Inhaltsverzeichnis

Tightening Torques Rotax 912/914 – Maintenance Manual Heavy

Source: BRP-Rotax Maintenance Manual Heavy (MMH) 912/914 Series, Ed. 2 / Rev. 1 (November 2025).
All values are taken from the procedure steps of the manual; values shown only in the exploded views are marked (fig. only). The column „Page“ refers to the chapter page in the MMH.

  • Accepted torque accuracy acc. to MMH: ±10 %
  • Unless specified otherwise, threads are not lubricated (dry) when fastened.
  • Procedure acc. to MMH: screw in all fasteners by hand → apply half the torque → tighten to full torque; with multiple fasteners use a crisscross pattern.
  • Conversion: 1 Nm = 0.737 ft.lb = 8.85 in.lb
  • Always refer to the latest issue of the manufacturer's manual!

24-20-00 Internal Generator (ignition housing, stator, flywheel)

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Bracket on ignition housing (Allen screw + washer A6) M6x16 10 89 in.lb 17
Stator fixation (incl. charging coil grounding cable) 5 44 in.lb Apply LITHIUM-BASE GREASE to contact areas, screw heads and lock washer 18
Cable clamp 15/M5 for stator cable (Allen screw + lock washer A5) M5x16 5 44 in.lb 18
Ignition cover on housing (7 Allen screws + lock washers) M6x30 10 89 in.lb tighten evenly 20
HD electric starter only: Allen screws with cap nut M5 or hex nut M5 + lock washer A5 M5x45 6 53 in.lb 20
Spacer/rubber buffer of electronic module on bracket (hex nut) M6 10 89 in.lb 21
Cable clamp with grounding cable on SMD electronic module (Allen screw) M5x25 2.5 22 in.lb LOCTITE 243 21
Fly wheel hub assy. (10 screws, alternating 5x M6x30 and 5x M6x25 with lock washers A6) M6 10 89 in.lb LOCTITE 243 22
Central screw fly wheel (with washer 17/36/5 and lock washer 16) M16x1.5 45 + 180° 33 ft.lb + 180° tighten immediately after screwing in 22
External trigger coils (all Allen screws, after adjusting air gap IH02) 5 44 in.lb 23
Ignition cover (3 hex. screws) M6x16 5 44 in.lb LOCTITE 243 23

24-30-00 External Alternator

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
V-belt pulley on pulley carriers (8 Allen screws + lock washers A5) M5x16 6 53 in.lb 7
Alternator – pre-mounted Allen screw M6 M6 10 89 in.lb 8
Alternator – pre-mounted Allen screw M8 M8 24 18 ft.lb 8
V-belt tension – hex. screw M10 M10 40 30 ft.lb after adjusting the belt tension 9
V-belt tension – hex. screws M8 M8 22 16 ft.lb after adjusting the belt tension 9
(Overview of all torques: Fig. 3.1 „Tightening torque“) 3

37-10-00 Vacuum Pump

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Vacuum pump gear (Allen screw) M8x14 25 18 ft.lb LOCTITE 648 10
Countersunk screw with thrust washer (ball bearing retention) (fig. only, Fig. 4.3) M5 6 53 in.lb LOCTITE 243 4
Studs M6 for vacuum pump (if loose) M6 5 44 in.lb LOCTITE 243 11
Vacuum pump on studs (4 hex. nuts + lock washers) M6 10 89 in.lb 11

61-20-00 Governor

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Countersunk screw with thrust washer (ball bearing retention) M5x12 6 53 in.lb LOCTITE 243; Fig. 5.3 shows 5 Nm / 44 in.lb 14
Governor drive gear (Allen screw) M8x16 25 18 ft.lb LOCTITE 648 15
Governor flange: 4 Allen screws on crankcase + 2 Allen screws on flange (oil feed line) M6x20 / M6x16 10 89 in.lb LOCTITE 243 16
Governor pressure oil line on governor flange (banjo bolt, sealing rings A10x14) M10x1x23 15 133 in.lb 16
Governor pressure oil line on oil pump housing – 912 M10x1x23 15 133 in.lb sealing rings A10x14 16
Governor pressure oil line on oil pump housing – 914 M10x1x34 15 133 in.lb sealing rings A10x14 16
Cable clamp governor pressure oil line – 912 (hex. nut M8 + lock washer A8) M8 15 133 in.lb LOCTITE 243 18
Cable clamp governor pressure oil line – 914 (hex. screw + distance sleeve + lock washer A8) M8x25 15 133 in.lb LOCTITE 243 18
Plug screw M8x1 10 89 in.lb LOCTITE 243 18
Governor studs (if loose) 15 133 in.lb LOCTITE 243 18

