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Original scooter motor suddenly burnt out. Bought new one, but need to make sure.

Hello: My electric scooter is ESSENTIAL to my income. No recreation here. Cannot tell you how stressed I am about having the electric motor burn up. 

The scooter is a first generation GT Tsunami (2004 I believe). No electronics to speak off, just the 2 x 12v batteries, wiring harness (with 40 amp fuse), charge port, speed throttler, brake shut off and motor. 600 watts motor, I believe this was an upgrade by the original owner.

Probably makes no difference, but I mention it just in case: I have been using a heavy duty on-off switch instead of the throttle for 5 months just fine. The throttle cord has only three wires: red, brown and black, which I had soldered  to the switch. Today one of the wires came lose, so I took it apart to clean up and re-soldered. I cleaned them up with alcohol and let them dry.  Then I put the scooter on a stand and tested the wires again by making contact....The motor worked as expected. Unconnected the wires, power off. 

When I came back to get ready to soldered the wires, I turned on the power and just by habit I tested the wires again. Nothing. Again. Nothing. Then suddenly I hear a classic electric burn "bubbling" and see tons of smoke coming from the motor. I take it off, opened up the casing and....a little transistor/resistor/what-have-you falls off I can see a melt down of black where the main wires enter the motor on the side the electronics disc. Gone. Burnt to a crisp.

So, I bought a new one today (the silverlining would be that it is a 750 watts motor instead of 600 watts) BUT...I am dead afraid of burning that one as well. 

Is there ANYTHING other than age (it was, after all, a 12-11 year old-motor) that could have provoked the motor to suddenly burn up? I thought that was what the fuse supposed to prevent, but it is still intact. 

One additional data: I think I had the charger plugged  in when I did the second test that burnt the motor, not that it should matter, right?

Any information would be welcome. And I really mean that. 

Having the battery charger plugged into the scooter could not have caused the motor to fail. The motor's failure sounds to me like it was from old age.

If the scooter is a first generation 2004 GT Tsunami then it has a brushless motor. Also from your description of the parts that the scooter has on it it would have a brushless motor because a speed controller is not mentioned in the parts list.

These type of brushless motors that the first generation of GT Tsunami scooters have are finicky about how they are operated and are prone to burning out without giving any warning the way yours did. That is why Currie only used them on their scooters for a couple of years and then switched over to brushed motors for all of their subsequent year models of electric scooters.

These type of brushless motors for Currie electric scooters are discontinued and no longer available. All scooter parts stores have sold out of them nearly a decade ago.

I notice that you purchased a brushed motor which is the only motor option available for the GT Tsunami scooter. However this brushed motor will require a speed controller and throttle in order to make it run. We sell a speed controller and throttle kit that is compatible with the motor you purchased. It is our item # KIT-600 which is sold at this link.


Ok, thanks for the explanation. I am glad to see you guys are on top of these posts. I went ahead and bought the kit you linked. I assume the kits comes with some sort of explanation of connections. 

Three questions?

Will this motor be quieter or louder? 

Being 750 watts, will the batteries run out faster?

Will the speed controller come with connecting instructions?

Thanks for the help. II hope you guys can get it out of the door by Wednesday night. Probably the only time you guys have someone who actually uses a scooter as a work tool. ;)


You are welcome and thank you for your business.

The kit only includes the parts and basic wiring directions so I will post more specific wiring directions for it below.


As you can see installation is very intuitive. The old motor is unplugged from the scooter and the controller is plugged in to the plug that was previously plugged into the motor. Then the new throttle and motor is plugged into the controller. Those are the only required connections.

If the scooter has a brake lever switch then it can be connected controller's brake connector. The controller's charger port + connector is another optional connection that can be used or not.

The new brushed motor will be very quiet as that is the nature of brushed motors. The only noise that you should be able to hear is the chain.

