My sons atv makes a clicking noise only when in gear and moving. When bike is in neutral and revs it sound normal. When I push it in neutral it sound normal. When running in gear it clicks. Sound seems to come from front sprocket. I tried it with the sprocket cover on and off. No difference. I tried taking some tension off the chain since it was very tight when we bought it. No difference.. before I go exploring i was curious if anyone had any experience with this. Motor has been running fine it just clicks

 

Could be the chain bouncing off the frame

 

I do believe your right. Maybe it should have a slightly larger front sprocket