BRP ROTAX FR 125 MAX Operating instructions

RepairManualFR125MAXandFR125JuniorMAX
Page1 Edition 11/2000
EO2
REPAIR MANUAL
for ROTAX-engines type FR 125 MAX
FR 125 Junior MAX
Version: FR 125 MAX (21 kW)
Engine configuration no.: 37.125.1301
Version: FR 125 Junior MAX (15 kW)
Engine configuration no.: 30.0125.130
Edition: 11 2000
Bombardier-Rotax GmbH
A-4623GUNSKIRCHEN
WelserStrasse32
AUSTRIA
http://www.rotax.bombardier.com

RepairManualFR125MAXandFR125JuniorMAX
Page2 Edition 11/2000
Preface
This Repair Manual contains essential advice and data for professional maintenance and repair of the
ROTAX kart engines, type FR 125 MAX and FR 125 JUNIOR MAX.
The Repair Manual is based on the state of knowledge at the time of publication.
BOMBARDIER-ROTAX reserves the right to make technical modifications to the engine in view of further
developmentwithout updatingthis Manual.
Alldata andproceduresinthisRepair Manualaredescribed tothe bestofour knowledge,however excluding
anyliability.
We reserve all rights including technical modification and possibility of errors. Reprinting, translation or
copies, in whole or in part, authorized only after written permission by
BOMBARDIERROTAX GMBH
Motorenfabrik
A-4623 Gunskirchen - Austria

RepairManualFR125MAXandFR125JuniorMAX
Page3 Edition 11/2000
Table of contents
Preface........................................................................................................................................................2
IMPORTANTINFORMATION .........................................................................................................5
Repeating symbols .....................................................................................................................................5
General precautions and safety information................................................................................................5
Technical data .............................................................................................................................................7
Check and service intervals of engine components....................................................................................8
Special tools, securing and sealing agents .................................................................................................9
Location of the engine serial number ........................................................................................................10
ENGINEREMOVAL FROM THE CHASSIS ............................................................................... 10
Engine removal .........................................................................................................................................11
Setting up the engine on the trestle ...........................................................................................................12
ENGINEDISASSEMBLY ........................................................................................................... 12
Removal of the radiator .............................................................................................................................12
Removal of the intake silencer and of the carburetor socket ....................................................................12
Removal of the electric starter ..................................................................................................................12
Removal of the centrifugal clutch ..............................................................................................................13
Removal of the cylinderhead cover and combustion chamber insert .......................................................14
Cylinder-removal .......................................................................................................................................14
Piston – removal .......................................................................................................................................14
Disassembly of the drive for the balance shaft and waterpump shaft.......................................................15
Separation of the crankcase halves ..........................................................................................................15
Crankshaft removal ...................................................................................................................................16
INDIVIDUALCOMPONENTMAINTENANCE............................................................................. 16
Crankcase.................................................................................................................................................16
Removal and refitting of bearings and oil seals.........................................................................................17
Crankshaft.................................................................................................................................................22
Replacement of the crankshaft repair set .................................................................................................23
Balance shaft ............................................................................................................................................24
Drive of the balance shaft..........................................................................................................................24
Drive of the waterpump .............................................................................................................................25
Waterpump shaft.......................................................................................................................................25
Centrifugal clutch ......................................................................................................................................26
Bearing of the clutch drum assembly........................................................................................................27
Clutch drum with chain sprocket assembly...............................................................................................28
Cylinder assembly.....................................................................................................................................29
Exhaust valve assembly ( only on engine version FR 125 MAX )..............................................................29
Disassembly of the exhaust valve (only on engine version FR 125 MAX) .................................................30
Installation of the exhaust valve (only an engine version FR 125 MAX ),.see fig. 39..................................31
Exhaust socket..........................................................................................................................................32
Reed valve assembly and carburetor flange .............................................................................................33
Cylinder .....................................................................................................................................................34
Piston and piston ring................................................................................................................................35
Piston pin, needle cage, piston pin circlips................................................................................................36
Combustion chamber insert......................................................................................................................37
Cylinder head cover ..................................................................................................................................37
Ignitionunit ................................................................................................................................................38
Sparkplug .................................................................................................................................................39
Starter reduction gear assembly ...............................................................................................................39

