Hey
Mine did the same thing. I check the compression and found out that I needed a top end rebuild. I would check the compression 1st. You can buy a compression tester for $30.00 at an auto parts store. make sure you get the right size.
Can some one please tell me how to make an air screw adjustment. I will be re jetting this weekend and I am not sure how to make this adjustment. 290 and 46. thank you