Do I need to go to a mechanic?

[muttmechanic]

I have a 2009 15 hp 2-stroke yamaha. I ran it today on some rabbit ears in the drive way and I would rev it up prolly 1/3 of what it could do and it would backfire about every other time. Is this something I need to have someone check out or is that something common for engines like this. This is my first boat motor I've ever owned so please pardon my ignorance toward the subject. Thanks for any help you can offer