Checking The X-Distance - KTM 250 EXC EU Repair Manual

18 ENGINE

18.5.20 Checking the X-distance

Info
The X-distance is the distance defined for the piston protrusion, when the cylinder is clamped down and the piston is at top
dead center.
The X-distance must be checked very carefully. If the X-distance is too large, the compression decreases and the engine loses
power. If the X-distance is too small, the engine knocks and overheats.
–
Slide the cylinder over the piston.
–
Push the cylinder down carefully.
308142-10
–
Mount nuts
Guideline
Nut, cylinder base
308139-10
(All 250 models)
–
Apply special tool
Adjustment gauge (54829001100) (
–
Position the piston at top dead center.
–
Check the X-distance using the special tool.
Feeler gauge (59029041100) (
X (upper edge of piston to upper
308141-10
edge of cylinder)
» If the specified value is not attained:
–
(All 300 models)
–
Place straightedge
–
Position the piston at top dead center.
–
Check the X-distance using the special tool.
Feeler gauge (59029041100) (
X (upper edge of piston to upper
edge of cylinder)
303053-10
on both sides and tighten in a crisscross pattern.
3
to the cylinder.
1
Adjust the X-distance. ( p. 180)
on the cylinder.
1
M10 35 Nm
(25.8 lbf ft)
p. 273)
p. 275)
0... 0.10 mm (0... 0.0039 in)
p. 275)
0... 0.10 mm (0... 0.0039 in)
179