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

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