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Electric starter...........................................................................................................................................39
Radiator.....................................................................................................................................................40
Intakesilencer ...........................................................................................................................................40
Carburetor .................................................................................................................................................41
Fuel Pump.................................................................................................................................................42
Exhaust system ........................................................................................................................................42
ENGINEREASSEMBLY ............................................................................................................ 43
Crankcase assembly ................................................................................................................................43
Installation of the balance shaft and water pump drive..............................................................................45
Pistoninstallation ......................................................................................................................................46
Cylinderinstallation ...................................................................................................................................47
Installation of combustion chamber insert and cylinder head cover..........................................................48
Checking and adjustment of the squish gap between piston and combustion chamber insert.................49
Starter reduction gear installation..............................................................................................................50
Centrifugal clutch installation.....................................................................................................................51
Pick-up coil for ignition unit - installation ....................................................................................................52
Spark plug - fitting......................................................................................................................................52
Electric starter - installation.......................................................................................................................52
Radiator and intake silencer- installation ...................................................................................................53
Fuelpump-installation ...............................................................................................................................53
Carburetorinstallation ...............................................................................................................................53
Filling of gear compartment with oil...........................................................................................................54
ENGINEINSTALLATIONONCHASSIS...................................................................................... 54

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IMPORTANT INFORMATION
Repeating symbols
Payattention withoutfail tothefollowingsymbolsthroughout theManual emphasizingparticularinformation.
▲ Warning: Identifies an instruction, which if not followed may cause injury or endanger the life of the
rider, mechanic or third party.
■ Attention: Denotes aninstruction whichif notfollowed mayresult insevere damageof theengine. Non-
compliance might lead under certain conditions to health hazards.
◆ Note: Information useful for better execution and understanding of instructions.
➩Denotes a working instruction
✔Denotes a checking instruction
General precautions and safety information
▲ Warning: The ROTAX engine Type FR 125 MAX is planned and has been developed solely for the use
in karts, which are exclusively run an specified tracks. Any applications beside that is not as
agreed and releases the manufacturer of any liability.
■ Attention: Informationstatedin thisManual arebasedon data andexperience ofexperts, applicable at
standard working conditions. These guidelines are useful and necessary but they are never
a substitute for proper theoretical and practical training.
■ Attention: Replacement parts must meet the requirements defined by the engine manufacturer. This is
onlywarranted bytheuseofGENUINE-ROTAX partsand/ oraccessories(seeReplacement
parts list ). If using other than GENUINE ROTAX parts and / or accessories any warranty
granted by ROTAX will lapse.
■ Attention: modifications on engine and changes to sphere of engine (carburation, exhaust system etc.)
not approved by ROTAX releases the manufacturer of any liability and warranty.
■ Attention: towarrantproperrepair, utilizationof thespecifiedspecial tools,fixtures,lubricating,-sealing,-
and securing agents is required.
■ Attention: Adhere to specified tightening torques without fail.
■ Attention: Removed sealing rings, gaskets, circlips, O-rings and oil seals have to be always renewed
at an engine overhaul.
■ Attention: Use only clean screws and nuts. Check thrustfaces and thread for damage. If doubtful use
new screws and nuts.
■ Attention: Decisive for life span and instant troublefree operation is to meet the specified schedule of
maintenance and to observe sundry technical data.

RepairManualFR125MAXandFR125JuniorMAX
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■Attention: Always secure engine safely on trestle.
■Attention: After assembly verify components for tight fit and check engine for flawless operation.
■Attention: Rectify minor defects without delay, thus preventing engine failure.
■Attention: Pay attention without exception to all additional safety measures of the kart manufacturer.

