2.15 Piston and piston bolt
The purpose of the silicon bearing cast lightmetall alloy piston is to pick up the pressure from the
burnig fuel. The oscillation of the piston caused by the work cycles is transformed into the
necessary rotational movement by the crank. The sealing of the piston toward the cylinder walls is
achieved by the presence of two 2,5mm wide piston rings which are secured against rotating by
safety lock pins, to protect them from getting into the transfer ports, which could otherwise do harm
to the engine. The piston is connected to the crank by a specially hardened lapped piston bolt that
is secured against shifting by circlips.
Image 14. Orientation of aggregate, right side
2.16 Fan
An axial load supercharger forces fresh cool air onto the cooling fins of the cylinder to cool the
warm air that is being produced by the cycle process of the running engine. The axial load
supercharger is made from two components: a light metal fan casing and an air guiding cover that
directs the air.
The flywheel is driven by a 8x5x474 drivebelt. The drivebelt is hooked onto the left crank pivot
secured by a beltdisc. A supercharger alarm system consisting of a contact and an orange pilot
lamp on the right hand side of the instrument panel, supplies the appropriate control and security
incase of possible blockage or snapping of the belt.
2.161 Inspection of the blower beltdrive
The belt for the flywheel should be loosly streched. It should also easily put the flywheel into
motion. If fitted too loose, it will lead to the belt „throbbing“, bearing the danger that the belt will
make contact to the housing and thus be subjected to premature wear. Also when the belt is
installed too tight, it will show signs of premature wear, because the tension that occurs during
operation adds to the initial tension of the belt. This leads to excessive friction on the belt´s profile,
which will cause the belt to eventually snap.
It is hard to give an exact value for the tension necessary for the belt but it´s safe to say, that when
you can push the installed drivebelt in by about 1/3 of an inch, that the tension set is just about right
to achieve the longest endurance of your belt. By using distancing strips between the blowercase
and the clutch lid the right tension of the belt can be set.
