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Discussion Starter · #1 ·
My son has a MX650 that he rides around the back. He hasn't ridden it for a few months over the winter. The weather has been getting warmer and I noticed that the motor was starting to sound a little rattly the last few times he rode it but didn't think anything of it. Yesterday it completely stopped working. The battery charges and when I turn the throttle the motor makes a high pitch sound but the wheels won't turn.

Is this a bad motor? or does anyone have any suggestions?

If it is the motor can I swap it out for the 36V 800Watt without changing anything else?

Thank you again for all your help!
 

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Test the motor by unhooking the speed control and taking the chain off then jump the battery pack directly to the motor with jumper cable be prepared for a small spark and the motor should run.

No you cannot upgrade to a higher wattage motor without changing the speed control it will burn up the speed control...
 

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Discussion Starter · #3 ·
MrKitty,

Thank you for the suggestion. After looking at some youtube videos and more closely at the bike I realized that chain tension spring had broken. The motor was just spinning causing that sound.
 

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That's funny, I was going to say that's exactly what it was was the tensioner. It just happened a week ago on a friend of mine's MX650. And don't worry, you can upgrade to a 750 or 800 watt motor and it will be okay. Every controller will eventually burn up. I am personally running a 24 volt 500-watt motor on the exact same 36 volt stock controller. And then it has been running fine for quite a long time. I'm basically running a 700 to 750 watt setup being over volted to 36 volts. (The motor that is)
I've had friends running 750 watt Motors on the MX650 chassis for years with no problem.
The controller doesn't care what motor is running, it's going to produce 30 amp Max and that's it. The motor can try to do whatever it wants
 

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I agree with ATVrunner the controllers are so cheap who cares if they burn up in fact the controllers are so cheap you might as well buy the right controller for the motor and then keep the OEM one as a spare
 

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Yep, that’s what we did for my buddy. Put the stock stuff on the shelf, installed another stock controller/throttle and the 800w motor with brand new SLA,s. That was over a year ago. Things a beast. I think it was hitting 20mph regularly
 

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I believe, don't know for a fact that the old 750 motor was upgraded to the 800. I don't even know if it really is an 800 watt it might even still be the 750 remarked as an 800 but either or it's an upgrade over the 650
 
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