KTM 250 SX - Manual (Page 42)

Checking cylinder for wear
Measure diameter of cylinder approx. 10 mm (0.4 in.) below top of
cylinder edge. Check diameter in several corresponding places to see if
cylinder in worn oval.
Recoated cylinder
NOTE: If the cylinder diameter is larger than e.g. 66.360 mm the cylinder
must be regenerated or replaced.
For reconditioning of the old cylinder all exhaust control components
must be removed. The intermediate flange
1 remains with the cylinder.
The piston size is stamped into the bottom of the piston.
Nikasil coating of cylinder
Nikasil is the brand name for a cylinder coating process, developed by the
piston manufacturer Mahle. The name is derived from the two materials
used in this process - a nickel layer into which the particularly hard silicon
carbide is inbedded.
The main advantages of the Nikasil coating are:
● excellent heat dissipation and thus better power output
● low wear
● low weight of the cylinder.
NOTE: The worn coating can be regenerated at low cost provided that
the cylinders running surface is flawless.
5-5C
x
y
10mm
1
Engine Cylinder Ø Piston size
250
67,500 - 67,512 1
67,513 - 67,525 2
300
72,000 - 72,012 1
72,013 - 72,025 2
380
78,000 - 78,012 1
78,013 - 78,025 2
250 66,340 - 66,350 1
starting with the 2000 mod 66,351 - 66,360 2
300 71,940 - 71,950 1
starting with the 2000 mod
71,951 - 71,960 2