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36V 800W controller for Razor MX500 upgrade

We have a Razor MX500 version 2. We purchased a 36v 800w controller as the old one was dead. The issue is that the controller has a power connector with 2 pins (red and black) while the bike's power connector has 4 pins (large red/sm red/ large black) so the connectors don't fit. 

What can we do? I tried removing the connector from the old controller and inserted the two wires. So a 2 pin male connector into a 3 pin female connector. It burned the fuse. 

Would love some help. Thanks

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*Correction: bike power connection with 3 pins sm red, lg red, lg black wires
You will need to bypass the power switch and wire the controller's battery connector red and black wires directly to the battery pack's red and black wires.

If there is enough wire length then the controller's battery connector wire terminals can be removed from its 2-terminal plastic connector and installed into the old 4-terminal plastic connector so that red goes to red and black goes to black.


The terminals can be removed from the connector by pushing in their locking tab to remove them and then restoring the original position of the locking tab before reinstalling them.


Then wire the controller's electric lock wires directly to two of the power switches terminals.


Please let us know if you have any questions. 

Honestly that seems a little more than I can handle. If I return the controller that I have now, can you suggest a different controller to buy. We are seeking more torque and speed from stock. We are not sure if our unitemotor MY1020 is a 500 or 650 w but wanted to squeeze a little more out of it. Our MX500 is a version 2 and we have the 4 pin throttle with it. Can you suggest the best controller to get with this setup? Hopefully with the 4 pin throttle, if not please suggest the correct one to use to be able to plug and play with a little muscle.

We do not know of any higher power controllers that are plug and play for the Razor MX500 electric dirt bike. The original controller that the MX500 has is wired in a very unique way so other controllers are not wired like they are.

However, we do sell adapters that will allow the controller you purchased to plug directly into the MX500 dirt bike without modifications. Here are links to these adapters:



Thank you for the great info. So if I order the two adapters it should work. Do you have pics of how to connect everything? Would like to plan it out so there are no more delays or extra spending involved. Thx!
We do not have any photos showing how to connect everything together, however, we do have this wiring direction drawing.


Please let us know if you have any questions.
Connectors worked well. One more issue to address. I replaced the charging port as it was damaged and installed the 3 new 12v 15Ah batteries. Now when I go to charge it, the light on the charger always stays green and not red as it is supposed to do. I checked the voltage of the charger, charging port and battery pack and all seem correct. The controller has several 2 pin connectors for charging port, indicator and brakes. It’s presently in the charging connector. Any suggestions?
If the charger's output plug has Voltage and the charger port has Voltage then that indicates that both of these parts are working. It would be a good idea to verify that the plug and port terminal polarities match up with each other, for example, that terminal 1 on the plug and port are both positive, and terminal 2 on the plug and port are both negative.

If the charger plug and charger port polarities both match then it is possible that the red light in the charger is malfunctioning and the charger is working otherwise.

To test if the charger is working or not; test the battery pack Voltage with the charger unplugged from the bike, and then plug the charger into the bike and wall as you continue to monitor the battery pack Voltage.

If during this test the battery pack Voltage slowly rises then the charger is working. However if during this test the battery pack Voltage stays the same and does not rise then the charger is not working.

Please let us know how it goes.

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