71-00-00 Power Plant (engine suspension frame)

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Engine suspension frame – first side (Allen screws + lock washers A10) M10x35/110 60 44 ft.lb LOCTITE 243 20
Engine suspension frame – second side (Allen screws + lock washers A10) M10x35 60 44 ft.lb LOCTITE 243 20

72-10-00 Propeller Gearbox

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Bearing cover propeller shaft (4 hex. screws, hardened washers 7.2/18.8/3) M7x16 15 133 in.lb LOCTITE 243 26
Oil spray nozzle in gearbox housing (banjo bolt) M8x1 18 159 in.lb LOCTITE 243 26
Blinding shim in crankcase (countersunk screw with thrust washer) – configuration 2 M5x12 6 53 in.lb LOCTITE 243 31
Stud gearbox housing (fig. only, Fig. 8.3) 6 53 in.lb 5
Gearbox housing to crankcase – screw M6 (fig. only, Fig. 8.3) M6 10 89 in.lb 5
Gearbox housing to crankcase – screw M8 (fig. only, Fig. 8.3) M8 25 18 ft.lb 5
Hex. nut drive gear on crankshaft (fig. only, Fig. 8.3) 300 221 ft.lb LOCTITE 7063 + LOCTITE 648 5

72-20-00 Engine Block

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Hex. collar nut sprag clutch housing M34x1.5 150 111 ft.lb degrease with LOCTITE 7063, secure with LOCTITE 603 12

72-30-00 Cylinder Head

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Cylinder head studs (screwing in) 6 53 in.lb LOCTITE 648 13
Coolant elbow (2 Allen screws + washers 6.4) M6x20 10 89 in.lb 28
Fitting cylinder head: hand-tighten 2 collar cap nuts + 2 hex. nuts diagonally M8 max. 5 44 in.lb until cylinder head rests on cylinder; lightly lubricate flat surfaces of collar cap nuts, no grease on hex. nut contact areas 32/33
Intake manifold on cylinder head (2 Allen screws + washer each) M6 10 89 in.lb 33
Cylinder aligning tool 877262 on intake flange (4 Allen screws) M6x25 10 89 in.lb 34
Cylinder head tightening torque procedure step 3: all collar cap nuts + hex. nuts M8 10 89 in.lb sequence acc. to fig.; always torque both cylinder heads of one side together! 34
Cylinder head tightening torque procedure step 4: all nuts M8 30 (−5) 22 ft.lb (−4) sequence acc. to fig. 34
Cylinder head tightening torque procedure step 5: loosen each nut 360°, then M8 10 + 150° 89 in.lb + 150° one at a time following the torque sequence 34
Valve cover (Allen screw + washer 6/12/1, new O-rings 105×2.5 and 6.4×1.8) M6x30 10 89 in.lb 35

73-00-10 Carburetor – Single Parts

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Stop lever + throttle lever (hex. nut + spring washer 8.3/13.6/0.4) M8x1 5 44 in.lb 17
Choke lever / starting carburetor (hex. nut + spring washer 8.3/13.6/0.4) M8x1 6.5 57 in.lb O-ring 5×1.5 with lithium-base grease 17
Float chamber – 914 only (attachment screw, O-ring 15.6×1.78) 5.5 49 in.lb secure with safety wiring (912: spring clip) 22
Fuel connection on carburetor – 914 (Fig. 13.3) 10 89 in.lb 4

