Need new motors? break a chain? brakes not work? swapping out pinions or sprockets?

Moderators: robnewyork, bassiclyLouDog, gameboy

By chevyfried
Hey everyone,

Looking for a good motor to drop in my Dune Buggy. Currently running 3x9ah SLA batteries through YK31C 36v 800w controller. Nothing that will make the buggy do wheelies :roll: but something that will push it a little faster top speed. Currently does about 12mph. Would love 15mph. The stock 24v motor is starting to get very warm. I would rather refrain from changing the gearing.
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By zen_racer
chevyfried wrote:I saw that it was 2500rpm, when I overvolt it, it wont spin at a higher rpm???

yes 2500rpm @ 24v would be 3750rpm @ 36v

rob suggested trying to track down the higher RPM version of that motor, would be 4500rpm @ 36v
exactly , 500 rpms for free is rare .. i have seen a guy get an imod to 29 mph on 36v with the 3000rpm motor which is unreal considering the stock motor on 36v usually maxes at 25 mph with a light rider.i know theyre not common but id check some scooter sites
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By zen_racer
chevyfried wrote:For the life of me, I cannot find any 24v 3000rpm motors, they all look to be 36v. Any ideas???? :?: :?: :?:

rob may have some leads but i suspect the 24v 3000rpm bracketed Unite motor has been out of production for some time...

if you can weld and/or fabricate a mount, there are quite a few options @ 24v. i'd go with the previously mentioned 2500rpm motor as a starting point, run that @ 36v and you should meet your speed goal plus notice a slight increase in torque going from the stock 250w motor to the 500w.

if you get bored w the 24v 500w unite, there's always the industrial option... i'm sure it'll ge a few mentions lol

i think w/ any motor swap for the dune buggy relocating the controller is unavoidable, though this is an easy fix. you may have already found this post:

"Thunderkart Jr - Razor Dune Buggy"

Maurtis' project is a great reference point and may give you some ideas of what to expect with the dune buggy motor swap.
Thank you for all your help.

So i found this Unite 500w 24v on ebay for $60: ... mw&vxp=mtr

If I pop that sucker in, should I raise the pinion tooth? Going by what I know about bikes, if I pop on a 13t it will provide more speed, less torque.

Also, what bore is the motors? Is it 8mm or 5/16"?

PS-I included some pics of the lighting and control plate I did, hope you like.
By robnewyork
8mm should be the d or dd bore .. its metric for sure.. also adding a 13 tooth will the same amps will result in less torque than stock but if the rider is small no assuming you are running 36v and 36v charger ?? if its still 24 then perhaps the 13 tooth is a viable cheap idea, at 36v you should be doin 14.5 mph
By chevyfried
Quinc wrote:mine is also held together with zip ties! Looks great! =)


robnewyork wrote:8mm should be the d or dd bore .. its metric for sure.. also adding a 13 tooth will the same amps will result in less torque than stock but if the rider is small no assuming you are running 36v and 36v charger ?? if its still 24 then perhaps the 13 tooth is a viable cheap idea, at 36v you should be doin 14.5 mph

You have it all right i think. I'm running 36v through the stock controller and motor. I have a YK31C 36v 800w controller ready to go in. As for gearing, I love riding it around and I weigh 165 so I dont want anything that will slow me down too.

So there is 2 motors I specced out to fit my needs:
1) Unite my1020 24v 500w
2) Currie 24v 500w

Now the Currie is much smaller than the Unite my1020 (why?) and also doesnt have the mounting brackets. I do not have welding equipment so fabricating a mount is out of the question. I could get some all-thread hardware I suppose.
By chevyfried
zen_racer wrote:
chevyfried wrote: I do not have welding equipment so fabricating a mount is out of the question. I could get some all-thread hardware I suppose...

you could go with U bolts like this guy:

or you could drop in a currie 24v 450w bracketed motor, uses the same mounting pattern as the stock motor: ... urrie.html

Question: is the Currie motor at much smaller than the my1020 going to provide equal or more performance? Or the my1020 at almost 2 times the size a better idea?
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By zen_racer
chevyfried wrote:Question: is the Currie motor at much smaller than the my1020 going to provide equal or more performance? Or the my1020 at almost 2 times the size a better idea?

the Currie uses higher quality windings and better magnets, from what i've read on other builds. as such its been reported to handle overvolting much better than Unites.

if you shop around you'll see that Currie motors generally price out higher than equivalent Unites. i tend to believe you get what you pay for in most cases...
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By zen_racer
robnewyork wrote:i ran a rusty 500 watt 24v currie on 48v 67 amps and it kept running lol

wow how long did that last?? i know a guy here posted up his dune buggy running the 24v 900w currie at 48v, very interested to see how thats holding up too.

robnewyork wrote:in my experience the currries do take a beating zen.. it took a yk43b to fry one.

i was doing some homework for a motor swap and read a bunch of posts on other forums where the consensus was currie was the better motor than unite when it came to low end china made motors...
i never killed that motor to be honest , it was a swhinn 500 watt.. i later fried a 750 watt currie on the 41.6 mph mx500 project..the one guy is running a 24v 900 watt at 48v and seemed to be fine.
By chevyfried
Thank you I already ordered a motor.

