Gutless stock KLX 140 how/what to mod?

Just bought a 2011 KLX 140 for wife and daughter. Only. Probably 2 hours use so it's like new. Anyone out there know what size to change the jets for a bit more life. What pipe do you recommend. Anything else?

That thing is supposed to be gutless.. :ride:

My xr100 was gutless until I discovered the valves were to tight and weren't closing. It is a low performance 140cc bike.

Really, it's meant as a entry level trail bike for kids, it's gonna be gutless. It's supposed to be docile and un-intimidating.


Opening the airbox, trimming the CV diaphragm spring (cut a loop or two off), going up a size on the main, and a slip on or modded stock muffler can wake it up a little bit, kind of the standard "uncorking" procedure. Most bikes run lean out of the box.  Going further, you can probably get a higher compression piston and hotter cam for it.


My TW200 was a dog out of the box-again, a low performance, mildly tuned trail bike.  but airbox mod, rejetting, slip on, hi-comp wiseco piston, and a Webcam did make an appreciable difference. It didn't suddenly turn into a fire breathing animal, but definitely improved it's capability.

No replacement for displacement.

Bore kit with all the extra mods.

Get ready to spend big bucks doing it.

Thanks yes I guess I just want a bit of a wake up, just a little sharper it seems to be dumbed down. Thanks for the info.

buy a 170cc bore kit from indoneasa on ebay with stage 1 camshaft there cheap and work very well, comes with gaskets high compression piston and was onlt $300 with freight to Aus.  38 to 40 pilot jet 110 main jet thats what worked for me and its a different bike.... :ride:

I replaced the stock main jet with a 105 and the pilot with a 42. I also removed the exhaust baffle/spark arrester. I modified the airbox lid by drilling five 1 inch holes into it and installed Uni airbox vents in them. It seems to pull slightly harder, nothing earth shattering. But the gain was definitely worth the small amount of time and money invested.

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