Checks And Overhaul; Cylinders Heads; Valves - Guides - Seats - Kohler KD 425-2 Workshop Manual

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KD 425-2 Workshop Manual_cod. ED0053029360_1° ed_ rev. 00

Cylinders heads

Parts shown in figure 9.
1.Head - 2.Tappets - 3.Valves - 4.Seats - 5.Guides - 6.Seals - 7.Lo-
wer washers - 8.Springs - 9.Top washers - 10.Valve locking split co-
nes - 11.Rocker arms - 12.Rocker pins - 13.Gaskets - 14.Push rods
- 15.Cover tube - 16.O-ring - 17.Camshaft.
The heads are made off aluminium with valve guides and seats are
made of cast iron.
Do not disassemble the head when the engine is hot to
avoid deformation.
Clean heads of carbon deposits and check the cylinder mating sur-
faces; if they are deformed they must be ground to a maximum of
0.3 mm. Check that there are no cracks or other imperfections in the
heads. If defects are encountered the heads must be renewed. In this
case consult the spare parts catalogue.

Valves - Guides - Seats

Clean the valves with a wire brush and renew them if the valve heads
are deformed, cracked or worn.
a mm
Guide b mm
7,00÷7,01
Inlet 6,960÷6,970
assembly
Exhaust
6,945÷6,955
Check the dimensional conformity of the valve stems (fig. 11) and
the clearance between valve and guide, bore out the guides to the
dimensions indicated in the table (fig. 10).
Renew both guide and valve if the clearance is greater than 0.1mm.
It is always necessary to grind the valve seats when new guides are
fitted.
Oversize valve guides with external diameter increased by 0.10 are
available.

CHECKS AND OVERHAUL

c mm d mm
13,025÷13,037 0,8÷1,0
X
e mm
13÷13,01
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