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

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10
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KD425-2 Workshop Manual_cod. ED0053031750_1° ed_ rev. 00

Checks and overhaul

Cylinders heads

Parts shown in figure 9.
1.Head
2.Tappets
3.Valves
4.Seats
5.Guides
6.Seals
7.Lower washers
8.Springs
9.Top washers
The heads are made off aluminium with valve guides and seats
are made of cast iron.
Warning
• Do not disassemble the head when the engine is hot to avoid
deformation.
Clean heads of carbon deposits and check the cylinder mating
surfaces; if they are deformed they must be ground to a maxi-
mum of 0.3 mm. Check that there are no cracks or other imper-
fections 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
Guide
mm
Inlet 7,00÷7,01
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.
10.Valve locking split cones
11.Rocker arms
12.Rocker pins
13.Gaskets
14.Push rods
15.Cover tube
16.O-ring
17.Camshaft
b c d
mm mm mm
13,025÷13,037 0,8÷1,0
4
e
mm
13÷13,01
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