I have a 2010 klx 250sf that I bought a 3 years ago with 3600 miles on it (now has 7100). It already came with upgraded exhaust and jetting. It ran great and always started right up with the choke on for the first year and a half. Then I let it sit for a couple months and now it wont start. It cranks but wont fire up. This was a year ago and I just put it in the garage to sit. Fast forward to now and I have gone through the check list of things to do to get it going:


- cleaned carb with carb cleaner, removed and sprayed out the jets

- emptied out the old gas and put in new gas

- put in a new gel battery reading 12.67v

- replaced the spark plug and tested for spark (it sparks)

- checked valve clearance (all four within factory specs and on the loose side)


Not sure where to look next. It cranks but never sounds like it even tries to fire up. Any and all help is appreciated.


Cheers- rj

 

Well from experience of letting my KLX sit around for long periods of time it fights with me big time. For storage always use a fuel stabilizer if you didnt. I always use Marvel Mystery Oil in my fuel and Ive never had an issue no matter how long that carb sits with gas in it. Cheap and works very well. When it comes to starting it I most of the time have to jump the bike with a car because Ill kill the battery every time just trying to get the thing to start up without a car battery to help. My last and final thing I do is mount the bike, hold onto that front brake lever and rock that thing hard back and fourth. It helps slosh the gas in the carb and can help free up and debris that may be clogging up my carb. Works every time. Take a decent amount of effort but it works. Hope any of that helps.

 

Thanks KLX boy. I will remember to use the Mystery Oil in the future. When jumping from a car, do you start the car or leave it off?

 

You are going to have to fully dismantle your carb. Clean or replace your pilot jet and all pilot system passageways(circuits). Clean or replace the emulsion tube and all primary fueling circuits. Check and clear the choke system circuit. Doing all this "right" is not a trivial task but when done correctly, and with a fully functional float system (and proper float settings), she'll run like new..

As a side benefit, when you gain the knowledge, then the tools and skills, to do this correctly, you are ready for the next time you lay up the bike with fuel in it !

P.S. Don't overlook cleaning/clearing the pilot systems' transfer ports..

 

I leave the car off. No need for that much juice going to a small motorcycle battery. Not running the risk of frying my bike.

 

Thanks KLXster. I thought I did a pretty good job of tearing apart and cleaning the carb but I might end up digging back into it again. I sprayed carb cleaner through every port and jet and they seemed like they were clear of any debris. If I do it again I will end up just replacing the jets instead of cleaning them (cheap enough to replace). I am definitely learning as I go. I have worked on cars quite a bit in too.

 

Thanks- I will give it a go tomorrow.

 

I've never had any luck cleaning jets with carb cleaner seems there's not enough pressure in the can to push the junk out of the jet. I've used a small gauge wire to clean em out. Hold it up to the light you can see if it's clogged up or clean, unless your like me blind in one eye can't see out of the other.

 

OP when you cleaned the carb, did you specifically remove the pilot jet? After cleaning could you see completely through the hole in the pilot jet? It's not unusual to need to use a fine wire in conjunction with high pressure air to blow out the residue in the pilot jet.

The only odd thing I notice in your case is that the bike won't start with the choke. The choke seldom plugs up with fuel residue. It's usually the case in a fuel varnished carb for only the pilot to be plugged which keeps the bike from running without the choke or it only runs when the throttle is at or near wide open so it runs on the main jet circuit.

Some KLX's are hard starters due to needing the starter circuit brass jet to be drilled out to a bigger size. But you say you didn't have problems until the bike sat, so it looks like the pilot circuit jet or the pilot circuit passages are still plugged. Good spray carb cleaner works quite well, but it usually has to be used in conjunction with compressed air to completely blow through all the circuits. Of course you should have all jets out and all passages open...pilot jet, main jet, fuel/air screw, needle, etc. I'd recommend you remove the slide and rubber diaphragm when blowing compressed air into the carb. And on that fuel/air screw, it has a spring, a small washer, and a small o-ring that stays on the screw. Don't lose them. The o-ring likes to stay in the carb sometime...just pick it out.

 

I would check your pitcock is getting fuel to the carb.
RULE #1: If your not riding later that day and/or anticipating not riding for a while (over 2 days), I turn of the fuel and run the carb dry!