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KTM LC4 400-660LC42003 engine. Manual - part 6

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

Working on the right housing half

Remove shaft seal rings and heat housing half to approx. 150° C by
means of a hot-plate.

Roller bearing of crankshaft

Proceed as for left housing half.

Cylinder roller bearing of counter shaft

Remove shaft seal ring. Press old bearing inwards. Press in new bearing
from inside as far as stop.

Oil ducts

Use compressed air to clean all oil ducts. Ensure that the oil ducts are
not clogged.

Counter shaft seal ring

Press in new shaft seal ring from outside until flush.

Crankshaft seal ring

Press in new shaft seal ring from outside until flush.

NOTE: Engine with an electric starter have a stop disk instead of the
shaft seal ring

. Do not remove this disk.

Needle bearing of main shaft

Pull old bearing from bearing seat using bearing extracto and insert. In
order to apply the bearing extractor in an vertical position, a steel plate
(see special tools) must be laid on the sealing area of the housing. The
bearing extractor jaws should fit as close as possible up to the housing
walls. Then press in new bearing from inside until flush.

Oil nozzle

For the cleaning of the oil nozzle and the oil duct simply blow it
through with compressed air from the nozzle side. If the oil nozzle is
disassembled, secure it with Loctite 243 when mounting again.
Then check the lubrication bore

of the crankshaft roller bearing for

free passage.

After the case half has cooled down, check bearings for secure fit.

5-3D

Needle bushes of the clutch disengagement
– Pull out the needle bushes of the clutch disengagement with a gear

puller and insert from the housing half.

– Oil the needle bushes.
– Press the first needle bush

to stop.

– Press the second needle bush

so that it is flush.

5-4D

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

5-5D

Working on the left half of the housing

Remove shaft seal rings and heat housing half to approx. 150° C by
means of a hot-plate.

Needle bearing of counter shaft

Press in new needle bearing from inside until flush.

Shaft seal ring of kickstarter shaft

Press in new shaft seal ring from outside with sealing lip facing inwards
until flush.

Grooved ball bearing of the balancer shaft

Use an extractor and insert to remove the grooved ball bearing from
the housing half.

Shaft seal ring of crankshaft

Press in new shaft seal ring from outside with sealing lip facing inwards
until flush.

Retaining plate for main shaft grooved ball bearing

If the retaining plate has been removed, use Loctite 243 for the two
countersunk bolts during assembly.

Oil ducts

Use compressed air to clean all oil ducts. Ensure that the oil ducts are
not clogged.

Roller bearing of crankshaft

From outside press crankshaft roller bearing inwards using a suitable
mandrel.
Press in new roller bearing from inside up to the stop.

Grooved ball bearing of main shaft

Press in new grooved ball bearing from inside up to the stop.

CAUTION

O NOT USE FORCE WHEN PRESSING THE GROOVED BALL BEARING AGAINST THE

RETAINING PLATE

TO AVOID A BENDING OF THE PLATE

WHICH WOULD RESULT IN

EXCESSIVE AXIAL PLAY OF THE MAIN SHAFT

Needle bearing of kickstarter shaft

Press in new needle bearing from inside until flush.

Bypass valve
Test valve piston, tight fit and pressure spring for damage.

Minimum length of the pressure spring

: 23,5 mm

NOTE: The opening pressure of the bypass valve is reduced when the
length of the pressure spring decreases below 23,5 mm. This reduces
the oil pressure and causes engine damage.

Ensure that neither the lubrication bore of the roller bearing

nor the

oil ducts of the oil pumps are clogged.

– After the housing half has cooled down, check bearings for tight fit.
– Finally, insert both dowels so that the dowel with internal diameter

15.4 mm is mounted at the rear (swingarm pivot).

5-6D

Crankshaft

If the conrod bearing is replaced, take care to properly position the
crankpin. The bores of the crank web

and crank pin

must

coincide.

CAUTION

F THE CRANK PIN IS PRESSED IN THE WRONG POSITION

THE CONROD BEARING IS

SUPPLIED INSUFFICIENTLY OR NOT AT ALL WITH ENGINE OIL

WHICH RESULTS IN

BEARING DAMAGE

If the crankshaft is continued to be used, check crankshaft journals for
run out. Place crankshaft on a roller block or a similar device and check
the outer end of the journals for run out with a dial gauge.

run out of crankshaft journals: max. 0.04 mm (0.0016 in)

The radial clearance and axial clearance on the conrod bearing must be
checked.

radial clearance: max. 0.05 mm (0.0019 in)

axial clearance: max. 1.00 mm (0.04 in)

– If the crankshaft roller bearings are replaced, the inner rings on the

crankshaft should also be changed.

– Heat special tool on a heating pad up to approx. 150°C and slip it on

the inner ring immediately. Press the special tool together tightly to
obtain a good heat transfer and pull the inner ring off the crankshaft.

– To mount the new inner ring, heat the special tool again to approx.

150°C, engage the inner ring and slip it on the crankshaft journal
immediately.

– In order to safely press on new rings, a middle panel should be

inserted between the crankshaft webs. This panel should be big
enough to be supported on both sides, so that the crankshaft lies
free and accessible.

NOTE: Because LC4-E models have different diameters of inner
crankshaft bearing rings, it is necessary to have both special tools
(584.29.037.040 and 584.29.037.043).

