chain play vs chain deflection

Been seeing discussion here about recommended chain "play" which is a different term than chain "deflection". Chain "play" is slack movement of the chain or free play in the chain. Deflection is total movement of the chain, meaning you take all the slack out of the chain and continue to push on it until it won't move anymore. Deflection is usually larger than slack. If the manual states "3/8 inch play" that means the chain has 3/8" of free play movement, not 3/8" of total movement. Thoughts?

OK, I'll think. Here's what the 68 'Riders Handbook' says:

"Tighten the rear nut (illustration 6, item D) on adjusting eye bolt until, with the finger through the filler cap orifice, it can be felt that the chain is dead tight. Then slack off the rear nut and carefully tighten the forward nut until there is a total up and down movement of 3/8 in. Then securely tighten the rear nut to lock the assembly. Check the adjustment in more than one position of the chain and adjust, as above, at tightest place...."

Now how hard does one engage the finger?

Actually I like to loosen the primary until there is good clutch action and the gearbox is working nice, which for me seems to be a bit more than the 3/8" described above. Just me.

Dave
69S

Use read chain to pull triplex tight then use gb adjuster to pull forward till a bit over 3/8" free play from hanging slack. Rear chain must be let off 1st. Then ride fast-far enough to reach full temp and check then to know for sure. Only takes one over tight event for bad juju to appear before its time in whole drive train and crank.