VESPA 633844 IT, Руководство по обслуживанию, Страница: 133 / 308

020393Y Piston fitting band
Inspecting the cylinder head
- Using a trued bar and feeler gauge check that the
cylinder head surface is not worn or distorted.
Maximum allowable run-out: 0.05 mm
- Check that the camshaft and the rocker pin ca-
pacities exhibit no wear.
- Check that the cylinder head cover surface, the
intake manifold and the exhaust manifold are not
worn.
Characteristic
bearing «A»
Ø 12.000 - 12.018 mm
bearing «B»
Ø 20.000 ÷ 20.021 mm
bearing «C»
Ø 37.000 - 37.025 mm
Inspecting the timing system components
- Check that the guide shoe and the tensioner shoe
are not worn out.
- Ensure that the camshaft control pulley chain as-
sembly and the sprocket wheel are not worn.
- If you encounter wear, replace the parts or, if the
chain, sprocket wheel and pulley are worn replace
the whole assembly.
- Remove the centre screw with the washer and
the tensioner spring. Check that the one-way
mechanism is not worn.
- Check the condition of the tensioner spring.
- If examples of wear are found, replace the whole
assembly.
Vespa GTV 250 i.e.
Engine
ENG - 39