CYLINDER/PISTON
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33
Wear tolerances
Cylinder
Inspect the cylinder bore against the
light. As long as the surface layer has not
been broken through, the cylinder is in
working order.
Aluminium from the piston can be
removed using emery cloth, particle size
approximately 120 grit. Carefully clean
after sanding.
Wear tolerances
Cylinder
Inspect the cylinder bore against
the light. As long as the surface
layer has not been broken
through, the cylinder is in
working order.
Aluminium from the piston
can be removed using emery
cloth.
Piston
Wear is at its greatest at the bottom of
the piston by the inlet and exhaust ports.
A study of the machining lines after
manufacture give a picture of wear. If the
piston has been worn completely smooth
by the ports you should consider replace-
ment.
Characteristic for a worn piston is that
the machine is difficult to start due to
the piston's reduced valve function.
Piston
Wear is at its greatest at the bott-
tom of the piston by the inlet
and exhaust ports. A study of
the machining lines after manu-
facture give a picture of wear. If
the piston has been worn com-
pletely smooth by the ports you
should consider replacement.
Piston ring groove
Measure the piston ring groove using
feeler gauges. If the piston ring groove is
greater than .06 in./1.6 mm the piston
must be replaced. Fit a complete piston
kit with piston rings, needle bearing and
gudgeon pin.
Piston ring groove
If the piston ring groove is
greater than .06 in./1.6 mm the
piston must be replaced. Fit a
complete piston kit with piston
rings, needle bearing and gudge-
on pin.
Piston rings
Piston ring wear can be measured
by inserting the piston ring into the
cylinder and measuring the piston ring
gap using feeler gauges. The piston ring
gap may be max. .04 in./1.0 mm.
Use the piston to press in the piston
ring exactly flat, about one inch/a few
centimetres from the base of the cylinder.
Piston rings
Insert the piston ring in the
cylinder with the help of the
piston, about one inch/a few
centimetres from the base of the
cylinder. The piston ring gap
may be max. .04 in./1.0 mm.
Piston ring play
Measure the piston ring play using feeler
gauges. If play exceeds .006 in./ 0.15 mm
the piston ring groove should be measured
as set out below.
Piston ring play
If the piston ring play exceeds
.006 in./0.15 mm the piston
ring groove should be measured
as set out below.
.06 in.
1.6 mm
.04 in.
1.0 mm
.006 in.
0.15 mm
