08 KLX 140L Starts but won't idle?

We bought an 08 KLX 140L last night for my son as a biginner bike and when we got home we noticed that it fires right up but won't idle.  We brought the bike from about 4500ft elevation to our elevation at about 2400 and are wondering if it may be a jetting issue.  The us we bought it from also said it hasn't been ridden for about a year.  Wondering also if it may be bad gas?    Going to pull the carb off this morning and clean the bowl and also the air filter and see what's up.  Bike also has a pipe on it.  Any other ideas or what do you think might be the problem with this bike.  Seems in great condition for the year.  And the price was right.  It's was raining super hard when we picked up so the owner basically fired it up and I said let's load it and get out of here.  Hoping it's not a big deal. 

You're on the right track. I agree it's probably bad gas, a jetting issue or a combination of the two.

Old gas, get rid of it. And yes change the jets out and clean the carb while you're in there. I changed them on the wife's bike and what a huge difference it made. I went with the suggested 40/100 sizes that Jets R Us recommends. Aside from the jets, the carbs on these bikes are super moody when the bike sits even for a short period of time. In the past I was always having to pull the carb apart to clean the jets when the bike sat for too long so eventually I began routinely starting the bike up once a week and running it to help prevent them from clogging up again and that seemed to help significantly. Also fuel stabilizer helps or even ethanol free gas will be your best bet if you can get it in your area.

The jetsrus link above is awesome. But be aware that the FUEL screw could actually be an AIR screw if you're fine tuning. At least in our 2017 it is...


that means when the screw is fully seated it's as rich as it can be, and as u back the screw out it gets LEANER - opposite of my MX bike


Hope this saves u a few hours of confusion that I already went thru for ya. 👍

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