MISFIRE PREVENTION ROTAX 125 evo engine series


(James McMahon) #1

Battery Maintenance

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Maintenance is a determining factor for the life span of the battery.
• Keep the battery fully charged.
• Charge the battery especially during winter storage.
• Use a suitable charging device. Rotax recommends:
:black_small_square: Part number 265148 for AGM and
:black_small_square: Part number 581325 for Li-Ion batteries.
Available at your ROTAX Dealer.
• We recommend to charge the battery after every race.
• After 2-3 years the battery should be tested for capacity. If the battery shows a significant loss in capacity please replace it.

Ignition System

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The following tips will increase robustness against misfire.
• Keep the spark plug and spark plug cap clean to avoid any external arcing! (Video available, link on the next page)
• Use a tie wrap and attach the ignition cable to the cooling water hose to reduce wear of spark plug and spark plug cap.
• Use only genuine ROTAX NGK spark plugs:
:black_small_square: Part number 298102 for MICRO / MINI
:black_small_square: Part number 298103 for JUNIOR / MAX / DD2
Available at your ROTAX Dealer.
• To increase the resistance against misfiring we recommend to use the red NGK spark plug cap 866707.
Available at your ROTAX Dealer.
:black_small_square: Make sure not to exceed the maximum allowed spark plug gap:
:black_small_square: JUNIOR / MAX / DD2 gap must be < 1mm
:black_small_square: MICRO / MINI gap must be < 1,2mm

• Please find the 2018 Rotax Max Challenge Regulations on our website:
https://www.rotax-kart.com/de/Max-Challenge/MAX-Challenge/Regulations/Regulations-2018
• Please find the spark plug video here:
https://www.rotax-kart.com/de/Community/Videos/Rotax-125-MAX-evo-Engines/141-ROTAX

Crankshaft Positioning Sensor

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The right of gaskets at the CPS socket grants a smooth run of the engine.

INSTALL gaskets “431500” on crank cases:
• 684234 DD2 and
• 295914 MICRO / MINI / JUNIOR / MAX
This crank cases have a non-machined CPS seat.
You can fit up to two gaskets without any negative impact.
DO NOT INSTALL gaskets “431500” on crank cases
• 684235 DD2 and
• 295915 MICRO / MINI / JUNIOR / MAX
This crank cases have a machined CPS seat.
If you fit gaskets here, the engine may not start or have misfire.
IMPORTANT
• If you install too many gaskets the engine may not start.
• Installing the right amount of gaskets will grant a smooth run of the engine.

Wiring Harness

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The correct installation of the wiring harness plays an important role:
• Check with the Rotax “Installation and Operators Manual”.
• Please find the manuals for all engines on our website:
https://www.rotax-kart.com/de/Products/MAX-Engines
• Follow the installation Manual by applying the tie wraps.
• To prevent wire breakage please fix the cables coming out of the ignition coil and solenoid valve shortly after the connector with a cable tie to reduce movement and vibration.
• Make sure the cables are properly fixed to the chassis or seat and are not bent directly after the connector!
• If you are not racing a DD2 engine make sure that the shift contact is properly isolated.
It will cut the ignition every time it has contact.
• Make sure that the rubber cap is covering the charging socket for the battery charging device.
• Please remove any grease out of the counter-connector of the starter switch.
• Silicone content of the grease can harm the internal contact of the starter switch.

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In General, make sure to never pull directly on the cables when disconnecting them. Grip
the connector and plug to prevent mechanical stress on the cables – as this may damage the
cables and lead to a misfire. If you have any doubt that the harness is not OK, you can make a
quick and easy check with the wiring harness tester “276231”.

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All Rotax genuine spare parts or devices mentioned in this issue of the TECH TIPS are available at your Rotax dealer.

If you have any questions or concerns – please ask your Rotax dealer.
They will be happy to help you in any case.

Kind regards,

Your Rotax Team