Understanding valve seals

you won't need to pull the heads to check guide wear. with the cylinder you're checking at bdc poke in as much cotton clothes line rope through the spark plug hole into the bore as you can then turn the motor toward tdc. you can now remove the valve spring/s with no fear of the valve dropping into the bore. if the rope's jammed tight against the valve drop the piston slightly so you can feel for guide wear then back up tight for reassembly. i always do it this way when changing seals, i don't like the idea of compressed air stopping the valve dropping and i know it's common practice but the rope method is guaranteed to hold the valve. :thumbsup:
neil.