Here is my experience with changing the rear sprocket and tire gearing. See link. It's long, so in a nutshell:
I wanted taller gearing because I've ridden many 600 mile days in my travels and wanted less RPM at 85, and higher mph. So, early on, I went 1 tooth down on the rear, along with 190/55 rear tire. Also ran 200/50 but didn't really like that size. All seemed ok for a while, then I got power cut, and ERROR CODE 24 with most of the dash dead and flashing. After I restarted, it ran fine, except for the dash flashing and not working. Only the tach and fuel gauge worked. After a bunch of bullshit from Kawasaki Warranty Dept, first stock rear spkt, then stock size rear tire, new ECU, and new wiring harness, NOT fixed. Then the dealer switched out the rear speed sensor. FIXED.....I rode all last summer, stock, with no issues. Then we were going back to Deals Gap in Sept and I knew I had a couple 600 mile days so I thought I would try the 1 tooth lower rear spkt for the trip. Well, 600 miles to The Dragon, and 100 or 200 miles down there, the Error Code 24 and dead dash came back. I changed back to the stock spkt, still dead dash. I kept riding since the bike ran fine. When back home, I finally replaced the rear speed sensor,,,,,,,,,,,,,and fixed AGAIN and still fine after about 2,000 miles.
The moral of the story for me is, I'll be keeping to stock gearing and tire size. Quite frankly, just that small change in gearing made no noticeable difference. Also, my 2016 ZX14r SE ABS never seems to lug in 6th, unless under about 2,000 RPM, but there's no reason to do that. I can accelerate from 40 RPM in 6th just fine, I wouldn't do that under full throttle. Also, brisk passing from 60-70 in 6th is strong. The tq of this engine is so tractable, unless a super pass is needed, I just leave it in 6th and roll into it. But that's me.
If you, or anyone changes gearing on the ABS, traction control ZX14, I'm interested to hear your experience. Is my bike just odd??? Or some really odd coincidence?
http://zx14ninjaforum.com/messages.cfm?threadid=B0E8A658-C7CB-9F7E-106AFDA7E2CC32A0
ominousone