BRP Rotax 125 MAX evo Operation and maintenance manual

for ROTAX®-engines type
125 MAX evo
125 JUNIOR MAX evo
125 MINI MAX evo
125 MICRO MAX evo
Part no.: 297732 Edition: 09/2016
BRP-Rotax GmbH & Co KG | Rotaxstrasse 1 | 4623 Gunskirchen, Austria | T: [phone] | F: [phone]
www.rotax.com | www.rotax-kart.com
Installation instructions and
Operator‘s Manual

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
General information
BRP-Rotax recommends products of the following companies:

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For information regarding the repair of the engines 125 MAX evo/Junior MAX evo/Mini MAX
evo/Micro MAX evo contact an authorized service center or consult the workshop manual
(available on the internet at www.rotax-kart.com).
We ask to hand over this manual, the engine identity card and the product and service
registration document to the new owner in case of a change of ownership.
Preface
This document and all technical data and procedures therein are property of BRP-Rotax GmbH &
Co KG and are based on the state of knowledge at the time of publication. The manual has been
drawn up to the best of our knowledge. However, we exclude any liability.
We reserve all rights including technical modification and possibility of errors.
Reprinting, translation or copies in whole or in part, are authorized only after written permission by
BRP-Rotax GmbH & Co KG.
BRP-Rotax GmbH & Co KG reserves the right at any time to discontinue or change specifications,
prices, designs, features, models or equipment without incurring any obligations.
Engine performance may vary depending on, among other things, general conditions, ambient
temperature and altitude.

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Introduction
Congratulations on choosing the ROTAX engine Type 125 MAX evo / Junior MAX evo / Mini MAX
evo / Micro MAX evo.
The ROTAX engine Type 125 MAX evo / Junior MAX evo / Mini MAX evo / Micro MAX evo has
been developed exclusively for use in go-karts, which must only be run on specified tracks.
pWarning: Before starting with installation and operation of the engine, observe the
installation instructions and operator’s manual and follow all instructions.
pWarning: This engine performs better than comparable products.
Repeating symbols
pWarning: Identifies an instruction, which - if not followed - may cause injury or
endanger the life of the driver, mechanic or third party.
¢Attention: Denotes an instruction which if not followed may severely damage the engine. Non-
compliance might lead to health hazards under certain conditions.
¿Note: Information useful for better execution and understanding of instructions.
ÆDenotes a working operation
PDenotes a checking operation
TIP This information gives you additional advice and tips
End of section:
End of chapter:

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INSTALLATION INSTRUCTIONS FOR ROTAX ENGINE TYPE
125 MAX evo, Junior MAX evo, MINI MAX evo, Micro MAX evo

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Table of Contents of Installation Instructions
1. General...................................................................................................................................6
2. Installation and connection of the fuel system...................................................................7
2.1. Installation and connection of the fuel pump....................................................................7
3. Installation and connection of the carburetor..................................................................... 9
4. Installation of the Bowden cable for carburetor control...................................................10
5. Installation of the radiator ..................................................................................................12
6. Finalizing of mounting plate...............................................................................................14
7. Fitting of the spark plug...................................................................................................... 15
8. Installation and connection of the RAVE control unit...................................................... 16
9. Check of oil level in gear box ............................................................................................. 19
10. Engine attachment to chassis........................................................................................20
11. Installation of the wiring harness...................................................................................21
12. Installation of the battery and ECU................................................................................ 24
12.1. Install ECU into the battery holder.................................................................................24
12.2. Installation of the battery................................................................................................26
13. Fitting of the drive chain................................................................................................. 28
14. Installation of the intake silencer with integrated air filter...........................................28
15. Installation of the exhaust system................................................................................. 30
16. Finishing work................................................................................................................. 32

