My son bought a 2002 Fatboy (Black so it would go faster!). It has 20,000 miles. Should he be checking the cam chain tensioners for wear yet?

 

it sure wouldn't hurt! I would do it.

 

He should see about getting a service manual for it. Unlike the owners manual it will tell him not only when to check things, but how to adjust them as well.
I believe the self adjusting primary tensioner wasn't introduced until 2007 so a 2002 TC88 motor not only needs to be 'checked', but manually adjusted periodically.
Fortunatly they did provide an inspection plate on the side of the primary housing for you to do it through.
I don't know the exact recomendation for mileage, but with 20,000 on the clock I would have checked/adjusted it at least once before and consider it a good time for another go around. No matter what the previous owner may have said, or not said about it.

 

People have had problems with the cam chains at 15k and some poeple not until 50K. I have 32k on mine and am yet to check. It will done at the next service for me. IT can't hurt, that is for sure. I second getting a service manual.