I just picked up a 76 Puch a few days back, cleaned the carb SEVERAL times, finally on the 6th attempt it fired up and ran great. Rode for a good half hour before parking it. This was two days ago. Today I go to ride, fires right up, but this time a LOT of white smoke came from the exhaust. I ran for about half a block before the smoke went away. I'm riding some more, not even 5 minutes, and it starts to bog down on me. I go to give it gas, and it bogs worse. Eventually it dies. I park, prime and choke the carb, and it starts again. I go for about half a block, and it does the same. So I repeat, until I get back to my shop. This happens about 5 times. When there I fire it up on the kickstand, and I could rev it ALL day if I wanted to and it would run great. NEVER once did it die when on the stand. I went to ride again, and same thing happened. ANY idea what this might be? Should I clean the carb once more? What was with the smoke? Why will it run on the stand but not with me on it? ANY help would be great. THANKS!