CAUTION

EVER CLAMP THE CRANKSHAFT WITH A CRANKSHAFT JOURNAL OR WEB IN THE

VICE

AND NEVER TRY TO KNOCK THE INNER RING FREE

. T

HE CRANKSHAFT WEBS

MAY BE COMPRESSED THEREBY MAKING THE CRANKSHAFT UNUSEABLE

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

5-7D

Measuring and adjusting of crankshaft axial clearance

– Should the crankshaft, engine housing, or a roller bearing be

replaced, the axial clearance of the crankshaft should also be
checked.

– The housing should be laid inside upwards, then measure the

distance from the sealing area to the inner rings of the roller
bearings. Note the readings and then add on 0.3 mm to allow for
gasket thickness.

– Measure the crankshaft at touching points and then subtract the

measured value from the housing dimensions. This figure will be the
axial play of the crankshaft, which should be 0.03- 0.12 mm (0.001-
0.005 in).

EXAMPLE:
Left-hand housing half

33.0 mm 1.300 ( in)

Right-hand housing half

+ 32.8 mm 1.290 ( in)

Gasket

+ 0.3 mm 0.012 ( in)

Total housing dimension

= 66.1 mm 2.602 ( in)

Crankshaft dimension

– 65.8 mm 2.590 ( in)

Axial play present

= 0.3 mm 0.012 ( in)

The compensating washers should be equally distributed between the
two sides of the crankshaft. In our example, one compensation washer
(≠ 0.1 mm / 0.004 in.) must be mounted on either side.

Checking the piston

– Replace the piston in the case of excessive oil consumption or

grooves in the piston skirt.

– If reinstalling the old piston perform the following steps:

1. Piston bearing surface - check for damage
2. Piston ring grooves - the piston rings must move easily in the

groove. Old piston rings or sandpaper (400 grit) may be used to
clean the piston ring grooves.

3. Piston rings - check for damage and end gap (see below).
4. The piston pin must move freely in the piston when mounted. If the

piston pin changed its color badly or shows running traces, it must
be replaced. Insert piston pin also into the conrod and check for
clearance. Maximum clearance in the conrod eye 0.08 mm (0.003
in).

NOTE: When in place, the piston pin may not have any play. It must be
possible to shift it with slight counterpressure.

5-8D

Mounting instructions for piston rings

– Insert the oil scraper ring in the lower ring groove. Side of ring

marked facing piston head.

– Mount compression ring (tapered compression piston ring) in middle

ring groove. Side of ring marked facing piston head.

– Insert the compression ring (rectangular ring) in the upper piston ring

groove (the surface marked must be on top).

Piston ring end gap

– Insert pisto ring into the cylinder and adjust. Piston ring must be

approx. 10 mm (1/2 inch) from top of cylinder.

– The end gap

can now be checked which a feeler gauge.

Compression rings: max. 0.60 mm (0.023 in)

Oil scraper ring: max. 0.80 mm (0.03 in)

If the end gap is greater check piston and cylinder for wear. If piston
and cylinder wear are within the permitted tolerance limits, replace the
piston ring.

Measuring piston and cylinder, determining the piston
fitting clearance

– In order to determine the wear of the cylinder, measure the cylinder

center of the running area with a micrometer.

– Measure the diameter of the x-axis and the y-axis in order to check

for oval wear, if any.

– The piston is measured on the piston skirt across to the piston pin as

shown in the illustration.

– The cylinder diameter minus the piston diameter yields the piston

assembly clearance.

Piston assembly clearence: see Technical Specification

ELKO

ARIAS

Ø 89 mm

Ø 95 mm

Ø 101 mm

Compression ring

N 100

Tapered ring

TOP

N 101

Oil scraper ring

ELKO

TOP

–––

Repair manual KTM LC4

Art.-Nr

. 3.206.006 -E

Cylinder – nikasil coating

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 embedded. The main advantages of the Nikasil
coating are excellent heat dissipation and thus better power output, low
wear and low weight of the cylinder. The worn coating can be
regenerated at low cost provided that the running surface of cylinder is
flawless.

Recoated cylinder

If the Nikasil coating of your cylinder is worn but undamaged, you may
obtain a recoated cylinder at your KTM dealer (new Nikasil coating on
used cylinder).
It may be that your spare cylinder shows color changes on the exterior
side.

5-9D

Three-Bond Dichtmasse
Three-Bond Gasket

Disassembling the cylinder head and checking the
components for wear

– Mount cylinder head in vice using the studs. Do not allow it to rest

on sealing surface.

– Mark valves and remove using special tool (see illustration).
– Clean all parts.

Sealing area
Check spark plug threads and valve seats for damage or cracks. Check
the sealing area to the cylinder for distortions with a straightedge and a
feeler gauge. Distortion limit 0.10 mm (0.004 in).

Valve guides
The valve guides are checked with a limit plug gauge

(Ø 7.05 mm).

If the limit plug gauge can be easily inserted into the valve guide, the
guide must be replaced in a specialized workshop.

Valve seats
The valve seats must not be pocketed. Seat sealing width: intake max.
1.5 mm (0.059 in); exhaust max. 2.0 mm (0.079 in). Grind valves if
necessary.

Valves
Check valve heads for wear and run out. Max. run-out on valve heads
0.03 mm (0.001 in). Valve seats should not be pocketed. The sealing
area must be located in the center of the valve seat. The valve stem is
hard-chrome plated. Experience shows that wear appears primarily on
the valve guide.

Valve springs
Only visual check for breakage or wear is necessary.

Valve stem seals
Always renew valve stem seals when the valves are removed.

Intake flange
Check flange surface for distortion, scrape on glas plate if necessary.

5-10D

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