Losing spark on front cylinders over half throttle area please help

[Christoph]

Hey all, I have been battling with this bike for a period of time now. First the carbs were dirty-cleaned jetted and reninstalled. Then had to locate a stock air box since the owner had changed out the stock one for 4 cone filter- found and changed. Now bike is running great for fire up, idle and through half throttle area maybe a little more. Then it’s like it is hitting a rev limiter. I put a timing light on it and zip ties it to my handle bars and went for a ride through town at night. Switch along all my coil wires. Found that when it starts doing it, looks like I’m losing spark on front 2 cylinders. Almost looks worse on front left cylinder. Say in the manual it says if the speed sensor fails that it will drop the rev limiter down. My speedo is working and seems to be reading correct. I haven’t put a tach on it yet but it does it at about 50km in first gear and about 70km in second gear give it take a few km. Anyone experienced this before or thoughts on cause or where to look. The bike is new to me and am starting to pull my hair out. I really just want to ride and been screwing with it for he past month. Thanks in advance.

[djh3]

Swap coils from front to rear and see if trouble follows it.