Last week I bought a 07 klx250 and its awesome. My buddy just so happen to have a full fmf pipe for it with the fat header and the Q4 pipe. So I plan on putting that on but why stop there. What size jet would you recommend for the carb and air filter and spark plug recommendations. I wanna wake this thing up a bit

 

If you're near sea level, I can get you to about 23hp really easy. Order a $2.00 DJ144 main jet from DJ and the DJ slide spring. While you're putting on the full FMF exhaust system, put in the 144, the slide spring, (use the stock needle), pull the airbox lid, optionally do the Marcelino Cam Mod (MCM), and hang on..