RepairManualFR125MAXandFR125JuniorMAX
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Technical data
Engine Type FR 125 MAX
FR 125 Junior MAX
Bore/Stroke 54,0 mm / 54,5 mm
Displacement 125,0 cm3
Performance ( max.)
FR 125 MAX
FR 125 Junior MAX 21 kW at 11.500 rpm 15 kW at 8.500 rpm
Torque (max.)
FR 125 MAX
FR 125 Junior MAX 21 Nm at 8.750 rpm 17 Nm at 8.500 rpm
Idle speed 1.500 rpm
Speed limit
FR 125 MAX
FR 125 Junior MAX 13.500 rpm (at operation on the track, under load) 12.200 rpm (at operation on the track, under load)
ATTENTION: Do not operate the engine without
load!
Ignition unit Breakerless, digital battery ignition, DENSO
Spark plug NGK BR10EG, M14x1,25 or
DENSO IW31, M14x1,25
Electrode gap 0,5 - 0,6 mm (NGK)
0,6 - 0,7 mm (DENSO)
Fuel Premium fuel, unleaded
RON (min.) 95 octan
Cooling system Liquid cooled, cooling circuit by integrated coolant
pump
Flowrate of the coolant pump 22 l / min. at 11.000 rpm.
Coolant mixture 50% Antifreeze (al - compatible)
50% Water (distilled)
Coolant quantity 0,6 l
Engine lubrication system Mixture lubrication, super 2-stroke oil
Fuel mixing ratio 1:50 (2% oil)
Lubrication of the balance shaft drive Motoroil SAE 15W- 40
Oil quantity for lubrication of balance shaft drive 0,05 l ( = 50 ml)
Clutch Centrifugal clutch, dry
Clutch engagement speed Approx, 4000 rpm
Power transmission from centrifugal clutch to the
rear axle of the kart Roller chain
Chain dimension 7,75 x 4,6 x 4,5
Number of teeth of the drive sprocket 11, 12, 13 or 14 teeth
Weight (dry) Approx. 12 kg without silencer, carburetor, fuel
pump, radiator, muffler and battery
Table 1

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Check and service intervals of engine components
▲Warning: All maintenance and service activities have to be carried out by a trained mechanic only.
Component Inspection or maintenance
schedule Checking, remedy
Chain sprocket Inspection before each kart
operation Inspect for wear or deformation of teeth,
renew as required
Exhaust system After each kart operation Apply oil against corrosion
Filter element in the intake silencer Latest after every 10 hours of
operation (depending on conditions
of operation)
Clean and apply oil,
Renew damaged filter element
Coolant pump Inspection before each kart
operation Inspect for exit of oil or coolant from the leakage bore in the crankcase.
In case of leakage let engine
overhaul carry out by an authorized
distributor or Service Center
Coolant elbow fitting on crankcase
and cylinder head cover. Inspection before each kart operation Checking for tight fit and sealing, reseal with securing - and sealing
agent ERGO 4052 as required
Function of exhaust valve Latest after every 10 hours of
operation Check for easy moving of the valve and correct fit of the single
componentes
Oil in the gear compartment After every 2 hours of operation Check oil level,
replenish as required
Drive gears for the balance shaft After every 10 hours of operation Inspect for wear,
renew worn parts
Oil in the gear compartment After every 50 hours of operation or
at least once a year Oil change
Starter reduction gear assembly Latest after every 10 hours of
operation (depending on conditions
of operation)
Clean and apply grease on bearing
seats
Needle cage or bearing bush of
clutch drum After every 2 hours of operation Clean and grease, replace worn parts
Friction lining of the fly weights After every 10 hours of operation Inspect for wear replace worn fly
weights
Insulating mat of aftermuffler After every 10 hours of operation Replace
Engine overhaul After 50 hours of operation,
Inspection of the following
components: Piston, piston pin and
needle cage, oil seals of crank
shaft, drive of balance shaft,
sealing of the waterpump shaft
Let the engine overhaul carry out by
an authorized distributor or Service
Center.
Table 2

