  Some intermediate polars show outbursts that are much shorter than those
observed in normal dwarf novae, and whose origin has remained unelucidated for
a long time. We examine here the case of V1223 Sgr, an intermediate polar that
showed a short outburst in 1984, and compare the outburst characteristics with
the predictions of the magnetospheric gating model. We use the archival data
from the AAVSO from which we extract the outburst profiles. We use our code for
computing the time-dependent evolution of an accretion disc truncated by the
white dwarf magnetic field, using a simple description of the interaction
between the disc and the magnetic field, as in D'Antona and Spruit (2010). We
find that V1223 Sgr underwent a series of short outbursts, with a rise lasting
for typically two to three hours, and a slightly longer decay. When applied to
intermediate polars, the model by D'Antona and Spruit (2010) accounts well for
the observed outburst duration and intensity. We confirm, however, that the
model outcome depends sensitively on the rather poorly constrained model's
assumptions. We have also searched the AAVSO database for short outbursts in
other IPs, identifying individual short outbursts in FO Aqr, TV Col, NY Lup and
EI UMa, but no series as those observed in V1223 Sgr. We also found a
superoutburst, followed by a reflare in CTCV J2056-3014. Although the
magnetic-gating accretion instability model is clearly responsible for the
series of V1223 Sgr short outbursts and most probably for similar events in
other intermediate polars, the model describing this process needs improving,
in particular concerning the interaction of the white-dwarf's magnetic field
with the accretion disc. This difficult task might benefit from further
comparison of the model outcome with additional observations having good time
coverage and time resolution.
