Rotax 125 DD2 MAX EVO User manual

OPERATOR‘S
MANUAL
125 DD2 MAX EVO
KART ED. 03/2021
PART NO. 297732
ROTAX-KART.COM

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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:

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Table of Content
Chapter INTRO – GENERAL INFORMATION
Chapter 1 – Technical Description
Chapter 2 – Operating fluids and battery
Chapter 3 – Engine calibration
Chapter 4 – Engine operation
Chapter 5 – Preservation and transport
BRP-Rotax
Operators Manual

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BRP-Rotax
Operators Manual

BRP-Rotax
Operators Manual
Chapter: INTRO
GENERAL INFORMATION
Preface Before operating the engine, read the Operators Manual carefully.
If any passages of the Manual are not clearly understood or if you have questions, please
contact an authorized Distribution or Service Center for ROTAX®-kart engines.
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.
Contents This Operators Manual contains instructions about how to operate the ROTAX®-Engine
Type 125 MAX DD2 evo.
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
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TIP This information gives you additional advice and tips
mWARNING
This vehicle may exceed the performance of other vehicles you may have ridden. Take
time to familiarize yourself with your new vehicle.
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INTRO
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Chapter: 1
TECHNICAL DESCRIPTION
TOPICS IN THIS CHAPTER
Design of the ROTAX engine 125 MAX DD2 evo.......................................................................................2
General ................................................................................................................................................2
Cooling circuit .......................................................................................................................................2
Balance gear.........................................................................................................................................3
Ignition unit ...........................................................................................................................................3
Electric starter.......................................................................................................................................3
Electro pneumatically exhaust timing control ...........................................................................................3
Intake silencer.......................................................................................................................................3
Exhaust system.....................................................................................................................................4
Gearbox ...............................................................................................................................................4
Electronic Shifting Assistant (ESA) .........................................................................................................4
Fuel pump ............................................................................................................................................4
Carburetor ............................................................................................................................................4
Centrifugal clutch ..................................................................................................................................5
Overload clutch .....................................................................................................................................5
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DESIGN OF THE ROTAX ENGINE 125 MAX DD2 EVO
Figure 1.1
GENERAL
The Rotax 125 MAX DD2 evo engine is a single cylinder two stroke engine with reed valve
controlled inlet and 125 cm3displacement. Mixture lubrication is achieved by adding oil to
the gasoline in a specified mixing ratio.
The power transmission to the rear axle takes place via a manually shift able integrated 2-
speed gearbox.
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COOLING CIRCUIT
The coolant is pumped from the radiator to the water pump which is driven by the clutch
shaft. The water pump conveys the coolant through cylinder and the cylinder head back to
the radiator.
The cooling circuit is equipped with a thermostat (opening point 45 °C / 113 °F). It assures
that the engine reaches its operating temperature quickly and keeps it at a relatively con-
stant level.
The thermostat is integrated in the cylinder head cover.
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BALANCE GEAR
