I just can't say I've heard of a direct connection between low RPM running, or even consistent lugging, and excessive carbon build-up and/or burned valves.This is what I was going to point out -- the new D.I. Honda Fit w/CVT runs at very low rpms compared to the M/T model! Hmm, but the CBR250R isn't direct inject, only port injected.
My father-in-law's Suburban (small block Chevy V8) runs about 1700 RPMs on the highway, and it's nearing 200,000 without any excess carbon or burned valve issues.
This story just doesn't add-up for me.