Ok that's good to know when I adjusted it it was on a center jack balanced on the swingarm pin and the front wheel so the swingarm wouldn't have been compressed at all. The only way I could think of compressing it would be to use a ratchet strap, is there a better way to do it or would this be good enough do you think? Surprised it isn't mentioned in the service manual at all! All it says is:

1. Stand the motorcycle on a level surface.
WARNING _
Securely support the motorcycle so that
there is no danger of it falling over.
NOTE:
_
Place the motorcycle on a suitable stand so
that the rear wheel is elevated.
2. Spin the rear wheel several times and find
the tightest position of the drive chain.