I want to go faster.

Moderators: robnewyork, bassiclyLouDog, gameboy

Hi guys. Longtime Powerwheels/Razor modifier here. Just starting to crank up the voltage on a MX500. I have already converted to 48V and smoked the motor, my son puts this bike thru a lot of sand and mud is my guess for the motor burning up. I just order this kit from Ebay as well as a 96T sprocket from Rebel Gears.

Has anyone tried these "Conversion kits" before?
http://www.ebay.com/itm/161601339407?_t ... EBIDX%3AIT

How should I expect it to perform after the mods?

Anyone have a tutorial for the Shunt mod on the Razor controllers?


conversion should be fine, and yes many shunt mods some are wrong some right.. i think thats a 750watt motor but either way im surprised 48volts killed the 500 watt motor.. the torque should be insane with 96 tooth if hes under 80 lbs , top speed wont increase much but if he likes sand and mud it will pull him through it ..,if it is an 800watt im not sure how u will mount it , i guess we will see.but seems to me the 500 w was old and tired when u went 48 because usually they have no problem with kids overvolted to 48v... maurtis has a 66 amp controller running on 48v and stock 36v motor, 80 lb kid doin 21 mph or so..and tony has one with 750watt running yk43b 200 amps at 36 volts tugging him a grown man at 18 mph no issues reported.
Yea, I image the motor was tired and worn. Lots of mud, sand, and over a year of abuse. I kinda regret going with a 48v 800w motor vs a 36v 800w motor. The 36v would have been faster, correct?

I will have to cut the mounting bracket off to mount the motor, which isn't a big deal. My main goal was to give him low end torque and still be at least a little faster than a stock MX650. I hope I made the right choices.... What do you think??

Thanks for the input!!!
http://tncscooters.com/index.php?route= ... uct_id=186

That link is for the yk42-4, the yk42-4-S is out of stock. I think they are the same controller, just the -S is smaller?

It is a 48V 50A controller. The one on my son's MX500 (48V 12AH, stock motor) pulls 67A under full throttle. So not as beastly as the yk43b which we have seen pull 196.5 amps under load, but still considerably more torque than the stock 30A controller. My son weighs 105 lbs and the bike runs great and we have not had any heat problems. But then we only ride on fairly flat ground at the park across the street from us, it sounds like your son puts his bike through a much more rigorous workout.
Hey Rob, how about your 1500W brushless motor on this bike? That would give his son a kick in the pants for sure and in a small package!
I doubt it will fit without grinding off the existing mounts and mounting it above the swingarm instead of in between like the stock motor.
Uh oh, I hope it fits. It is the same dimensions as the stock motor. I will have to cut the useless bracket off of the new motor. I hope I don't have to weld on it... But if I do, I might as well go all out to 60v and 1000w+. :)

The kit is scheduled to arrive Monday!!!
Ok, got the kit installed! Well, the motor, 96T sprocket, and chain. I had to trim half of the bracket off with a grinder and remove the washer from the motor back bolts and grind the bottom one down to clear the swing arm. The bolt heads aren't recessed like the stock motor. Loctite is your friend. The controller wouldn't plug up to one of the plugs, went from a 3 wire plug stock to a 2 wire on the new controller. I don't spend much time looking into it because the stock controller worked good. It hauls butt now, and has serious torque.

Sooo, he rode it a few times and today it wouldn't work. Turn the switch on and everything lights up, but no response when you give it throttle. Any ideas on where I should start checking? I will post pics of the mods needed to make the motor fit when I get to a computer. Thanks for the advice!!!


The bracket that I ground one side off of.

Notice the bolt head ground down.

The final product
Last edited by TexasTiger01 on Tue Mar 17, 2015 2:36 pm, edited 1 time in total.
Ok, fuses are good and throttle voltage lights light up. Tested motor, it's good. Voltage is at 51V. I think the controller is shot. What is a good plug and plug upgrade controller for 48V batteries setup with a 800W motor? The controller that came in the kit doesn't have the 6 prong plug and the plug that goes to the switch only has 2 14 gauge wires, and the stock setup has 2-14 & one 20gauge going to the switch. Help me fellas!! Thanks!!
id eather get a kelly micro controler
(good but a pain in the arse to wire)
or the other option is a 1000w scooter controler which is easy enouth to wire
there like 48v @ 30amp
http://www.ebay.co.uk/itm/Control-relay ... 3ce106ec58
not this controler but the usa equivelent
1/2 the wires arnt needed and can be unsoldard to keep things tidy
other than that a yk should be interesting
So I pulled the stock controller and wired up the YK31C that came with the kit. I had to eliminate the brake wires and jump the key switch plug. Also modified the battery connector. It's running great now. Thanks for all the help fellas!! How much more speed/accelerating could I get out of it with one of the better controllers? YK36B?

I ordered a voltage meter to install to monitor battery level so it doesn't discharge to much.
60-100AMP micro controler fully programable 0-100amps
(dont go for the 30-50amp)
(the price is resonable allso )
then once its wired you can tweek the settings whenever you want :D
iv used one of these for over a year with no problems on a 1000w unite motor set at 1600w
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