Changing the oil/oil filter

I just got a 97 ZX9 and had the same issue... until I read the service manual. You need to remove the oil pipe flange bolt in order to get enough room to be able to remove the filter between the exhaust header and the motor case. Of course, unthreading the filter is an issue by itself. If you do not have the cap (tool) that fits over the end of the filter and provides access for a rachet tool to unscrew it, then you probably need to do what I ended up doing... punching a screwdriver through the old filter in order to gain the leverage needed to start unscrewing the filter.