Well I've modded my 2010 klx250s. I rejetted it with a 128 main, drilled the pilot jet next size bigger since I didnt have a bigger pilot jet in stock. I drilled the slide vent to 7/64". I have a FMF Q4 silencer but my mega bomb header is on back order. I have the KLX300 taper needle set on the second notch from the top. I have the KDX 200 snorkel installed. Still has stock airfilter but my UNI filter should be in next week. It seems to be runnin out of fuel when I really rev the crap out of it under a load. You rev it up to the rev limiter in 1st gear and let off to shift into second and you get back on the throttle and it seems to run out of fuel. After a few seconds it sputters back to life. Basically the same symptoms when the gas valve is on and the bike starts sputtering then you switch it to reserve and it comes back to life. It ONLY does it when you drive it like you stole it. I checked the float level as best as I could while riding it and when not riding it and it looks good. Any other suggestions of what this could be before I tear this thing back down? Anyone run into this prob when they did their mods?

 

You may want to wait until all of your parts for your tune are in, but the stumble almost sounds like a possible air leak, as in a loose clamp or other. Wait until all of your goodies are in, then do a plug chop after break in to get the feel of the new gal. good luck

 

Hopefully my airfilter will be in tomarrow. I thought it was my gas cap, it never shut very good and the key lock on it was gettin hard to turn. I lubed it and thought that fixed it since I thought it wasnt venting properly. Next day it was doin the same thing. I did lower my taper needle one notch. I have a 128main right now. I test road it and so far so good. Guess we will see if it worked after i take it to work in the mornin. I wish my header pipe would get here!