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Razor MX650 Upgrade to 1000 Watt Motor

I am thinking of modifying my son's Razor MX650 electric dirtbike to a 36v 1000watt motor.

Here is the bike I have for my son.

Besides the motor could you tell me what other parts to order ?

What else do I need to consider before I start this upgrade?

Any advice or suggestions are welcome.



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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.

Thank you for the clear explanation. I am looking into getting a welder, before I decide to jump in. Thanks.

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. 

That is a great tip. Thank you!

That might be the way to go for me. I just bought the bike last week (Oct. 2015) 

Would you guess I have the 12Mah or the 15Mah battery?

I heard it could be either one.

Could I add an in-line switch to only activate the extra battery when I wanted to? Mostly leave it off. But sometimes after getting the motorcycle to 12mph or so then hit the switch? If waiting until it is up to speed would that help preserve the motor and controller? It would be used like a power boost button. If so what button/switch should I use? Thanks

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.

exactly which battery and charger will i need to add another 12v battery to stock MX650?

And if I want to upgrade the controller, exactly which 48v model should I buy?

any other small parts i need to order from tncscooters to complete the job?

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.

Please recommend 48v controller and wiring directions, please.  

For 48v charger, which amp rating should I use.. i assume 3A is ok and I can swap out the plug easily if you don't have XLR style in stock

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.

My version number is 25.  Please recommend all specific parts needed for 48v upgrade - 4 batteries, charger, and controller.  Thank you!

Several of our customers have installed four 12V 12Ah batteries in the Razor MX650 to upgrade it from 36 Volts to 48 Volts. The MX650 originally has three 12V 12Ah batteries so the fourth battery requires custom installation. There is a great article with many photos showing how to install a 48 Volt battery pack on the Razor MX500 dirt bike, which has the same frame as the MX650 dirt bike, at this link:

We custom make a larger rear sprockets for the MX500 and MX650 which can be ordered from this page:

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.

Our 12V 15Ah batteries are the exact same size as 12V 12Ah batteries so they could be used for even more ride time than the 12V 12Ah batteries would provide. In order to have a throttle with working power indicator lights the original MX650 version 25 throttle would need to be replaced with a different throttle when replacing the original controller with a 48 Volt controller, so I will include a compatible throttle in the parts list below.

Here is the parts list:

Batteries: 4 quantity of item # BAT-12V12A or BAT-12V15A

Charger: 1 quantity of item # CHR-48V3AXLR or CHR-S48V3AXLR (the CHR-S48V3AXLR costs a little more and is a higher quality charger)

Controller: 1 quantity of item # SPD-481000C

Throttle: 1 quantity of item # THR-88

Please note that installing a 48 Volt battery pack and controller require custom installation and they are not bolt-and-go or plug-and-play.

We can make a kit out of the controller and throttle so they will have matching and labeled connectors that are plug-and-play with each other. If you are interested in that please let us know.

yes, I want to purchase these items. And yes, please make the kit with proper matching and labeled connectors.  How do I indicate the kit when ordering?

Batteries: 4 quantity of item # BAT-12V12A 

Charger: 1 quantity of item # CHR-48V3AXLR 

Controller: 1 quantity of item # SPD-481000C

Throttle: 1 quantity of item # THR-88

make that BAT-12V15A, not the 12A

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