Rotax 125 MAX DD2 evo Operation and maintenance manual

for ROTAX®-engines type
125 MAX DD2 evo
Part no.: 297733 Edition: 10/2019
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

General information
BRP-Rotax recommends products of the following companies:

For information regarding the repair of the engine 125 MAX DD2 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 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.

Effectivity: 125 MAX DD2 evo Content
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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 MANUAL

Notes
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Edition /Rev. 0
NOTES
BRP-Rotax
INSTALLATION MANUAL

BRP-Rotax
INSTALLATION MANUAL
Chapter: INTRO
Preface
For information regarding repair of the engine 125 MAX DD2 evo contact an authorized
service center or consult the workshop manual
(available on internet under 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.
Contents
This Installation Manual contains instructions for all the installation work on the ROTAX®-
Engine Type 125 MAX DD2 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.
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.
Effectivity: 125 MAX DD2 evo INTRO
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INSTALLATION MANUAL
Symbols used
This Manual uses the following symbols to emphasize particular information. This
information is important and must be observed.
mWARNING
Identifies an instruction, which if not followed may cause injury or endanger the
life of the driver, mechanic or third party.
ATTENTION
Identifies an instruction which, if not followed may cause injury or endanger the
life of the driver, mechanic or third party.
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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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 DD2 evo.
The ROTAX® engine Type 125 MAX DD2 evo 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.
mWARNING
Non-compliance can result in serious injuries or death!
This engine performs better as comparable products
Effectivity: 125 MAX DD2 evo INTRO
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INSTALLATION MANUAL
UNBOXING AND PURCHASED PARTS PACKAGE
By buying a ROTAX Engine, you will receive two boxes. The engine box and the accessory box.
Figure 1.1: Unboxing
Engine box
The engine box contains the pre-assembled engine with the secure sticker, which de-
scribes the run-in procedure. Take the engine out of the box.
Accessory box
The accessory box contains all required parts for running the engine. Lay down all parts,
so you have a good overview of the parts. Check, if all parts of the following table are
delivered.
INTRO
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Effectivity: 125 MAX DD2 evo INTRO
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Figure 1.2: 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
13 Paddle shift system O
INTRO
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ENGINE INFORMATION
Engine serial number
The engine serial number is stamped on the clutch side housing-half.
Figure 1.3: Serial number of the engine, TYPICAL
Effectivity: 125 MAX DD2 evo INTRO
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Information sticker
The information sticker is glued to the intake socket. It does not only prevent dust from
coming inside the engine during the transport, it also provides you with information about
the run-in procedure and general tasks you must do at the initial run of the engine.
Figure 1.4: Information sticker
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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Chapter: 1
ENGINE INSTALLATION
TOPICS IN THIS CHAPTER
Installation of overload clutch and engine with rear axle .........................................................................2
Engine installation with engine brackets .................................................................................................3
Direct attachment of the engine to chassis..............................................................................................5
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INSTALLATION OF OVERLOAD
CLUTCH AND ENGINE WITH REAR
AXLE
NOTE
The overload clutch is the link between the en-
gine and the rear axle of the kart. In case that
the rear axle has been blocked by (e.g. break-
ing), the overload clutch is slipping slightly and
is not transferring the peak load from the rear
axle to the engine.
The plain bearings (pos. 2) are inside of the
overload clutch (pos. 1).
Figure 2.1
1 Overload clutch 2Plain bearings
Step Procedure
1Slide the clamp ring (pos. 1, following
figure ) the thrust washer (pos. 2) and
the overload clutch (3) to the middle of
the rear axle.
NOTE
The rear axle of the kart must have a smooth
surface (no grooves for keys) in the area of the
4 plain bearings of the overload clutch.
NOTE
Do not tighten the overload clutch and clamp
ring yet (see section Engine attachment with en-
gine brackets).
Figure 2.2: Overload clutch
1Clamping ring 2Thrust washer
3 Overload clutch 4Allen screw M6x25
5 Allen screw M5x30
1
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ENGINE INSTALLATION WITH
ENGINE BRACKETS
Tools required:
• Allen key 8mm
• Allen key 5 mm
• Allen key 4 mm
• Torque wrench
See Figure: Tightening sequence and Engine
brackets.
The engine has to be fixed to the chassis by means
of 2 engine brackets (pos. 1). Due to different distan-
ces of the 2 main rails of various chassis brands, the
engine bracket is not included in the scope of supply.
Figure 2.3: Engine brackets
FIGURE SIMILAR
NOTE
The 125 MAX DD2 engine can only be mounted
on specially prepared chassis for this engine
type.
mWARNING
Non-compliance can result in serious injuries
or death!
For engine attachment to the chassis, please fol-
low the instruction of the chassis manufacturer.
Step Procedure
1Slide the engine onto the rear axle and
align the rear axle and the engine by
measuring the distance between the
front and the rear axle
2 After engine alignment, tighten the 4
Allen screws M8 x 25 to fix the upper
engine bracket to the engine with 28
Nm (20.65 ft. lb). Fix and tighten the
lower engine bracket to the upper
bracket with 4 Allen screws M8 x 30
with 22 Nm (16.22 ft. lb). Secure the
Allen screws with LOCTITE 243
blue.
NOTE
The minimum screw in length of the screws fix-
ing the engine brackets onto the crankcase is
16 mm to 20 mm (0.6 - 0.95 in.).
Step Procedure
3Slide the overload clutch, thrust wash-
er and clamp ring along the axle to the
hollow shaft and then fix to the rear
axle. Tighten the screw on the clamp-
ing ring with 10 Nm (89 in. lb).
4Tighten the 6 Allen screws (pos. 1, Fig-
ure Tightening sequence) on the over-
load clutch with 7 - 8 Nm (62 - 71 in.
lb). Make sure that every screw is
tightened with the right tightening tor-
que, repeat procedure if necessary.
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Figure 2.4: Tightening sequence
1 Allen screws
1
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DIRECT ATTACHMENT OF THE
ENGINE TO CHASSIS
If the frame of the chassis is specially prepared for in-
stallation of the ROTAX® 125 MAX DD2 evo, then 2
sheet metal brackets with holes are welded onto the
two frame tubes. The engine is clamped between the
two brackets with 4 bolts.
NOTE
The minimum screw in length of the screws fix-
ing the engine brackets onto the crankcase is
16 mm to 20 mm (0.6 - 0.95 in.).
NOTE
Secure bolts with bolt adhesive e.g. LOCTITE
243.
Step Procedure
1 Mount engine directly on the brackets.
NOTE
Check for easy access to the pick-up sensor
(pos. 1). There are two options to install the
pick-up sensor. Choose the orientation which
gives you the best fit for your chassis
installation.
mWARNING
Non-compliance can result in serious injuries
or death!
For engine attachment to the chassis, please fol-
low the instruction of the chassis manufacturer.
Figure 2.5
1Pick-up sensor
Effectivity: 125 MAX DD2 evo 1
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Notes
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NOTES
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BRP-Rotax
INSTALLATION MANUAL
Chapter: 2
FUEL SYSTEM
TOPICS IN THIS CHAPTER
Installation and connection of the fuel pump...........................................................................................2
Installation of the Bowden cable for carburetor control...........................................................................4
Installation and connection of the carburetor ..........................................................................................6
Effectivity: 125 MAX DD2 evo 2
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