2 stroke overrev sounding like 4 stroke? is my bike losing compression?

You may be revving to the limit to clear the jumps,which would indicate that it may not have enough power to do the jump. That may be do to worn piston rings or cylinder damage, that would result in low compression. Other thing is, most of the time when a 2 stroke over revs,it's sucking air. Common place is crank seal by the stator. Take the cover off and start the bike,then spray a little electrical cleaner that won't hurt rubber at the crank seal. If RPM's increase,you have a leak. It will require replacing the crank seals. That's worse case scene. Check to be sure all the jug and head bolts on the motor are tight. Also the reed cage and carb bolts and clamps. Too lean a mixture can also cause this. Check your plug.A lite chocolate brown color is ideal. Check out the simple things first. Whatever you find,it's pretty easy to fix. Just to be sure,also check the throttle cable,(how old is it) at WOT,could it be sticking somewhat? I probably shouldn't mention this,but it is a possibility. One of our suzuki's would over rev at WOT intermittently,and it turned out to be the the spring on the slider in the carb. At wide open,the air coming thru the carb had enough pressure to overcome the spring and not allow the throttle to close until lower rpm's. It lost some tension somehow. A new spring fixed it. Same thing happened on my friends kids Kawi 65,and I said,change the spring,and it worked. It's something you never think of,but that's why you ask the questions on here to see everyone's experiences. I have a couple questions out here myself. No one knows everything.Good luck.Just remember,when diagnosing any problem on anything,always check the easiest things first.

Is it a new bike to you? May also be a timming issue, but if it just started its probly one of the problems mx5471 posted.