual float position above the carb body with the carb upside down can be misleading sometimes and requires complete removal of the carb from the bike. Sometimes the bouyancy of the float can vary a tiny bit, so the physical measurement of the float resting on the needle can be different.

Using the actual fuel level method in the float bowl with the gas on is truly the best method. You can use a simple clear plastic line that fits tightly on that overflow nipple on the float bowl...chainsaw fuel line or battery vent tube line works great. Set the bike as level as possible in a straight side-to-side position. Raise or lower the the front or rear of the bike so that the carb is as horizontal as possible to the ground. This should put the carb in as "flat" a position to the ground as possible for best results. The carb is normally tilting toward the front of the bike. Now you can bend that clear plastic line...without kinks...down from the float bowl nipple and up against the side of the carb body and float bowl. Insure you have enough length of line to run up the side of the carb body so you don't get a gas bath. Now turn on the fuel petcock and then open the allen head screw on the float bowl nipple. You'll see gas flow into the clear line and rise to a certain point against the carb. Ideally the gas level should flow to a point right where the float bowl and carb body meet. I believe there is a "tolerance" level of about +1 or -1 mm above or below this junction line of the float bowl and carb body.

If the level is not within this amount, you must adjust it. If you see the fuel level in the clear line rise well above the junction line where the float bowl and carb body meet, you've found why you have fuel flowing out of the overflow nipple...if you've eliminated all the aforementioned mentioned issues of a "stuck" needle and seat due to wear, dirt, or debris...or a sticky float pivot pin. A high or low fuel level in the float bowl requires bending of that "tang" on the float assembly that I mentioned earlier. You bend the tang up or down to affect the way it pushes the needle into the seat to raise or lower the real fuel level in the carb. Honestly, this is a lot easier than it all sounds.

Really, I think it's best to just bite-the-bullet and remove the carb and perform a really complete cleaning with compressed air and carb cleaner. You remove the pilot jet, the fuel/air screw, float, main jet, and vacuum slide. You spray the heck out of the carb body and all its little holes and orifices, and then you use compressed air to blow out those same holes and orifices. Be sure you can see completely through that little hole in the pilot jet. Reassemble the carb and set it in a vise or other method to steady the carb in a flat and level position. Perform the clear plastic line method of inspecting the real fuel level in the float bowl as outlined above, using either the bike's fuel tank or another source of fuel to the carb from a small tank or such, positioning the fuel tank above the carb for gravity operation. When you get the carb truly clean and set the actual fuel level in the bowl to the exact required level, you know you're ready to go.

 

Guys are correct, for some reason your float valve is leaking a little and that lets the fuel keep flowing into the carb. And carb overflows.

Before pulling the carb to inspect the float valve assy, there is one trick that sometimes restores a slightly stuck float to a working order.

1. Get the bike running
2. Turn off the petcock and keep running the engine until it dies from running out of fuel
3. Give the carb float bowl couple gentle taps with the handle of a screwdriver
4. Open petcock
5. Look see if the carb is still dripping fuel

With little bit of luck that procedure can get the float unstuck and/or flush little debris from the float valve.

If that didn't work do what TNC said.

--
Mikko

 

FlyingFinn pretty much nailed it for a stuck float/needle/seat. BUT the bottom is a drain with the screw. If the screw is not seated or tight, the bowl will drain there and is supposed to if the screw is loose. I would loosen and tighten the screw to be sure.

If not, I have a complete carb off an 09 SF all jetted and starter jet drilled I will sell you cheap.

David

 

Wow guys! Thank you so much for all the feedback. I'm a newb here and have to say this forum rocks with guys like you participating. Will double check the screw and give it a tap as suggested. Thanks again!

 

Your float needle valve is not completely closing.
Tipping the bike over from side to side and/or bouncing the bike around may free it up.
If the leaking stops, keep your eye on it for awhile. Should it start leaking again in the next few weeks, replace the needle valve.

CAUTION: Check your oil level. If it is overfull, change the oil before starting the bike. Sometimes a stuck float valve will allow gas to flow through the intake and into the oil.
Craig

 

This is true. I forgot to mention this potentially nasty outcome. Many bikes, depending on how your bike may have been sitting at the time, will allow overflow fuel to back up into the airbox and then enter the crankcase breather tube. This lets fuel enter the crankcase oil. This happened on a KLR650 I owned, and it killed the clutch plates before I realized I had about 2 quarts of fuel in my oil. Amazingly I had no detectable engine problems or damage as a result of this. I even pulled the cams to inspect the head, but luckily, no issues. Maybe fortunately for me, the excess crankcase level pushed oil into the airbox which fouled a plug after a few miles.