I bought a used 2009 KLX250s with 2500 miles. It starts right up with choke and can remove choke within 5 seconds and the bike will idle. However, it must warm for a long period before you can rev it up. It bogs down when you slightly open the throttle. You can get it to rev by working the throttle but it is erratic.

You can find a partial choke position that will allow the engine to rev smoothly.

After the engine is hot. The bike runs good up to about 5000 rpm and maybe higher for gears 1-3. It may be more load dependent. Certainly in 6th gear when I hit 5000 to 6000 rpm the performance is erratic. It will eventually rev further but it is erratic.

The top of the air cleaner box is missing as well as the plastic piece that pushes the foam filter tight against the drum. The air cleaner still fits pretty good.

 

sounds like you arrent getting enough gas, could be a number of things, dirty main jet, needle stuck or possibly slide not working

 

Tap a new cover on the intake, leave a 1"x3" opening. Try it then and report back.

 

Did you mean Tape?

 

As mentioned above, it sounds a lot like a plugged main jet, or needle problem, float height problem etc.

I don't see how the 1x3 airbox mod is a good way to troubleshoot since a stock bike will rev about 5,000RPM without problem without the mod. If doing a 1x3 mod was necessary to rev above 5,000RPM, we'd all need to do it.

I start with the carb, checking the main jet first.

 

Thanks for the advice. I was thinking it was not enough fuel. I simply stuffed a towel in the air box and put back on the seat and it runs great. I will fabricate a more permanent solution tomorrow or spend a $100 dollars to get the factory box cover and other parts.

 

be better to save the $100 and get a dynojet kit!

 

BAM! NAILED IT! Weenies!

 

If it's an 09 with only 2500 miles then I'm sure it's sat around here and there. Might be worth getting a DJ kit because it's not only lean from the factory but it might be worth opening up the carb and cleaning it regardless. It's a twofer!

 

Can you say 'Band-aid'???