My friend actually did the most of the work, because i'd rather help someone who's experienced with engine fixing than doing it myself for first time
. We did it 2 maybe 3 hours. I suggest to do it with someone experienced who knows what to do.
Engine doesn't have to be taken off, just take away cylinder head-to-frame mounting (triangles with holes), and some obvious things like a tank, chrome head covers etc. As OldNTired said head bolts aren't all the same, but not everyone is other than rest, maybe you will remember which is which
. One of them has a washer that should be replaced. There are 2 head bolts under valve caps too. Oh, and about this one bolt - as OldNTired said, you have to place it in cover before you'll put it on engine.
Most of the time is taken by cleaning head to get rid of the old paste (cleaning). Don't scratch it with screwdriver or something sharp
. There's also an round plastic camshaft sealer that is needed to be cleaned too. After sealing everything you'll have to wait until it gets harder (to start the bike). Time length depends on type of sealing paste you're going to use. It usually takes couple of hours to get hard.
Engine could work a little different in first minutes after first start, but after them it should work normally. Maybe you'll experience slight power increase and better (healthier) engine sound.
PS. This repair is great occasion to look how camshaft and chain looks like. When my ex-GZ125 had been sealing (don't know if i used correct form
) it also came out that camshaft chain need to be replaced.