BRP ROTAX FR 125 MAX Repair Manual
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BRP ROTAX FR 125 MAX Repair Manual

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REPAIR MANUAL
for ROTAX-engines type
Version:
Engine configuration no.:
Version:
Engine configuration no.:
Edition:
Bombardier-Rotax GmbH
A-4623 GUNSKIRCHEN
Welser Strasse 32
AUSTRIA
http://www.rotax.bombardier.com
Page 1
Repair Manual FR 125 MAX and FR 125 Junior MAX
EO2
FR 125 MAX
FR 125 Junior MAX
FR 125 MAX (21 kW)
37.125.1301
FR 125 Junior MAX (15 kW)
30.0125.130
11 2000
Edition 11/2000

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Summary of Contents for BRP ROTAX FR 125 MAX

  • Page 1 Repair Manual FR 125 MAX and FR 125 Junior MAX REPAIR MANUAL FR 125 MAX for ROTAX-engines type 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...

  • Page 2: Preface

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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 development without updating this Manual.

  • Page 3: Table Of Contents

    Repair Manual FR 125 MAX and FR 125 Junior MAX Table of contents Preface ................................2 IMPORTANT INFORMATION ......................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 ENGINE REMOVAL FROM THE CHASSIS ................
  • Page 4 Repair Manual FR 125 MAX and FR 125 Junior MAX Electric starter ............................39 Radiator ..............................40 Intake silencer ............................40 Carburetor ..............................41 Fuel Pump ..............................42 Exhaust system ............................42 ENGINE REASSEMBLY ......................43 Crankcase assembly ..........................43 Installation of the balance shaft and water pump drive ................45 Piston installation ............................46 Cylinder installation ...........................47 Installation of combustion chamber insert and cylinder head cover ............

  • Page 5: Important Information

    Repair Manual FR 125 MAX and FR 125 Junior MAX IMPORTANT INFORMATION Repeating symbols Pay attention without fail to the following symbols throughout the Manual emphasizing particular information. Warning: Identifies an instruction, which if not followed may cause injury or endanger the life of the rider, mechanic or third party.
  • Page 6 Repair Manual FR 125 MAX and FR 125 Junior MAX 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.

  • Page 7: Technical Data

    Repair Manual FR 125 MAX and FR 125 Junior MAX Technical data Engine Type FR 125 MAX FR 125 Junior MAX Bore/Stroke 54,0 mm / 54,5 mm Displacement 125,0 cm Performance ( max.) FR 125 MAX 21 kW at 11.500 rpm FR 125 Junior MAX 15 kW at 8.500 rpm Torque (max.)

  • Page 8: Check And Service Intervals Of Engine Components

    Repair Manual FR 125 MAX and FR 125 Junior MAX Check and service intervals of engine components Component Inspection or maintenance Checking, remedy schedule Chain sprocket Inspection before each kart Inspect for wear or deformation of operation teeth, renew as required Exhaust system After each kart operation Apply oil against corrosion...

  • Page 9: Special Tools, Securing And Sealing Agents

    Repair Manual FR 125 MAX and FR 125 Junior MAX Special tools, securing and sealing agents Figure 2 Figure 1 Pos. ROTAX Teile-Nr. Bezeichnung Verwendung 277 380 crankshaft fixation tool for locking of the crankshaft 277 362 sprocket fixation tool for fitting of the sprocket 276 015 puller assembly...

  • Page 10: Location Of The Engine Serial Number

    Repair Manual FR 125 MAX and FR 125 Junior MAX Location of the engine serial number The engine number is imprinted on the clutch side crankcase half. Always state the engine 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...

  • Page 11: Engine Removal

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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.

  • Page 12: Setting Up The Engine On The Trestle

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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...

  • Page 13: Removal Of The Centrifugal Clutch

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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.

  • Page 14: Removal Of The Cylinderhead Cover And Combustion Chamber Insert

    Repair Manual FR 125 MAX and FR 125 Junior MAX Removal of the cylinderhead cover and combustion chamber insert Note: If only the crankcase has to be taken to pieces the completely assembled unit of cylinder with reed valve, carburetor socket, exhaust valve assy, exhaust socket and combustion chamber insert and cylinderhead cover, can be...

  • Page 15: Disassembly Of The Drive For The Balance Shaft And Waterpump Shaft

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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 cleaning agents in accordance with the effective environment issues.

