Aprilia MA MY 50 Workshop manual - Scootergrisen

Cylinder-head-piston unit
We have already inspected the cylinder head combustion
chamber , so we do not need to discuss this.
Inspect the cylinder head for warping, using a surface
plate or rigid straight edge and feeler gauge. The
cylinder head must be flat within 0.03 mm (0.0012 in).
If the cylinder head is out of level more than 0.03 mm
(0.0012 in), lap it in, using 400-600 abrasive paper
placed on a perfectly flat surface plate, until the entire
gasket surface shows an even frosted looking surface.
Work the cylinder head in a figure 8, as shown in the
illustration, turning the head regularly in your hand to
ensure a perfectly flat surface.
Cylinder - check
Carefully remove all carbon deposits from the inlet
manifold, but, again, do not go overboard and remove
any aluminum. A rounded scraper , or a fine abrasive
flap wheel, is helpful in this operation.
Inspect the cylinder liner , and the condition of the
cylinder bore. Slight longitudinal scoring is acceptable,
but any scores deeper than 0.01 mm (0.0004 in), and
any sign of seizure whatsoever , calls for reconditioning
or replacement of the cylinder . Carefully remove
any carbon deposits which remain in the transfer ,
inlet, or exhaust ports.
3-4
Release 00 2000-01
ch. 3
MA50 - MY50