Ok guys I'm new to this so I will just get into it my first gen.cranks and runs ok until I give it throttle then it starts popping and white smoke let off and it runs fine

 

Welcome to the forum. You'll want to fill out your signature line so people know what you have. They're all similar, but not the same. Certain years had certain common failure points etc.

 

valve adjustment possibly?

 

Runs fine under no load? First and easiest is fuel filter.

If that doesn't help, you may have air infiltrating the system, poor fuel delivery, or a timing issue.

We need a little more info.

Welcome to the First Gen Sanitarium.