The reaction gammad --> pi X-0 has been measured with TAPS at MAMI in the e
nergy range E-gamma = 140-300 MeV. Using the Glasgow tagging spectrometer a
photon energy resolution of 0.8 MeV was achieved. The energy excitation fu
nctions of integral and differential total cross-sections show no structure
s of statistical significance > 2 sigma. Upper limits for the production of
narrow isoscalar or isovector dibaryons with masses m less than or equal t
o 2100 MeV/c(2) were deduced. They are in the range 2-5 mub averaged over t
he 0.8 MeV energy resolution.