Question for the experts out there. When doing the valve adjustment, the service manual says to turn the crankshaft 180". I can eyeball how much I turn the wrench and look at the valves to see how much they are open and get an approximate 180 degree turn, but is there a proper method for knowing when you have turned the crank 180 degrees?

 

There are engraved marks (mine are also painted) on the cam gears that will line up in various ways with each other and / or the lip of the head. The book has diagrams showing how these marks will line up for each cylinder.

 

Another way to tell is that you want the cam lobe pointed away from the rocker arm on which it wipes. The Honda method doesn't really do this (not 180 degrees), but is close enough. Make sure that the cam lobe is pointing away from the rocker, that's where you want to do the adjustment.