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Crazy Cart Upgrade -

I am looking at motor sprockets compatible with the 36v 1000w currie motor ($134.95) which I know can be modified to fit into the Razor Crazy Cart.

Is this motor compatible with "Single Set Screw Motor Sprockets"?

I looked at the photo but couldn't quite make it out.



Do you have any advise on different sprocket sizes? 


I am updating a Razor Crazy cart and hope to be able to pull 100Kg (including cart) up a 30º incline at around 10km/h or more. Hoping for a top speed on the flat that is near or above 30km/h (Currently 36v on stock motor getting 22km/h on flat ground).



I think the cart has a 55 Tooth wheel sprocket and wonder if I'd get much advantage in getting a larger one or should I just change the motor sprocket?


Basically I was considering trailing either 11T/15T/18T motor sprockets with the 55T (3 bolt) wheel sprocket.


Can you advise me generally or specifically on my intentions?

I assume that you want to decrease the gear ratio for better hill climbing ability by decreasing the size of the motor sprocket or increasing the size of the wheel sprocket.

The 36V 1000W Currie motor has a 10mm bore shaft. The factory installed sprocket is attached with a 3mm roll pin that goes through a hole drilled in the middle of the motor's shaft. The original sprocket can be removed by punching out the roll pin.

A sprocket that attaches with one or two set screws could be used on the motor's 10mm shaft as long as the sprocket has a 10mm bore. Our set screw mount sprockets with either 8mm or 3/8" bores could be machined to have a 10mm bore to fit the 36V 1000W motor. However I just noticed that the 36V 1000W Currie motor has an 11 tooth sprocket, and it may be hard to find a sprocket smaller than 11 teeth that can be bored out to 10mm.

I think that in this circumstance you may have a better chance of succeeding at increasing the size of the wheel sprocket than decreasing the size of the motor sprocket.


I hope this helps steer you in the right direction. Please let me know if you have any questions.

Hey, Steve - I am also starting to upgrade my Crazy Cart.  I am looking to install a 350-watt or 400-watt motor. 


How many teeth does the sprocket on the original 250W motor have?


Also, I managed to shoehorn a LiFePO4 battery into the thing - 25.6V, 10 Amp-hours. About 170 bucks on ebay, but it actually charges up to about 27.6 volts. More than twice the cruising range, and doesn't go bad as fast as lead-acid batteries do. 
The plastic housing mostly fits back on,mostly.  Thank god for zip ties.


Also found a little LED volt-meter on ebay that I wired to the power switch, so whenever it's switched on, you can see how much charge you have left.


And the day I finished that upgrade, my kid popped the tire, so I got a couple of solid rubber tires for it. 


I can't imagine it with a 1000 watt motor, that's pretty ambitious.  Might make more tire smoke than forward motion.  Can the chain hold up?  Also 1000W/24V = 42 amps.  Hasn't it got a 30-amp fuse?  And can your battery put out that many amps for long?  My new battery says the maximum pulsed discharge is 40 amps, for no more than 2 seconds!  Sustained discharge: 25 amps for 30 seconds.


Be (a little) careful!


But if you know how many teeth the sprocket has, that will help me pick an upgrade motor from this website!

Hi Etherist


The stock Crazy Cart has a 55T Wheel Sprocket and a 9T Motor Sprocket.


You might like to join the Google Plus: Crazy Carters community. There are a few people doing up their carts there. 

The reason I am considering this motor is that someone there has used it and managed to fit it on the cart. There are not a lot of motors that will fit inside the Crazy Cart forks. This person is able to pull a substantial weight uphill with his setup. This is something I want, to carry myself and my 2 year old twins.


I also have a 36V setup so am chasing a 36v rated motor where the Amps will be closer to 30A. I might over volt to 48V (~20A) I have heard some people are doing this. I will match a new speed controller / fuse with the power system. 


I'm only on SLA batteries at the moment. I have a current (Amp) meter on the way to see what kind of Amps my setup pulls. 


After getting the rest of the kit sorted I will consider what battery to run. LiPo if I am over keen on power (I have spares form RC models) or more likely a LiFePo4 for user-friendliness. LiFePo4s are very time and cost expensive for me to have shipped to Australia.


Where did you get your LiFePo battery? 

Good points.  No hills at all where I live, so I don't need that kind of torque.  Not aiming for maximum speed, either.  Don't want me or my kid to get hurt.

I bought the battery on ebay: K2 Energy K2B24V10EB
http://www.ebay.com/itm/K2-Energy-K2B24V10EB-LiFePO4-24V-10Ah-Lithium-Iron-Phosphate-Battery-BMS-/231538147284?pt=LH_DefaultDomain_0&hash=item35e8bfbfd4

It was $180 USD shipped.  I chose this one because it was more or less the right size, I wouldn't have to make it from individual cells (would have been more expensive), and has a battery management system integrated, so no balancing of cells, etc.

Once I started looking at battery upgrades, I realized that there a million different battery packs for e-bikes, and a ton of different motors for scooters, and that they are modular. 

I have also bought a $50 DC power supply to charge the battery faster (5A) and to a tiny bit higher voltage.  Waiting on a new power connector plug to fit to some lamp cord.with some ring terminals as well.

I thought about LiPo, very good bang for the buck.  Sometimes too much bang, though.  I couldn't trust my kid to charge it properly, etc., and didn't want to risk having the house burn down.  Sounds like you know more than me about LiPo though.  I haven't done any RC.

You're right that they are expensive.  I think the unit I bought had been assembled into some industrial power pack, "never used", then disassembled into component parts and sold off.  That's why there's a little bit of glue on the bottom.  But it shipped to me from elsewhere in the U.S., so cost/time not bad.

Most of the ebike batteries come by boat from China, you're right.

Have you considered a volt meter as well as ammeter? (*moderator replaced competitors link) http://www.electricscooterparts.com/meters.html

I use it as a gas (sorry, petrol) gauge.

Thanks for the tip about Google  Plus group.
Have you considered changing gearing on your cart?  I found a site with different wheel sprockets and motor sprockets: 

(*moderator replaced competitors link) http://www.electricscooterparts.com/sprockets25chain.html


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