I like to use a jumper wire to ground coil wire, need to attach to clean ( unpainted ) ground - bolt, bracket, ground cable away from carb./ fuel. You can also diconnect coil feed wire ( + ) to stop spark altogether. If fuel injected disable fuel supply, unplug injector, fuel pump, fuse, ect. Block open throttle so there is good air flow into intake. As @DanE said they should be even, under100psi would be getting worn but will still run.