There are two 250 engines, a
single and a twin, both with almost identical capacities. The single
is half of the original 500 and shares its 5 speed gear cluster. The
250 twin is an absolute gem of an engine, Franco Lambertini himself
said that the 250 was the most balanced design. It seems that the
engine had originally been conceived as 250 twin and 125 single.
Because of its modular design the engine was easily enlarged to 350cc
when it was decided that that was the market to aim for. Although
it's not mentioned in Mick Walkers book, this fact was mentioned by
Lambertini in a Q&A section on the official Morini website. The
250 twin design was shelved until France introduced a tax break at
240cc and it was put into production as a slightly de-stroked 239cc.
The single was apparently aimed at the Italian municipal market. It
clearly suffered from enough vibration for Morini to rubber mount the engine.
250 Single
