Former zx10r guy here. I recently bought a 2008 zx14 from a private party a few weeks ago. Guy said bike had been sitting and I noticed on the initial test ride that it wasn’t revving all the way up to redline. He explained that it was probably bad gas still in the tank. I negotiated the price accordingly and rode the bike over an hour home at 100-110mph with low power. Max rpm I could get was around 5.5-6k in 6th and maybe up to 7k in lower gears (1st-2nd).
I brought it home and took the fuel pump out the next day and thought I found the issue when I found the filter plugged with rust bits. I ordered a new filter and cleaned the remaining rust out of the tank with ball bearings. A few days later I reinstalled the pump with the new filter and it redlined for the first time in neutral! I thought the problem was fixed so I decided to ride to work. Halfway through my ride I discovered that the gremlin had returned. I ordered a new fuel pump(not entire assembly) from eBay. A week later and the problem still persists but has gotten worse since new filter and pump have been installed maybe 3k-5k rpm in lower gears. Bike has a pc3 but no other performance mods that I am aware of. Can someone please point me in the right direction! I’m planning on pulling the tb out today and taking a look at the injectors.
Rpm’s increase as throttle is backed off. Max power seems to happen at the 0 mark (50%) throttle on the pc.
Bike has 20k miles and seems to be in very good condition in every other aspect.