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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1. General
pWarning: For the best possible engine operation, compliance with the following advice
regarding installation of engine and equipment is required.
pWarning: Engine operation is permitted only with equipment supplied by ROTAX.
pWarning: Modifications to engine or equipment are not allowed.
pWarning: Besides the engine-specific installation advice, also take note of information
of the respective chassis manufacturer.
¿Note: An engine identity card stating date of delivery and company has to be issued for
the customer by the authorized service center.
¿Note: The data entered in the engine identity card is required for verification of a warranty
claim. Without a completely filled-in engine identity card no warranty claim will be
granted.
¿Note: In case of participating in the ROTAX MAX CHALLENGE (RMC), the engine must
be verified for conformity with the technical regulations and sealed.
The serial number of the seal must be entered in the Engine Identity Card.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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2. Installation and connection of the fuel system
2.1. Installation and connection of the fuel pump
ÆThe retaining plate, rubber buffers, fuel pump, fuel hose (with 230 mm and
1800 mm length) are already pre-assembled. See Fig. 1.
Fig. 1
ÆInstall the support bracket (pos. 1) with fuel pump on the carburetor socket using 3
screws M6x30 (pos. 2). Tightening torque 6 Nm / 53 lbf in. See Fig. 2.
Fig. 2
ÆThe fuel hose with 230 mm length will be connected later to the carburetor, see
carburetor installation in section 3.
ÆThe larger fuel hose (pos. 1) should be connected to the fuel filter (pos. 2) and
furthermore to the fuel tank. See Fig. 3.
Fig. 3
TIP: Facilitate the assembly of fuel hose by slightly widening the hose end with a pair of
circlip pliers.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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¢Attention: Fuel hose can be damaged! Avoid excessive widening of the fuel hose.
Fig. 4
2.1.1. Concerns all engines except 125 MAX evo
For engines without exhaust slide, a direct connection (with vacuum hose) between the
gearbox and the fuel pump must be installed, see Fig. 5
ÆTherefore, cut a 400 mm (15.75 in.) long piece of fuel hose.
¿Note: For engines with exhaust slide, see chap. 8.
ÆSecure the vacuum line (pos. 2, Fig. 5) on the gearbox housing to prevent
disengagement using a tie wrap (pos. 1).
Fig. 5
ÆInstall the connection between the fuel tank and the fuel filter. The length of this line
may vary from chassis to chassis.
¢Attention: Route the fuel line from the fuel tank to the fuel pump so that it does not touch any
moving parts or the track and attach the fuel line onto the top side of the chassis
tube.
¢Attention: The flow in the impulse hose and fuel lines must not be restricted by the use of tie
wraps.
¢Attention: The use of an extra fuel filter must not cause further flow resistance in the fuel line
between the fuel tank and the fuel pump.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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3. Installation and connection of the carburetor
See Fig. 6.
ÆRemove the transport plug from the carburetor.
ÆFit the carburetor (pos. 1) into the carburetor socket and secure with a hose clamp
(pos. 2) in vertical position.
ÆConnect the outlet hose of the fuel pump with the fuel inlet on the carburetor (pos.
3).
Fig. 6

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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4. Installation of the Bowden cable for carburetor control
See Fig. 7.
ÆCarefully remove the carburetor cover and the rubber ring (pos. 7, 8).
¢Attention: Reset spring (pos. 6) of carburetor slide presses against carburetor cover and might
eject carburetor cover at removal.
ÆRemove nipple screw (pos. 5) with A/F 10 wrench from carburetor piston (pos. 2).
ÆEngage nipple of Bowden wire (pos. 9) in nipple screw (pos. 5).
ÆFit nipple screw in carburetor piston and tighten with A/F 10 wrench.
ÆInsert carburetor slide (pos. 2) into carburetor body with recess of slide towards
intake silencer.
ÆPass Bowden wire through compression spring (pos. 6) and through cover with
rubber ring (pos. 7, 8) of carburetor.
ÆFit carburetor cover (pos. 7) on carburetor.
ÆThread Bowden wire through Bowden conduit and through adjustment screw on
chassis.
ÆConnect Bowden cable to throttle pedal.
Fig. 7
¿Note: Shorten Bowden cable as required.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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ÆRoute the carburetor Bowden cable on the top side of the chassis tubes and attach
with the tie wraps supplied. Make sure that the Bowden cable does not touch any
moving parts or the track.
pWarning: The carburetor Bowden cable must not be kinked or restricted as the
carburetor piston might get stuck in full throttle position.
ÆSet and secure the adjustment screw for Bowden cable on chassis such that the
carburetor piston will remain in closed position when throttle pedal is not activated.
ÆSet and secure the stop screw for throttle pedals such that, with pedal completely
pressed down, the carburetor piston will be in fully open position. The Bowden cable
must not be under full tension when the throttle is in fully open position.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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5. Installation of the radiator
¢Attention: To warrant the best possible engine cooling, ensure that the air stream covers the
complete radiator area.
ÆPre-mount radiator with coolant hoses and radiator support as shown in Fig. 8.
¿Note: Radiator (Pos. 1) shown in Fig. 9 fits to engine types 125 MAX evo, Junior MAX evo
and Mini MAX evo. The small radiator (Pos. 2) fits to engine type Micro MAX evo.
The installation of both radiators is similar.
Fig. 8(K00428)
ÆAttach the pre-assembled radiator to the engine with Allen screw M8x75 (pos.1) and
washer (pos.2), see Fig. 9
Fig. 9

