2018 250 w/FMF P4 review
 

I decided to purchase the FMF slip-on pipe not necessarily for an increase in power or performance but more for looks, weight reduction, and sound. Install was fairly easy and yes bending the right bracket a good 1/4" was required but not big deal with a large crescent wrench. Rode bike gently on the road for about ten miles. A few minor decel pops but nothing significant. Took bike out yesterday for the first time and put it into the dirt and rode it like a real dirtbike. I had to remind myself what this might was built for. The issue I am experiencing is when doing sudden hard braking many times the bike would die as if the idle is too low. On long straights it runs fine. Have not done any airbox mods or anything else. My friend rides a KTM 500 with EFI. He installed a Lexx slip-on. He had the same problem. Took his bike to the KTM dealer and they made some change to throttle position sensor or something like that, remap, and charged him $100 for labor. His bike runs perfect. Is this what I will need to do also at the Kawasaki dealer. I don't mind a remap but was not planning on buying a tuner and messing with that. I was hoping that a basic slip-on the computer would adjust and nothing else would be required. I do like my new bike!

While STFT's will start making fueling changes fairly quickly, LTFT's take longer. This means your bike will need several hours of runtime (usually) - in a varied ride - like single track riding, fast then slow then fast then... in order to fully compensate.

No one times the start/end points of fast trail rides - so you'll have to guess..

This is the norm, but with the '18 KLX, not guaranteed - as we know nothing of the '18 KLX250S EFI inner workings at this point.

Point is, you will not know if/whether you have a problem until the EFI has enough proper run time to fully compensate closed loop operations ( closed loop ops are usually all ops below approx 60% throttle and/or 40% loadings )

Thanks for your reply. For now I will continue to ride the bike as is, and wait to see how it performs over the next few months. That friend of mine says the first thing he always does is chunk the snorkel on all his bikes regardless of brand. What do you think? I guess I could remove it and see how it performs.

You certainly can remove it - to see if the EFI will eventually correct for it.. But wot (open loop ops) CANNOT SELF CORRECT ! So watch for the signs of running hot and lean when terrorizing..