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By Laundrydude
I just got a used MX500 cheap. It was missing batteries and controller. I put in 3 new 15ah batteries, a YK33F controller, headlight, brake light, and it was running good on the old 500w stock motor until now. My kids were letting their friends ride it until it "smelled funny". They brought it back with the motor smoking. I think the kids were holding full throttle on hills it couldn't climb and the motor cooked. So I just ordered a 36v 800w motor to go in and another battery and 48v controller. Will post some pics soon.
Here is the motor I ordered: ... EBIDX%3AIT
I hope it fits without modifications, just don't feel like fabricating right now lol
By robnewyork
its pretty straight forward, the motor swap.. u might need one small piece of brack for one of the holes.. should be very fast with the overvolted 800 , very cool!
By robnewyork
I always wanted to do a 125tooth rebel gear on the back of mine for serious wheelie power, never got around to it
By Laundrydude
I was thinking about the rear sprocket, but only going up to 96. I was looking at this motor on eBay that looks nice
But I am already over my "budget" for toys. It is the same length as the 800w. I also want a 48v 30ah lithium battery pack to lol.
By Laundrydude
I installed the 800w motor. I notched out the frame for the motor bolt head and it fit fine. Next I want to do 48v and rear sprocket.
By Quinc
Will be fun with the 800! You should find a 40amp controller for it though. I have the MX650 with a 28amp controller and my buddies MX500 with stock 32amp controller out pulls me and is much more fun. With 40amps it will be a beast. :)
By Laundrydude
I did solder up 1/3 of the original shunts to increase amperage, but I haven't put an amp meter on it yet to see if it made a difference. I was riding it following my son on the quad and it pushed pretty good. I'm afraid with a higher amp controller my kids might burn out the motors quicker too. I do want to try a brushless system soon. Who knows what I'll try next. Let me know how that controller performs.
By Laundrydude
So we have 2 of these mx500s and now the 2nd one smoked the motor. This one has a 36v 800w controller from ebay. It was fine on flats, but hills is too much. The mx500 I put the 800w motor is still ok, but gets hot. So before I go to 48v I think I should put on a 100T sprocket on the rear from rebel gears. I am still looking at the 1800w 48v brushless setup on eBay, wandering how it would be.
By robnewyork
jeez, people been blowing motors daily ..I saw the 1500 watt brushless motor for cheap recently , dont recall where , maybe it was on one of those chinese alibaba type sites. yea, if its getting hot already , 48v will be doom
By Quinc
Laundrydude wrote:. So before I go to 48v I think I should put on a 100T sprocket on the rear from rebel gears.

I would be interested in a 100T sprocket too. Do they give discounts if you buy more then one? :D
By Quinc
frazzled wrote:We are using this controller @ 48v, w/ a 96tooth gear and 36v 800watt motor and it's the right mix for my 10 year old. Might give the 40amp controller a shot, not a lot of investment: ... Ciid%253A1

I wonder if it works with 36? Little confused by the info they post. is it 48-60 or 24-60? It also looks like the YB 190amp controller.

Type: Motor Brush Controller
Rated Voltage: 48V-60V
Compatible With: 24-60V
Rated power: 48-60V 1500 watts
Rated power: 24-36V 600 watts

Operating Conditions: -25~45
Color: as shown in the picture
By robnewyork
the mini yk43b works all the way to 21 volts, but it has blown 2 motors in recent weeks so im guessing it is pushin way more than 45 aamps ,
By Laundrydude
Quinc wrote:
Laundrydude wrote:. So before I go to 48v I think I should put on a 100T sprocket on the rear from rebel gears.

I would be interested in a 100T sprocket too. Do they give discounts if you buy more then one? :D

I need 2 of the 100T sprockets, I will ask about discounts lol
By Laundrydude
I finally installed the brushless setup. So far so good. I cut the base off the motor which is made of aluminum. I mounted the top batteries sideways cause they fit better that way. Better torque than the 800w motor. Here's a video:
By Laundrydude
The brushless controller has a input for 3 speeds so it limits the motor rpm but the torque is the same. Now I might try modding the controller for even more torque.
By robnewyork
those motors have been run at 100amps on a standup with good results, so 40-50 would be very fast with a kid
By Laundrydude
That's awesome. The motor is not getting hot yet so I have room to push it. It does quite well with a 180lb rider too. I probably looked a bit silly chasing my son around the neighborhood while he was on the dirt quad. Not all people we drove by were smiling. Now he wants me to put brushless motors on everything. This site has been inspirational to my projects and fun for my kids.
By Laundrydude
So just to follow up on the mx500. The brushless motor is at least twice a powerful as the 800w and a quarter of the heat. I recommend this route to anyone, and no need to regear. Easy to add a forth battery. No welding required.
By Quinc
Very cool! Love the speeds too! Can you post a link to the motor and controller you used?
By Riverie
Besides the torque and no heat on the motor. Do you see any significant improvement on the top speed? I was thinking to get those exact boma motor before, but ended up getting the brushless outrunner.
By Laundrydude
Motor rpm is around 4100 (no load). The bike goes about 22mph with a 180lb rider. Depending on terrain and rider weight speed could vary. The highest torque is at a lower rpm, like on a hill you slow down but only to a point and it climbs. Batteries are lasting longer but don't have numbers on that yet. How's the outrunner you got?
By rhyoo
Sorry I'm the same person, didn't realized I have 2 different accounts here. Got mixed up with my other hobby forum. My outrunner system is still WIP. If you see red schwinn s500, that's mine.
That boma motor looks like a good workhorse and I see a lot of people played with it with great result. They rewind the spool, modified the controller, and to my surprise they got really fast scooter. One guy reach 45mph by modding it to 16s 3700w. I don't have that skills to do it of course, just wondering what kind of performance I can get out off the bat.
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By maurtis
Nice motor upgrade! I may have to follow in your footsteps soon. 10 months ago (!) our son was riding two-up with his friend on his MX500 (48V, 50 amp controller) and said "something smelled funny". Of course they kept riding... When they were done I went into the garage to plug it in and smelled the carnage and the motor was untouchable. This is after two years of abuse with the extra battery and bigger controller.

After cooling down it still seems to run fine, maybe a little down on power but not too much. It definitely gets hot pretty fast so on its way out. I am shocked that almost a year later after the overheating incident and it is still hanging in there.

One of the reasons to upgrade soon is he is getting the itch to move up to my 36V Mongoose electric bike. So if he takes that over then I get the MX500 and will surely kill that old motor in no time.
By Laundrydude
The brushless motor runs great and no heat or power issues. It is a good upgrade over the 800w brushed motor. I think you would like it.
MX500 Project

The brushless motor runs great and no heat or powe[…]