Honda CBR 600 F4i - NEED HELP!?

High mileage? 70,000 km is only around 42,000 miles and my bikes are barely broken in at that mileage.

Since it sounds like the missing is engine rpm related rather than ground speed or throttle opening related, I suspect either electrical or mechanical. As far as the crankshaft position sensor goes, they should know better than to think it may be the problem. Those things don't fail at certain rpms, they fail either with a rise in temperature or just fail instantly. As far as the sensor on the clutch, I'm not sure what that one is supposed to be.

As the other poster said, at first glance you'd think it was the rev limiter. I'm not sure, but if it's incorporated into the CDI box, that rules that out.

Try pulling one spark plug wire and try getting it up to that rpm and see if it still misses (in addition to the missing cylinder with the wire removed) and try this one at a time to see if you can narrow it down to a certain cylinder.

Since it seems the dealer was at first methodical and then grasping at straws to find the problem, I'm going to suggest something really off the wall. If you can narrow it down to a certain cylinder or even if you can't, have them check to see if one of the valve springs is broken. Normally you don't remove the bucket over the springs, so that's something you wouldn't notice when adjusting the valves. Most bikes use two, an inner and an outer to eliminate harmonic vibrations in the springs. If one spring is broken, the remaining spring would still close the valve at lower rpms, but at higher rpms you would most likely experience valve float on that valve. That would explain the stuttering, loss of power and crappy sounding starting at the same rpm regardless of the gear your in.

Let me know what you find out, you've piqued my interest.

ADDITIONAL

Dave made a good point but there would be certain, variable conditions associated. If the vacuum drops too low to keep the petcock open (assuming your bike has a vacuum operated petcock), swtiching the petcock to prime should fix the problem. In addition, the fuel starvation would be associated with throttle opening and not engine rpm. To top it off, it that is the problem, there will be a time delay between when the fuel stops flowing to the carbs and when the level in the float bowls drop low enough to reduce fuel flow. That said, the engine should exceed 9k initially and run ok for a bit and shortly thereafter start running badly. If that's the symptoms, turn it on prime and if that fixes it, kudos to Dave!

I have never met anyone in all of my 47 years of riding that has used a torque wrench on a spark plug on a motorcycle or car.You tighten it finger tight and like the other person said maybe 1/8 to a 1/4 of a turn. You do not Superman a spark plug.

The problem is in the vacuum to your petcock, this controls the amount of fuel to your carb's, had the same problem and if i eased off the throttle it would run smooth again...

Hope you did not pay for them changing parts...

Almost sounds like the rev-limiter is kicking in. What's the red-line?

And why do you wring the snot out of a high-mileage older bike?