The 750 Watt motor will draw a little more power from the battery pack than the old 600 Watt motor when it is run at full throttle. You could run it at less than full throttle to match the power consumption of the old motor though.

The speed controller will come with basic wiring directions. The same wiring directions that it will come with are available at this link:

We have a lot of customers who use their electric scooter to get to and from work but this is the first time I can remember that someone actually uses their scooter as a commercial work vehicle.

We are open tomorrow and I sent a request to the shipping department to ship your orders out tomorrow. They will not be picked up by the post office until Wednesday though due to the holiday.

Kudos on the service. Holy crap. I have not seen such quality response from a company in a long, long time. No wonder you guys are "it" when it comes to scooters. 

Thanks a lot.

Thanks for the parts, I put them on an all worked just fine except for a few small nagging issues: 

A) Is there a way to change or adjust the speed at which the controller turns the motor to full speed? I realize that having been using a simple on/pff switch probably affects how the scooter feels now as before it was "full power", but the "ramping" effect feels very slow. I need stronger torque from the start. 

B) More importantly, while the motor seems faster once it reaches full speed, it does not do as well on hills. The prior motor was 600 watts, this one 750 watts and yet feels less powerful, without much initial torque at all. 

Thanks in advance.

I believe that the reason for the speed "ramping" effect is not because of the controller and is being caused by a combination of the new motor's higher RPM rating and the gear ratio between the motor and rear wheel.

Early models of Currie scooters which had brushless motors were designed to go fairly slow and have a good amount of torque for climbing grades. This was accomplished by using brushless motors with shaft rotation speeds in the 2000 RPM range and gear ratios that allowed for top scooter speeds in the 12 MPH range. Here is a gear ratio calculation for a Currie scooter with a brushless motor.


Later models of Currie scooters with brushed motors were designed to go faster and subsequently not have as much torque for hill climbing. This is because second generation electric scooter buyers were now looking to buy faster electric scooters than they already had and the scooter's top speed specification was an important purchasing decision factor. Here is a gear ratio calculation for a Currie scooter with a brushless motor.


With the new 2600 RPM motor that you installed the top speed has been increased by around 20% and the acceleration and torque at the rear wheel has been decreased by 20%.

Brushless motors are around 90% efficient and brushed motors only have an efficiency rating of around 80% so the new 750 Watt brushed motor will not have a lot more power then the old 600 Watt brushless motor did.

One thing that could be done to help solve this problem would be to install a smaller sprocket on the new motor to lower the gear ratio. If the motor's 15 tooth sprocket was replaced with an 11 tooth sprocket then the gear ratio would be significantly lowered from 6:1 to 8.18:1. This would reduce the top speed from 15.52 MPH to 11.38 MPH. That is enough of a top speed reduction to gain some serious torque.


Installing an 11 tooth sprocket on the motor would require removing the 3mm roll pin that holds the 15 tooth sprocket onto the motor, and then driving a new roll pin into the new sprocket and motor shaft to secure the new sprocket onto the motor. This should be done with the sprocket secured against a support such as a small block of wood so the entire force of removing and installing the roll pin is not transferred to the motor bearings.

We would be glad to send you an 11 tooth motor sprocket at no charge if you would like to give it a try?

Wow. You guys are really awesome. Yes, I suppose I will definitely give it a try and I appreciated it. The speed for me matters not as much as the torque chiefly because I need to pull that trailer I showed you. Also, I am  in the middle of traffic daily and the lack of torque has already trigger I few close calls.

I am going to look for any youtube video or tips on how to do this replacement. Thanks for the heads up with the pin roller. 


Thanks for your kind words. We will send the 11 tooth sprocket to you today. It will help a lot with the torque.

Removing the roll pin is a fairly easy job. The original 15 tooth sprocket and new 11 tooth sprocket both use a 3mm roll pin.

You can use 3/32” or 2.5mm pin punch, or 3mm roll pin punch to remove it. A 4D finish or box nail with its tip filed flat may also work.


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