73-10-00 Fuel System and Distribution

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Clamp block fuel manifold (Allen screw) M5x16 6 53 in.lb refit in the same position 18
Fuel pressure regulator – 914: cap nut of adjustment screw 5 45 in.lb LOCTITE 243; approx. 250 hPa above airbox pressure 20
Intake manifold (4 Allen screws + washers) M6 10 89 in.lb 23
Hex. screw with new gasket 6×10 (compensation tube) M6x6 5 44 in.lb LOCTITE 243 23
Clamping block – 912 only (Allen screw) M5x16 5 44 in.lb 23
Rubber flange carburetor (hex. screws + washers, new O-ring 47×2) M8x25 / M8x30 15 133 in.lb LOCTITE 243 24
Airbox 914 – fuel line (banjo bolt, sealing rings 10×14) M10x1x19 15 133 in.lb 26
Airbox 914 – plug screw 1/8-27 NPT 10 89 in.lb LOCTITE 243 26
Airbox 914 – both hose nipples M6 M6 2 18 in.lb LOCTITE 243 26
Airbox 914 – hex. nut M6 + hose nipple M6 M6 2 18 in.lb LOCTITE 243 26
Fuel pressure regulator 914 – two hose nipples 4/6 (banjo bolts, sealing rings 10×14) M10x1x19 15 133 in.lb 28
Fuel pressure regulator 914 on airbox (hex. screws + lock washer A6) M6x16 8 70 in.lb 28
Studs fuel pump (longer threaded end into gearbox) M8 6 53 in.lb LOCTITE 243 29
Fuel pump (hex. nuts + lock washers A8) M8 15 133 in.lb LOCTITE 243, tighten evenly 29
Nipples / adapters on fuel pump (new gasket rings) 10 89 in.lb LOCTITE 577; ensure correct position 29
Fuel hose assy. with distance sleeve (banjo bolt, sealing rings A8x13) M8x1x27 10 89 in.lb 31
Feed line + fuel hose assy. (banjo bolt, sealing rings A8x13) M8x1x27 10 89 in.lb 31
Slotted head screw with sealing ring 10×14 M10x1x8 15 133 in.lb LOCTITE 243 31
912: fuel line (from tank) on pump 32 24 ft.lb 31
912: fuel feed line (to carburetor) on pump 27 20 ft.lb 31
Ring hose nipple 3/4 return, banjo bolt with pilot jet 0.35 mm (without fuel pressure gauge) M8x1 10 89 in.lb sealing rings A8x13; banjo bolt marked yellow or „FUEL“ 32
Double hose nipple assy. with pilot jet 0.35 mm (with fuel pressure gauge) M8x1x17 10 89 in.lb sealing rings A8x13 32
Collar nut (pressure connection line 914) 10 89 in.lb 33
Fuel line on fuel pressure regulator 914 (banjo bolt, sealing ring 10×14) M10x1x19 15 133 in.lb 33
Fuel line connector on carburetor (new gasket ring A8x13, both sides) 10 89 in.lb 33

Acc. to MMH (chapter 73-10-00, inspection): in the event of leaks at banjo bolts, the max. permissible torque must never be exceeded; a visibly oval hole = overstretched → replace.

74-20-00 Distribution (ignition)

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Ignition coil bracket on rubber buffer (hex. screw + lock washer A6) M6x10 10 89 in.lb LOCTITE 243 18
Attachment screws double ignition coils M5 6 53 in.lb 19
SMD electronic module (Allen screws + lock washer A5 / cable clamp 11.3/M5 with grounding cable) M5x25 2.5 22 in.lb LOCTITE 243 21/23
Ignition assy. on crankcase (Allen screw + lock washer A8) M8x10 24 18 ft.lb 22
Bracket ignition assy. (hex. screw + lock washer A6) M6x10 10 89 in.lb 22
Intake manifolds with pre-assembled ignition assy. (4 Allen screws + lock washers, crosswise) M6x25/70 10 89 in.lb 22
Grounding cables on intake manifold (hex. screw + lock washer A6) M6x16 10 89 in.lb 23
Spark plugs (fig. only, Fig. 16.3; text refers to MML chapter 12-20-00) 16 142 in.lb Silicone Heat Compound WACKER P12 5

