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I have a razor mx650 and the original motor burned out after only a year of use. I am wanting to up grade to the 750W 36v motor. And add an additional battery to make it 48v. What do I need for this mod? I am thinking I will need a 750W 36V motor, extra 12v/12ah battery, 100a/48v controller, and 48v battery charger. Is this all? Any helpful tips?

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You are definitely on the right track with all of the parts that you selected. For anyone else reading this everything I am about to say applies to Razor MX500 dirt bikes also because the only difference between the MX650 and MX500 dirt bikes are their motors.

The item # MOT-36750 36 Volt 750 Watt motor is the same size as the original Razor MX650 motor so it will bolt right onto the MX650 frame without any modifications. A 36 Volt 750 Watt motor running on 48 Volts can produce 1330 Watts, and our item # SPD-481000C 36 Volt 1000 Watt controllers can output up to 1440 Watts, so they are a good match for each other.

Our item # CHR-48V1.6AXLR 48 Volt 1.6 Amp battery charger is the right size to recharge a 48 Volt battery pack made with 12Ah or 15Ah batteries and it will work with the MX650's original charger port.

The MX650's original throttle will work with the new 48 Volt controller however its indicator lights will not work with a 48 Volt battery pack and will always read that the battery pack is full even when it is empty. If you want a throttle with working battery pack indicator lights then a new throttle with 48 Volt indicator lights such as our item # THR-88 would be needed.

An extra 12V 12Ah battery could be added to the existing 36 Volt battery pack to make it a 48 Volt battery pack. I would think of this as a temporary battery pack though because mixing batteries together into the same pack which are different ages and brands usually does not create a battery pack that will last very long. The reason for this is that the older batteries will discharge faster than the new battery will, so their Voltages will become unbalanced over time which will cause some of the batteries to be overcharged and some to be undercharged. Overcharged and undercharged batteries do not last as long as properly charged batteries will. It will work for a while though just don't expect the mixed battery pack to last as long as a new battery pack made with four brand new batteries will.

Please let us know if you have any questions.

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