Rotax 125 senior MAX evo User manual

INSTALLATION
MANUAL
125 SENIOR MAX EVO
125 JUNIOR MAX EVO
125 MINI MAX EVO
125 MICRO MAX EVO
KART ED. 03/2021
PART NO. 297732
ROTAX-KART.COM

Follow us:BRP-Rotax GmbH & Co KG
Rotaxstraße 1
4623 Gunskirchen, Austria
T: + 43 7246 601 - 0
F: + 43 7246 6370
www.rotax-kart.com
GENERAL INFORMATION
BRP-ROTAX RECOMMENDS PRODUCTS
OF THE FOLLOWING COMPANIES:

Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo Content
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Edition: March 01 2021
Table of Content
Chapter INTRO –
Chapter 1 – Engine installation
Chapter 2 – Fuel system
Chapter 3 – Electric system
Chapter 4 – Cooling system
Chapter 5 – Exhaust system
Chapter 6 – Installation of the accessories
Chapter 7 – Finishing work
BRP-Rotax
INSTALLATION INSTRUCTION

Notes
Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo
Edition October 01 2019/Rev. 0
NOTES
BRP-Rotax
INSTALLATION INSTRUCTION

BRP-Rotax
INSTALLATION INSTRUCTION
Chapter: INTRO
Preface
For information regarding repair of the engine 125 MAX contact an authorized service
center or consult the repair manual (available on internet under www.rotax-kart.com).
Also check out our YouTube-Channel:
Figure 1.1: QR code
Make sure 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.
Contents
This Installation Manual contains instructions for all the installation work on the ROTAX®-
Engine Type 125 MAX evo, 125 Junior MAX evo, 125 Mini MAX evo and 125 Micro MAX
evo.
General
This document and all technical data and procedures therein are property of
BRP-Rotax GmbH & Co KG and based on the state of knowledge at the time of
publication The Manual has been drawn up to the best of our knowledge. However,
excluding 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 obligation.
Engine performance may vary depending on, among other things, general conditions,
ambient temperature and altitude.
NOTE
The registration document and engine identity card must be provided to the final
consumer upon delivery by the authorized service center with handover date and
company stamp.
NOTE
The data entered in the registration document and/or engine identity card is
required for the verification of a warranty claim. Without a completely filled-in
engine identity card, no warranty claim will be granted.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo INTRO
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BRP-Rotax
INSTALLATION INSTRUCTION
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.
Safety Messages
The types of safety messages, what they look like and how they are used in this guide are
explained as follows: The safety alert symbol indicates a potential injury hazard.
mWARNING
Indicates a potential hazard, if not avoided, could result in serious injury or
death.
mCAUTION
Indicates a hazard situation which, if not avoided, could result in minor or
moderate injury.
ATTENTION
Indicates an instruction which, if not followed, could severely damage vehicle
components or other property.
ENVIRONMENTAL NOTE
Environmental notes give you tips on environmental protection.
NOTE
Indicates supplementary information which may be needed to fully complete or
understand an instruction.
✔Denotes a checking operation
TIP This information gives you additional advice and tips
INTRO
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
Safety information
mWARNING
Non-compliance can result in serious injuries or death!
For the best possible engine operation, compliance with the following advice regarding
installation of engine and equipment is required.
mWARNING
Non-compliance can result in serious injuries or death!
Engine operation is permitted only with equipment supplied by ROTAX®
mWARNING
Non-compliance can result in serious injuries or death!
Besides the engine-specific installation advice, also take note of information from the
respective chassis manufacturer.
Introduction
Congratulations on choosing the ROTAX engine Type 125 MAX.
The ROTAX® engine Type 125 MAX has been developed exclusively for use in Go-karts,
which must only be run on specified tracks. This product has numerous technical
innovations.
mWARNING
Non-compliance can result in serious injuries or death!
Before starting with installation and operation of the engine, observe the installation
instructions and Operator’s Manual and follow all instructions.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo INTRO
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BRP-Rotax
INSTALLATION INSTRUCTION
UNBOXING YOUR ROTAX POWERPACK
Congratulations on choosing a ROTAX engine! Your ROTAX kart engine comes delivered
in two boxes.
Figure 1.2: Unboxing
Engine box
The engine box contains the assembled block engine pre-filled with gearbox oil.
Accessory box
The accessory box contains all required parts for running the engine. Check integrity of
the accessory kit using the table below.
INTRO
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
Figure 1.3: Accessory box
Pos. Description Check mark
1 Radiator with coolant hoses O
2 Mounting plate with ignition coil, solenoid valve and spark plug cap O
3 Battery box and wiring harness O
4 Battery charger O
5Intake silencer O
6Fuel pump with fuel hose O
7Exhaust system O
8 Manuals and engine identity card O
9Several small parts (spark plug, screws,...) O
10 Hose package for RAVE control unit O
11 ECU O
12 Carburetor O
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo INTRO
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BRP-Rotax
INSTALLATION INSTRUCTION
ENGINE INFORMATION
Engine serial number
The engine serial number is stamped on the clutch side housing-half.
Figure 1.4: Serial number of the engine, TYPICAL
Gear oil and fuel specifications
See the latest Operators Manual.
Equipment and modifications
Modifications to engine and/or equipment are not allowed.
INTRO
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
Chapter: 1
ENGINE INSTALLATION
TOPICS IN THIS CHAPTER
Engine installation to the chassis............................................................................................................2
Attachment via engine pedestal ..............................................................................................................3
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 1
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Edition: March 01 2021

