No, it will never go away completely. It's just the nature of straight cut gears.
It will quiet down some though. The best thing you can do is research the various ways folks here deaden the sound coming through the big teardrop shaped side cover.
They are all home made solutions. Some use a cardboard insert on the inside, some use rubber inside, some use rubber outside, you will get the picture.
Oh yeah, about every 100 miles or so, put a pea sized blob of quality grease on the gears, right where they meet. Only a pea sides blob or you will just make a mess of things down the road.
Actually there is a whole bunch of really simple maintenance things that these motors need to last for thousands of miles.
http://motorbicycling.com/f30/guide-bicycle-motor-preparation-care-354.html
I also recommend reading Norm's help section. If only to familiarize yourself with all the quirks and wonders that these little engines have.