Glad to be back.
Yep, reversion (from cam timing, exhaust setup or airbox harmonics) could cause that. Seems like the effects often happen at multiples of about 4k..... ie, 4k, 8k, 12k, etc..... plus or minus a few hundred RPM.... just as a generality.... its late, i'm tired, i'll try to explain more later
As for the charts, yes, I love the fact that they show the whole throttle range. 100% throttle dyno charts are better than nothing, but..... really are more bragging rights than anything else.
Who gives a shit if the bike makes awesome power at 100% wide open throttle, but is so jerky and sloppy that you take forever to get to 100% throttle because you're worried about high siding yourself before u get there?
I'd rather have a little less 100% power, and SMOOTH, LINEAR, PREDICTABLE power between 0-80% throttle...... specifically 0-40 percent or so.... and the higher HP the bike, the lower than percentage is. On a built 1000, you better have that bike stood up pretty well straight up and down before u try going past half throttle...... on mine its either wheelie or wheelspin in the first 3 gears.... and thats straight up and down....