It starts when you remove the auto tensioner, turn the engine to TDC that's the point of least pressure on the cam chain, now if this is an older higher mileage engine i would remove the cam cover and zip tie the chain to the cam sprockets. Now remove the plunger and spring from the auto tensioner (so it doesn't extend when removing the tensioner) then remove the tensioner and adjust the manual tensioner to approx 1/2 to 1 mm short of the auto tensioner length. install the manual tensioner then remove the zip ties. Turn the engine forwards and turn the manual tensioner slowly inwards about a quarter turn then rotate engine back and forth if there is any play repeat forwards 1/4 more turn and so forth until you see no more and just no more slack. OK but you have just removed the minimum slack looking for optimum performance that means just a little wear on that chain and you'v lost optimum performance so its something on a road bike id check on every 3-4000 miles when changing oil certainly. Track bike well its something that needs doing far more regularly. The idea of just fitting and turning in until the noise goes away concerns me, whats that noise valves on pistons maybe! At best its the cam chain slapping against the guides! If you have a built motor those valves are damned close to the pistons. And what if when you remove the auto tensioner worn chain & guides thats front back and top guides all combine and the chain pops out the sprocket teeth so when you rotate engine forward whilst screwing in you retard one or both cams a tooth??? I am sure just pulling out the auto tensioner and throwing in the manual and screwing until all the noise stops will work most of the time certainly on newer lower mileage bikes.........But........ for a few hours more you can get it spot on with less of a gamble and no excessive wear and tear added. Thats just me though :wink2: