Just picked up a 2014 KLX250 with 800 miles on it, now has 2k miles & I'm having an issue while on the highway. The bike starts up fine & drives like it should, It rides fine around town & off road; except for highway speeds. It seems to loose power for about 1 second & then surges power for a few seconds & just seems to happen around 40 - 60 mph, over & over again. It does this the whole time I'm driving it on the highway. Almost like it's running out of gas momentarily over & over, but just for a second. It's been doing this for about 1k miles & getting slightly worse. Doesn't seem temp related & don't think fuel level affects this.
Anyway, I'd appreciate any help.
My altitude is 150 ft, Houston area, & temps are 80*.


Also, the tire keeps loosing air & I've changed the tube 2x. It doesn't drop below 17 psi though. First bike with a tube too.

 

I'd check the fuel filter - it's inside the fuel tube where it connects to the carb..

 

Thanks, I'll check tomorrow. Wouldn't that cause problems throughout instead of bogging senation at highway speeds though?

 

Depending on your riding style, the largest draw on the bowl could be sustained high speed/relative high RPM highway usage.. So the answer to your question is no/yes/maybe..

 

Float height issue maybe? If the fuel level in the bowl is slightly low it could be momentarily starving for fuel at high throttle settings.
Also wasn't there a ground issue that would cause a slight hesitation? Good luck.

 

I changed the coolant, scrubed the bike & chain clean, increased the preload and set the damping rates to stock. I'm not sure why, but the pulsing is completely gone and it rides soooo much better now.
I think the chain may have been binding at speed causing the pulsing sensation. It was very very dirty/rusty so I scrubed it with simply green & mass airflow sensor cleaner and a brush.