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Special tools, securing and sealing agents
Figure 1
Figure 2
14
16
15
17 18
Pos. ROTAX Teile-Nr. Bezeichnung Verwendung
1 277 380 crankshaft fixation tool for locking of the crankshaft
2 277 362 sprocket fixation tool for fitting of the sprocket
3 276 015 puller assembly to pull off the starter gear from the crankshaft
4 944 230 cover 12 to protect the crankshaft end
5 676 010 fitting sleeve installation of crankshaft oil seals
6 676 020 fitting punch installation of waterpump oil seals
7 676 030 fitting punch removal and installation of needle bushing for
starter reduction gear
8 676 040 fitting punch for plain bearing of sprocket with 11 t.
9 676 035 insertion pusher piston pin circlip installation
10 876 762 trestle assy engine support at service and maintenance
work
11 676 050 mounting plate for ROTAX engines type 100 and FR 125 MAX
12 297 040 "ROTAX" - seal with registered serial no.
13 296 160 gasket set for the engine
14 897 655 ERGO 4052 securing agent, medium strength (2 gr.)
15 297 434 LOCTITE Anti Seize preventing fretting corrosion (50 ml.)
16 899 788 LOCTITE 648 securing agent, high strength (5 gr.)
17 897 161 MOLYCOTE 111 silicone grease (100 gr.)
18 297 386 SILASTIC 732 RTV sealing compound (100 gr.)
Tabelle 3

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Location of the engine serial number
Theengine numberis imprintedon theclutch sidecrankcasehalf. Alwaysstate theengine
number on inquiries, when ordering replacement parts and in case of a warranty claim.
ENGINE REMOVAL FROM THE CHASSIS
◆ Note: There is no need to remove the engine from the chassis to repair the
following components:
Centrifugal clutch
Cylinder assy with combustion insert and cylinder head cover
Exhaustvalve
Reedvalve
Piston
▲Warning: Before proceeding with repair work disconnect the battery (first the minus
pole. Caution: High voltage at ignition unit!

RepairManualFR125MAXandFR125JuniorMAX
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Engine removal
▲ Warning: Strictly observe removal and installation directives of the kart producer
➩ Let the engine cool down first
➩Clean the Kart
➩Disconnect the battery
▲Warning: Disconnect the battery only with
ignition switched off. First detach the
cablefrom theminus terminalandthen
from the plus terminal
➩Remove the exhaust springs and remove the
exhaust system
➩Remove the lower engine pedestal brackets
➩Remove the drive chain
➩Disconnect the plugs for ignition coil (1), for pick-
up(2) andfortheelectricstarter(3)fromthecable
harness by releasing the respective catch.
■Attention: Pullonlyon theplug,neveronthecable
➩Detach the ignition coil (4) by removal of the two
lock nuts (5)
➩Pull off the fuel hose from the carburetor which
connects fuel pump with carburetor
➩Pull off and plug the fuel hose from the fuel pump
which connects fuel tank with fuel pump.
▲ Warning: Anyspilledfuelmustbe absorbedat oncewith abonding agentand disposed
offecologically
➩Slacken the clamps (6) and (7) and remove the
carburetor
▲Warning: When removing the carburetor fuel
could flow out. Do not smoke or allow
naked flames. Prevent any contact of
fuelwith hotengine partsor equipment
–Risk of fire and explosion. Never
handle fuel in closed rooms.
➩Remove the engine along with radiator and intake
silencer.
Figure 4
Figure 3
8
67
3
4
1
2
5

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Setting up the engine on the trestle
➩Remove the engine pedestal from the cleaned engine, place the engine on the trestle
and secure with 4 fixing screws.
◆ Note: Special tool –”trestle assembly”
ROTAX part no.: 876 762, 676 050
ENGINE DISASSEMBLY
Removal of the radiator
➩Loosen the two hose clamps on the coolant hose elbow fittings of the engine.
➩Remove the lock nut (1) from radiator support on engine side.
➩Pull off the hose along with the radiator from the lower 90°elbow fitting and drain the
coolant.
▲ Warning: Risk of scalding when draining the coolant or removing the radiator cap at
operating temperature. Let the engine cool down first.
➩Afterwards pull off the hose from the top elbow fitting.
Removal of the intake silencer and of the carburetor socket
➩Pull off the impulse hose (2) from the fitting on the gear cover
➩Removethe 5Allen screws(M6) onthe carburetor
socket (3)
➩Remove the intake silencer (4) along with support
bracket (5) and fuel pump (6)
Removal of the electric starter
➩RemovebothAllenscrew M6, securingtheelectric
starter on the crankcase
➩Remove the electric starter (7)
Figure 5
2
5
7
6
1
3
4

