You have probably heard all this already but do all the easy stuff first like a new NGK plug (check the gap), clean air box and air filter. Fresh fuel+oil mix. I saw in your post that you already cleaned the carb out. Also, make sure carb settings are appropriate for temp and pressure. If you are uncertain about jetting, there are guys here who can tell you almost exactly what jets u should be using. In the past, I have often overlooked somthing simple when I had a problem.