POLINI engine crankcase 170.0200 for PIAGGIO 50 CIAO BRAVO BOXER BOSS GRILLO SI CBA for models with contacts without electronic ignition

POLINI engine crankcase 170.0200 for PIAGGIO 50 CIAO BRAVO BOXER BOSS GRILLO SI CBA for models with contacts CYLINDER PORT DIAMETER 50 mm Polini Motori has created this engine crankcase to increase the power of your moped. The crankcases are supplied in three versions depending on the type of moped. (See technical data sheet). This crankcase can be used both to mount original cylinders or oversized cylinders: piston 41-43-46. With the new crankcase it is not essential to modify the crankshaft because the intake valve is further advanced than the original; however, if you have an already advanced crankshaft (as per drawing A) you can still fit it because it will not compromise the maximum power of the engine, but will improve power at low speeds. To fit the new crankcases it is necessary to remove the engine block from the frame, dismantle the entire engine and carefully wash all the parts to be reused including the new crankcases. ATTENTION: to dismantle the crankshaft it is necessary to heat the crankcases to a temperature of approximately 250 degrees. Check the main bearings, the connecting rod roller cage and the gudgeon pin roller cage (if provided). If there is excessive wear, replace them. Mount the main bearings on the crankshaft, heat the new crankcases to a temperature of approximately 250 degrees, mount the oil seals, position the central crankcase gasket and mount the crankshaft, closing the crankcases evenly. Assemble the cylinder fixing studs, cut the excess crankcase gasket with a blade, position the base gasket, assemble the piston checking that the pin stops have entered their seat perfectly and have no play, assemble the segments, the cylinder and the head locking nuts evenly; mount the intake manifold with the appropriate gasket and secure it with the screws supplied. IGNITION: for the version with contacts, bring the advance to 2.2 mm before top dead center or mm. 29 measured on the flywheel band corresponding to 23.4 degrees. The start of opening of the contacts must correspond to the above-mentioned values and have a maximum opening of the contacts of 0.6mm. For the version with electronic ignition, the phase does not require any adjustment. Complete the assembly of the various parts and position the engine on the frame.