keeping constant throttle, running jerky

At 5000 rpm, keeping constant throttle and running below 100 kph, the bike seems to run jerky.

It acts as if I would slightly open the throttle and shortly after that it acts as if I would keep it steady at 5000 rpm. (it sort of swings you back and forth as it cycles this behavior)
This translates in a rough but noticeable running and it is very noticeable in the first 3 gears. Experiencing this on smooth pavement surface, so the bumps aren't doing this.


It hadn't had this problem since I took it in service last week for a stator and Regulator Rectifier replace and a check of the charghing system (roughly 14v on the battery with the bike started and at idle).
The rectifier looks a bit not-stock, I will look into if it is what I need on my bike.

But I doubt this would be the issue. I tried checking the chain for uneven wear and tight spots but it feels the same throughout its length.

One other thing I am doing now is checking if the gas the bike has might be of poor quality so I am going to burn this one and change the gas station company.

Is the bike stock or has it been modified with anything like aftermarket exhaust, power commander, etc?  How many miles on it?  My first thought was that it sounded electrical.  Have you checking all the wiring and made sure the battery cables are clean and tight on the posts?


Rollin

Stock pipe, pair valves on, everything stock, no PC or any modifications. It has 52000 km on the clock, bought from a dealership here that had it from the first and only owner but they most of the time subtract the number of miles, so I wouldn't trust that mileage very much.

Check Valve Sync, fuel (may contain water),

if the RPM is not dropping - check brake/rotor ...may be out, Even a chain that is worn off may give a similar symptom

When was the last time you changed the spark plugs?

It was the gas. My guess it was some kind of 95 gas on the rocks or something. Those bastards...