  We analysed all X-ray data on the low-mass X-ray binary Cygnus X-2 obtained
with Ginga. The analysis of the spectral and fast timing behaviour of these 4
years of data provides new insights in the behaviour of this Z source. We
confirm the previously observed recurrent patterns of behaviour in the X-ray
colour-colour and hardness-intensity diagrams (HIDs) consisting of shifts and
shape changes in the Z track. The source behaviour is correlated with overall
intensity. When the overall intensity increases, the mean velocity of the
motion along the normal branch (NB) of the Z track increase, as well as the
width of the NB in the HID. Contrary to previous results we find that, during
different observations, when the source is at the same position in the NB of
the Z track the rapid X-ray variability differs significantly. During the
Kuulkers et al. (1996) ``medium'' level, a normal branch quasi-periodic
oscillation (QPO) is detected, which is not seen during the ``high'' overall
intensity level. During the high overall intensity level episodes the very-low
frequency noise on the lower NB is very strong, whereas during the medium
overall intensity level episodes this noise component at the same position in
the Z track is much weaker. The explanation of the different overall intensity
levels with a precessing accretion disk is difficult to reconcile with our
data. Furthermore, the frequency of the horizontal branch QPO decreases when
Cyg X-2 enters the upper NB, giving a model dependent upper limit on the
magnetic field strength at the magnetic equator of ~8.5x10^9 G. We also report
5 bursts, with durations of ~5 s, whose occurrence are uncorrelated with
location in the Z track, overall intensity level or orbital phase. The burst
properties indicate that they are not regular type I bursts.