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Removal of the centrifugal clutch
➩Remove the spark plug
➩Fit the crankshaft fixation tool (7) completely into
spark plug tapping (fig. 7)
◆ Note: Special tool –”crankshaft fixation tool”
ROTAX part no. 277 380
➩Remove the hex. nut (1)
➩Remove the thrust washer (2), clutch drum with
chain sprocket (3), needle cage (4) and the thrust
washer (5).
◆ Note: On the chain sprocket with 11 teeth a bearing bush pressed into the chain
sprocket will be used instead of the needle cage (4).
➩Remove the hex. nut (6)
➩Inclinethe engineandwiththecrankshaft pointing
upwards,place thecover12(8)on crankshaftend.
◆Note: Special tool –”cover 12”
ROTAX part No. 944 230
➩Attach the puller assy (9) with 2 Allen screws M6 x
20 on the starter gear.
◆ Note: Special tool –”puller assembly”.
ROTAX part no. 276 015
◆ Note: Turn in the M6 screws only so far into
the starter gear that a gap of at least 1
mm will remain between the screws
and crankcase.
➩Press off the starter gear by turning-in the puller
screw M10 (fig 7)
➩Remove the two Allen screws securing the
reductiongearcover (10)andremovethereduction
gear cover.
➩Remove the starter reduction gear assembly (11)
and the trustwasher (12) underneath.
➩Remove the crankshaft fixation tool (7) from the
spark plug tapping.
Figure 6
Figure 7.1
Figure 7
9
8
7

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Removal of the cylinderhead cover and combustion chamber insert
◆ Note: Ifonly thecrankcase hasto betaken to
pieces the completely assembled unit
of cylinder with reed valve, carburetor
socket, exhaust valve assy, exhaust
socketand combustionchamber insert
and cylinderhead cover, can be
removed from crankcase.
➩Remove 4 Allen screws M6 (1) (fig. 8)
➩Remove the cylinderhead cover (2)
➩Take off both O-rings (3) and (4)
➩Remove 5 Allen screws M8 (5) and lock washers
➩Remove the combustion chamber insert (6) and
O-ring (7)
Cylinder-removal
➩Remove 4 hex. nuts(8) with a A/F 11 spanner
➩Remove the cylinder (9) from the crankcase
■Attention: Take care not to damage the piston
➩Remove the cylinder base gasket (10)
Piston – removal
➩Force out the piston pin circlips (11) with a suitable
tool
■Attention: Prior to the removal of the piston pin
circlips cover the crankcase opening
witha cleanrag(fig. 9)toprevent piston
pin circlips from dropping into the
crankcase.
➩Pushoutthepistonpin(12)with theinsertionpusher
◆ Note: Special tool –”insertion pusher”
ROTAX part no: 676 035
■Attention: Alwayssupportthe pistonby hand(fig.
9) whilst pushing out the piston pin to
avoidabending momentontheconrod.
➩Remove the piston (13) along with needle cage
(14)
Figure 8
Figure 9
Figure 10