75-00-00 Cooling System

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Water pump impeller (with special tool 877295) 15 133 in.lb LOCTITE 243 on shaft thread, stainless compensating shim 19
Water pump housing on ignition housing (2x M6x90 + 2x M6x35 with lock washers, new gasket) M6 10 89 in.lb 21
Allen screw stainless steel with new sealing ring 6×10 M6x35 10 89 in.lb 21
Water inlet elbow (2 Allen screws + lock washers, new O-ring 32×2) M6x20 10 89 in.lb 21
Coolant temperature sensor in cylinder head (fig.; text see 76-70-00) 7 62 in.lb LOCTITE 243 6

75-20-00 Mechanical Rev. Counter

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Rev counter housing (Allen screw + lock washer A5) M5x16 6 53 in.lb 8

76-50-00 Wiring Harness (914)

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Starter cables on terminals (hex. nut + washer 6.4) M6 10 89 in.lb 13

76-70-00 Sensors and Actuators

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Oil temperature sensor (OTS) in oil pump housing 7 62 in.lb LOCTITE 243 (not if housing is not dry → use gasket ring) 24
Oil pressure sensor (OPS) in oil pump housing 15 133 in.lb LOCTITE 243; close PIN A with LOCTITE 5910 or similar 24
Coolant temperature sensor in cylinder head (cyl. 2 and 3) 7 62 in.lb LOCTITE 243 25
Resistance thermometer (airbox temperature) – 914 min. 5 44 in.lb LOCTITE 243; until aligned correctly 25
Airbox pressure sensor – 914 (Allen screw + washer 6.2/14/1) M6x14 5 44 in.lb LOCTITE 243; MMH erroneously states „133 in.lb“ 26
Three-way solenoid valve – 914 (2 Allen screws + washer A6) M6x14 8 70 in.lb 29

78-10-00 Exhaust

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Exhaust studs on cylinder head M8 6 53 in.lb LOCTITE 648 13/15
Exhaust flange on cylinder head (2 new lock nuts) M8 15 133 in.lb LOCTITE Anti Seize on socket 13/15
Exhaust bend clamp – 912 6 53 in.lb 13
Exhaust pipe connection – 912/914 (fig. only, Fig. 23.2/23.3) 10 89 in.lb LOCTITE Anti Seize 5/6
Studs M8 for muffler on turbocharger – 914 (longer thread into turbo) M8 6 53 in.lb LOCTITE Anti Seize 14
Exhaust bracket (Allen screw + washer 10.5 + lock washer A10) – 914 M10x50 60 44 ft.lb LOCTITE 243 14
Muffler assy. on turbocharger (nuts + washers 8.4) – 914 M8 25 18 ft.lb 15
Support plate (hex. screw + washer 8.4) – 914 M8x16 25 18 ft.lb 15
Muffler clamp – 914 15 133 in.lb 15
Check screws/nuts on exhaust manifold assy. – 914 25 18 ft.lb 16

78-20-00 Turbocharger (914)

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Oil sump assy. (hex. screws, cable support, new O-ring 15.9-2.3) M6x55 10 89 in.lb safety wire between both screws 17
Studs turbine housing (4x M8x19.5/13 + 1x M8x30/13, longer thread into turbine housing) M8 6 53 in.lb LOCTITE Anti Seize 17
Turbocharger on manifold bracket (Allen screw + 2 washers 8.4 + hex. nut M8) M8x25 25 18 ft.lb LOCTITE Anti Seize 19
Turbo bracket (Allen screw + lock washer A10 + washer 10.5) M10x50 60 44 ft.lb LOCTITE 243 19
After exhaust is mounted: 4 hex. screws turbine housing + Allen screws exhaust manifold M8x16 / M8x25 25 18 ft.lb 19
Manifold bracket (if replaced, Allen screw) M8x50 30 22 ft.lb 19
Rope sheave servo motor (Allen screw + washer A5.2×14.8×1.5 + lock washer A5) M5x20 6 53 in.lb hold rope sheave against rotation! 21
Screw nipple Bowden cable on rope sheave 2.5 22 in.lb 22
Turbo pressure oil line on turbo (banjo bolt) (Fig. 24.2; text see 79-00-00) 10 89 in.lb 3
Cap nut check valve turbo pressure oil line (fig. only, Fig. 24.2) 25 18 ft.lb 3
Turbo oil suction line on turbo (Fig. 24.2; text see 79-00-00) 20 15 ft.lb 3
Attachment (2 screws, Fig. 24.2 bottom) (fig. only) 10 89 in.lb 3

