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Please note that installing our 36 Volt 1000 Watt motor on the Razor MX650 requires major modifications to the bike's swingarm which requires metal fabrication and welding to accomplish.

To modify the Razor MX650 electric dirt bike to have a 36 Volt 1000 watt motor the space that the motor mounts into the rear swingarm will need to be widened. The MX650's original motor is around 5-1/4" long, and the 36 Volt 1000 Watt motor is around 6" long. Modifying the MX650 swingarm to accept a 1000 Watt motor requires cutting, fabricating, and welding. If you do not have a welder then most local welding shops could do this job.

The other parts needed for the upgrade would be a 36 Volt 1000 Watt speed controller, such as our item # SPD-361000B. Please note that installing the SPD-361000B controller on the Razor MX650 requires custom wiring to accomplish.

Also depending on which version of MX650 is being converted, the throttle may need to be replaced in order for its battery gauge lights to work.

Another thing to consider is upgrading the battery wiring harness to 12 gauge wire. The original wiring harness is made from 14 gauge wire which is a little thin for a 1000 Watt load.

Once you decide which parts to use we can draw a wiring diagram that shows how to wire all of the new parts into the MX650.

A popular modification for the MX650 is to add one extra battery to make the battery pack 48 Volts, and then replacing the 36 Volt battery charger with a 48 Volt battery charger. All of the other parts can be left as is. This will over-Volt the motor by 12 Volts and it will run faster and have more power which essentially turns it into a 1000 Watt motor. Although many people have good reliability with this modification, some have experienced early controller or motor failure. I think the reliability of the bike when this modification is done depends how hard the bike is driven. I know this 48 Volt modification has been done by many people though and is a very common way of modifying the Razor MX650 dirt bike. If the original 36 Volt controller fails then it can be replaced with a 48 Volt controller, however, the 48 Volt controller requires custom installation. 

A switch could be used to activate the extra battery and turn the 36 Volt battery pack into a 48 Volt battery pack. This would be fairly easy to wire. Our item # SWT-154 switch could be used for this purpose.

With this type of system two battery chargers would be needed; one 36 Volt charger and one 12 Volt charger. The reason two chargers are needed is because the three batteries that consist of the 36 Volt battery pack would discharge more than the 12 Volt battery whenever the switch was in the 36 Volt position. This would cause an imbalance in the voltages between the 36 Volt pack, and the single battery that turns it into a 48 Volt pack. So the three batteries in the 36 volt pack would need to be charged with a 36 Volt charger, and the fourth battery with a 12 Volt charger. Since the MX650 already has a 36 Volt charger all it would take is a new 12 Volt charger for the single battery. A second charger port would also need to be installed for the single 12 Volt battery. I would use a charger port with a different number of ports than the original has for the single 12 Volt battery to prevent the 36 Volt charger from being plugged into the 12 Volt battery pack, and visa-versa. For example the original XLR charger port has 3 ports so the second XLR charger port could have 4 ports. Or another type of charger port altogether could be used for the 12 Volt battery such as an inline charger port instead of an XLR.

Here is a wiring diagram showing how to wire the SWT-154 switch to the batteries and speed controller, and the battery charger ports to the batteries.

When adding a fourth battery to the Razor MX500 or MX650 it should have the same Ah rating as the batteries in the existing battery pack. The MX500 and MX650's original batteries are 12Ah. If the bike currently has 12Ah batteries then our BAT-12V12A battery could be used. However I only recommend adding an single extra battery if it is wired along with a power boost switch and second battery charger port as shown in the illustration above. If you want the bike to have a full time 48 Volt battery pack that is charged with a 48 Volt battery charger then all four batteries should be replaced at the same time because mixing different brands of batteries together is not recommended due to the different discharge and recharge rates that they have.

If you want to upgrade the controller to 48 Volts then since there are no plug-and-play 48 Volt controllers available for the MX series dirt bikes. any 48 Volt 1000 Watt controller for brushed motors such as our SPD-481000B could be custom installed on the bike. We can help with wiring directions for a 48 Volt controller if needed.

If the bike will have a battery pack made from four 12V 12Ah batteries then a 48 Volt 1.6 Amp charger is recommended and will recharge a deeply discharged battery pack in around 5-6 hours. A 48 Volt 3 Amp charger could be used for a faster recharge time if needed. We have both of these chargers available with XLR plugs.

Recommending the 48 Volt controller is easy however the wiring directions depend on the MX650 version. Version 1-7 has a different throttle than version 8 and up. Do you know what version Razor MX650 dirt bike you have?

The version number is coded into the Razor ID Tag which looks like this.

The seventh and eighth numbers between the two dashes are the version number.

https://electricscooterparts.com/custom-made-sprockets.html

The MX500 and MX650 along with the SX500 rear wheel freewheel has an F4 mounting pattern which can be specified when ordering a custom sprocket from us.