It's definitely not normal. None of mine do it.

The only time I've ever had mine cut out was either A: when they were mistuned, or B: mud had the air filter so badly clogged it wouldn't stay running.

Clean the outside of the engine, clean and re-oil the air filter, set the carb to defaults, then tune as per this video:

[youtube]http://www.youtube.com/watch?v=ma2_CghxiUk[/youtube]