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BRP-Rotax

Operators Manual

CHOOSE OF GEAR RATIO

In spite of its 2 gears, the 125 MAX DD2 evo engine offers a broad performance band.
Therefore, the frequent changing of the primary gear ratio is not necessary.

NOTE

It is not possible to change the 1

st

and 2

nd

gear individually.

On most of the Kart circuits you will be well served with the standard gear ratio (35/62
which is equivalent to 12/90 for 1

st

gear and 14/79 for 2

nd

gear).

If due to the special shape of the circuit (e.g. extremely sharp corners or long straights), it
is deemed necessary, the primary gear ratio can be changed both, a shorter or a longer
ratio.
If the rpm. range from 9.200 to 12.200 rpm. is not sufficient because of a particular track
shape (extremely long straight), the maximum engine speed of 13.600 rpm. should be
aimed for.

NOTE

A basic requirement for the full use of the speed range between 12.200 to 13.600
rpm. is optimized carburetor jetting (see chapter 4.1. Carburetor calibration).

The acceleration potential between 9.200 and 12.200 rpm. is essentially higher than be-
tween 12.200 and 13.600 rpm. Therefore, it does not always make sense to use this rpm.
range (high top speed on a straight) and to not take advantage of the acceleration poten-
tial of the lower rpm. range (out of sharp corners).
This is a suggestion. The optimum choice can only be found with the exact knowledge of
the race track.
To approach and optimize the reduction gear ratio, the following charts should be helpful.
The optimization procedure regarding the reduction gear ratio for a new race track is ex-
plained step by step by the following example:

Procedure

Start with the standard gear ratio (35/62, equivalent to 12/90 at 1

st

gear and 14/79 at 2

nd

gear).

Based on the following criteria, you must decide, whether a shorter or longer gear ratio is
necessary.

Does the engine reach 12.500 rpm in 2

nd

gear at the end of the longest straight?

IF YES, proceed
as follows

Procedure

Choose the next longer gear ratio (36/61 equivalent to 12/87 in 1

st

gear and 14/76 in 2

nd

gear).

IF NO, proceed as
follows

Procedure

Choose the next shorter gear ratio (34/63 equivalent to 11/87 in 1

st

gear and 14/83 in

2

nd

gear).

.

Effectivity: 125 MAX DD2 evo

3

Page 15

Edition: March 01 2021

Summary of Contents for 125 DD2 MAX EVO

Page 1: ...OPERATOR S MANUAL 125 DD2 MAX EVO KART ED 03 2021 PART NO 297732 ROTAX KART COM...

Page 2: ...Follow us BRP Rotax GmbH Co KG Rotaxstra e 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...

Page 3: ...rch 01 2021 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...

Page 4: ...Page 2 Edition March 01 2021 Effectivity 125 MAX DD2 evo NOTES BRP Rotax Operators Manual...

Page 5: ...eatures 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...

Page 6: ...ce and tips m WARNING This vehicle may exceed the performance of other vehicles you may have ridden Take time to familiarize yourself with your new vehicle ____________________________________________...

Page 7: ...eneral 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 E...

Page 8: ...____________________________________________________ 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 th...

Page 9: ...itch re set from START to ON is integrated ________________________________________________________________ ELECTRO PNEUMATICALLY EXHAUST TIMING CONTROL The engine type 125 MAX DD2 evo is equipped wit...

Page 10: ..._____________________________________________ 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 g...

Page 11: ...4 000 rpm the centrifugal clutch is completely engaged ________________________________________________________________ OVERLOAD CLUTCH The engine has a mechanical overload clutch which is installed...

Page 12: ...Page 6 Edition March 01 2021 Effectivity 125 MAX DD2 evo NOTES BRP Rotax Operators Manual...

Page 13: ...hapter 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 Effectivity 125 MAX DD2 evo 2...

Page 14: ...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 te...

Page 15: ...e 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 gen...

