problem running

Hello everyone, I recently put together a 49cc 4 stroke kit I bought online and after about an hour of off and on use the clutch exploded. After buying a new clutch I put it in and after a few more minutes of riding the engine started running REALLY rough. I left it in the shop for a day and...

about a year ago, i built a 2 stroke 49cc kit. ran excellent, no problems. at least until the engine seized. bought a new engine last week (80cc), installed it, got it running, but it doesn't run well at all. the only thing that has changed is the engine. when i rotate the idle needle on the...