I need some help from some gurus, multiple people have told me they have no clue what the problem is. Just bought a 2008 ZZR600 with 3750 miles on it. It starts and rides, goes through all the gears smooth, and can redline no issues.
THE PROBLEM- In-between upshifts, with the clutch pulled in, the rpms shoot up a couple thousand to near 4-5 thousand before falling back down or completing the shift. This is only after accelerating, so basically this only happens when upshifting because of the needed throttle to get up to speed for a good shift. This happens every single time, no matter what gear, as long as the throttle is opened up and the bike accelerates before pulling the clutch in. This can lead to some pretty rough shifting when accelerating through the gears because the rpm's shoot up between the upshifts, especially if I'm going fast and raising the rpm's before shifting.
THE OTHER PROBLEM- aside from the rev spike between upshifts, the rpm's are always slow to return to to idol speed, and sometimes hang up around 2-4 thousand without dropping back down to idol at all, unless I intervene and adjust the idol screw on the left side of the bike. This is annoying obviously, and not right. Every time I start the bike, with the choke on or off, the rpm's immediately shoot way high to like 5-7 thousand before going back down. I assume this is related to the rpm spike when upshifting since I see this does not happen with other ZZR600's.
WHAT I'VE DONE ABOUT IT- Not much honestly. I adjusted the clutch at the lever and the cable housing by the clutch cover. I adjusted the throttle play at the lever. I got into the airbox so make sure thats not clogged, its not. The oil is terribly dirty, but cant imagine thats related. The bike has likely been sitting for a while, The kid I bought it from seemed like he didnt ride it and the tires were flat when I test rode it..... I did not clean the carbs yet, because I want to know more about that process before breaking into the very specifically adjusted four carburetors this bike has.
LET ME KNOW WHAT YOU THINK, if you've had similar issues, any suggestion or tips are much appreciated. Thanks
ALSO- Just noticed that two of the four cylinders are not firing. It is the second and fourth pipe when looking head on that are out. They are cool from start up to after a ride. whats crazy is the bike is still performing, I can redline the gears, its fast, pushes me up to 70 mph redlining second gear