Page 16: ...nge 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...

Page 17: ...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 t...

Page 18: ...ath Never perform mixing and fuelling in closed rooms handle fuel in well ventilated areas only m WARNING Non compliance can result in serious injuries or death Fuel the kart only when engine is not r...

Page 19: ...r 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 o...

Page 20: ...Page 8 Edition March 01 2021 Effectivity 125 MAX DD2 evo NOTES BRP Rotax Operators Manual...

Page 21: ...rocedure 2 Performance graphs 2 Carburetor calibration 4 Automatic set up 5 Manual set up 8 Change of the carburetor main jet 12 Choose of gear ratio 15 Exchange of gear reduction ratio 17 Operation o...

Page 22: ...15 min up to 10 000 rpm 15 min up to 12 000 rpm 15 min full load 2 Reduce the main jet size step by step e g 172 170 168 NOTE Make sure that the coolant temperature reaches a minimum of 55 C 130 F At...

Page 23: ...BRP Rotax Operators Manual Figure 3 1 Performance graphs ______________________________________________________ Effectivity 125 MAX DD2 evo 3 Page 3 Edition March 01 2021...

Page 24: ...l no longer apply if the carburetor calibration is carried out improperly and causes engine damage The following application for smartphones shows the individual setting of your ROTAX 125 Max DD2 evo...

Page 25: ...pp will automatically provide all the nec essary information regarding weather and geographical position Figure 3 2 Step Procedure 2 To select your engine type for the calculation click on one of the...

Page 26: ...eted all fields of the weather data and having selected the en gine type you can press the white CALCULATE button on the bottom of your screen to find out the suitable jet for your engine type and env...

Page 27: ...e 4 Now the recommended main jet value will be provided In case a second calculation needs to be made you can start over by simply pressing the button saying RESET next to the calculated value Effecti...

Page 28: ...space next to Temperature Altitude Atmos Pressure and Humidity you are able to enter the required information In terms of Atmos Pressure the atmospheric pressure at sea level has to be entered usually...

Page 29: ...nce users can decide if they would like to use the metric or the imperial system You can change between Celsius and Fahrenheit by simply clicking on the small C or F next to the value for temperature...

Page 30: ...Figure 3 7 Please scan the following QR code for a detailed instruction video Figure 3 8 QR code App Download Please scan the following QR code for your mobile device 3 Page 10 Edition March 01 2021 E...

Page 31: ...understanding and as help for carburetor adjustment the following figure de scribes the effect of the various adjustments depending on the throttle position Figure 3 11 Various adjustments ___________...

Page 32: ...ammable and explosive under certain conditions m WARNING 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 t...

Page 33: ...n and fit the corresponding main jet see ROTAX Max Jetting Guide 5 Fit and hand tighten the plug screw pos 27 and gasket ring pos 26 Needle position 1 2 3 4 5 K00403 9 8 10 11 7 5 4 3 6 2 1 12 13 14 1...

Page 34: ...nlet 8 Refit the fuel filter pos 32 the gasket ring pos 33 and hex screw pos 34 NOTE When trying to start the engine it will take a few seconds for the fuel pump to fill the float chamber and for the...

Page 35: ...d 12 200 rpm is essentially higher than be tween 12 200 and 13 600 rpm Therefore it does not always make sense to use this rpm range high top speed on a straight and to not take advantage of the accel...

Page 36: ...of primary drive gear Number of teeth of secondary drive gear Gear ratio Traditional gear ratio in sprocket size Theoretical max speed in km h mile h at 12 500 rpm and wheel diameter 870 mm 34 25 in...

Page 37: ...ry and secondary gears please note that the sum of the last digits of the teeth number must always be 7 or 17 35 62 EXCHANGE OF GEAR REDUCTION RATIO Tools required Torque wrench Allen key 5 mm Allen k...

