Crankshaft end float

[bikerboy]

If you tap the crank with a mallet the dial gauge will jump and possibly move giving a false reading. Push pull by hand or light lever action is best.

Which is exactly what I meant but I made it sound different somehow 

[BSA_54A10]

We set the dial gauge on the oil pump side then put a couple of the primary bolts back in with a length of bar under them
We use that as a fulcrum for the wrecking bar on the end of the sprocket.
The same wrecking bar then goes under the cush drive to move the crank in the opposite direction.

[bikerboy]

An extra use for my wrecking bar  that idea always appeals