Always in the same year and following the arrival of Franco Lambertini directly from Ferrari (no kin to Dante Lambertini who preceded him on the Morini technical staff), a new combustion chamber was designed and tested which gave life to the Morini Corsaro type 4 known as the ‘flat head.’ This engine was mounted in the old Ronzani frames equipped with new tanks (type 5) in advanced test phase.
This ‘creature’ of Franco Lambertini was characterised by a large flat head with combustion chamber worked from the piston head, breathing conduits and an ‘arched’ exhaust to improve combustion. It was the motor of the new competition model which however did not find any commercial success but was used only in competition during the whole of 1971.
From this showy and still more powerful version known as ‘flat head’ a kit was assembled made up of camshaft, pistons, cylinder head and exhaust (with right side exit) which allowed performance improvements, adding around 1.5 horsepower.
Various private riders purchased and mounted the kit and were very pleased and on the Fiamme Gialle (Yellow Flames) riders’ bikes it always gave the results hoped for.
This important modification included a complicated exhaust which had no special technical innovations but allowed some leeway around the regulations which were becoming ever more of a headache for the four strokes.
A big handicap in those years was the fact that 4 stroke engines were very noisy compared to the 2 strokes. In international competitions in these years acceleration trials were often accompanied by sound testing and there were numerous penalties imposed.
To avoid this inconvenience a stratagem was adopted which consisted of a mobile exhaust which for acceleration trails could be silenced simply by resting the heel on the terminal.
In fact the terminal had two positions: after taking a rather curious path it exited normally within the motor more or less at the height of the carburettor but by simply turning the terminal externally (180°), this could be rested on the heel of the rider.
It was enough to keep the heel pushed against the exhaust for a few seconds, the time required to leave behind the phonometer in order not to incur uselss penalties. The modification was without doubt ingenious but from a sporting point of view not correct and it all ended as quickly as it occurred.