79-00-00 Lubrication System

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Oil pump housing – 912 (Allen screws + washers 6.4, crosswise) M6x50 10 89 in.lb first crosswise by hand 25
Oil pump housing – 914 (Allen screws + washers 6.4, crosswise) M6x65 10 89 in.lb first crosswise by hand 27
Plug screw oil pressure regulator M12x1 25 18 ft.lb oiled thread; safety wire 26/28
Plug screw (if no governor installed) with sealing ring 10×14 M10x1 10 89 in.lb LOCTITE 243 26
With governor: pressure oil line(s) on oil pump housing (oiled banjo bolt, 3 sealing rings 10×14) – 914 M10x1x34 15 133 in.lb 28
Without governor: pressure oil line + spacer 10.5/15/10 (oiled banjo bolt, 3 sealing rings) – 914 M10x1x34 15 133 in.lb 28
Turbo return line (oiled banjo bolt, sealing rings 10×14) – 914 M10x1x23 15 133 in.lb 28
Hose nipple 4/6 (oiled banjo bolt, sealing rings 10×14) M10x1x23 15 133 in.lb 28
Oil tank drain screw (new gasket ring C 12×18) M12x12 25 18 ft.lb 33
Governor pressure oil line on governor flange – 914 (banjo bolt, sealing rings 10×14) M10x1x23 15 133 in.lb 37
Governor + turbo pressure oil line on oil pump housing – 914 (banjo bolt) M10x1x34 15 133 in.lb without governor: with sleeve 10.5/15/10 37
Turbo pressure oil line on turbo housing (sealing rings A8x13) M8x1x17 10 89 in.lb install ball + spring of check valve in correct order! 38
Turbo oil suction line on turbo 20 15 ft.lb 38
Turbo oil suction line on oil pump housing (banjo bolt, sealing rings 10×14) M10x1x23 15 133 in.lb 39
Cable clamp turbo oil suction line on turbocharger bracket 6 53 in.lb 39
Cable clamps on turbo pressure and suction line 6 53 in.lb 39
Oil filter threaded nipple (fig. only, Fig. 25.4/25.5) 60 44 ft.lb LOCTITE 243 5/6
Connection nipple oil inlet on oil pump housing (fig. only, Fig. 25.4/25.5) 35 26 ft.lb LOCTITE 648 5/6
Hose nipple oil inlet (fig. only, Fig. 25.4/25.5) 22 16 ft.lb LOCTITE 243 5/6
Plug screw on oil pump housing (with O-ring) (fig. only, Fig. 25.4) 15 133 in.lb LOCTITE 243 – check deviation from text „M10x1 = 10 Nm“ 5
Screw at bottom of oil pump housing – 914 (fig. only, Fig. 25.5) 12 106 in.lb engine oil 6
Bracket turbo oil line – 914 (fig. only, Fig. 25.5) 10 89 in.lb 6
Oil tank: screw on cover (fig. only, Fig. 25.6) 12 106 in.lb engine oil 7
Oil tank: hose connections (fig. only, Fig. 25.6) 25 18 ft.lb 7
Crankcase: plug screw (fig. only, Fig. 25.6) 25 18 ft.lb LOCTITE 5910 7
Crankcase: lower plug screw (fig. only, Fig. 25.6) 35 26 ft.lb LOCTITE 243 7
Crankcase: 2 banjo bolts oil lines (fig. only, Fig. 25.6) 30 22 ft.lb 7
Crankcase: connection nipple (fig. only, Fig. 25.6) 25 18 ft.lb LOCTITE 648 7

80-00-00 Electric Starter

Fastener Thread Nm in.lb / ft.lb Locking / Note Page
Assembling HD starter (Allen screws) M5x180 5 44 in.lb 16
Starter on crankcase (hex. nut M5 + lock washer A5 or cap nut M5) – standard and HD M5 6 53 in.lb 17/18
Positive pole on starter 4 35 in.lb 17/18

Discrepancies in the MMH