The balance gear is mounted on the primary shaft and rotates counter-wise to the crank-
shaft to reduce engine vibration.
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IGNITION UNIT
The control of the ignition system is exercised by the ECU (Engine Control Unit). To calcu-
late the ignition timing, an engine speed sensor is needed, which is installed on the bottom
of the engine housing. There is no manual adjustment of the ignition system necessary
and/or possible.
If the power button is pressed once, the ignition is activated and the button lights up. To
start the engine, it only needs to be pressed once again. To turn off the engine as well as
the ignition, proceed in reverse order.
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ELECTRIC STARTER
By pressing the "START" button, the circuit between the battery and the electric starter will
be closed by a relay. The electric starter drives the starter gear on the crankshaft via an in-
termediate gear with free wheeling, until the engine starts to run. An automatic switch re-
set from "START" to "ON" is integrated.
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ELECTRO PNEUMATICALLY EXHAUST TIMING CONTROL
The engine type 125 MAX DD2 evo is equipped with an electro-pneumatic exhaust con-
trol. The E-RAVE (Electronic ROTAX Adjustable Variable Exhaust) system is controlled by
an electro-pneumatic valve via the ECU. The vacuum required is provided by the engine
crankcase.
If the engine is running at idle speed or below the opening point of the E-RAVE system
(between approximately 8000-9000 rpm) the exhaust valve is closed. With the engine run-
ning, it closes or opens the electro-pneumatic valve of the exhaust depending on the
speed and, therefore it provides optimum performance characteristics.
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INTAKE SILENCER
The intake silencer incorporates an air filter to clean the intake air. The intake silencer has
been designed for optimum reduction of air intake noise level and represents a tuned sys-
tem with the engine.
The air filter consists of several layers and has been optimized in the area of air passage
and filter efficiency. If soiled or during engine maintenance work, clean the filter with biode-
gradable products.
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EXHAUST SYSTEM
The exhaust system is designed as resonance system with an after-muffler and repre-
sents a tuned system with engine.
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GEARBOX
The power transmission to the rear axle takes place via manually shiftable integrated 2-
speed gearbox and not as usual, via a maintenance intensive chain drive. Changing the
gear activates the gear shift fork as well as a shifting sleeve, which slides on the hollow
shaft between the 1st and 2nd gear and then engages in the respective idle gear.
The gear is kept in position by an index pin, which keeps the gearshift fork in the selected
position, 1st gear, neutral or 2nd gear.
To allow shifting into 2nd gear without lifting the foot from the gas pedal, the ignition is cut
off for a moment when actuating the shifting paddle.
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ELECTRONIC SHIFTING ASSISTANT (ESA)
To optimize the shifting from 1st to 2nd gear, the ignition is interrupted for a short time. This
releases load from the gearset and, gear shifting is faster and less stressful for the
gearset.
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FUEL PUMP
The fuel pump functions due to the alternating negative pressure and overpressure in the
crankcase and sucks fuel from the fuel tank into the carburetor via the fuel pump.
In the suction side of the fuel pump (between fuel tank and fuel pump) a fuel filter is in-
stalled to prevent contamination of the fuel pump and carburetor.
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CARBURETOR
The carburetor (DELL’ORTO VHSB 34) is a slide type carburetor with float system. The
standard main jet is suitable for almost all operating conditions. For extreme operating
conditions, the main jet size must be adjusted to the actual conditions according to this
manual.
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CENTRIFUGAL CLUTCH
The engine is equipped with a centrifugal clutch operating in an oil bath. This clutch sepa-
rates the engine from the gearbox at less than 2.500 rpm. Only at an engine speed of ap-
prox. 4.000 rpm. the centrifugal clutch is completely engaged.
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OVERLOAD CLUTCH
The engine has a mechanical overload clutch, which is installed on the rear axle. It is to
protect the crankshaft from hard shocks from the drive components which are not usual
during normal operation (e.g. the blocking of the rear axle).
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Operators Manual

