My cousin has a 2006 KLX250s that died right after we got done doing our 13/45 sprocket mod to both our bikes (I have a 2007). He was driving it down the main road after it starting up fine (from being warmed up) and going down the road fine. As he approached the driveway, it started to sputter a little and lose power. When he went to go up the driveway, the bike wouldn't go and stalled. He started it back up and attempted to go, but again, died.

He has been complaining about it starting hard, and was told it was idling low, so he has been messing around with the idle, which I think was turned up to high now. By the time I got down to him at the bottom of the driveway, he got it to start for the last time, and when it started it shot way up to around 6,000 RPMs (I think he had the choke on, but still, way too high) and then died when he went to move.

The bike will still turn over and act like it wants to start, but never fully fire and run now.

As I stated, the idle is turned up way too high, which we turned back down, but it still won't start. He went through half a tank of gas before it died, so I am thinking it's probably not bad gas. We pulled the spark plug out and it was dry, so it's not flooded, and there was some spark, but we are going to try new spark plug to see if that fixes anything.

Other than that, we aren't sure what could be the problem. If it's getting spark, I would think the plug is okay, and since he went through half a tank of gas, I would think the gas is okay, but could the idle still be stuck far too high, or maybe something in the carburetor?

The bike only had 400 miles when he bought it last summer, and it now has about 1200 miles.

Any suggestions or advice would be greatly appreciated!

Thanks!

 

I am not trying to be a smart *** but did you check to see if it had gas ?

 

It could also be a blockage in the carb. It doesn't take much to plug a jet. A small little piece of anything can make a well running bike run very poorly in short order. Maybe a good idea to check that?

 

As mentioned, eliminate the easy stuff first.

Check the petcock and set it to reserve if the tank is around 1/3'rd full. Or fill the the tank. Check your oil too (color, level)

Can you hear it firing but it just won't run?

Is the bike 100% stock? (outside of the sprocket)

 

Thanks for replies.

Yes, you can see gas in the tank, so it has gas, and the fuel is on (not off or on reserve).

There is oil in it (you can see it in the oil window).

The bike is 100% stock, aside from the sprockets now.

The bike will wind when you hold the starter button on, but never fires. I guess we'll have to try the new spark plug, and if that doesn't fix it, take the carb apart.

Thanks everyone, if anyone else has any ideas, let me know.

 

Air, fuel, and spark as always. Sounds like you are getting air as it's highly unlikely for something to "all of a sudden" block airflow...though I have seen an owner's manual or other object vibrate to the air inlet and cover it. On the spark, it sounds like you have spark and that the plug isn't fouled. The hardest gremlin to diagnose in a case like this is where you have intermittent spark because of a wonky ignition component, bad ground, etc.

The fuel. Sounds like you're not just out of gas from your inspection. Intermittent fuel feed from a clogged filter or petcock sock...a kinked fuel line...a clogged fuel tank vent...and so on.

The carb. This can get more confusing and requires more diagnosis. The jets in a carb seldom all clog at the same time, so you can usually get the bike to run but just not run anywhere close to properly. Your bike sounds like it's not getting much if any fuel at all. I'd check the tank vent first.

 

I cannot stress this enough. The point at which the bike "runs out of gas" and you are forced to use the reserve setting is seriously like 1/3rd of the tank. You can be "out of gas" and still see quite a bit of gas sloshing around in there. Set the petcock to reserve, let it sit for a few moments and try starting it. Make sure not to run your battery down too much either.

From what was written, it sounds exactly like the bike ran out of gas.

Lets eliminate this from the equation entirely and just set the petcock on reserve just in case. Once you give that a try, we can begin considering other troubleshooting options as TNC suggests.

 

"Some spark" is not good. It should be a crisp strong spark.

Sorry I got nothin' constructive for you, just that comment. Do the plug, they're cheap. In addition drain the gas out of the float bowl in case there might be water in it from the gas or from washing the bike. You never know.

 

Take the hose off the carb and see if fuel is coming out from the tank.
If it is, take the carb off and see if there is fuel in the carb bowl. Inspect the float and make sure it floats & the needle valve is not stuck.

 

ive read some 90 degree bend in the fuel hose is where the filter is I think
and if you have taken out the carb, or did anything that could mess up that bend
it could mess up the filter inside



you float could be stuck in the carb
jet fell out or loose

easy enough to check those
at the same time see how fast fuel flows out the line



almost sounds like a fuel starvation or something with the carb
if the tank isnt flowing fuel you can carefully blow it out through the fuel lines with an air compressor maybe the pickup tube in the tank is clogged
just make sure to have gas cap off and rag over it


or you have some sort of air leak like a hose or air intake
messing up the mixture causing it to run bad

any changes to the air filter, exhaust, hoses could cause it to run bad so make sure no mods were done that you dont know about