KTM 250 SX-F 2005, Repair Manual

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5-16
Repair manual KTM 250 SX-F
Art.-No. 3.206.027-E
– Remove the valve spring retainer
1
and valve springs
2
from the
cylinder head.
– Pull the valve stem sealing
3
off the valve guides and take out the
spring washers
4
.
– Check the sealing areas of the spark plug thread and the valve seats
for damage and cracks. Use a ruler and a feeler gauge to check the
distortion of the sealing area to the cylinder. Distortion max. 0.10
mm.
– Check the valve guides using the limit plug gauge 770.29.026.000
5
(Ø 5.05 mm). If you can easily slide the limit plug gauge into the
valve guide, it must be renewed and reamed in a special workshop.
– Valve seats may not be impacted. Sealing seat width: Inlet max.
1.50 mm; outlet max. 1.50 mm. Grind the valves if necessary.
– Check the valve disks for wear and runout. Runout at the valve disk
max. 0.05 mm. The valve seat should not be impacted. The sealing
area should be in the center of the valve seat. The valve stem is
hard-plated, wear usually appears at the valve guide.
– Check the valve springs for ruptures or wear (visual check), measure
the length with a sliding gauge. Minimum length 38.5 mm. Replace
the spring if it is shorter.
– Always replace the valve stem seal if dismounting the valves.
– Measure the thickness of the valve spring retainers, minimum
thickness 0.9 mm.
– Insert the valve spring retainers in the cylinder head.
– Mount the valve stem seals on the valve guides and oil.
– Thoroughly oil the valve stem and insert in the valve guides.
NOTE: Make sure the valves are in the correct position when mounted.
– Position the valve springs, insert the valve spring retainers in the
valve springs.
NOTE: mount the valve springs with the end with the larger diameter
on the bottom.
– Pretension the valve springs with the special tool and mount the
valve keys.
NOTE: make sure the valve keys fit correctly, use a little grease to
attach them to the valve.
– Finally, tap on the valve spring retainer several times with a plastic
hammer.
1
2
3
4
5