This is the
marque from which we start because it represents the once italian engineering excellence, and because it is the most prestigious, loved and prolific
motorcycle constructor having a lot of original documents and pieces.
We don't write about of the history of this brand because this is not the right web-site, however the
"Guzzi" production surely begins in 1921 with an original engine of 500 cc; this engine stays in the years with the same architecture and he extends up to the years
The "Guzzi" planning and production shows in the years an obsessive conservatism; in 40 years the evolution was extremely slow but continuous, and we finds again in fact some solutions that were in the "Normale" one (the first produced) still in the last one "Guzzi", the "Falcone".
But later, we discover several and several little differences among the various models, even if the basic planning is the same. So, our purpouse is to to discover these details and try to give a technical explanation. The investigation is started in a systematic way dividing, for example, the engine at
opposed valves by those with valves in head, and developping the crank
shaft, distribution, cylinders etc. We have a lot of material about the
crank gear, (all the class 500 engine), and we are beginning the distribution and particularly the cams and valves. In this page some example is shown.
gear " means the whole the crankshaft, con-rod, pivot and piston; every type of
"Moto Guzzi" crank and the whole production (since the beginning) we evaluated, but we have divided the study in engine with
opposite valves and the ones in wich the valves are in head. Besides examining entirely the (similar) types of the crankshaft, a very important (but once unknown) factor is examined too: the
"balancing factor". It is very good to check the particular values of this type of engine, its architecture and its disposition on the
frame, for example, it is amazing evaluate the the piston
offset, a typical Twentys planning solution to reduce the lateral forces;
a technic extended up to the last motors.
Moto Guzzi" model crank gear layout
type crankshaft with tubular con-rod, mounted from "Normale",
to "Sport 15" models to 1933. Very light
con-rod, its weight is less than "Dondolino" and
"Falcone Sport" models one.
rods with rolling bearings since 1933 ("Sport 15"
con-rod is for "Dondolino" and "Falcone
sport": it weights 22% less than others models.
Con-rod sections, from the first tubular of the
"Normale" (1921) to the "Falcon Sport Dondolino" completely milled and lighter. Bottom: different sections in which the con-rods of the various models
"Guzzi" can be found.
Scheme engine cranckshaft 4
gears with different lengths among the various models.
with con-rods on the last "Falcone" and "Ercole",
In the first volume of
"IL MANUALE DI
HANDBOOK OF CLASSIC ENGINEERING") you can find all this one:
a complete historical, technic and photographic documentationon about the
"Guzzi 500 cc" engine crank
"Falcone Sport". In the "Handbook" is published also an Eng. Serpilli book,
"THE CRANK GEAR , FROM THE NORMALE TO THE
FALCONE", chapter n°1 in the first volume. Click here to order the "Handbook" and other classic products!!!
engines the timing is different if the valves are
opposite or not
15", "S" and
"Alce") up to the beginnings of the
WWII , even if already from 1934 serial "V" engines were produced with the valves in head. The distribution in these engines is very articulated: it is composed from various parts (see the images below).
The reason for this is to have a greater reliability. In fact in an engine layout with the valves in head we can observe that the scheme of cam device is not properly "rods and balancing" but similar to a "single sided rocker" that replaces the driven
tappet. This system is reliable even more because it annuls the lateral side force on the
tappet on its guide.
layout at opposite valves (2D). Cam, rocker, push and valves are
layout at opposite valves (3D)
opposite valves distribution
"Sport 15" with separate gear and united with pins. The engine with valves in head had the whole gear in block with the cams,
but also the
"GT 20" and the "Alce".
layout, with cam, push , rod, balancing and valve.
valve lift is derived by the cam profile... with a lot of
method of analysis for a cam proflile (in this exhample, the
cam shaft with gear, CODE 14023
Comparison of cam lift among: "Dondolino", "Ercole" and "GTW bitubo"; to get the valve lift is necessary to multiply for the final leverage ratio between cam and valve
(or to consider the interposition of the hammer and the balancing).
crank gear study, the complete
documentation about Guzzi 500 distribution is published
"Falcone Sport" and
many others models). Informations, data and never-published draws.
This documentation is published in the "MANUALE
DI INGEGNERIA D'EPOCA" ("The
handbook of classic engineering"), the first volume.
Click here to order the "Handbook"!