Checking Cylinder For Wear; Recoated Cylinder; Nikasil Coating Of Cylinder - KTM EXC Repair Manual

5-5C
10mm
x
y

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
1
must be regenerated or replaced.
For reconditioning of the old cylinder all exhaust control components
must be removed. The intermediate flange
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.
Engine Cylinder Ø
67,500 - 67,512
250
67,513 - 67,525
72,000 - 72,012
300
72,013 - 72,025
78,000 - 78,012
380
78,013 - 78,025
250 66,340 - 66,350
66,351 - 66,360
starting with the 2000 mod
300 71,940 - 71,950
71,951 - 71,960
starting with the 2000 mod
Piston size
1
2
1
2
1
2
1
2
1
2
1
remains with the cylinder.