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2013 kx250f lean pop/no power

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Hey guys, this is my first efi bike but it's showing strong symptoms of running lean. The exhaust pops all the time, it gets hot real fast, the idle wavers, and the bike makes no power then bogs when you open the throttle. How do I fix this? I know my carbs by heart but efi is new to me. Thanks in advance

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I'm curious, with your bike does it have an aftermarket exhaust as well as an improved, over OE, air filter?  If yes and yes, do you have a fuel programmer/controller.  The bike may very well be running lean if it's still running the OE ecu without being flashed for your upgrades, a fuel controller can help with this also.

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I'm curious, with your bike does it have an aftermarket exhaust as well as an improved, over OE, air filter?  If yes and yes, do you have a fuel programmer/controller.  The bike may very well be running lean if it's still running the OE ecu without being flashed for your upgrades, a fuel controller can help with this also.


Thanks for the reply. The bike does not have an aftermarket pipe, and I just changed the air filter for a brand new twin air filter, properly oiled. I do believe the bike is running lean, and I have a feeling this is due to the upstream fuel injector (injector that takes over after a certain rpm). The engine runs strong and revs perfectly when in neutral or not under a load, but when i ride the bike and try to open up the throttle, the bike will backfire, bog, and produce inconsistent/little power. I hope the injector is my issue, but if not then yes it does have an ECU. What would the issue be with the ECU if this is so? Would it just need reprogramming?

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If it's not a lean problem, then yes, it could be a programming/ecu problem. I'm not very savvy with EFI dirtbikes so I'm not much help with all this.  

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Has the engine been worked on recently? This could also be valve timing off by one tooth or excess exhaust valve clearance.


The motor has low hours On a fresh rebuild, I have already shimmed the exhaust valves and triple checked timing. What's peculiar is when cold, I can kick my bike over in under 5 kicks. I can leave it in neutral and rev it, run it as long as I want and so long as I keep it in neutral and hit the kill switch, it will start back up every time first kick. It's just when I actually go to ride the bike in first, it stalls when I crack open the throttle and it becomes a bitch to start after this until it gets cold again. I can ride it, but only when I putt the engine around. Any idea why this happens? Thanks

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Well ..... based on tour last post, perhaps you may be right on top it it and not see it? Gear position sensor : neutral sensor ?


Exactly, I believe I found the problem. When I unplug the TPS sensor, the bike still runs lean but now it will actually rev out when I'm riding it. I just picked up a multimeter to test the voltage to the sensor, so if it reads perfect I may have to calibrate it but I'll keep you updated

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