  • Page 16: Crankshaft Removal

    Repair Manual FR 125 MAX and FR 125 Junior MAX 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.

  • Page 17: Removal And Refitting Of Bearings And Oil Seals

    Repair Manual FR 125 MAX and FR 125 Junior MAX check the leakage bore (1) of the sealing system of the waterpump shaft for free passage and if necessary clear with compressed air. inspect the bore for the waterpump shaft for traces of wear check all ball bearings and the needle bushing of the starter reduction gear for easy motion and...
  • Page 18 Repair Manual FR 125 MAX and FR 125 Junior MAX take the preheated clutch side crankcase half (1) from the heating unit and drop it on a plane wooden plate. The impact with release the ball bearing of the crankshaft (2) and of the balance shaft (3) from the crankcase half.
  • Page 19 Repair Manual FR 125 MAX and FR 125 Junior MAX 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.
  • Page 20 Repair Manual FR 125 MAX and FR 125 Junior MAX 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 the closed side of the ball cage towards balance drive gear fit the retaining washer (2) and the countersink...
  • Page 21 Repair Manual FR 125 MAX and FR 125 Junior MAX apply Molycotc 111 around the sealing lip of both oil seals (10 x 26 x 7). Note: Molycote 111 ROTAX part no. 897 161 press the first oil seal with the fitting punch (1) fully home such that the closed side of the oil seal is visible.

  • Page 22: Crankshaft

    Repair Manual FR 125 MAX and FR 125 Junior MAX Crankshaft clean the crankshaft with a non-aggressive cleaning agent. clean the taper for starter gear assy and the two threads from remains of the securing agent inspect the crankshaft for damage or traces of wear on, threads taper bearing seats...

  • Page 23: Replacement Of The Crankshaft Repair Set

    Repair Manual FR 125 MAX and FR 125 Junior MAX Replacement of the crankshaft repair set Attention: Repair of the crankshaft requires special tooling and ought to be carried out exclusively by a Repair Shop with respective experience. If this repair service is not available, replace the complete crankshaft.

  • Page 24: Balance Shaft

    Repair Manual FR 125 MAX and FR 125 Junior MAX Balance shaft Inspect the groove (1) for the retaining ring for damage and wear Check the diameter of the bearing seats M10 and M11 for wear M10 = 14,94 mm M11 = 24,94 mm Note:...

  • Page 25: Drive Of The Waterpump

    Repair Manual FR 125 MAX and FR 125 Junior MAX Drive of the waterpump Inspect the drive gear (1) the idle gear (2) and the waterpump pinion (3) for cracks. Inspect the tooth flanks of the idle gear (2) and of the waterpump pinion (3) for wear.

  • Page 26: Centrifugal Clutch

    Repair Manual FR 125 MAX and FR 125 Junior MAX Centrifugal clutch Remove the 3 retaining rings (1) and the washers (2) placed underneath. Attention: Do not overstress the retaining rings at removal Gradually remove the 3 flyweights along with the engaged springs from the bearing pins on the starter gear (5), utilizing a suitable tool (see fig.

  • Page 27: Bearing Of The Clutch Drum Assembly

    Repair Manual FR 125 MAX and FR 125 Junior MAX Place the 3 rubber sleeves (6) on to the supporting pins on the starter gear (5) (see fig 35) Fit the 3 fly weights (3) on the bearing pins of the starter gear (see fig 35) Note: When fitting the flywheel set, take care...

  • Page 28: Clutch Drum With Chain Sprocket Assembly

    Repair Manual FR 125 MAX and FR 125 Junior MAX Press out the bearing using the fitting punch Note: special tool ”fitting punch” ROTAX part no.: 676 040 Place the new plain bearing (7) with the chamfered end (8) on the chain sprocket (with 11 teeth) and press it fully home into the chain sprocket.

  • Page 29: Cylinder Assembly

    Repair Manual FR 125 MAX and FR 125 Junior MAX Cylinder assembly Note: If the cylinder assembly has bean taking to pieces, it is recommended to check the following components Exhaust valve assembly ( only on engine version FR 125 MAX ) Note: The cylinder is equipped with a pneumatic exhaust control which optimizes the performance characteristic.

