KTM 690 LC4 2007, Repair Manual

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Repair manual KTM 690 LC4
Art.-No. 3.206.045-E
– Remove the valve keys with special tool 590.29.019.000 and
773.29.060.000 and relieve the valve springs.
– Remove the special tool; remove the spring retainers and valve
springs.
– Pull the valve out of the bottom of the valve guide, pry off the valve
stem gasket and remove the lower valve spring retainer.
NOTE: if you are mounting the used valves again, they must be
remounted in the same valve guide as before. For this purpose, place
the valves in a box, marking the position they were mounted in the
cylinder head (see photo).
– Check the valve guides with the limit plug gauge 590.29.026.006
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(Ø 6.05 mm). If you can easily slide the limit plug gauge into the
valve guide, have it replaced and reamed at a special machining
shop.
– Check the sealing area of the spark plug thread the valve seats for
damage or cracks. Use a straight edge and a feeler gauge to check
the warpage of the sealing area towards the cylinder. Warpage: max.
0.10 mm.
– Valve seats should not be impacted. Sealing seat width: inlet max.
1.60 mm; outlet max. 2.00 mm. If necessary, grind the valves.
– Check the valve disk for wear and runout. Max. runout at the valve
disk: 0.05 mm. The valve seat may not be impacted. The sealing
area should be in the center of the valve seat. The valve stem is
hard-chromium-plated, the valve guide is usually subjected to wear.
– Check whether the valve springs are broken or worn (visual check).
Also measure the length with a sliding caliper.
Minimum length 42.3 mm
NOTE: replace the spring if it is shorter.
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