The manual say to put the piston at TDC with both valves at TDC when measuring clearances. That means setting the crank to TDC for cylinder 1-4 and check whatever of the two that have the lobes pointing towards each other. Once measured, turn crank 180 degrees and do the same for the suitable one of 2-3. Another 180 and the other of the 1-4 pair and finally the last 180 and the final cylinder.
Having the lobe just point away from the valve should be sufficient, but I learned on my KZ650 that it actually does matter where the lobe sits when you measure and taking the trouble to measure at TDC is worth it.
1977 KZ650B1
1980 F1 engine
B1 3-phase alternator
B1 Points ignition