  • Page 30: Disassembly Of The Exhaust Valve (Only On Engine Version Fr 125 Max)

    Repair Manual FR 125 MAX and FR 125 Junior MAX Disassembly of the exhaust valve (only on engine version FR 125 MAX) disengage spring clip (1) and remove the valve cover (2) along with adjustment screw (3) and the compression spring (4) underneath. Remove the two Allenscrews (5) and spring washers Remove the valve rod housing assy (6) and gasket (7) from the cylinder Remove the hose spring (8) from the bellows (9) and by applying by pressure remove...

  • Page 31: Installation Of The Exhaust Valve (Only An Engine Version Fr 125 Max ),.See Fig. 39

    Repair Manual FR 125 MAX and FR 125 Junior MAX Installation of the exhaust valve (only an engine version FR 125 MAX ),.see fig. 39. Slide the exhaust valve (12) with the fitted stud (11) into the cylinder in the specific position as depicted in the fig.

  • Page 32: Exhaust Socket

    Repair Manual FR 125 MAX and FR 125 Junior MAX Exhaust socket Verify the joint between cylinder (1) and exhaust socket (2) for tightness. Renew the gasket (3) as required. Verify the tight fit of the exhaust socket (2) on the cylinder Inspect the ball joint of the exhaust socket (2) for wear.

  • Page 33: Reed Valve Assembly And Carburetor Flange

    Repair Manual FR 125 MAX and FR 125 Junior MAX Reed valve assembly and carburetor flange Remove the five Allen screws (5), the carburetor flange (6) and the hose champ (7) Remove the reed valve (8) and gasket (9) from the cylinder Inspect the rubber coating on the valve body (8) for peeling off.

  • Page 34: Cylinder

    Repair Manual FR 125 MAX and FR 125 Junior MAX Cylinder Remove calcareous deposits from the water jacket (1) of the cylinder. Clean exhaust port and exhaust valve duct (2) from combustion deposits. Clean the o-ring groove (3) and inspect for damage Inspect all threads for good condition Ensure that all sealing surfaces are clean and plane...

  • Page 35: Piston And Piston Ring

    Repair Manual FR 125 MAX and FR 125 Junior MAX Piston and piston ring Inspect the piston for cracks, pressure marks and piston seizure. Inspect the bore for the piston pin for wear and scoring Check the groove for the piston pin circlips for good condition Verify free movement of the piston ring in the groove Note:...

  • Page 36: Piston Pin, Needle Cage, Piston Pin Circlips

    Repair Manual FR 125 MAX and FR 125 Junior MAX Take readings of the piston dia. using a micrometer, at 20 mm from bottom end of piston and 90 degrees to piston pin axis. Determine the piston-to-wall clearance by deducting the piston dia. from the cylinder dia.The wear limit M21 must not be exceeded.

  • Page 37: Combustion Chamber Insert

    Repair Manual FR 125 MAX and FR 125 Junior MAX Combustion chamber insert Clean the combustion chamber (1) from combustion deposits and the water jacket surface from calcerous deposits. Inspect the combustion chamber insert for cracks and verify the spark plug thread (3) for good condition.

  • Page 38: Ignition Unit

    Repair Manual FR 125 MAX and FR 125 Junior MAX Ignition unit Note: Ignition timing is controlled by the digital battery ignition unit consisting of the trigger coil on the crankcase and an ignition coil with the integrated electronic. Manual ignition adjustment is neither required nor possible.

  • Page 39: Spark Plug

    Repair Manual FR 125 MAX and FR 125 Junior MAX Spark plug Note: The engine from the serial production will be supplied with a spark plug of type NGK BR 10 EG or DENSO IW31 remove deposits from mass- and centre electrode with a wirebrush verify or adjust the electrode gap M23 of the spark plug with a feeler gauge.

  • Page 40: Radiator

    Repair Manual FR 125 MAX and FR 125 Junior MAX Radiator Clean the cooling fins of the radiator from dirt. Inspect the radiator (1) for cracks and damage. Note: slight local deformation of the cooling lamination can be rectified by straightening out.

  • Page 41: Carburetor

    Repair Manual FR 125 MAX and FR 125 Junior MAX Carburetor Note: At malfunction of the engine caused by the carburetor take the carburetor to pieces, clean it and check some of the components Take the carburetor into single parts as shown in fig.

  • Page 42: Fuel Pump

    Repair Manual FR 125 MAX and FR 125 Junior MAX Fuel Pump Note: Only the diaphragm and gasket set of the full pump can be replaced. If the cause for an engine malfunction is suspected to be the fuel pump, it can be found out only by replacement of the pump.

