Do you see the wear mark from the exhaust bridge? Did you do a leak down test? A 97? How bad does it smoke? Chances are really good that the right crank seal is gone. Them black rubber seals can get hard over the years, ALL the black rubber on your bike as a matter of fact. You really need a service manual, and replace all the engine seals. If not the crank and trans bearings also. Then you should have a solid engine. Take your intake and airbox boots and bend them slightly, look for cracks. When they fail, it will suck debris and ruin the engine. Watch the clamps also, if they screw in all the way closed, they are stretched and shot. Lastly, check the airbox seal, reeds and change the silencer packing. And the power valve, leave the cover off and start it. Does it open after half throttle?