Bike will only idle - please help!

[motoxxx]

I have a 1985 Kawasaki en450 and it starts right up and idles great. Then above 2500 rpm the engine bogs, wont rev out, and will occasionally sputter and pop out of the exhaust. I got the bike in this condition and Im driving myself crazy trying to fix this issue. Please help! I am starting to think the issue is electrical, but dont know where to start.

Spark plugs are reading rich, even with the stock jetting.

I have been through the carbs more times than I can remember, thoroughly cleaned them, and tried multiple different jetting combinations, including stock. I ran it with and without the airbox, and even tried a new set of aftermarket carbs. I have also pulled the cylinder and heads for inspection. Everything looked good, and valves are adjusted properly. Nothing I did seemed to help my issue. I am almost at the point of giving up and selling this thing. Wondering what I could do next.

Any help would be greatly appreciated!

[motoxxx]

I have done some testing and found that my charging system output is not within spec. The service manual calls for 14-15v and the voltage should increase with engine rpm. On my bike im seeing around 13.8v at the battery during idle and the voltage decreases to 13.4v as rpms go up. Is this normal?

I also did some testing at the stator and found the AC output was only about 14v AC @3000rpm when the manual was calling for 60v at 4000rpm.
Other than that, the stator coil and pickup resistances were within spec.

After taking it apart it looks like the stator may have been lightly scrubbing on the flywheel magnets. Do you guys think replacing the stator will fix my problem?

[motoxxx]

Update- I was getting nowhere with testing the charging system, so I decided to focus on the fuel system again. I cleaned the oem carbs multiple times, and could not get them to work no matter what i did. Even after being rebuilt, trying oem jets, then richer/leaner mains ,the engine would still only idle.
I almost gave up, but I decided to try the aftermarket carbs again. Engine immediately ran better, but i still had a bog down low. I spent all day trying different jetting combinations. My baseline was the oem 35pilot, 125 main. Final setting was 40pilot, 125main. Finally got the thing running right!!

I realized through testing that the bike would idle fine on a wide range of pilot jets. BUT if the PILOT WAS TOO LEAN, it would bog when you gave it throttle. I believe this was my issue the whole time. Glad I finally got it figured out!

[motoxxx]

After more road testing/holding it wide open, my jetting still needed work. I had to go richer on my main jet and needle.