KTM 400-660 LC4 1998-2005, Repair Manual

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Three-Bond Dichtmasse
Three-Bond Gasket
Disassembling the cylinder head and checking the
components for wear
– Mount cylinder head in vice using the studs. Do not allow it to rest
on sealing surface.
– Mark valves and remove using special tool 590.29.019.000.
– Clean all parts.
Sealing area
Check spark plug threads and valve seats for damage or cracks. Check
the sealing area to the cylinder for distortions with a straightedge and a
feeler gauge. Distortion limit 0.10 mm (0.004 in).
Valve guides
The valve guides are checked with a limit plug gauge
1
(Ø 7.05 mm)
580.29.026.007. If the limit plug gauge can be easily inserted into the
valve guide, the guide must be replaced in a specialized workshop.
Valve seats
The valve seats must not be pocketed. Seat sealing width: intake max.
1.5 mm (0.059 in); exhaust max. 2.0 mm (0.079 in). Grind valves if
necessary.
Valves
Check valve heads for wear and run out. Max. run-out on valve heads
0.05 mm (0.002 in). Valve seats should not be pocketed. The sealing
area must be located in the center of the valve seat. The valve stem is
hard-chrome plated. Experience shows that wear appears primarily on
the valve guide.
Valve springs
Only visual check for breakage or wear is necessary.
Valve stem seals
Always renew valve stem seals when the valves are removed.
Intake flange
Check flange surface for distortion, scrape on glas plate if necessary.
5-10E
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