How hard is it to swap my GPZ500’s engine?

I’ve a Kawasaki GPZ500 with loads of top-end grief, including a new camchain and tensioner, so I’m thinking that another engine for around 100 quid could be the best deal, although its condition is an unknown quality. Will it be a big job swapping engines over?
davidsilver, MCN forums

Fortunately for you the GPZ500 is one of the easier bikes to swap engines on. If you look at your bike, just below the top fairing and behind the radiator are two bolts in the frame. There are also two behind the gear and rear brake levers. This lets the front sections of the wrap round frame be removed to ease engine removal.

So tank off, fairings off, exhaust off, front sprocket off (to release chain). Then as you remove wiring plugs and any pipes, make a note of what they look like and where they go (or take lots of staged photos).

You should set aside a day and have a mate free for the heavy lifting and lining up of the engine bolts. Once it’s in place tighten all the bolts up gradually to make sure the engine is mounted centrally in the frame, and use a torque wrench to tighten them up to the correct measurement.