Servicing On Individual Components - KTM 250 1998 Repair Manual

4.0 Servicing on individual components

Chap. Component / Component unit
4.1 Right housing half . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
4.2 Left housing half . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
4.3 Crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
4.4 Piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
4.5 Piston ring end gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
4.6 Measuring cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
4.7 Exhaust control in cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
4.8 Preassembly of cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
4.9 Nikasil coating of cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.10 Exhaust control in clutch cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.11 Preassembly of clutch cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.12 Reed valve, intake flange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.13 Kickstarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
4.14 Preassembly of kickstarter shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
4.15 Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.15.1 Assembly of main shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.15.2 Assembly of countershaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.16 Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9
4.17 Replacing outer clutch hub . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9
4.18 Shift mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10
4.19 Preassembly of shift shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10
4.20 Ignition (Kokusan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
4.20.1 Spark plug (NGK BR 8 ECM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
4.20.2 Check stator and pulse generator (Kokusan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
4.21 Ignition (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
4.21.1 Spark plug (NGK BR 8 ECM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
4.21.2 Check stator (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
Engine housing
N : R
OTE EAD THROUGH THE FOLLOWING SECTION BEFORE COMMENCING WORK
HOUSING HALVES ONLY NEED TO BE HEATED UP ONCE BEFORE REPLACING THE BEARINGS
H
AVING FIRST REMOVED THE DOWELS
BE PLACED ON A SUITABLY LARGE PLANE SURFACE
.
BEST USED AS A BASE
B
EARINGS OR SHAFT SEAL RINGS SHOULD NOT BE HAMMERED INTO THEIR SEATS
HAMMER THEM IN WITH GREAT CARE
150° C.
A ,
FTER COOLING SHOULD THE BEARINGS FAIL TO LOCK IN THE BORE
.
MUST BE REPLACED
,
IN ORDER TO EXPEL THE BEARINGS OR REMOVE THEM WITH LIGHT MALLET BLOWS
,
SUPPORTING THE WHOLE OF THE SEALING SURFACE WITHOUT DAMAGING IT
. C
OLD BEARINGS WILL PRACTICALLY DROP INTO THEIR SEATS AT AN ENGINE HOUSING TEMPERATURE OF APPROX
,
. T
HEN DETERMINE THE ASSEMBLY SEQUENCE SO THAT THE ENGINE
.
. I
F NO SUITABLE PRESS IS AVAILABLE
THEY ARE BOUND TO ROTATE AFTER WARMING
Page
,
THE HOUSING HALVES MUST
. A
WOODEN PANEL IS
,
USE A SUITABLE MANDREL AND
.
. I
N THAT EVENT THE HOUSING
4
1