well, i just read this whole post and im hoping itll fix my issue, same deal, cuts out right around 5k-5500 RPM in most gears, speedo still reads, gear still reads, needle drops to nothing, then after a moment or two kicks back in. i havnt looked into my spring on my kick stand because the previous owner painted it and its firm to kick up and down, probly wouldnt even need a return spring, but i had the issue come up when i was riding it right before winter and it happened rarely. After i put a new battery in it a few weeks ago, an started riding it again, it started happening more frequently. As i was about to start digging into the matter, i hit a wet spot coming out of a turn an high sided my bike, so it was the least of my concerns. I got a new shift lever put on it an patched it up a bit an went for a ride to check adjustments earlier, and it was happening EVERY time i hit 5k under light acceleration or cruising so i jumped on here to research the issue(i just registered yesterday) ill let you know what i find, but sounds very promising.
My bike is a k6 1000 with full race yoshi tri oval exhaust, power commander V and K&N filter. fingers crossed.