BRP-Rotax
INSTALLATION INSTRUCTION
ENGINE INSTALLATION TO THE
CHASSIS
Tools required:
• Allen key 8mm
• Ratchet wrench
NOTE
These instructions may differ depending on the
type of chassis. They are for general information
only
NOTE
Apply abrasive paper between the chassis and
the engine brackets to prevent the engine from
moving under racing conditions
Step Procedure
1 Install the upper part of the engine
brackets (2) to the engine (1).
2Place the abrasive tape strips (3) in
the area, where you will apply the en-
gine to your chassis.
3 Place the engine onto the frame and
pre-install the bottom engine brackets
(4) to the engine (1). Make sure not to
tighten them up now, so that the en-
gine is still movable onto the frame.
4Put the engine back as far as possible.
5Put the chain around the rear axle and
fit the chain to the front sprocket first.
6 Fit the chain also to the rear sprocket.
7Move the engine forward to tighten the
chain.
8If you adjusted the correct chain ten-
sion, use the stopper to keep the en-
gine in the correct position.
Step Procedure
9 Tighten the screws for the engine
brackets.
10 Make sure that the rear sprocket and
the front sprocket align to each other,
use a ruler to check it.
Figure 2.1: Example of Engine installation
1Engine 2Upper engine bracket
3Abrasive tape strips 4Bottom engine bracket
1
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
ATTACHMENT VIA ENGINE
PEDESTAL
When using an engine pedestal for the ROTAX® en-
gine 125 MAX evo/Junior MAX evo/Mini MAX evo/
Micro MAX evo, the engine is inclined at 0° to 15° in
the driving direction.
Step Procedure
1 Drill 4 holes (8.5 mm dia / 0.315 in. =
drill size) on the coordinates 80 mm x
102 mm / 3.15 in. x 4.016 in. in the top
plate of the pedestal suitable for the
chassis.
ATTENTION
Non-compliance can result in serious injuries!
When drilling the holes in the pedestal, pay atten-
tion to the advice of the chassis manufacturer.
Step Procedure
2 Connect pedestal with engine crank-
case with 4 screws M8 (min. strength
grade 8.8). Tighten screws to 24 Nm /
212 in. lb.
ATTENTION
Pay attention to chain alignment as advised by
chassis manufacturer.
NOTE
Do not fasten engine on chassis until chain is in
position and properly aligned and tensioned.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 1
Page 3
Edition: March 01 2021

Notes
Page 4
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo
Edition October 01 2019/Rev. 0
NOTES
BRP-Rotax
INSTALLATION INSTRUCTION