I found a seller on Amazon selling the Currie XYD-6B motor for $59 shipped. I emailed him asking if they had the 6B2 which has the MY1016 style motor mounts already installed and they do, so he will be shipping me that one. Otherwise I found 4" U-bolts made for exhaust systems that will fit the motor.

So hopefully by the weekend I will have the YK31C installed with the new motor. It comes stock with an 11t pinion, may bump it up a tooth or two once I test it out.
Made out like a champ.

Got the motor and 4 new tires and tubes. Bought Cheng Shin knobby tires, had good reviews from other Razor owners. I know the knobby wont roll as good street tread, but maybe I can drift now :lol:

Question: the buggy doesnt have a differential. Anyone have a hack to alleviate the effect of not having one? The kart has to be pointed forward when starting otherwise she wont move an inch. Also, the front wheels don't turn at the same degree as soon as it goes off center causing a bit of oversteer, is that normal?
By chevyfried
Yep, got the motor, 4 new knobby tires the key switch and 4 new tubes. The old wheels and tubes are pretty worn so I wanted to replace them so I can overfill the tires to lower the resistance. The controller is at home already. Got my work cut out for me.
By robnewyork
it will go by fast, wait and guessing the top speed will be 14 ish and the torque should be good ..hopefully it will take off no matter what position the wheels are in.. as an aside test the motor temp every few minutes as u ride.we wanna make sure it stays only warm for a longer duration
By chevyfried
Will do. 14 will be a nice top speed. It will do 12 with my little son in it, he weighs about 40lbs. I need it be to be faster than the nieghborhood kids Razor E175. Right now they have the same top speed just about, but the buggy just slows down crazy when turned.

Also bought a crazy heavy duty toggle switch so on the fly i can switch between 36v and 24v.
By nastety92
robnewyork wrote:all normal , the stock buggy has soo little power it barely moves with any strain , thats why people always mod them.. heres some buggy drifting.


Rob is that you riding the dune buggy?
By robnewyork
sounds good, if it did 12 before it may do 15 plus, we will see.i would run at 36v and see how the temp goes over time.. Only problem i see is the 36v controller will not turn on on 24v as the lvs is set for 31.5v.. im thinking of a solution now.basically u will only be able to run the 36v as is
By chevyfried
Oh that makes sense. Oh well, no 24v. I can make a physical limiter if I need to. Will definitely check the temperature. Am I able to pop the can off the motor and drill out some vents? Or pop a heatsink on it from a computer? I got tons of heatsinks lying around.
YES TO BOTH.. putting the brushes back in place is tough but ive seen this done on numerous occasions .. vent holes combined with fans seems to be the most effective because the heat stems from the armature and commutator.. ive seen this fan employed. ... SwgQ9VqAiy

let me find a cheaper 36 v version, 3 of these wired to each battery with independent toggle switches will also personally test the basic setup first ... Swv-NWVlUq
OK boys and girls, got her running today. Other than getting the wiring right, everything fit perfectly, motor is completely drop in, the throttle works perfectly, and we have a boatload more torque. It gained about 1 to 2 mph. 1mph with me in it, 2mph with my kids :lol: but accelerates much faster. It will drift with me in it and lots of throttle. 8-)

Like I said the only issue was getting the wiring between the throttle and speed controller working. The speed controller is red 5v, black ground and blue signal. The throttle was 6 wires; red, black, blue, yellow, white, brown. So wires match up...but they dont match mechanically. Was able to find a wiring diagram on a website, found that the red and black match, but the blue on the speed controller (which is the signal wire) goes to the white on the throttle. After that the brown is loose and the yellow and blue go to the power light on the controller (red and black separate).

The 12v big buttocks fan i had lying around. It's brushless lol. Mounted quite well to the old speed controller mounts. Few zip ties later, and she was blowing air right on the endbell. Used that ziptie for cable management too. Im not anal about that, just needs to be secure enough to not get grabbed by the chain. It moves a very large amount of air at a full 12v.

The motor and the controller were nothing but warm after driving my buttocks around for a few laps. Im thinking next will be a 12 or 13t pinion to squeeze just a little more top end out before giving in to safety :roll:

Thank you all for your help!!!
User avatar
By zen_racer
thanks for posting up pics! always nice when the motor drops in, builds seem to get up and running faster that way.

maybe down the road add a fan shroud when you get the bigger sprockets, much better cooling efficiency when the air is focused.
also , beware.. the battery running the fan will run lower than others.. it will need to be charged both individually and with the pack in order to keep a balance on all 3 batteries.. all thould read 12.7 to 13.0 after charging.
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