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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ÆAttach the pre-assembled upper coolant hose to the engine using 1 hose clamp
(Pos. 3), see Fig. 10.
Fig. 10
ÆAttach the pre-assembled lower coolant hose to the engine using 1 hose clamp
(Pos. 4), see Fig. 11.
¿Note: The length of the upper and bottom hose is supposed to be different, but equal at
delivery. Therefore, cut the bottom hose using scissors or a knife.
Fig. 11

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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6. Finalization of mounting plate
¿Note: The retaining plate, the mounting plate, the solenoid valve (except engines without
exhaust slide, Fig. 12) and the ignition coil are already pre-assembled.
Fig. 12
Variant 1: Engines without exhaust slide
Fig. 13
Variant 2: Engines with exhaust slide
ÆInstall mounting plate to crankshaft housing (pos. 4) using 2 Allen screws M6x20
(pos. 1), washers (pos. 2) and lock nuts M6 (pos. 3).
Fig. 14
¿Note: The position of the mounting plate may vary (depending on the engine type and
position of the seat stay), see Fig. 15.

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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Fig. 15
7. Fitting of the spark plug
See Fig. 16.
The engine will be supplied with a spark plug of the type NGK Iridium.
ÆRemove the transport plug from the cylinder head.
ÆCheck electrode gap of spark plug. Adjust as required.
¿Note: The electrode gap of the spark plug should be 0,7 mm (0.027 in) to 0,8 mm wide
(0.032 in) (for NGK spark plugs). Only slight bending of the ground electrode is
permitted.
ÆFit supplied spark plug (pos. 1) and tighten 25 Nm (221 lbf in) to 27 Nm (239 lbf in).
ÆInstall the spark plug connector (pos. 2), ensure correct engagement.
¿Note: The engine type 125 Micro MAX evo has a special spark plug. It has been designed
for this engine exclusively. For more details, have a look at the spare parts manual.
Fig. 16

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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8. Installation and connection of the RAVE control unit
¿Note: The hose package of the RAVE control is already pre-assembled.
¿Note: The impulse restrictor is offered optionally.
Insert impulse nozzle (pos. 6) about 25 mm into the 420 mm pressure line (pos. 7)
using an Allen key SW4. Pay attention to the mounting direction! It also works
without an impulse nozzle, this only serves to delay the opening of the exhaust
valve.
¿Note: In order to prevent the displacement of the impulse nozzle (pos. 6), a small tie wrap
(pos. 8) should be attached to the pressure line directly afterwards. Do not tie up the
pressure line completely.
Fig. 17
Fig. 18

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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ÆAttach the end of the T-fitting (pos. 1) to the bottom of the fuel pump (pos. 2).
Fig. 19
ÆAttach the fuel line (pos. 1) to the impulse nipple on the engine housing and secure
the line with tie wrap (small) (pos. 2).
Fig. 20
ÆAttach the black hose of the hose package (pos. 1) to the metal connector (pos. 2)
of the magnetic valve.
Fig. 21

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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ÆFix another tie wrap (pos. 1) at the fixing point (bore) on the engine housing. Secure
both lines with tie wrap (pos. 3), ensuring that the black hose (pos. 2) is on top. See
Fig. 22
Fig. 22
ÆAttach the 280 mm pressure line (pos. 1) to the exhaust valve (pos. 2) and to the
magnetic valve (pos. 3). Secure the pressure line on the magnetic valve with a tie
wrap (pos. 4).
Fig. 23

ROTAX 125 MAX evo, Junior MAX evo, Mini MAX evo, Micro MAX evo
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9. Check oil level in gear box
The gear box is already filled with the appropriate amount of oil 100 cc (0.026 gal) by the engine
manufacturer. However, before the engine is installed in the frame, the oil level must be checked or
replenished. See Fig. 38.
ÆPlace engine on a horizontal surface and/or assembling trestle.
¿Note: To measure the oil level exactly, drain the gear oil and determine it using a
measuring cup.
ÆLoosen Allen screw (pos. 1) with gasket ring (pos. 2) and absorb the leaking oil in a
measuring cup. If necessary, remove the air vent screw (pos. 3) to ensure a better
oil drain.
ÆDetermine the gear oil using the measuring cup.
¿Note: Oil capacity at new filling is 100 cc (0.026 gal).
¿Note: Specification of gear oil: engine oil SAE 15W-40.
ÆTighten the Allen screw (pos. 1) with new gasket ring (pos. 2). Tightening torque
10 Nm.
ÆReplenish new gear oil in the air vent hole.
ÆHand-tighten the air vent screw (pos. 3).
Fig. 38