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Disassembly of the drive for the balance shaft and waterpump shaft.
➩Remove the lowest Allen screw of gear cover (1)
and sealing washer and drain the oil.
▲ Warning: Dispose of all operating fluids and
cleaningagents inaccordance withthe
effective environment issues.
➩Afterwards remove the remaining 7 Allen screws
M6 and remove the gear cover (1) and the gasket
(2)
➩Remove the waterpump pinion (3) and the
waterpump idle gear (4)
➩Remove the needle pin (5) and the thrust washer
(6) from the waterpump shaft
➩Remove the retaining rings (7) with a pair of snap-
ring pliers
▲ Warning: At reassembly use new retaining rings
withoutfail
➩Remove the drive gear (8) from the crankshaft.
➩Preheat the two balance gears (9) uniformly with a hot air gun and remove them from
the balance shaft
➩Remove the O-ring (10) from the crankshaft.
Separation of the crankcase halves
➩Remove all the 10 crankcase fasteners (M6)
➩Take off the engine from the trestle
◆ Note: For the separation of the crankcase
halves the 2 Allen screws M6 x 60 of
the puller assembly must be used.
◆ Note: Special tool ”puller assembly”
ROTAX part no. 276 015
➩Turn-in the 2 Allen screws (11) simultaneous thus
separating the crankcase halves uniformly.
➩Remove the waterpump impeller (12) with the
pump shaft.
➩Removethe balanceshaft(13) fromthecrankcase
➩Take off the gasket from the crankcase joint.
Figure 12
Figure 13
Figure 14
11
11

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Crankshaft removal
➩Firmly hold the crankshaft with on hand. Remove
the crankshaft from the crankcase half by smart
blows with a mallet on the crankshaft end.
▲Warning: Be aware of the weight of the forced
out crankshaft. Risk of injury.
INDIVIDUAL COMPONENT MAINTENANCE
▲Warning: Any component with wear in excess of the specified wear limit or with
shortcomings detected at inspection which will impair engine operation
has to be replaced.
■Attention: Risk of burns when handling hot engine parts.
◆ Note: When taking dimensional readings in the order of accuracy of 0,1 mm or
even more precise, the temperature of the part must be between 20°C-
25°C.
Crankcase
➩Cleanboth crankcasehalves, ballbearings andall
bearingsealswitha non-aggressivecleaning lotion.
■Attention: Donotusedegreasingorcold cleaning
agents.
➩clean all sealing faces carefully.
✔inspect both crankcase halves for cracks and
damage.
✔inspect all sealing surfaces for damage.
✔verify all threads for good condition.
✔check the oil ducts (1) for the main bearings for
free passage and clear if necessary with
compressed air.
Figure 15
Figure 16
11

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✔check the leakage bore (1) of the sealing system
of the waterpump shaft for free passage and if
necessary clear with compressed air.
✔inspectthe borefor thewaterpump shaftfortraces
of wear
✔check all ball bearings and the needle bushing of
the starter reduction gear for easy motion and
pitting.
◆ Note: Before checking the ball bearings and
the needle bushing oil them. The inner
race of the bearings must rotate freely
and without noise. In case of doubt
renew the bearings.
◆ Note: If oneofthe twoball bearingsofthecrankshaftor balanceshaftisdefective
always renew both bearings.
◆ Note: At replacement of the crankshaft bearings or the balance shaft bearings
renew all the associated oil seals too.
Removal and refitting of bearings and oil seals
➩remove the oil seals (2) and (3) for the crankshaft with a suitable tool from the two
crankcase halves.
➩removethetwo oilseals (4)of the waterpumpwith
a suitable tool.
➩detachthepick-up (5)oftheignition unitbyremoval
of the two Allen screws (6).
➩remove the venting screw (7)
➩removethe countersinkscrew(8) andtheretaining
washer (9)
➩preheatthe twocrankcase halves30 min.in ahot-
air heater set to 100°C
▲Warning: Use heat protecting gloves when
handling the hot crankcase
Figure 17
Figure 18
1

