Marzocchi fork is quite generously sized for the weight of bike and
has a decent stiff set of yokes. However the damping is really quite
crude. It simply works by forcing the oil through fixed orifices.
This means that the forks are underdamped at low velocities
(undulations in the road, braking, etc.) but overdamped at high
velocities (a step in the road surface for example).
'cartridge' forks use sophisticated 'shim stacks' which can give
almost any response curve desired. It's possible to get the Marzocchi
forks converted to modern internals (Maxton
for example), but it's expensive. A cheaper option is to use
'cartridge emulators'. These separate the low and high speed damping,
a simple hole for low and a spring loaded valve for high. The oil
weight in conjunction with the hole sets the low speed damping. The
rate of the spring and the amount of preload on it changes when the
high speed damping comes in and how much effect it has.
I bought a
pair of these from PDQ but
they're made by Race Tech in