Engine Leak down Test

For some reason, I can't keep the tested piston in place when I connect
the compressor line to the leak down tester.

I position the piston at TDC (one way I do this is using a piece of
wire to feel when the piston is at TDC as I tap the starter, and the
other is to feel air come out of the cylinder through the leak down
tester rubber hose connection before attaching the tester). So I'm
pretty certain I'm at TDC.

I then put the bike in first gear (safety mechanism on transmission
will not allow me to put the bike in second or higher gear while on the
kick stand).

When I connect the compressor line, there's enough psi (about 45 psi
and I can't accurately operate the leak down tester at a lower psi) to
push the piston down and start opening the exhaust valves that releases
pressure and causes a bad reading. I don;t understand where all the
"play" is coming from even with the bike in gear.

I want to avoid taking the engine side cover off since it's a long
process removing the pipes and the forward controls.

TIA for any tips, suggestions, comments, etc. that would be greatly
appreciated.

Manjo