  • Page 43: Engine Reassembly

    Repair Manual FR 125 MAX and FR 125 Junior MAX ENGINE REASSEMBLY Attention: Always renew removed gaskets, circlips, 0-rings and oil-seals at engine repair. Attention: Risk of burns at handling of hot components Crankcase assembly preheat both crankcase halves with bearings and oil-seals already fitted in a hot air stove at 50°C for 30 min.
  • Page 44 Repair Manual FR 125 MAX and FR 125 Junior MAX Warning: Always wear heat-protective gloves when handling the hot crankcase Place the preheated clutch-side crankcase half on the ignition side crankcase half. bolt together the two crankcase halves with 9 Allen screws Note: Observe the diffent length of the Allen screws.

  • Page 45: Installation Of The Balance Shaft And Water Pump Drive

    Repair Manual FR 125 MAX and FR 125 Junior MAX Installation of the balance shaft and water pump drive Insert the o-ring (1) into groove on the crankshaft preheat the balance gears (2) and (3) to 50°C fit the preheated balance gear (2) with hub collar outwards, on the crankshaft such that the markings (4) on crankshaft and balance gear align fit the preheated balance gear (3) with hub collar...

  • Page 46: Piston Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Piston installation Apply engine oil to lubrication ducts for the crankshaft main bearings and to big-end conrod bearing as well as to piston pin and needle cage. Note: Cover the crankcase with a clean rag to prevent any foreign matter from dropping into crankcase.

  • Page 47: Cylinder Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Place the circlip insertion tool such on the piston that the open ends of circlip point to 6 o’clock position Note: The insertion punch centers itself in the piston pin support piston with one hand and push the circlip from the locating sleeve into the piston (see fig.

  • Page 48: Installation Of Combustion Chamber Insert And Cylinder Head Cover

    Repair Manual FR 125 MAX and FR 125 Junior MAX Installation of combustion chamber insert and cylinder head cover Place the o-ring (1) into groove of cylinder Put on the combustion chamber insert (2) and attach with 5 hex. screws M8 (3) and lock washers. Tighten the screws crosswise to the specified torque M27 M27 =...

  • Page 49: Checking And Adjustment Of The Squish Gap Between Piston And Combustion Chamber Insert

    Repair Manual FR 125 MAX and FR 125 Junior MAX Checking and adjustment of the squish gap between piston and combustion chamber insert. Note: The gap between the piston (in T.D.C.) and the combustion chamber insert is defined as squish gap and is of essential influence on performance characteristic of the engine.

  • Page 50: Starter Reduction Gear Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Attention: The smaller the squish gap the higher the compression of the engine and the move critical the engine reaction on jetting of the carburetor at changing ambient conditions (temperature, atmospheric pressure, humidity) Note: It is recommended to set the squish to the larger end of the respective range.

  • Page 51: Centrifugal Clutch Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Centrifugal clutch installation Screw the fixation tool (see fig 7) fully into the spark plug tapping Note: special tool – ” crankshaft fixation tool” ROTAX part no.277 380 Degrease the bore of starter gear (see fig 35) and the taper of the crankshaft. apply LOCTITE 648 on taper bore of starter gear and fit the starter gear assembly (fly weights already fitted) on the crankshaft taper.

  • Page 52: Pick-Up Coil For Ignition Unit - Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Pick-up coil for ignition unit - installation Note: The pick-up coil for the ignition unit is attached with 2 Allen screws M6x16 on the sand-cast crankcase. On the crankcase in die-casting this pick-up coil is attached with 2 taptite (self tapping) screws M6x16.

  • Page 53: Radiator And Intake Silencer- Installation

    Repair Manual FR 125 MAX and FR 125 Junior MAX Radiator and intake silencer- installation Note: The support bracket for the radiator and the support bracket for the intake silencer are attached on the cylinder together with the reed valve assy and the carburettor flange (see section reed valve and carburetor flange) connect the radiator with the two coolant elbow fittings on the engine according to fig.

  • Page 54: Filling Of Gear Compartment With Oil

    Repair Manual FR 125 MAX and FR 125 Junior MAX Filling of gear compartment with oil Remove the venting screw (3) fill gear oil of specified quality M37 and quantity M38 through the opening into the gear compartment. M37 = SAE 30 M38 = 50 cm³...

This manual is also suitable for:

Rotax fr 125 junior max

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