My 14 year old son races motocross here locally, next year nationally...we bought him this 2012 KX250F bc he outgrew his KX100 and CRF150R. So basically we don't know much about this DFI on these newers bikes...we had to completely have his bike rebuilt after we bought it bc his crank locked up. So everything is new...the crank...connecting rod, piston, rings, all bearings, seals and gaskets, timing gear, cam chain. Everything! We took him out to a local track and he ran the ***** off of it for a good long while and it ran fine. We got up Sunday and went to another local track and about half way through the day his bike started acting up. He is hitting the rev limiter VERY hard between 1/2 and 3/4 throttle even when running through the gears!! Ive changed the plug so far and no good. Ive changed the gas thinking maybe it had water in it...no good. Im at WITS END ya'll!! PLEASE HELP MEE!!!! Thanks!!

 

There's a mod you do up by the clutch switch that cancels the apprx 7500rpm rev limiter if you have FI-which I guess is what you mean by DFI.

Here's one link, but there are many more if you hunt around

How to soup up KLX250 EFI the easy way - Bike Chat Forums

 

Can you please explain exactly what is happening on the bike. You post is hard to understand.