Motorcycle Questions? Ask a Mechanic.
Hi and thank you for your question.
It is certainly possible we could have some issues with the power valves. They are not impervious to having various problems. However, to make sure we are not overlooking the obvious, I suggest starting the diagnostic process with a compression test. The symptoms for power valve related issues and compression related issues are very similar. A compression test is an easy test to perform. Remove the spark plug, install the compression tester, put the spark plug back in the spark plug cap and lay it on the cylinder head, hold the throttle wide open and give it a half dozen or so really swift kicks of the kick starter. You can watch the needle on the compression tester and when it stops making significant jumps in readings, you have achieved your goal.
Let me know what you get and we can take it from there.