RepairManualFR125MAXandFR125JuniorMAX
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➩take the preheated clutch side crankcase half (1)
fromtheheatingunit anddropit onaplanewooden
plate. The impact with release the ball bearing of
thecrankshaft (2)and ofthebalance shaft(3) from
the crankcase half.
➩turn over the crankcase half and push out the
needlecage(4)with thefittingpunch (seefig.19.1).
◆ Note: special tool ”fitting punch”
ROTAX part no.: 676 030
◆ Note: If the cooling water elbow will be
replaced, screw - in the new elbow
fitting only so far that one course of the
thread remains visible.
➩Apply securing –and sealing compound ERGO
4052on thedegreased threadofthecoolingwater
elbow fitting (5).
◆ Note: ERGO 4052
ROTAX part no. 897 655
➩Screw - in and fix the elbow fitting into crankcase
in horizontal position until the securing –and
sealing compound has hardened.
➩take the ignition side crankcase half (6) from the
heating unit and drop it on a plane wooden plate.
The impact with release the ball bearing (7) of the
crankshaft from the crankcase half.
➩turn over to crankcase half and drop it with the
sealing surface of the gear cover on to the plane
wooden plate. The impact with release the ball
bearing(8) ofthebalance shaftfrom thecrankcase
half.
◆Note: The wooden plate must be with
recesses for the two dowel pins (9) as
well as for the locating pin (10) to
warrant a plane support of the
crankcase half on the wooden plate.
◆Note: If the locating pin (10) needs renewal
remove it from the hot crankcase with
a pair of pliers.
Figure 19
Figure19.1
Figure 20

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➩let the crankcase halves cool down to room temperature (20°C)
➩clean the bearing seat with a non-aggressive cleaning agent.
✔measure the dia of the bearing seats in both crankcase halves.
✔measure the outside dia of the new ball bearings
✔calculate the interference fit between the ball bearings and the corresponding bearing
seat in the crankcase.
■Attention: Theinterference betweentheball bearingouterraceandthe corresponding
bearing seat in the crankcase must be at least 0,01 mm. If this is not the
case, the crankcase has to be replaced.
➩preheat again both crankcase halves by hot air to
100°C
➩take the preheated clutchside crankcase half from
the heating unit and place it with the crankcase
joint surface down on a plane wooden plate
➩press the needle cage (1) fully home into the
crankcase half with the inscription of the needle
cageshowing outwards,usingthe fittingpunch(2).
◆ Note: special tool, ”fitting punch”
ROTAX part no.: 676 030
➩turn over the crankcase half
➩apply grease between the sealing lip and the dust
lip of the oil seal (25 x 38 x 7) for the clutchside crankcase half.
➩press oil seal fully home with the fitting sleeve from the inside of the crankcase half,
with the open side of the oil seal pointing inwards.
◆ Note: special tool,”fitting sleeve”
ROTAX part no.: 676 010
◆ Note: On an engine with the crankshaft installed, the oil seal can also be fitted
from outside with the help of the fitting sleeve.
➩push ball bearing (3) for crankshaft fully home into
crankcasehalf, withtheclosed sideofthe ballcage
pointing towards the crankshaft
➩push the ball bearing for the balance shaft fully
home,with theclosed sideofthe ballcage pointing
towards balance shaft.
➩let the crankcase half cool down.
Figure 21
Figure 22
1
2
3

RepairManualFR125MAXandFR125JuniorMAX
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➩Take the ignition-side crankcase half from the hot
air heater and place it with the crankcase joint
surface down on a plane wooden plate
➩push the ball bearing (1) for the balance shaft fully
home,with theclosedside ofthe ballcagetowards
balance drive gear
➩fit the retaining washer (2) and the countersink
screw(3) suchthat thechamfer sideof thewasher
points towards the screw.
➩Apply grease between the sealing lip and the dust
lip of the oil seal (28x38x7) for the ignition-side
crankcase half.
➩Presstheoilseal(4)fullyhomewiththefittingsleeve
(5) from the outside of the crankcase half with the
openside pointingtowardsthebalanceshaft drive.
◆ Note: Special tool „fitting sleeve“
ROTAX part no.: 676 010
◆ Note: On an engine with the crankshaft
installed the oil seal can also be fitted
from the outside with the help of the
fittingsleeve
◆ Note: if the locating pin (9,see fig 20) has been removed, press the new locating
pin with the chamfering leading, fully home into the crankcase.
➩Turn over the crankcase half
➩Push the ball bearing (6) for the crankshaft fully
home into the crankcase half, with the closed side
of the ball cage pointing towards the crankshaft.
Figure 23
Figure 24
Figure 25
6
4
5
1
2
3