Right, took me just over 2 hours.
Before starting, check the plug spanner is in the Bird toolkit - you WILL need it!! Also check the plug gaps on the new ones - mine were fine. You will need a socket set and cross head screwdrivers.
I would also suggest a LED head torch so you can see what you are doing!!
Best done in the garage - loosen tank, put a towel over the battery then slide tank back. Bit of rope over a joist, tip tank back as far as it will go and tie up. No need to disconnect anything.
Airbox top off.
Coils off - single captive nut can be removed without removal of any plastics with a bit of care.
Air filter out.
'Trumpets' out - 3 captive screws on each.
Air box base out, only need to remove oil breather pipe from the front end. Pull back and tie up ~no need to remove anything else.
One plug at a time - plug cap off - they are a tight fit and a bit of grunt needed to pull off.
Drop the plug spanner down the hole and wiggle about to drop over plug.
Socket over end of plug spanner and ratchet out.
Drop of oil on the new plug thread, into socket and ease down hole. Gently turn until thread engaged - don't force it!! Half s turn is plenty once the thread starts tightening up.
The plug to the right looking forward is much harder to get to than the other three, so start on that one, it only gets better!! You will need an extension bar and maybe even a 'knuckle joint' on the top to get this one out - go behind the frame bar, rest accessed from the tank side of the frame bar.
And, as Mr Haynes says, replacement is removal of above sequence!!
Add one houir if you drop anything inside the plastics.