I have a not sure what year grizzly 660 I was wondering if I could start it using a 50amp boost just to get it running not charge it with that

 

I would be a bit careful. Don't touch the 4WD switch when doing this, it is apparently a guaranteed way to blow the shift motor, but the CDI/ECU and regulator also have delicate electronics in them, and I wouldn't do it on an EFI bike.