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Operators Manual
Chapter: 2
OPERATING FLUIDS AND BATTERY
TOPICS IN THIS CHAPTER
Coolant....................................................................................................................................................2
Battery.....................................................................................................................................................3
Battery charging unit...............................................................................................................................4
Fuel .........................................................................................................................................................6
See also table “important information (summary)” in Chapter 5.
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COOLANT
Use only distilled water as engine coolant. If the kart is stored below the freezing tempera-
ture of water, make sure to drain the water from the cooling radiator and engine
completely.
Step Procedure
1Open radiator cap and fill the system with coolant.
Small radiator: approx. 0.52 liter / 0.137 gal for the complete cooling system
Big radiator: approx. 0.7 liter / 0.185 gal for the complete cooling system
2 Close radiator cap.
ATTENTION
Observe the storage conditions.
Storage below the freezing temperature of water could lead to a damage of the cooling
system and the engine.
ATTENTION
Exceeding the engine temperature could lead to serious engine failure.
The engine temperature should not exceed 85 °C / 185 °F.
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BATTERY
See Fig. Pos. 1: Charging connector, TYPICAL.
The power for the ignition unit and electric starter is only supplied from the battery. With a
fully charged battery of 12 V and 6.5 Ah, the engine can be started approximately one hun-
dred times and operated over a period of approximately five hours. With the battery volt-
age decreasing to approximately 11 V the point will be reached when the battery voltage
is too low to generate a spark for ignition.
ATTENTION
The lifespan of the battery will be drastically reduced by exhausting the battery
completely.
Fully re-charge the battery before and after any operation of the kart.
NOTE
It is recommended to always carry a charged spare battery. The installed battery
should be replaced with a fully charged battery before it is completely exhausted.
NOTE
If the spark plug is removed, to check if the battery still generates a spark, consid-
er the following: with the spark plug removed it is easier for the electric starter to
crank the engine, which reduces current absorption of the electric starter, result-
ing in battery voltage adequate to generate a spark. If the spark plug is fitted
again, it may happen that the engine does not start.
NOTE
To charge a battery, the delivered battery charging unit specified by ROTAX®
should be utilized (battery charger part no. 265148). When using the lithium bat-
tery available as spare part, the battery charger Optimate Lithium (part no.
581325) is mandatory.
NOTE
To be able to use the battery charger in your home country, please contact your
nearest authorized ROTAX® distributor or one of their ROTAX® Service Centers
to receive an adapter plug or adapter cable, respectively.
NOTE
This battery charger will switch over automatically to maintenance charge as soon
as the target voltage is reached. Therefore overcharging with the result of ruining
the battery will be impossible.
ATTENTION
Use of any other battery charger can impair the battery life or may ruin the battery.
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BATTERY CHARGING UNIT
When charging the battery take note of the following:
Step Procedure
1Connect battery charger to the charging connector (pos. 1).
Figure 2.1: Pos. 1: Charging connector, TYPICAL
Step Procedure
2 Connect the battery charging unit on 110-230V, 50 - 60Hz power supply.
During the charging procedure, the charge indicating lamp will light up red.
3At completion of the charging process, the control lamp will change to
green, but the charging current will remain, thus warranting a fully charged
battery.
4 The charging time amounts to approx. 12 hours.
NOTE
The battery charger may be connected to the battery for a longer period, as the
battery takes just the current required to be fully charged.
NOTE
A non-extinguishing red control lamp, even after 24 hours of charging, indicates
that the charging capacity of the battery is diminishing.
NOTE
A red/green blinking of the charging control lamp indicates transition from main
charging to additional charging and does not signal a faulty battery charger.
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Step Procedure
5Unplug power supply to battery charging unit.
6Remove output wires of the battery charger from the battery.
7The battery is ready again for use.
ATTENTION
In addition to these directives, follow the advice of the battery charging unit
manufacturer.
NOTE
When the battery is charged while not mounted on the kart, use the connector ca-
ble (part no. 266022). If needed, contact your authorized distributor or one of their
ROTAX® Service Centers.
The charging condition of the battery can be estimated by using a commercially available
measuring instrument.
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FUEL
For engine operation, a mixture of unleaded gasoline of at least ROZ min. 95 / 91 (RON
+MON) / 2 and fully synthetic two-stroke oil, mixed at ratio 1: 50 (2% oil) has to be used.
ATTENTION
Carry out a correct running-in procedure.
See Chapter 4 section: Running-in procedure for the engine.
mWARNING
Non-compliance can result in serious injuries or death!
When mixing fuel and fuelling do not smoke or allow open fire. Gasoline is highly flam-
mable and explosive under certain conditions.
mWARNING
Non-compliance can result in serious injuries or death!
Never perform mixing and fuelling in closed rooms, handle fuel in well ventilated areas
only.
mWARNING
Non-compliance can result in serious injuries or death!
Fuel the kart only when engine is not running and the combination switch is at OFF
position.
mWARNING
Risk of fire and explosion!
Make sure that fuel will not splash onto hot engine components or equipment. Always
wipe off any fuel spillage from the vehicle.
mWARNING
Non-compliance can result in serious injuries or death!
Pay attention to the safety advice of the kart manufacturer.
ATTENTION
Possible engine trouble!
Too much oil in the fuel mixture (more than 2%) could lead to engine trouble (e.g. coking
of the exhaust valve, piston ring sticking).
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ATTENTION
Possible engine blow-up!
Insufficient amount of oil in the fuel mixture (less than 2%) could result in e.g. piston
seizure.
ATTENTION
Engine damage and damage to the intake system may occur.
Do not try any different sorts of fuel.
ATTENTION
Before each fuelling, shake fuel container well to ensure adequate mixing of the gaso-
line with the oil.
ATTENTION
Ensure that no contamination enters the fuel tank and the carburetor.
ATTENTION
Unleaded fuel has a limited storage life.
Store only the quantity of fuel in a container which will be needed in the near future.
ENVIRONMENTAL NOTE
Don’t spill fuel. Absorb spilled fuel with appropriate drying agent and ensure ecological
disposal.
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NOTES
BRP-Rotax
Operators Manual