Oh yeah, the valves being out of adjustment can really tone the power down.

Do you know how to set up your plug for a reading and how to read what the plug is saying? I'd like to see what the plug sez.

Also, make sure none of your brakes are dragging. That's easy, fire up your machine and ride it a good distance without using the brakes. Then feel the brake hubs or wheels to see if they're dragging and the friction is creating heat.

I've also seen where guys have accidentally placed a rag or something over an intake to air box - that can really kill power.