I have a 05 Kawasaki ZZR 600... Back in September I took it in for service to check if the valves were in the correct place, along with a few other things. When he took out the carb rack, he noticed that there was a crack in it. He said that the previous owner put long screws in it, so slowly, over time, the crack formed. Before the service I noticed that the power had been getting progressively less over time (but not by much). He said that I needed another carb rack, but that if I didn't get one I would notice a huge difference. I decided not to have it done because I figured it wouldn't ride much more different then before the maintenance. I was wrong... Whenever I go above 45 mph, there is a dramatic loss of power until I hit the power band around 8k rpm. The engine staggers (kind of like twisting the throttle back and fourth). Once I hit the power band she smooths out a bit, but I can still feel bits of hesitation. If I decide to accelerate from there, I have to pull the throttle all the way back, wait a few seconds, then it takes off. Also, the top speed of the bike is now 100 instead of 150. All of what I just stated is what the mechanic predicted would happen.
I figured I'd run it by you guys to get a second opinion before I spend $600 to get this problem fixed. Thanks