I'm having my grizzly 660 rebuilt boring it over to 101mm new crank, and putting in mud buster cam. My question is do i need to put in new cam bearings with the new cam? The dealer ship said the head is in good shape.

 

you should be able to use the old ones as long as there in good condition.

 

I have never seen a cam bearing go out on ANY ATV - ever. So you could replace them if you wanted to but is probably not necessary.

 

I went ahead and replaced my outer cam bearing when I put my WebCam in, but that was just because I already had it apart and figured it was worth the $10 just in case I damaged the old bearing driving it off the stock cam.