Polini MINARELLI Instructions De Montage page 2

MINARELLI - YAMAHA - APRILIA - MALAGUTI KIT
WARRANTY: before assembling the new Polini power unit, carefully read the warranty
manual provided with the product.
ASSEMBLING INSTRUCTIONS - Remove the engine from the scooter and fully
disassemble it. Fully disassemble the engine crankcase too for the best results. Ream out
the crankshaft housing as shown in figure A. Align the crankcase with the ports of the
new cylinder, taking care to avoid the formation of steps that could interfere with the free
aspiration of the fuel mixture. (We suggest assembling the Polini crankshaft with the
special connecting rod for the piston with Ø12 pin). Carefully re-assemble the crankcase,
lubricating all moving parts with two stroke oil. Fit the piston and cylinder and measure
the squish. To do so, insert a piece of solder wire, 47.6 mm long and maximum 0.8 mm
thick between the piston and the head, in the direction of the gudgeon pin. Fit the cylin-
der head, then delicately turn the flywheel so that the piston passes the top dead centre 3
times. With this done, remove the cylinder head and check the thickness of the wire with
a 0.01 mm precision gauge. Figure B illustrates the final result you must achieve. Only
when the squish is exactly as specified will you obtain the correct compression ratio of
15:1. For optimum results, also check the exhaust and inlet ports opening angle. Measure
the exhaust opening angle at the highest part of the port cross; this must not exceed
190°. See fig. C. If the cylinder has the exhaust with booster holes the measure must be
always taken from the highest point. The primary ports (near the exhaust) must open at
130° and the correction ports at 128°.
IMPORTANT - Once all the above operations have been completed accurately, proceed
to set the ignition advance:
- at 13° before top dead centre at 7000 rpm
- at 0.7 mm before top dead centre using a comparator
- at 14 mm along the flywheel rim.
ATTENTION! Silencers and tuned-up exhaust systems which replace the original ones
need a specific carburator's set up for the correct functioning of the whole group. Diffe-
rent calibrations can be pointedly different from our data or from the recommended jets.
If you decide to fit other Polini products together with the power unit, please look up in
our catalogues or visit our web site www.polini.com .
SPARK PLUG - We suggest NGK BR10EG spark plug.
ENGLISH
FUEL SYSTEM - To achieve maximum efficiency and optimum carburetion we suggest
you should fit: dell'Orto PHBG 19 mm carburettor, intake manifold, the reed valve and
the sponge air filter Ø32. The carburettor settings for the new engine have been specially
developed by Polini's technical department and require the following special Polini Motori
jets: size 98/100 main jet; size 262 AU atomizer; size 50 min. jet; size 40 valve; size W3
needle.
EXHAUST SYSTEM - We recommend you to fit the EVOLUTION muffler. Check the
union between the muffler mouth and the cylinder exhaust carefully.
GEARS - To make the best use of the significant increase in torque and maximum power
that this kit gives, fit the relevant Polini Motori gears to increase transmission ratio as
shown below. Specific ratios are required for each scooter model.
VARIATOR - A new variator has been designed to make the most of the tremendous
potential of this new cylinder kit. It includes: variator, belt, pulley, clutch and spring. With
their lengthy experience on racing tracks, Polini Motori technicians have specifically de-
signed an electronic internal flywheel rotor ignition system for this cylinder kit, complete
with flywheel, coil and control board.
IGNITION: Polini Motori's engineers, who developed long experience during the races,
have designed an electronic digital ignition system which is specific for this cylinder. It
includes flywheel, coil and CDI.
RUNNING IN - During the first 500 Km do not exceed ¾ of the accelerator opening
and avoid covering long upward runs which will put the engine under strain.
GENERAL SUGGESTIONS - Both during the running-in and after never try getting
maximum power before achieving the best running temperature. The bedding in of
the various parts will be obtained after an average of about 500 km. We suggest a
careful set up of the engine, the carburator and the variator. This kit has been studied
for extreme performance at high revolutions. A wrong calibration could compromise the
engine performance.
Therefore we suggest you using original Polini Motori spare parts only