41
6 - Motore
Release 00 Date 02/2005
– Remove spring caps 1 and valve springs 2 from the cylinder
head.
– Remove the valve stem linings from the valve guides and re-
move spring holders 3.
The 250 cc model fits conical springs.
Sealing surface
Check the spark thread and the valve seats for damage or
cracks. Using a straightedge and a thickness gauge, check to
see if any distortion is present. Maximum allowable distortion:
0.10 mm.
Valve guides
Check the valve guides with limit gauge
4
(Ø 6.05 mm). If the
gauge can be easily inserted into the valve guide, the latter will
have to be replaced.
Valve seats
The valve seats should show no signs of hammering-in. Width
of sealing surface: intake valve max. 1.50 mm; exhaust valve
max. 2.00 mm. If necessary, grind the valves.
Valves
Check the valve heads for signs of wear and floating. Maximum
allowable valve head floating: 0.03 mm. The valve seat should
show no signs of hammering-in. The sealing surface should be
at the centre of the valve seat. The valve stem is chromium-pla-
ted; wear generally occurs on the valve guide.
Valve springs
Visually check that the valve springs are not broken or worn.
Measure their length with a vernier caliper. The minimum al-
lowable valve length is 39.20 mm for the outer valve springs and
36.45 mm for the inner valve springs. Replace as necessary.
Valve springs for the 250 cc model
Visually check that the valve springs are not broken or worn.
Measure their length with a vernier caliper. The minimum al-
lowable length for the valve springs is 37.70 mm. Shorter
springs will have to be replaced.
Valve stems linings
Always replace the valve stem linings when the valves are re-
moved.
– Insert the four spring holders
3
into the cylinder head.
– Fit the valve stem linings on the valve guides and lubricate.
– Carefully oil the valve stems and insert the valves into the val-
ve guides. When refitting, ensure that the valves are properly
positioned.
– Fit valve springs
2
and insert spring caps
1
into the valve
springs.
1
2
3
4
Содержание RR 4T-250
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Страница 98: ...3 7 Carburettor Release 00 Date 02 2005 CARBURETTOR KEIHIN FCR M X 39 ...
Страница 109: ...3 8 Front suspension wheel Release 00 Date 02 2005 Four Stroke l ...
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