My 2002 Grizzly has a very noticable vibration in the handle bars when the 4 wheel drive is activated...I'm not talking about 4 wheel lock, just the normal 4 wheel drive mode...I rode the griz for about 35 miles in the 4x4 mode this hunting season due to the snow we received, and it became very uncomfortable because of the vibration...Almost feels like the front drive line is out of balance..

Is this normal or is it something I should be concerned about...

 

this is not uncommon to hear with the grizzly. have you checked your diff fluids latly? the front seal is known to go in it. this will leak( mide went at 700 miles) and if it goes dry, well, you know. the gears are square cut, for strenth. this does add some noise, as well as vibration, but vary little. mine has always vibrated since new, but again, vary little. i think that the seal going out on so many of them shows there is a vibration issue with them. ( seal is $9.00 and pritty easy to install) if it is major, then i would definetlaay check the u joint in the front driveshaft, or the front diffs. jack it up, and try pulling each front cv from side to side. if it slides out about 1 inch, then a clip broke in it, and needs to be replaced.
hope i helped ya out a little.