Page 38: ...ear pos 4 and secondary gear pos 5 and fit the gear pair of your choice NOTE At re assembly proceed in reverse sequence Tighten the screws to the following torque settings M6 10 Nm 88 lbf in M8 22 Nm...

Page 39: ...the gear shifting is very simple only some points have to be observed Engagement of the 1st gear ATTENTION It is prohibited to rev the engine up in idle mode in order to change engage the 1st gear Thi...

Page 40: ...adjustment of gear shifting please follow the instruction of the chassis manufacturer NOTE If the gearshift cables are excessively tensioned the gears are hard to shift 2 The distance between shift co...

Page 41: ...BRP Rotax Operators Manual Figure 3 15 Adjusted Effectivity 125 MAX DD2 evo 3 Page 21 Edition March 01 2021...

Page 42: ...Page 22 Edition March 01 2021 Effectivity 125 MAX DD2 evo NOTES BRP Rotax Operators Manual...

Page 43: ...RATION TOPICS IN THIS CHAPTER ENGINE OPERATING 2 Engine start 2 Stopping the engine 4 Setting of the exhaust valve timing 5 Maintenance schedule for engine components 8 Operating Limits 10 Effectivity...

Page 44: ...ons it s recommended to put the shifting device in Neutral no gear engaged At engine start proceed as follows Step Procedure 1 On a cold engine pull the choke lever pos 1 into a vertical position Figu...

Page 45: ...ately after kart operation Risk of burning m WARNING Non compliance can result in serious injuries or death During kart operation beware of any contact of body or clothing with moving parts of the kar...

Page 46: ...f the kart if engine is not running ______________________________________________________ STOPPING THE ENGINE See Fig Power button Step Procedure 1 Press the power button and the engine will stop NOT...

Page 47: ...nected This is important for the general function of the engine Variant 1 Additional cable on battery ground A See Ground wire The additional cable is NOTattached to the ground wire The control of the...

Page 48: ...lve timing is activated at 9100 rpm NOTE Isolate the additional cable with an electrical insulating tape to the ground wire so that a possible contact with the engine ground does not affect the functi...

Page 49: ...nual Figure 4 5 Cable on starter relay NOTE Either variant 1 or variant 2 has been installed in your engine ______________________________________________________ Effectivity 125 MAX DD2 evo 4 Page 7...

Page 50: ...valve and check if moving freely X Check overflow bottle empty if needed X Tear down inspection of engine must be con ducted by an authorized ROTAX Service Center X Inspect following com ponents and...

Page 51: ...ust system X Check fit and tightness of exhaust X Inspect for oil or water on the leakage bore at the crankcase X right after every collision Verify a tight fit and non leakage of radiator hoses and c...

Page 52: ...um specified operating temperature due to the low ambient temperature then the cooling efficiency of the radiator must be reduced by partially covering the radiator with adhesive tape ATTENTION Non co...

Page 53: ...ESERVATION AND TRANSPORT TOPICS IN THIS CHAPTER Preservation and transport 2 Preservation of engine and equipment 2 Transport of the kart 2 IMPORTANT INFORMATION SUMMARY 3 Notes 4 Effectivity 125 MAX...

Page 54: ...tem to prevent corrosion 5 Remove battery from the fixture and charge periodically with the specified battery charger ______________________________________________________ TRANSPORT OF THE KART If th...

Page 55: ...sp 91 MOZ 2 STROKE OIL Fully synthetic XPS Kart Tec OIL IN FUEL MIX ING RATIO During break in 1 33 3 oil During normal use 1 50 2 oil COOLING SYSTEM 0 90 0 237 Pure water resp antifreeze if kart is st...

Page 56: ..._____ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________...

Page 57: ...Assistant ESA 4 Engine calibration 2 Engine operating 2 Engine operation 1 Engine start 2 Exchange of gear reduction ratio 17 Exhaust system 4 F Fuel 6 Fuel pump 4 G Gearbox 4 General 2 I Ignition un...

Page 58: ......

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