BRP-Rotax
INSTALLATION INSTRUCTION
Chapter: 2
FUEL SYSTEM
TOPICS IN THIS CHAPTER
Installation and connection of the fuel pump...........................................................................................2
Installation of the Bowden cable for carburetor control...........................................................................5
Installation and connection of the carburetor ..........................................................................................7
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
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BRP-Rotax
INSTALLATION INSTRUCTION
INSTALLATION AND CONNECTION
OF THE FUEL PUMP
Step Procedure
1The retaining plate, rubber buffers, fuel
pump, fuel hose (with 230 mm and
1800 mm length) is already pre-
assembled.
Figure 3.1
Step Procedure
2 Install the support bracket (pos. 1) with
fuel pump on the carburetor socket us-
ing 3 screws M6x30 (pos. 2). Tighten-
ing torque 6 Nm / 53 lbf in.
Figure 3.2
1Support bracket 2Screws M6x30
TIP Facilitate the assembly of fuel hose by
slightly widening the hose end with a pair
of circlip pliers.
ATTENTION
Fuel hose can be damaged!
Avoid excessive widening of the fuel hose.
Figure 3.3
Step Procedure
3The fuel hose with 230 mm length will
be connected later to the carburetor,
see carburetor installation in section 3.
4The larger fuel hose (pos. 1) should
be connected to the fuel filter (pos. 2)
and to the fuel tank.
2
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
Figure 3.4
1Large fuel hose 2Fuel filter
Concerns all engines except 125 MAX evo
For engines without exhaust slide, a direct connec-
tion (with vacuum hose’) between the gearbox and
the fuel pump must be installed.
NOTE
For engines with exhaust slide, see chap. 8.
Step Procedure
5Cut a 400 mm (15.75 in.) long piece of
fuel hose.
6Secure the vacuum line (pos. 2) on the
gearbox housing to prevent disen-
gagement using a tie wrap (pos. 1).
Figure 3.5
Concerns all engines
Step Procedure
7Install the connection between the fuel
tank and the fuel filter. the length of
this line may vary from chassis to
chassis.
ATTENTION
Pay attention to the direction of the arrow on
the fuel filter.
This must point towards the fuel pump.
mWARNING
Non-compliance can result in serious injuries
or death!
Route the fuel line from the fuel tank to the fuel fil-
ter so that it does not touch any moving parts of
the track and attach the fuel line onto the top side
of the chassis tube.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
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Edition: March 01 2021

BRP-Rotax
INSTALLATION INSTRUCTION
ATTENTION
The flow in the impulse hose and fuel lines
must not be restricted by the use of cable ties.
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.
2
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
INSTALLATION INSTRUCTION
INSTALLATION OF THE BOWDEN
CABLE FOR CARBURETOR
CONTROL
Tools required:
• Open-end wrench 10 mm
Step Procedure
1Carefully remove carburetor cover with
rubber ring (pos. 7, 8).
mCAUTION
Reset spring of carb piston presses against
carburetor cover and might eject carburetor
cover at removal.
Step Procedure
2 Remove nipple screw (pos. 5) with
open-end wrench 10 mm from carbu-
retor piston (pos. 2).
3Engage nipple of Bowden wire (pos. 9)
in nipple screw (pos. 5).
4 Fit nipple screw in carburetor piston
and hand tighten with open-end
wrench 10 mm.
5Insert carburetor piston (pos. 2) into
carb body with recess of piston to-
wards intake silencer.
6 Pass Bowden wire through compres-
sion spring (pos. 6) and through cover
with rubber ring (pos. 7, 8) of
carburetor.
7Fit carb cover (pos. 7) on carburetor.
8 Pass Bowden wire through Bowden
conduit and through adjustment screw
on chassis (throttle pedal).
9 Connect Bowden cable to throttle
pedal.
Figure 3.6
1 Carburetor 2Carburetor piston
3 Jet needle K57 4Clip
5Nipple screw 6Compression spring
7 Carb cover 8Rubber ring
9 Bowden cable 10 Restrictor (Mini, Micro
MAX evo)
NOTE
Shorten Bowden cable as required.
Step Procedure
10 Route carburetor Bowden cable on the
top side of the chassis tubes and at-
tach with the cable ties supplied. Make
sure that the Bowden cable does not
touch any moving parts or the track.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
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BRP-Rotax
INSTALLATION INSTRUCTION
mWARNING
Non-compliance can result in serious injuries
or death!
The carburetor Bowden cable must not be kinked
or restricted as the carburetor piston might get
stuck in full throttle position.
Step Procedure
11 Set and secure the adjustment screw
for Bowden cable on chassis so that
the carburetor piston will remain in
closed position when throttle pedal is
not activated.
12 Set and secure the stop screw for
throttle pedal so that, with pedal com-
pletely pressed down, the carburetor
piston will be in the full open position.
The Bowden cable must not be under
full tension when the throttle is in fully
open position.
2
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Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo