Have to do some work on the kids badgers replaceing top ends and new valves. How do I set the cam to crank timing. Also how big of a deal is it to redo the clutchs they are starting to slip after warm up. Do I need to remove entire engine to do or just. Pop the cover off and go at it. Some people say y waste money on thee old things but heck they are 25 years old and still in full working condition the kids love them. Help me out